PrEP is an HIV prevention intervention in which antiviral medications are taken to interrupt sexual transmission of the virus. It is now being recommended by the WHO for, it seems all sexually active gay men. Actually it’s not quite that stark – they continue to recommend condom use as well. Despite this, many will probably see this as a recommendation to rely on PrEP as an alternative to condoms.
The WHO recommendation is a population based proposal, a public health recommendation as opposed to recommendations for specific individuals. Recommendations for individuals are different because they take into account individual circumstances, such as the extent to which a specific person is at risk. Population based recommendations are recommendations made across the board, in the case of the WHO, addressed to all men who have sex with men.
While assuring us that the recommendations are evidence based and providing the customary explanation of how the strength of evidence is graded, we learn that the WHO has made a sweeping worldwide population based recommendation on evidence provided by just one randomized study! This was the iPrEx study, which was beset with interpretative difficulties, not least because few took the medication as directed, if at all.
We simply do not know enough about PrEP to make a sweeping population based recommendation. . We have little idea of what adherence to the medication might look like in various populations, we know little about the degree of protection in specific sexual acts. Different sex acts carry different risks, for example, to the receptive or insertive partner in anal sex. Also, how effective is PrEP in situations of exposure to high and low viral loads. In addition we have little idea of the extent to which condom use will be abandoned.
It’s clear that there is a widespread view that PrEP is an alternative to condoms, despite official recommendations stating that PrEP should be part of a comprehensive prevention approach that includes condom use.
A more balanced response would have been a call for more research, and importantly, for a fuller description of those individual situations where PrEP use is a rational preventative intervention at the present time.
The use of PrEP by an individual is very different. The degree of risk to individuals will vary considerably and on an individual basis PrEP use can be a completely appropriate intervention in situations of very high risk, even if we do not have precise information of its efficacy without condom use. The use of PrEP could also be considered when there is an inability to maintain an erection with a condom. It might be an option to enable a fuller sexual expression among what is probably a large number of men whose difficulty with condoms, for whatever reason, stands in the way of satisfactory sex. Medical supervision is also more likely in individual situations. It is important to check for HIV infection and to monitor for sexually transmitted infections and drug toxicities.
Monitoring for sexually transmitted infections is important. Since PrEP alone offers no protection from the transmission of infections that might be interrupted by condoms we might expect an increase in such infections with a wide roll out of PrEP. The current increase in sexually transmitted infections among gay men in some cities is most likely attributable to an increase in unprotected sex. Many sexually transmitted infections facilitate the transmission of HIV which may be another factor that could drive an increase in new HIV infections.
The way PrEP has been promoted during the past few years has surely contributed to the poor support received for prevention education. One way in which this has happened is the shifting of budgets for prevention to those entities, private or government insurers that pay for drugs used in biomedical prevention.
There seems to be a widespread view that prevention education does not work. But we know that it can work. The adoption of safe sex practices including condom use in the early 1980s curbed the spread of the epidemic, although admittedly conditions are not the same today. There is little support for continued condom use, and rather than take the view that condoms don’t work, we might try to understand the obstacles that stand in the way of effective prevention education.
If prevention education has been ineffective it’s be because there has been so little of it, and what little there is has not been properly targeted. The move of the epidemic into African American communities during the 1990s was occurring in plain view yet the federal government was churning out expensive vacuous untargeted prevention messages in the form of “America responds to AIDS,” a futile exercise that helped to discredit prevention education.
I get the sense that some younger gay men feel they have missed out in not experiencing the abandon of the 1970s and see PrEP as a way to make up for this. The real lesson of the 1970s is that sex with multiple different partners on such a vast scale, as occurred in NYC in the 1970s, permits any pathogen that can be transmitted sexually to disseminate widely. That’s what started to happen with amebas and other intestinal parasites and HIV, and is happening with syphilis, gonorrhoea, herpes, hepatitis and many other infections. There surely will be others beyond HIV.
Since we really have very little information about PrEP, and almost none about its use on a population level such a broad recommendation by the WHO is absolutely inappropriate, so maybe faced with increasing HIV infections among gay men, the WHO is simply giving up and proposing an unproved intervention out of desperation. When I say unproven, I mean it is unproven as a viable population based intervention. Looked at this way, it’s a put down – a response that may be no more than gestural to people who continue to harm themselves by refusing to use condoms in sex with partners of unknown sero status.
This unwise WHO recommendation may also have the effect of increasing new HIV infections if it results in an increase in unprotected sex where adherence is inadequate.
I hope there will be a critical look at the WHO panel and funders responsible for producing such unhelpful recommendations.
Transmission of HIV from infants to their mothers.
This title may surprise some. In a paper (abstract, below) from a group at CDC I learned yet another HIV/AIDS related acronym. It’s CBWT, Child-to-Breastfeeding-Woman Transmission.
There have been several reports over many years of HIV infected infants born to mothers who were HIV uninfected. These infections were noted as early as the late 1980s in the former Soviet Union, in Libya in 1998, in Kyrgyzstan, Kazakhstan, Romania as well as in Africa. In every instance except in Africa, there cases were investigated with varying degrees of thoroughness. The sources of infection were invariably associated with contaminated blood, either from transfusions, or from procedures in unsafe healthcare settings, where for example sterilization of instruments is inadequate, or injection equipment is reused.
The infections noted in infants that were investigated occurred as outbreaks and all were determined to be nosocomial. Although infected infants born to uninfected mothers have been noted in Africa, remarkably, it appears that none have been investigated.
It will probably remain for a future historian to understand why cases of HIV infection in infants, horizontally rather than vertically transmitted, have yet to be investigated in Africa.
In those non-African outbreaks that were investigated transmission occurred through unsafe medical care, so what do we know of the safety of health care facilities in Africa ?
Unfortunately unsafe health care remains a problem in many facilities in high prevalence areas in Africa.
Taking Kenya as an example, Simon Colley has written in one of my blogs
“Where does Kenya fit into this picture? As UNAIDS admit, there’s not much data. But there is a document called the Service Provision Assessment which looks at conditions in various kinds of health facility, such as hospitals, clinics and pharmacies.
A few samples from this document may suffice to illustrate Kenya’s women capacity to prevent HIV transmission through unsafe injections and other healthcare practices: Between 10 and 15% of facilities don’t have adequate supplies of needles, syringes or latex gloves; between 55 and 70% don’t have running water or soap; many don’t have facilities for disposing of contaminated equipment or supplies of disinfectant; less than half have guidelines for infection prevention and less than 10% have guidelines for sterilization.
Although this document dates from 2004, we don’t know if there has been any change
There’s little doubt that unsafe health care is still a problem in Kenya and other high HIV prevalence countries. What’s not clear is how big a problem it is. Because, despite admitting that they don’t have the sort of data on unsafe health care that would allow an estimate to be made, UNAIDS and the WHO have failed to investigate or to carry out the research required”
As the title of this post indicates, infants infected either vertically or through exposure to contaminated blood are able to transmit HIV to seronegative women who breast feed them.
Mother to child transmission is the leading cause of HIV infection in infants. Some of these infected infants will be orphans and so place seronegative women who breastfeed them at risk. Wet-nursing is the complete nursing of another woman’s infant and still occurs as does cross-nursing which is the nursing of another infant by a woman while still nursing her own child. Estimates of the prevalence of these practices vary by region and the overall prevalence is not known.
Worldwide the greatest risk for CBWT is carried by seronegative mothers whose infants become infected through exposure to contaminated blood. Rates of CBWT were as high as 40-60% among mothers breastfeeding infants who became infected after birth.
This report on CBWT highlights the importance of unsafe health care facilities in the transmission of HIV. Of course HIV is not the only pathogen that can be transmitted in such settings.
A question that is unlikely to be addressed – it’s so rarely even asked, is: Why are infections acquired by exposure to blood, particularly in health care settings barely acknowledged, and never investigated when they occur in sub-Saharan Africa, but are investigated should they occur in Kyrgystan, Libya, Romania and elsewhere?
Why so few resources have been devoted to the improvement of health care facilities in developing nations is also puzzling. Could it be that like the provision of clean water and sanitation, improving health care facilities is not something that can generate much profit?
The benefits of improving infection control in these facilities extend far beyond effects in HIV transmission.
Perhaps it will be left to HIV activists in sub-Saharan African countries to alert funders and policy makers to the dangerous condition of many healthcare facilities in the developing world. HIV activists in the past have succeeded in bringing attention to important issues.
A group of individuals have been trying to bring attention to this issue for many years and I do recommend looking at the website that has been created to directly alert people in Africa to dangers in health care facilities with no or poor infection control procedures.
Unsafe medical practices in equatorial Africa about eighty years ago probably helped to set the epidemic in motion. Unsterile injections and transfusions by well-meaning colonial doctors provided conditions that enabled the initial spread of HIV (as well as of Hepatitis C and HTLV), before sexual transmission became the predominant way the epidemic advanced. This is described by Jaques Pepin whose account of the origin of AIDS is by far the most plausible.
To a greater or lesser extent, unsafe health care procedures are still contributing to the spread of HIV in parts of Africa. At least this source of HIV infections could be easily stopped.
A Review of Evidence for Transmission of Human Immunodeficiency Virus from Children to Breastfeeding Women and Implications for Prevention.
Kirsten M Little, Peter Kilmarx, Allan Taylor, Charles Rose, Emilia Rivadeneira. And Steven Nesheim.
The Pediatric Infectious Disease Journal Publish ahead of print.
Background: Child-to-Breastfeeding-Woman Transmission (CBWT) of HIV occurs when an HIV-infected infant transmits the virus to an HIV-uninfected woman through breastfeeding. Transmission likely occurs as a result of breastfeeding contact during a period of epithelial disruption, such as maternal skin fissures and/or infant stomatitis. Despite extensive epidemiologic and phylogenetic evidence, however, CBWT of HIV continues to be overlooked.
Objective: This paper summarizes the available evidence for CBWT from nosocomial outbreaks, during which nosocomially HIV-infected infants transmitted the virus to their mothers through breastfeeding. This paper also explores the CBWT risk associated with HIV-infected orphans and their female caretakers, and the lack of guidance regarding CBWT prevention in infant feeding recommendations.
Methods: We searched online databases including PubMed and ScienceDirect for English language articles published from January 1975 to January 2011 using the search terms “HIV”, “perinatal”, “child-to-mother”, and “breastfeeding”. The citations from all selected articles were reviewed for additional studies.
Results: We identified five studies documenting cases of CBWT. Two studies contained data on the number of HIV-infected women, as well as the proportion breastfeeding. Rates of CBWT ranged from 40 – 60% among women reporting breastfeeding after their infants were infected.
Conclusions: Poor infection control practices, especially in areas of high HIV prevalence, have resulted in pediatric HIV infections and put breastfeeding women at risk for CBWT. Current infant feeding guidelines and HIV prevention messages do not address CBWT, and fail to provide strategies to help women reduce their risk of acquiring HIV during breastfeeding.
Conflicts of interest in HIV medicine: The 2012 revised DHHS HIV treatment guidelines and what’s wrong with expert opinion
The most recent revision of the DHHS guidelines on the use of antiretrovirals in HIV infected adults and adolescents now recommends starting therapy at a CD4 lymphocyte count greater than 500/ mm3.,
For those with greater than 500 CD4 lymphocytes the recommendation is only supported by expert opinion – the opinions of the experts on the DHHS panel. Almost all of the non-governmental researchers on the panel have financial arrangements with entities that stand to gain from the decisions they make. There are plenty of other experts who are not members of the DHHS panel who are not so certain that starting treatment above 500 CD4 lymphocytes will confer a net benefit to the patient..
This particular recommendation is unlike those made for individuals with lower CD4 numbers where more reliable evidence from clinical trials clearly demonstrates a benefit to the patient
Evidence based medicine has brought us a long way from the days when clinical decisions were based on authority and tradition (“expert opinion”); it attempts to use the best available evidence on which to base clinical recommendations. The term “best available evidence “means that not all types of evidence are of equal quality. There are several systems that grade the relative strengths of evidence derived from different sources. All agree that evidence provided by randomized controlled clinical trials is of the highest quality and therefore the most reliable. Applied to HIV medicine, a strong recommendation that antiviral treatment be initiated at 350 or fewer CD4s can be confidently made because the evidence of substantial benefit is derived from a randomized controlled clinical trial.
At the other end of the scale rating the quality of evidence, is evidence based on “expert opinion”. This may not even be a marginal improvement on the bad old days when the doctor knew best; when there was no need to justify a recommendation other than by the authority of the doctor or by tradition.
The rating of the recommendation that people with more than 500 CD4 lymphocytes start treatment, according to the system used by DHHS is B III. It’s a moderate recommendation supported only by the opinion of experts.
But when expert opinion is the basis for a recommendation, this does not even mean that the opinion represents a consensus of all experts. It only represents the opinion of those experts chosen by the organization making the recommendation.
Making a recommendation based solely on expert opinion is particularly troublesome when the means exist to obtain evidence of the highest quality. The START trial that directly addresses the question of when it’s best to begin antiviral treatment is enrolling, and one must wonder why the panel did not defer making a recommendation concerning individuals with greater than 500 CD4 lymphocytes until the trial results become available. This is even more puzzling as individuals who have waited to start at CD4 numbers between 350 to 500 have in general done very well, so waiting to make a recommendation for some years until the START trial results are available seems to be a much more reasonable and prudent option than jumping the gun and making a recommendation based on evidence of the weakest quality.
Bur when we come to look at the associations of the experts on the DHHS panel, a recommendation based on expert opinion is even more problematic. We note that almost all of the non-governmental researchers have financial arrangements with entities that can benefit from the decisions they make. Some of these arrangements are quite extensive.
A conflict of interest becomes particularly troublesome when it’s only the opinion of the expert that supports a recommendation. Since people with greater than 500 CD4 lymphocytes represent a huge proportion of the HIV infected population, treating them will have an impact on expanding the market for antiviral drugs. With greater efforts to encourage testing, greater numbers of individuals with higher CD4 numbers will be identified, and now recommended to receive lifelong treatment with expensive and potentially toxic drugs whose benefit has not yet been proven to outweigh their harms.
The conflicts of interest of panel members are duly noted in the DHHS financial disclosures.
Early AIDS activists performed a great service for all individuals who must deal with illness, in asserting their right to make informed decisions concerning their care, and that the decisions are made free from coercion. Withholding information and supplying misinformation are forms of coercion.
Although the guidelines ask physicians to inform patients with high CD4 numbers that evidence for benefit is not conclusive I think it’s safe to conclude that individuals with greater than 500 CD4s will not always, and may only rarely informed be informed of this important caveat. As to informing patients of the conflicts of interest noted above, this isn’t even a consideration. They are also unlikely to be told that the recommendation that they start treatment is based on the opinion of certain experts only, and that there are other experts with a different opinion. In fact, the DHHS guidelines may be the only ones in the world to make this recommendation.
Undoubtedly the DHHS panel members believe that people with higher CD4 numbers will receive a net benefit from treatment. But the recommendations would have greater authority if the non-governmental researchers on the panel were better balanced with respect to members who had no financial arrangements with entities that stand to benefit from their decisions; in fact many would agree that such conflicts of interest should be a disqualification for panel membership.
The recommendations also refer to the prevention benefit of treatment. The greatest prevention benefit will result from the treatment of individuals with lower CD4 numbers who will have the highest viral loads. These individuals need treatment. On this point there is no doubt or debate. For those with higher CD 4 numbers, not known at this time to benefit from treatment, the prevention benefit is likely to be much lower as their viral loads will also, on average be much lower than those with more advanced HIV disease.
Providing treatment to everybody who needs it to stay alive should surely be our first priority. It is here that treatment will also have its greatest prevention benefit.
Conflicts of interest are of course common among those making treatment recommendations. However HIV medicine seems to be unique in that these conflicts of interest, which may be among the most egregious, seem to go almost completely unnoticed. In every other field of clinical medicine they occasion extensive discussion. The apparent indifference to conflict of interest issues and the influence drug marketing practices in HIV medicine is unfortunate, as precedents in that field may go unnoticed but will have implications for other fields of clinical medicine. The rapid approval of zidovudine by the FDA in 1987 may be such an example.
Two years ago in a tribute to Michael Callen I responded to similar recommendations to treat all HIV infected individuals irrespective of CD4 numbers.
I cannot express my reservations more clearly than with the words I used then:
I miss Michael Callen. He was my patient when AIDS began, but soon became my collaborator and friend.
For a time, Michael and Richard Berkowitz, another patient collaborator, were able to work out of an office adjoining my practice on W 12th street in New York City. It was in this setting that Michael and Richard learned about the medical aspects of this new disease and participated in the creation of some of the earliest organized community responses to the epidemic.
Michael and Richard helped in the formation of the AIDS Medical Foundation; they wrote the very first publication to recommend condom use by gay men. Michael played a role in the first attempt to protect the confidentiality of people with AIDS, and he helped to create both the Community Research Initiative and the PWA Health group.
A thread running through all of these endeavours is the notion of self empowerment. This extends beyond the belief that individuals who are fighting a disease should actively participate with their doctors in making decisions about the care they receive. Empowerment also means the inclusion of affected individuals at all levels of the response to the disease, from research to the provision of services.
The Community Research Initiative was sponsored by the PWA Coalition of which Michael was President. This is the very embodiment of self empowerment. It is people with a disease sponsoring research into that disease themselves and not waiting for some benevolent institution to come to the rescue.
Michael understood that his interests and priorities as a person living with AIDS might sometimes be at odds with those of some scientists conducting research into this new disease. He knew very well that he was living in a world that was still capable of cruel and discriminatory behavior towards him. Who better to protect the interests of those who had the most to lose than people living with AIDS themselves?
Self empowerment found expression in the Denver Principles. Michael and Richard were both signatories to this historic document. Michael played a major role in crafting the words of the Denver Principles.
Almost thirty years later these Principles remain as important as when they were first articulated.
One of the Denver principles asserts the right to obtain full explanations of all medical procedures and risks.
I wish Michael Callen were here today to bring attention to the violation of this right.
This is happening with little protest in places like San Francisco where antiviral medications are now recommended for healthier HIV positive individuals for whom the benefits of treatment have not been shown to outweigh the risks.
As always, you can’t beat the truth, and the truth is that for people with more than 350 CD4 lymphocytes, the best time to start treatment is not known. This may seem surprising as potent antiretroviral drugs have been available for fifteen years.
We have not yet done the kind of study that would most reliably provide the information those HIV positive individuals with higher CD4 numbers and their doctors need to make the best decisions about when to start treatment.
With information provided by a properly designed and conducted prospective randomized trial, we could know with confidence when in the course of HIV infection the benefits of treatment absolutely outweigh the risks.
Some feel that a decision can be made with less reliable information. But surely all would agree that a decision to start treatment or to defer it must always be an informed one voluntarily made by the individual considering treatment.
It is here that the principle asserting the right to a full explanation of the risks of medical interventions is being violated.
The San Francisco Department of Public Health in advising all HIV infected individuals to receive treatment is in effect telling them that at all stages of HIV disease the benefits of treatment outweigh the risks. This may be so, but apart from those with 350 or fewer CD4 lymphocytes, we just do not have the most reliable evidence to support this contention.
People with higher CD4 numbers have the right to know not only what evidence there is that immediate treatment will have a net benefit compared to deferring it, but also the quality of that evidence. They surely should also be made aware that experts hold differing opinions on whether treatment should begin immediately or be deferred.
A physician in San Francisco who recommended that all HIV infected individuals should start treatment immediately was reported to have said:
“If I’m wrong, we’ll start people [on treatment] a couple years earlier than we otherwise would. But if I’m right and we don’t start early, there’s no going back,”
Others who are concerned about drug side effects might feel that more may be at stake for HIV positive individuals with higher CD4 numbers. This also includes the possibility that fewer options may be available when treatment is definitely known to be needed.
This doctor is also reported to have said:
“The old paradigm was that drugs are toxic so we should wait as long as possible. The new paradigm is that while today’s drugs are not totally benign, they are less toxic than the virus.”
“The” paradigm? Is it not misleading to give an impression that his views on drug toxicities represent a consensus?
How on earth can the longer term toxicities of the newer drugs be known?
Just a few days ago it was reported that AZT and 3TC based therapies produced a metabolic abnormality called hyperhomocysteinemia. This is a condition associated with vascular abnormalities including a greatly higher risk of heart attacks. We have been prescribing AZT and 3TC for about twenty years, so what information does the San Francisco doctor have that gives him such confidence that the drugs in use for only a few years are less toxic?
Empowerment means that HIV positive individuals make their own decisions to start or to defer treatment. They have the right to clear and honest information to enable them to make this decision. Those with higher CD4 counts have the right to know that there still is uncertainty about when it is best to start treatment.
The views of the San Francisco Department of Public health and those who share them are just opinions; healthier HIV positive individuals should also know that these opinions are not held by all experts. Respect for the autonomy of healthier HIV positive individuals requires that opposing views on when it’s best to start treatment be presented together with the evidence supporting these views, so those who have most at stake can decide for themselves.
There will continue to be opposing views on when it’s best to start antiviral therapy as long as the question has not been put to the test.
The best way to resolve uncertainty in clinical medicine is by conducting prospective randomized trials. A properly designed and conducted trial could reliably and safely answer the question of whether, on average, immediate or deferred treatment is better or worse or makes no difference.
HIV positive individuals deserve the most reliable information to inform them in making treatment decisions. The START trial is a randomized prospective study that directly asks the question about the best time to start antiviral medications. We could really finally know what’s best, and no longer rely on opinions based on data of inferior quality.
Is an immediate or deferred initiation of treatment better or worse, or does it make no difference? If knowledge is power a demand to complete the START trial is the embodiment of the self empowerment of HIV positive individuals. The very antithesis of self empowerment is to allow researchers to persuade us with evidence of inferior quality, such as their personal opinions, presented as if there were a consensus, or with the results of embarrassingly uninterpretable studies such as NA-ACCORD so often used to justify earlier starts to treatment. NA-ACCORD was not a prospective randomized trial. It was a review of a large number of medical records. Such retrospective observational studies are beset with interpretative difficulties because subjects are not randomly assigned to receive one or another kind of intervention, in this case, to start treatment early or to defer it. We don’t know why a particular course of action was chosen. The reasons why decisions were made to start treatment early or to defer it may have determined the outcome rather than the time treatment was started.
In situations where prospective randomized trials cannot be conducted for whatever reasons, then we have to do the best with data of inferior quality. But fortunately this is not the case with HIV infection.
I miss Michael Callen. He would have reminded us that HIV positive individuals must demand that the best evidence be obtained to inform their treatment choices.
In my last post I wrote about the very small reduction in the absolute risk of HIV infection in the iPrEx trial among those taking Truvada as pre-exposure prophylaxis.
The 44% reduction in relative risk conferred by Truvada was the only efficacy measurement explicitly presented by the investigators. That the absolute risk reduction was only 2.3% was not mentioned in the various presentations.
I suspect that many reading press reports of this so called breakthrough were unaware that in fact, the actual risk to people taking Truvada was 2.8%. (36 infections in 1251 participants). True, this is less than the 5.1% risk to those on placebo, but by very little. Certainly not enough to justify the bewildering acclaim given to the iPrEx trial results.
Failing to clearly state the absolute risk reduction of an intervention is something we have come to expect from salesmen to inflate the efficacy of a product, but not from clinical researchers. Large reductions in relative risk can be associated with minute reductions in absolute risk when the events prevented are low to begin with.
Another important reason why absolute risk reduction should be stated in a report is that this allows one to calculate the number of people who need to be treated to prevent one event, in this case, one HIV infection.
Although the iPrEx investigators did not explicitly provide these numbers, they can be worked out from data presented, as I did in my last post and was also done in a letter published in the New England Journal of Medicine of April 7, 2011 in response to the iPrEx trial report, where the authors report that 44 people need to be treated to prevent one infection (I got 45).
They then went on to calculate that it would cost $400,000 a year to prevent a single infection.
This figure does not even include the cost of the necessary monitoring for infection. In another letter, it was suggested that such monitoring be done monthly to prevent the emergence of resistant virus by detecting infection early.
From Sean Strub’s calculations (in his comment to my post on the POZ magazine website) which included doctor’s visits and tests, the annual cost to prevent a single infection would be about $500.000.
These figures are based on drug costs in the US.
Truvada PreP not only does not work well enough it will cost a half million dollars a year to prevent a single infection.
Maybe this is indeed a “game changer” but not in the sense intended by the triumphalist reports coming from the recent Rome AIDS conference.
There definitely seems to be a perception that PrEP is a viable prevention option for everybody; there even have been calls for its general implementation. These cost estimates alone would make it unfeasible as a public health measure but there are additional reasons, importantly its relatively low efficacy.
PrEP is a reasonable option for only a very small number of individuals at high risk for infection who are able to be regularly checked for infection. I believe there is no disagreement about this; the controversy is only about its general use.
Implementation of PrEP on a wide scale will almost certainly result in an increase in new infections. It’s not only adherence to the drug regimen that will not be maintained by all. Adherence to a schedule of regular testing for infection cannot be relied on. Facilities for performing the needed tests may not even always be available.
The way PrEP has been promoted has probably already damaged targeted prevention education programs with support for continued condom use, an activity already in great need of support.
Drugs for prevention are paid for from a different budget than prevention education programs, and health departments already under budgetary constraints may feel that prevention needs can now be paid for by those entities that pay for drugs, private insurers or Medicaid/Medicare.
The amount of almost uniformly uncritical publicity given to PrEP is completely out of proportion to its utility. It’s a hugely expensive and very poorly effective prevention intervention, of use to only a very small number of individuals, and its misleading promotion has probably already damaged prevention education programs.
Considerable resources must have been devoted to publicize and promote PrEP over many years, in a way that has not taken care to reinforce prevention education with support for continued condom use. One can only wonder why.
Drs Dong Heun Lee, M.D. and Ole Vielemeyer, M.D of Drexel University College of Medicine in Philadelphia are the authors cited.
Pre-exposure prophylaxis (PrEP) to prevent HIV infection with Truvada is not sufficiently effective
There is a similar
post on the POZ magazine website.
PrEP is a prophylactic intervention where uninfected people take anti HIV medications before sexual intercourse to prevent becoming infected with HIV. The use of a vaginal gel containing an anti HIV drug has also been tested.
The results of several trials of PrEP have been reported in the past year, all but one hailed as huge successes, with reported efficacies of up to 90% among those adhering to the treatment regimen.
The efficacy of PrEP in preventing HIV infection was so great that this intervention has been trumpeted as signalling a revolution in HIV prevention. A new era has opened up we are told; PrEP is a “game changer”.
With such enthusiastic coverage it may come as a surprise that none of the reports explicitly told us what the actual efficacies of the interventions were in preventing HIV infection, perhaps because they were so low as I’ll describe.
Maybe what’s even more startling is that this omission seems to have gone completely unnoticed, at least in the universally jubilant press reports and equally enthusiastic press releases from AIDS advocacy organizations.
How has this been possible?
The reason is that the results have been reported as reductions in relative risk only. This tells you nothing about actual risk reduction. What is reported is a percentage reduction in risk from a number that was never clearly stated. For example in the iPrEx trial of PrEP among men who have sex with men, the drug, Truvada, was reported to reduce the risk of infection by 44%. But 44% of what? We were not explicitly told, although it’s possible to calculate what it is.
In fact we can calculate that the absolute risk reduction conferred by Truvada is a measly 2.3%, a number nowhere to found in the trial report.
The relative risk reduction may have been 44%, but this translates into only an actual 2.3% reduction in absolute risk, as is shown below.
Reporting relative risk reduction only is the oldest trick in the book to exaggerate the effects of an intervention, used by salesmen, but apparently also by clinical researchers.
What makes the unquestioning acceptance of these reports of relative risk reductions achieved by PrEP even more remarkable is that there is a tremendous amount of material explaining the difference between relative and absolute risk reduction. Just type the words “relative risk absolute risk” into the Google search box.
Relative risk reduction tells you the percentage reduction in risk in the treated group compared to that in the group receiving placebo, or how much lower the risk with the intervention is relative to the risk to begin with.
If you are not clearly told what the risk is to begin with, then you can’t tell what the actual reduction in risk is when taking the intervention; all you know is how much lower it is than a number that’s not clearly presented to you.
Although not included in the iPrEx trial report there is information that allows one to calculate the absolute risk reduction conferred by Truvada. To do this we need to know what the risk of infection is to begin with.
This is the number of infections occurring in the placebo group over the time period of the study.
64 out of 1248 people in the placebo group were infected, which is 5.1%, or 0.051 in 1. (since then there have been additional infections reported at the Rome AIDS conference, reflecting an increase in the number of infections over a longer time period).
In the group receiving Truvada 2.8% of 1251 people were infected.
The absolute risk reduction conferred by Truvada is simply 5.1 minus 2.8 which is 2.3.
A 2.3% reduction in absolute risk conferred by Truvada is the more accurate measure of its efficacy. Hardly something to celebrate.
A 44% reduction in relative risk sounds much better, although far from spectacular,but unfortunately this number tells you nothing about actual risk reduction.
Relative risk reduction is calculated as follows:
It is the number of events in the treatment group subtracted from the number of events in the placebo group divided by the number of events in the placebo group.
On its own, relative risk reduction is not a helpful number.
Of much greater help to a person considering Truvada PrEP is knowledge of the actual risk while taking Truvada (over the period of the study, a median of 1.2 years).
That number is 2.8%.
Knowing the absolute risk reduction allows one to calculate another important measure. This is the number of people who need to be treated to avoid one infection (NNT).
From information contained in the trial report 45 people need to be treated to prevent one infection. I did not notice this number in the trial report nor was the absolute risk reduction
of 2.3% reported. NNT is a useful number as it allows one to estimate what it would cost to prevent a single infection with Truvada.
The cost of the drug is the least of it. A person taking Truvada PrEP needs to be monitored at regular intervals for toxicity and importantly, for infection, in order to avoid the inevitable emergence of resistant viruses as a result of sub optimal treatment.
If Prep is implemented on a large scale which some AIDS advocates seem to be calling for, but is unlikely to happen, then there may well be increases in new infections with viruses resistant to the drugs in Truvada in men who have sex with men, in IV drug users and in African populations.
PrEP is not a success, at least not with Truvada.
However such a failure was transformed into a triumph, part of the explanation is the use of relative risk reduction numbers with care taken to remain silent on absolute risk reduction.
Despite all the literature available to help people tell the difference between absolute and relative risk reduction, this evidently was a resource not used by those cheering along this ineffective intervention.
Treatment as Prevention
Protecting patient autonomy
Patient autonomy is just a particular instance of individual autonomy, a term that may sound pretty dry and academic but if we used the term individual freedom we would essentially be talking about the same thing.
Respect for the autonomy of the individual may be the most important of the principles that form the foundation of medical ethics. (1)
One attribute of personal autonomy is: “the capacity to be one’s own person, to live one’s life according to reasons and motives that are taken as one’s own and not the product of manipulative or distorting external forces.” (2)
There is no disagreement about the importance of respect for individual autonomy but as I’ll explain, it seems that its pre-eminence is being questioned in some proposals to use antiretroviral treatment to prevent transmission of HIV.
The recent demonstration that antiretroviral treatment can prevent transmission of HIV among serodiscordant heterosexual couples is great news. However, when the person offered treatment has not yet been shown to personally benefit from it, an ethical issue needs to be addressed. It has not yet been reliably demonstrated that for people with greater than 350 CD4 lymphocytes, starting treatment immediately rather than deferring it confers a net benefit; indeed, it may even prove to be harmful. A randomized controlled trial now enrolling will provide needed information, but we will have to wait several years for its results.
The issue isn’t whether or not people with greater than 350 CD4 lymphocytes should receive treatment. A respect for their autonomy requires that the decision whether or not to do so is made by them and is made free from coercion.
A recent issue of the Journal, Public Health Ethics (3) is devoted to ethical issues associated with the proposal that a program of universal testing and treatment of infected individuals could bring an end to the HIV/AIDS epidemic. Such a proposal would involve the treatment of healthier HIV infected individuals not at this time known to personally benefit from antiviral medications which could even harm them.
In an article in the journal referred to above, public health ethics is said to require an approach where respect for individual autonomy is not paramount; a commitment to the supremacy of individual autonomy could have no place where the “primacy of collective wellbeing is the starting point”.
In that case I wonder just how desirable a collective wellbeing would be where individual rights were subservient to whatever was defined as the collective good.
I can only hope that this goes nowhere, as abandoning the pre-eminence of respect for individual autonomy opens the door to tyranny, paternalistic or otherwise. Individual freedoms have been hard won, and we should always be aware of harms that have been perpetrated in the name of the public good, even leaving alone the problem of who defines what constitutes the public good.
In public health, medical research and medical practice, concern for individual autonomy remains paramount. The only commonly agreed acceptable exemption is the restriction of personal freedoms to prevent harm to others such as limiting the movement of individuals with highly communicable diseases where the harm that may be done to others is considerable. That is, outside the criminal justice system, among individuals who are free.
People have the right to make decisions about their treatment, their participation in a research study, or in a public health intervention, free from coercion.
Providing misleading information is a form of coercion; withholding information may also be coercive.
Providers of health care have an obligation to provide patients with honest information to inform their decisions. This must include information about what is known about the risks and benefits of treatment, as well as what remains conjectural.
Information and the strength of the evidence upon which it rests:
It’s not enough to simply provide individuals with information concerning the benefits and risks of a particular treatment. In order for the information to be useful we must also indicate the strength of the evidence on which the information rests. (4)
The most reliable evidence regarding the effects of a particular treatment is provided by results of randomized controlled clinical trials. This is because the treatment in question has been put to the test in a protocol that minimizes bias; we can therefore have a greater degree of confidence that effects observed are in fact caused by the treatment.
Unfortunately information derived from randomized controlled trials is often unavailable. The clinical trial may not yet have been completed, or for whatever reasons the trial cannot be undertaken.
When this is the case we have to consider evidence of inferior quality, for example, evidence derived from reviews of patient records or observational studies, and the opinion of experts.
Observational studies are beset with interpretative difficulties because subjects are not randomly assigned to receive one or another kind of intervention. The particular reasons why participants were selected for study may influence the outcome rather than the effects of the intervention.
In all the systems I have seen that grade the quality of different kinds of evidence, expert opinion is at the bottom of the list. But expert opinion can be valuable to an individual in coming to a treatment decision when evidence of the highest quality is not available.
Respect for patient autonomy means that patients make their own decisions free from coercion. As noted, supplying misleading information is a form of coercion. To state that something is known to be the case, when it is only an opinion is misleading.
HPTN 052 is the study which demonstrated the efficacy of antiretroviral treatment in preventing transmission of HIV among serodiscordant heterosexual couples. Although the result was not unexpected it is nonetheless significant because it was obtained from a randomized controlled clinical trial.
We now know that the uninfected partners of individuals with greater than 350 CD4 lymphocytes will benefit from treatment of the HIV positive partner. At this time we can only have an opinion about whether starting treatment immediately or deferring it will benefit or harm the infected partner with greater than 350 CD4s or be without effect – apart from cost.
Most of the jubilant reports of the results of HPTN 052 do not mention the problem facing the healthier HIV positive partner in coming to a decision. Do the commentators just assume that it’s been established that all infected individuals receive a net benefit from treatment irrespective of CD4 numbers? Or do they not believe it to be important that patients make their own decisions regarding their treatment?
I wish I could say I was startled to read in one newsletter that “For treatment as prevention to work….. people need to be convinced that early treatment is in their interest.”
Convincing people to take a possibly perilous course of action based merely on opinion and evidence of inferior quality is a step on a road that ends with enforcement.
A respect for individual autonomy means that we respect the right of individuals to make decisions on their own behalf, free from even subtle coercion. Our obligation as providers of health care information is to not only provide information, but also an indication of the quality of the evidence supporting it.
At this time we do not know that individuals with greater than 350 CD4 lymphocytes receive a net benefit from antiviral treatment. There is evidence that they may, but until this is put to the test in a randomized controlled trial such as START, we must not mislead them by trying to convince them that “early treatment is in their interest”.
Given adequate information, a person with greater than 500 CD4 lymphocytes may reasonably decide to take antiretroviral drugs to lessen the risk of infecting a partner even knowing that there may be no personal benefit or that there is a possibility of harm.
Whenever treatment is offered for any reason other than for a person’s benefit, and where it has not yet been reliably demonstrated that there will be a net benefit, a consent process should be required. I doubt though that this will happen.
At the end of the day what’s of central importance is that we respect our patient’s right to make choices about his or her treatment, and provide honest information to inform that choice, recognizing the difference between expert opinion and established fact.
(1) Ever since Beauchamp and Childress published the first edition of their classic text, Principles of Biomedical Ethics, in 1979 it’s been commonly accepted that beneficence, nonmaleficence, justice and respect for autonomy, are four principles that should guide medical ethics.
The Four Principles are general guides:
Respect for autonomy: respecting the decision-making capacities of autonomous persons; enabling individuals to make reasoned informed choices.
Beneficence: this considers the balancing of benefits of treatment against the risks and costs; the healthcare professional should act in a way that benefits the patient
Non maleficence: avoiding the causation of harm; the healthcare professional should not harm the patient. All treatment involves some harm, even if minimal, but the harm should not be disproportionate to the benefits of treatment.
Justice: distributing benefits, risks and costs fairly; the notion that patients in similar positions should be treated in a similar manner.
Beauchamp and Childress; Principles Biomedical Ethics, OUP, 5th edition
(2) Christman, J, 2001″Autonomy in Moral and Political Philosophy”, The Stanford Encyclopedia of Philosophy (Fall 2007 Edition) , Edward N. Zalta (ed.), URL = <http://plato.stanford.edu/archives/fall2007/entries/autonomy-moral/>.
(4) Several systems have been devised to grade the quality of evidence.For example: http://www.cebm.net/index.aspx?o=1025 The GRADE working group has been working on assessing the quality of evidence since 2000. http://www.gradeworkinggroup.org/index.htm
Slightly different accounts were posted on the POZ magazine blog site and on aidsperspective.net
AIDS was first recognized in 1981. Interferon was found in the blood streams of people with AIDS later that same year, making it one of the earliest of the significant AIDS associated immunologic abnormalities to be noted. Large amounts of interferon were found that were present for very prolonged periods, a situation noted before only in auto-immune diseases like lupus.
The interesting story of how interferon came to be discovered in people with AIDS so early in the epidemic illustrates at least one way in which science can progress; it also demonstrates a way in which scientific progress can be retarded.
The production of interferon following viral infections is part of the innate immune response that is the immediate first line of defence against viral infections. Interferon has potent antiviral activity against a broad range of viruses. It also has widespread effects on the immune system as well as effects on other organ systems. Some of these effects are harmful if prolonged, so there are mechanisms for turning off the interferon response after a few days as other antiviral mechanisms come into play.
HIV and disease causing SIV infections differ from most viral infections in that the production of interferon is not turned off; it continues to be produced, sometimes at very high levels. The prolonged presence of interferon contributes to the disease process and is a factor in the loss of CD 4 cells.
The sustained activation of both innate and adaptive immune responses is now understood to be at the heart of AIDS pathogenesis.
Interferon continues to be produced, sometimes in large amounts, in HIV infected individuals. In untreated HIV disease we have the unusual situation where increasing amounts of interferon are associated with increased HIV replication.
Interferon can’t be exerting much of an antiviral effect in HIV infected individuals, but this did not deter investigators from injecting yet more of it into people with AIDS early in the epidemic.
This is even more puzzling as by 1983 we had evidence that interferon was able to suppress CD4 lymphocyte proliferation. Long before this we knew that treatment with interferon was associated with a low white blood cell count.
But if interferon was of no use against HIV it has been spectacularly successful against Hepatitis C, curing many people of this infection. It also may have a place in treating some people whose Kaposi’s sarcoma is unresponsive to antiretroviral drugs, possibly through its ability to inhibit angiogenesis, which is the process of new blood vessel formation.
Although there were lots of reasons to consider that prolonged exposure to high levels of interferon might have something to do with this newly recognized illness even in 1981, serious work on this possibility was delayed for many years. The zeal to administer yet more interferon to treat AIDS is surely part of the reason for this neglect.
The inexplicable enthusiasm to treat AIDS with interferon resulted in no benefit to patients; it probably accelerated the disease process in some.
It also had the unfortunate effect of delaying research into interferon’s role in the pathogenesis of HIV disease.
It’s only in the past ten years that we have gained some information on how prolonged exposure to interferon can contribute to the loss of CD 4 lymphocytes.
The discovery of interferon in people with AIDS
This is how we came to find interferon in people with AIDS so early in the epidemic.
Early in 1981 I had referred one of my patients to Dr Joyce Wallace. A biopsy taken of lesions seen in his stomach indicated that these were Kaposi’s sarcoma. Joyce called to tell me that she had contacted the National Cancer Institute to help identify experts in New York City who were familiar with Kaposi’s sarcoma because this was the first time she was confronted with this diagnosis (the first time for me as well). She had been told that over twenty gay men had been diagnosed with Kaposi’s sarcoma and that Dr Alvin Friedman Kien at NYU was treating a number of them. I knew Alvin through my association with Jan Vilcek, a long-time colleague in the field of interferon research. Alvin is a dermatologist but also worked in the NYU lab that Jan headed.
I immediately called Jan who confirmed that Alvin was treating a number of gay men with Kaposi’s sarcoma. Jan very kindly allowed me to work in his lab. I then arranged my time so that I worked in the virology lab in the mornings and saw my patients in the afternoons.
I was one of several scientists who thought it likely that cytomegalovirus (CMV) played a role in this newly recognized disease so initially my lab work centered on this virus.
In the early months of the epidemic Alvin had sent blood samples to Pablo Rubenstein at the New York blood center for HLA typing. HLA refers to the human leukocyte antigen system which allows the immune system to differentiate foreign antigens from self-antigens. It’s important in organ transplantation, where a match in HLA antigens between recipient and donor can prevent organ rejection.
HLA typing is important in investigating a newly recognized disease as there is an association of certain HLA types with some diseases, even some infectious diseases.
A serologic method was then used for HLA typing. It depended on the attachment of HLA specific antibodies to HLA antigens on the surface of leukocytes.
HLA typing of our first patients with Kaposi’s sarcoma proved to be difficult because the patient’s own antibodies were already coating the surface of their leukocytes, interfering with the test.
At the same time I had come across a preprint of a paper reporting an important observation by Jan Vilcek. The CD3 antigen is present on the surface of T cells. Jan had reported that an antibody against the CD3 antigen was a powerful inducer of gamma interferon.
As I read this report it occurred to me that Pablo Rubenstein’s observation that antibodies were attached to our patient’s leukocytes could mean that these blood cells were secreting gamma interferon, which we might be able to detect in their sera.
I discussed this possibility with Jan and Alvin and we immediately set out to test the sera of Alvin’s patients. This idea was to bear fruit, but not what we had expected. Rather than gamma interferon, large amounts of alpha interferon were found.
Jan Vilcek has also described this event, which can be seen by clicking here.
Maybe what’s important is to have a reasonable idea that can be tested, not that the idea need be correct. In fact much later, using more sensitive tests gamma interferon was eventually found in AIDS sera.
Robert Friedman is a colleague from the early days of interferon research, with whom I had published work on the mechanism of interferon’s antiviral action. He was – and still is, chairman of the pathology department at the Uniformed Services University of the Health Sciences in Bethesda. He, Jan and I have been colleagues since the 1960s when Alick Isaacs, a discoverer of interferon was still alive. We joined forces to study the association of interferon with AIDS.
Our extended findings including data obtained at both Jan Vilcek’s and Bob Friedman’s lab was published in the Journal of Infectious diseases in 1982.
Since there were so many names, it was left to me to decide their order, and I chose that they be listed alphabetically. Thus Gene DeStefano became lead author. He was a technician in Jan’s lab and I believe he went on to become a dentist. This is the title.
Acid-Labile Human Leukocyte Interferon in Homosexual Men with Kaposi’s Sarcoma and Lymphadenopathy
This early discovery prompted a pretty obvious question: could the sustained presence of interferon have anything to do with the pathogenesis of this newly recognized disease? From what was then known about the effects of interferon it was a question that certainly needed to be explored.
Although interferon had been discovered in 1957 through its antiviral properties, by the 1970s it was already known that it had widespread effects on the immune system.
In the first few years of the epidemic I was in a position to begin to explore the possibility that interferon played a role in this newly recognized disease.
I was able to obtain interferon assays on sera from my patients at Robert Friedman’s lab. Further interferon tests were done by Mathide Krim, then head of the interferon lab at Memorial Sloan Kettering cancer center.
Ann NY Acad Sci 1984, 437: 65
I also was able to obtain quite extensive immunological tests on my patients through my collaboration with David Purtilo at the University of Nebraska in Omaha. As a result I had (and still have) a small database of my own and so was able to produce further evidence for the association of high interferon levels with low CD4 counts, as well as some other associations with interferon. (2).
The numbers of patients was not huge but the following graphic shows that 7 people with over 50 units of interferon/ml had fewer than 50 CD4s, 12 people with 10-49 units had fewer than 500 CD4s while 17 people without interferon had about 700.
This was a CRIA presentation in the 1990s from the days when I was the medical director, but the data had first been presented in 1986.
There are several other interesting correlations. Interferon levels correlate with IgA levels and not surprisingly there is an inverse correlation between CD4 counts and IgA levels.
Several other features recognized among our first patients could also have been effects of interferon. Elevated serum triglyceride levels were characteristically seen. We routinely centrifuged blood before sending the samples to the lab and the turbidity of our patient’s sera was striking.
Interferon inhibits an enzyme, lipoprotein lipase that could have contributed to elevated triglyceride levels (TNF can have the same effect), HDL cholesterol was characteristically low which could also be an interferon effect.
Patients were noted to have low blood tryptophan levels, and even in 1981 we knew that gamma interferon, and to a lesser extent alpha interferon could induce an enzyme (indoleamine 2,3 dioxygenase – IDO) that degrades tryptophan. This was known to be the basis of interferon’s inhibitory effect on toxoplasma gondii, an effect recognized in the 1970s. It’s also possible that tryptophan degradation may contribute to neurocognitive disorders and more recently IDO has been implicated in the suppression of CD4 proliferation. The ability of interferon to inhibit CD4 proliferation was first reported in 1983 – at least 25 years before the effect of IDO was noted.
The early zeal to use interferon as a treatment for HIV disease also created a very strange situation concerning a molecule called beta-2 microglobulin (beta 2M).
It was well known that alpha interferon is the major stimulus for the synthesis and release of beta 2M, a component of the HLA system referred to above.
In the early years of the epidemic various markers were sought that could act as prognostic indicators. It was soon found that a raised beta 2M level in the serum of patients was an adverse prognostic indicator. High levels were indicative of a poor prognosis. But it appeared that many AIDS researchers were either unaware of this association or remained silent about it. At a meeting I attended on prognostic indicators there was a presentation on beta 2M, but as expected the word interferon was not mentioned.
I made a comment that this omission was strange considering patients with elevated beta 2M also had elevated interferon levels. The researcher leading this session looked puzzled and asked if anyone knew what I was talking about. I was rescued from this embarrassing moment by a reply from the investigator that interferon assays, unlike tests for beta 2M, were expensive.
One might have expected some discussion but none followed. At this time interferon was being injected into people who already were producing large amounts of it. Beta 2M levels were therefore raised, so the investigators reporting that raised beta 2M levels were adverse prognostic indicators were in effect suggesting that the presence of interferon indicated a poor prognosis – something hard to reconcile with injecting more of it.
In fact the adverse prognostic significance of serum interferon had already been reported early in the epidemic, as early as 1983, in studies on gay men and people with haemophilia, but neglected as was the case with a good number of early studies.
At least one noted AIDS researcher, in 1991 reported studies undertaken to evaluate the “hypothesis” that elevated beta 2M levels were associated with the production of interferon, an association that had been well known for about 20 years!
Beta 2M levels can be elevated in certain conditions where interferon is not detectable. But even before the onset of the epidemic we knew that when interferon levels are elevated we expect to see increases in beta 2M. Nonetheless this particular paper was noteworthy in that it discussed this association. Few others papers dealing with beta-2M during those years made any mention of it, thus avoiding the following question. If elevated beta-2M levels indicate an adverse prognosis should we not be concerned about administering interferon when there are already elevated beta 2M levels.
This of course doesn’t mean that beta-2M mediated any pathogenic effects, but it simply prompts the question about a role for interferon in pathogenesis.
Of course we now know that interferon mediates some of the pathological effects of HIV disease, and beta-2M can properly be regarded as a surrogate marker for interferon.
How is it possible to explain why in a disease characterised by low CD 4 lymphocyte counts and the presence of large amounts of interferon, it was thought that injecting yet more interferon could possibly be of help?
Dr Fauci and other investigators tried to explain the paradox of administering interferon to people who already had huge amounts of it in their blood stream by claiming that the endogenous interferon was different. The difference referred to was that the AIDS associated interferon could be partially inactivated by acid, whereas the administered interferon was resistant to acid (3).
But we knew that AIDS associated interferon was neutralized by monoclonal antibodies against administered interferon, meaning that the molecules were identical, and the interferon in patients’ blood had the antiviral activity expected of alpha interferon when tested in cell cultures. We were able to detect it in patient’s sera in the first place by assays that depended on its antiviral activity. It certainly was responsible for the beta 2M elevations.
In fact the sensitivity to acid is not a property of the interferon molecule but is conferred by other components. Interferon from patients that is partially purified loses its sensitivity to acid.
This justification for administering interferon that cannot stand up to even the most cursory scrutiny was apparently good enough for community writers on AIDS treatment.
I repeatedly tried to bring attention to the probable contribution of interferon to pathogenesis without success. For example I received no response to a letter written to a writer on AIDS that can be seen by clicking here.
In 1990 I was able to organize a meeting to bring basic researchers and clinicians together to discuss the role of interferon in pathogenesis and in treatment.
The meeting was very well attended, but I have no idea if it accelerated interest in interferon’s role in pathogenesis.
I probably angered a number of investigators when I tried – with the help of Michael Callen and Richard Berkowitz to inform people of the risks of receiving very high doses of interferon in clinical trials. We felt that information about interferon should be included in the consent form. We even went to the lengths of taking out a paid advertisement in the New York Native to inform people about potential problems associated with receiving high dose interferon. This can be seen here. Richard Berkowitz has posted the complete ad on his website, Richardberkowitz.com
It’s appropriate to emphasize again that interferon has been spectacularly successful in the treatment of Hepatitis C in co-infected individuals, even at lower CD4 counts.
It’s now more difficult to undertake studies that can investigate correlations between endogenous interferon levels and various immunological abnormalities. It would have to be done on material stored before AZT was introduced or on individuals not receiving antiretroviral drugs.
The reason for this is that antiviral therapy promptly removes interferon from the circulation. This is something that the group I worked with at Roosevelt hospital, including Elena Klein and Michael Lange found shortly after AZT was introduced. We had access to sera from clinical trials of AZT. In one of these trials AZT was administered for a week on alternate weeks.
We found that interferon promptly disappeared during the week on AZT, only to reappear just as promptly when AZT was discontinued.
Another report studying sera from the same trial looked at the effect of intermittent AZT therapy on beta 2M. The same saw tooth response of beta 2M was unsurprisingly seen, but my recollection is that the word interferon was not mentioned.
AZT treatment was started in these three patients at time 0: HIV p24 antigen and interferon are promptly removed.
The effect of prolonged treatment with AZT on interferon is shown below.
Interestingly, interferon reappeared before HIV p24.
Undoubtedly researchers today are looking at the significance of this almost immediate turning on and off of the interferon response in pin pointing the mechanism of its induction.
One interesting implication of the effect of AZT (and other antiretroviral drugs) on endogenous interferon levels relates to hepatitis C. It’s been noted that in coinfected individuals starting anti HIV drugs, sometimes there is an increase in liver enzymes as well as an increase in hepatitis C RNA. It’s possible that in some individuals, hepatitis C is controlled to some extent by endogenous interferon, and flares up when interferon is removed by the anti HIV drugs. Some researchers have commented on this although I don’t know it this possibility has actually been studied. There are also other reasons why liver enzymes can increase on starting anti HIV drugs.
The innate immune response is a first line of defence against infection coming into play within hours. Secretion of interferon is an important part of this response which also includes the inflammatory response. Innate immune responses are immediate attempts to localize and overcome infections. These beneficial responses last for a brief period because they become harmful if prolonged. There are mechanisms that turn them off. But in HIV infection and in pathogenic SIV infections innate immune responses are not turned off. Persistent immune activation involving the adaptive immune system as well is at the heart of HIV disease pathogenesis.
Why is the interferon response not turned off in HIV disease? Why does the innate immune response continue to be activated? What are the mechanisms that normally turn off interferon production and why are they not working?
The precise role of interferon in contributing to CD4 loss remains to be worked out, although several mechanisms by which this can occur have been elucidated.
But for years there was almost no work on identifying what induced such high levels of interferon and on determining which cell produced it. It took over twenty years since interferon was first identified in AIDS sera for work to be undertaken to identify the ways in which it contributes to pathogenesis. There is still much to be learned, and hopefully the findings can be translated into new therapeutic possibilities.
The reasons why the role of interferon in pathogenesis has been neglected for so long are undoubtedly multiple and complex. But one reason for this neglect was surely the early enthusiasm to administer it as treatment.
But many years have been lost by the neglect of a critical line of research the importance of which was evident in the same year that AIDS first came to attention.
I have chosen these three references from a growing literature to illustrate what we are beginning to learn about interferon’s role in the pathogenesis of HIV disease.
- Herbeuval JP, Shearer GM. HIV-1 immunopathogenesis: How good interferon Turns Bad.Clinical Immunology (2007); 123920:121-128
- Boasso A,Hardy AW et al. HIV-1 induced Type 1 interferon and Tryptophan Catabolism Drive T Cell Dysfunction Despite Phenotypic Activation. PLoS ONE (2008); 3(8): e2961
- Stoddart CA, Keir ME et al. IFN-α-induced upregulation of CCR5 leads to expanded HIV tropism in vivo, PLoS pathogens (2010); 6(2) e1000766
Some immunologic parameters in homosexual patients with Kaposi’s sarcoma (KS) or unexplained lymphadenopathy resemble findings in patients with autoimmune diseases such as systemic lupus erythematosus (SLE). Many patients with SLE have an unusual acid-labile form of human leukocyte interferon (HuIFN-α) in their serum. Sera from 91 homosexual men were tested for the presence of HuIFN. Of 27 patients with KS, 17 had significant titers of HuIFN in their serum. Ten of 35 patients with lymphadenopathy and three of four patients with other clinical symptoms also had circulating HuIFN. In contrast, only two of 25 apparently healthy subjects had serum HuIFN. All 32 samples of HuIFN had antiviral activity on resemble findings in patients with autoimmune diseases such as systemic lupus erythematosus (SLE). Many patients with bovine cells, a characteristic of HuIFN-α, and all of 14 representative samples tested were neutralized by antibody to HuIFN-α. In addition, the HuIFN-α in six of eight representative patients was inactivated at pH 2 and therefore appears to Some immunologic parameters in homosexual patients with Kaposi’s sarcoma (KS) or unexplained lymphadenopathy be similar to the HuIFN-α found in patients with SLE. These findings suggest that an autoimmune disorder may underly lymphadenopathy and KS in homosexual men.
Sonnabend J., Saadoun S., Griersen H., Krim M., Purtilo D. Association of serum interferon with hematologic and immunologic parameters in homosexual men with AIDS and at risk for AIDS in New York City.
2nd International Conference on AIDS Paris 1986. Abstract 100
There were several other interesting associations including a positive correlation between IgA and interferon, so needless to say, there is an inverse correlation between CD4 counts and IgA. In the early days I used easily obtainable IgA measurements as an unproven prognostic indicator.
I found a transcript of a meeting in New York where Dr Fauci answered questions posed people with AIDS and their advocates, where he explains this.
You can see this at the very end of another article I wrote about interferon and AIDS in 2009 that contains some of the same material in this blog.
A very similar article has been posted at the aidsperspective site.
Pre-exposure prophylaxis, or PrEP, is an HIV prevention intervention in which anti-HIV drugs are taken to prevent infection. A safe, effective and affordable drug that could achieve this would be a powerful prevention intervention even possibly capable of halting the spread of the epidemic.
Last week we were told the results of the iPrEx trial that tested the efficacy of PrEP with Truvada, a combination of two anti-HIV drugs, in reducing new HIV infections among a group of men who have sex with men considered to be at high risk for HIV infection.
The announcement of the results was greeted with almost universal jubilation.
“That’s huge,” said a prominent AIDS researcher, “That says it all for me.”
“Today marks a major step forward in our quest to combat HIV among MSM
“This discovery alters the HIV prevention landscape forever,”
“….. the new data “represents the most promising development in HIV/AIDS since the introduction of triple combination drug therapy in 1996.”
“This is a game-changing trial result,”
Science magazine reported that..
“The researchers applauded and some even cried when they heard the bottom line”; “I have not cried this hard in years” – said one researcher.
These exultant cheers are usually reserved for the most momentous of breakthroughs.
Demonstrating that a drug could be safe and effective in preventing infection would indeed be a momentous breakthrough as already noted.
But the iPrEx results, far from representing such a breakthrough, indicated that PrEP, at least with Truvada, together with counselling and provision of condoms, reduced new HIV infections among men who have sex with men only modestly. It’s unlikely that the 44% reduction in new infections that was seen is of sufficient magnitude to make PrEP with Truvada viable as a public health prevention intervention. Moreover, as will be described there are significant safety concerns, a demonstrated danger of the emergence of drug resistant HIV, and the drug is far from affordable.
A 44% reduction in new infections is not huge; even those extolling the trial results would agree (at least I think they would, but who knows considering the over-the-top responses).
But what is most troubling is that the researchers have squeezed an efficacy of Truvada of over 90% by a questionable statistical sleight of hand, an improper use of sub-group analysis, a technique of data dredging that has been soundly discredited. I’ll return to this.
This has resulted in headlines such as “PrEP works – if you take your pills”, I don’t know if this will persuade some people to abandon condoms and religiously take their pills. Unfortunately, as will be explained, the type of subgroup analysis that apparently allowed investigators and commentators to confidently claim a greater efficacy of PrEP is not reliable. Maybe consistent use of Truvada will reduce new infections by over 90%. Maybe not.
For the moment staying with the ability to reduce new infections by 44%: As a public health intervention to be used on a wide scale, this degree if efficacy is just not good enough to justify using Truvada to prevent a life threatening infection. Even if the risk of infection is low this must be balanced against the gravity of the infection. About 3% of participants in the Truvada arm of the trial became infected as opposed to about 5% among those receiving placebo.
Perhaps it’s on this issue that I’m at odds with the huge acclaim given to the trial results. Maybe the prevailing view is that a 44% reduction in new infections is indeed good enough; some commentators are even discussing implementation.
PreP proponents like to compare it to malaria prophylaxis. If the efficacy of malaria prophylaxis were of the same order as that of Truvada in relation to HIV, I suspect many people might think twice before visiting an area where there was a risk of malaria.
Let’s take a closer look at the trial results, particularly the claimed greater degree of efficacy in compliant participants reported in the New England Journal of medicine.
I have commented briefly on this in my blog on the POZ magazine website.
The medication used in the trial, Truvada, is a combination of two anti-HIV drugs, FTC and tenofovir. It was compared with placebo in over 2000 men who have sex with men, considered to be at high risk for HIV infection.
The 44% reduction in new infections was achieved in conjunction with counselling, provision of condoms and monthly tests to monitor for infection.
This is not a good enough performance to justify widespread use of Truvada to protect against infection. The investigators then looked at blood and tissue levels of the drugs in people who became infected and those who did not. They found that those who remained uninfected had detectable drug levels while those who became infected did not.
They incautiously trumpeted this result as proving that Truvada works well if the pills are taken consistently – stating that in those who took their pills more consistently the relative risk reduction was well over 90%.
On the surface this sounds good. Almost all the commentators thought so.
However looking at the results in a sub-group of participants can be misleading. Most particularly in a sub-group that is defined after randomization; who would or would not comply with treatment could not have been known. The problems with subgroup analyses will be clearer after a short account of intention to treat analysis.
Intention to treat analysis is the most reliable way to analyse clinical trial data. In such an analysis participants are analysed in the group to which they were randomized, irrespective of whether they dropped out, or didn’t adhere to the treatment or strayed from the protocol in other ways. This seems counter-intuitive, but there are sound reasons why intention to treat is regarded as the best way to analyse trial data, among them that it more reliably reflects what happens in real life, rather than in a clinical trial. For example, one reason why pills may not work is because they are not taken. If they are not taken in a trial we have to be concerned that they may not be taken in real life. Take a look at this excellent explanation of intention to treat: Making sense of intention to treat.
As noted, the trial investigators made a lot of the sub-group analysis showing greater efficacy in those who took Truvada pills as measured by finding the drugs in blood and tissue samples.
This is surprising as the pitfalls inherent in such post-hoc sub-group analyses have been recognized for years. Commentators, some of whom are clinical researchers, in their over-the-top exultation at the results of the analysis in those compliant with Truvada may have forgotten about the treachery inherent in sub group analysis. A few commentators give the problem only passing acknowledgement.
This is a classic paper on sub group analysis:
Yusuf S, Wittes J, Probstfield J, Tyroler HA: Analysis and interpretation of treatment effects in subgroups of patients in randomized clinical trials.
Journal of the American Medical Association 1991 , 266:93-98
This is from that paper:
“Analysis of improper subgroups, though seductive, can be extremely misleading, because a particular treatment effect may influence classification to the subgroup. Thus, an apparent subgroup effect may not be a true effect of treatment but rather the result of inherent characteristics of patients that led to a particular response or to the development of side effects”.
In iPrEx the subgroups were categorized by events that happened after randomization, so the adherent group is an “improper” subgroup. “Subgroups of clinical trial subjects identified by baseline characteristics … is a proper subgroup while a subgroup determined by post randomization events or measures is an improper subgroup”.
In actuality the attention given to the subgroup that had blood and tissue drug levels is an example of the treachery of such sub-group analyses.
As an illustration, the reduction in new infections seen in this group may well have resulted from the following possibility.
People who take their pills consistently are more likely to use condoms consistently and in general are more attentive to risk. So if it were possible to do a subgroup analysis of people who adhered to placebo we might conclude that the placebo also works – (and it’s cheaper).
This is not so fanciful.
“In one study , those who adhered to the trial drug (clofibrate) had reduced
mortality; but those who adhered to the placebo pill had the same reduction in mortality”.
This is from:
Coronary Drug Project Research Group. Influence of adherence to treatment
and response of cholesterol on mortality in the coronary drug
project. Engl J Med 1980;303:1038-1041
A classic example of the pitfalls of subgroup analysis is what it demonstrated in ISIS-2, a trial examining the effects of aspirin after myocardial infarction. A subgroup analysis showed it was of benefit to all except people who were either Libras or Geminis.
Maybe Truvada taken consistently can reduce new infections by over 90%; maybe not. There was no basis for the investigators and commentators to present the first possibility with such overwhelming confidence.
We must accept that a 44% reduction in new infections is at this time the most reliable estimate of Truvada’s efficacy as PrEP. Although, the confidence interval , a measure of reliability, was wide.
We have an intervention that can reduce new infections by 44%, if taken in conjunction with a program of counselling, condom use, and monthly tests for HIV infection. That is the benefit. What about the down side?
The two most important are the development of resistance of HIV to the component drugs of Truvada and the toxicity of the drugs.
The utility in treating HIV infection of FTC and tenofovir – Truvada’s component drugs is lost if the virus becomes resistant to the drugs. Moreover, some mutations conferring resistance to these drugs can also affect sensitivity to some other drugs. The danger of resistance, and even cross resistance to other drugs developing when Truvada is used as PrEP is not a trivial concern. Truvada used as PrEP provides a suboptimal dose in treating established HIV infections. This is precisely the situation in which resistance is likely to develop. There were in fact two instances of developed resistance in the iPrEx trial in individuals who became infected, but undetected before the trial began.
Resistant viruses in the community are a danger to all, so the risk of generating resistance is not confined to the individual taking Truvada as PrEP.
What about safety?
The claim in many reports that Truvada is without significant toxicity is also misleading.
Maybe poor adherence has some bearing on the lack of significant toxicity.
A median of 1.2 years exposure to Truvada can tell us little about cumulative and long term effects. Experience with long term use of Truvada in HIV infected people makes concern about toxicity realistic. Renal toxicity, sometimes severe occurs not uncommonly. It’s mostly but not always reversible on stopping the drug. Thinning of bones, osteopenia and osteoporosis is also seen. There are additional adverse effects associated with the drugs.
There were small abnormalities in some parameters measuring kidney function among those treated with Truvada. Although these changes were reversible on stopping the drug, the fact that they were seen at all is a reason for great concern about the effects of longer term treatment.
With the experience we have gained from longer term treatment with Truvada, it is disingenuous to stress its overall safety from just 1.2 years of very inconsistent use.
It’s important to point out that for HIV infected individuals, the benefits of treatment with Truvada far outweigh the risks. For uninfected individuals, an entirely different risk benefit analysis must be made.
Despite the disappointing results of iPrEx, PrEP is important.
Why is PrEP important?
There are at least two important reasons.
PrEP could protect receptive partners in sexual intercourse, both men and women, who are unable to ensure that a condom is used by their partner and for a variety of reasons are unable to refuse sex . The best and most respectful way of addressing this would be to find ways to empower these individuals; in some way providing them with the means to protect themselves could be seen to also have the effect of perpetuating their subjugation and abuse.
But there are women and men who need protection now and providing them with a means to prevent infection that they can control is vital. This can go hand in hand with working to empower them and helping them to try to ameliorate or leave abusive relationships.
Sex is one of life’s joys. It is vitally important to the human experience.
Condoms can be a barrier to intimacy which for many is the most essential aspect of sexual intercourse, for both receptive and insertive partners. So recommending the use of condoms without acknowledging the significant obstacle they may present to a fulfilling sexual experience is a real problem. Pleasure is part of that fulfilment and for some insertive partners condoms are a significant impediment to experiencing it. A fully effective and safe means of pre-exposure prophylaxis may also allow the removal of a barrier to conception.
But people are different; for example some individuals have found that condoms can increase intimacy in the reassurance they provide concerning their and their partners safety.
We should never minimize or trivialize the difficulties condoms can present. We should also keep in mind that their use is the most effective means of preventing sexual transmission of HIV.
Their use will remain necessary in order to remain uninfected until we are free from HIV or a safe an effective PrEP method can be found.
These considerations, a prevention method that the receptive partner can control, allow conception and remove an impediment to full sexual expression are some reasons to work towards finding a safe and effective form of PrEP.
Truvada unfortunately has not proved to be sufficiently effective and safe.
A few words about prevention education and condoms:
The consistent use of condoms is the most effective means to prevent sexual transmission of HIV.
PrEP proponents agree but many go on to say that people just don’t use condoms consistently. This is an attitude that has apparently concluded that prevention education does not work, and more importantly, cannot work.
But how can one conclude that it cannot work when there has been so little of it? This has some analogy with the claims made for the efficacy of Truvada. It works, if you take the pills
If prevention education has been a failure, it’s not because it doesn’t work, but because we have not provided it well enough. There has been too little and most has not been properly targeted.
Proper targeting to those most at risk is critical. I have written about this. We need more and better prevention education.
The CDC now tells us that the group at greatest risk by far in the US is men who have sex with men. Nothing has changed except the ethnic distribution, so why are they only telling this to us now? For over twenty years we were told that AIDS was an equal opportunity infection making prevention education targeted to those at greatest risk even more difficult.
It’s only now, 25 years too late, that the CDC appears to recognize the urgency of providing prevention education to gay men.
Neglect of properly targeted prevention education, with encouragement for condom use and continuing support to sustain their use helped to allow the spread of HIV into African American communities in plain view while millions were spent on “America Responds to AIDS” a vacuous prevention message.
Similarly we have known for years that in the US younger men who have sex with men are at particular risk. We know where to target prevention messages, but we don’t it well enough.
We know that highly targeted prevention education, when crafted by the communities at greatest risk can work. This was demonstrated in the earliest years of the epidemic in San Francisco and New York City.
In 1982 when Michael Callen, Richard Berkowitz and I first recommended condom use to gay men in New York City, we stressed that in doing so it was important to celebrate sex, recognizing that for some individuals condom use, or perhaps more precisely, HIV, could present a barrier to its full expression. We have come far in freeing ourselves from long standing societal constraints that for too many have stood in the way of a fulfilling sexual experience burdening it instead with guilt. It’s important to take care in providing continuing support for condom use and recognize that for many they do get in the way. But it’s really HIV that’s getting in the way, and consistent condom use can help to bring it to an end.
Finding conditions where sex without condoms is safe is important. On the showing of iPrEx – despite its ecstatic reception, PrEP unfortunately is not yet ready.
At the moment consistent condom use is the best protection there is.
The often uncritical response to iPrEx should not persuade anyone that Truvada is a safe and effective alternative.
iPrEx is a large and complicated study. The investigators deserve the highest praise for completing this phase and having provided a result. It may not be the result so many hoped for. But providing clear information is a major advance.
This blog more or less duplicates that at the aidsperspective.net site, explained in the “about” page above.
HIV Disease and Positive Feedback. An additional comment.
AUGUST 31ST 2010
A previous post focussed on the positive feedback interaction between HIV replication and immune activation. HIV replication and immune activation reciprocally enhance each other.
While HIV infection is an essential cause of the immune activation that’s characteristic of HIV disease, there are other factors that also contribute to it. In that post as well as in the blog I write on the POZ magazine website, I described some of these additional factors that can add to immune activation. As noted, viruses of the herpesvirus family, cytomegalovirus (CMV) in particular are the most important of these worldwide, while in parts of Africa certain endemic infections may be of great significance in contributing to immune activation.
Since sustained immune activation, involving both innate and adaptive immunity is at the heart of the pathogenesis of HIV disease an understanding of how it is perpetuated is critical.
Evidence for activation of innate immunity was noted in 1981, the year that AIDS was first reported, in the detection of large amounts of alpha interferon in the circulation of patients. We even knew then that interferon alpha and gamma could induce an enzyme, indole 2,3-dioxygenase (IDO), (IDO was known to be responsible for the inhibition of toxoplasma gondii by depletion of tryptophan in cells treated with gamma interferon) but we did not know then that this enzyme could contribute to the loss of T lymphocytes. Another observation of historical interest is that even before AIDS was first reported in 1981, interferon was known to preferentially inhibit CD4 lymphocyte proliferation in mixed lymphocyte culture.
Since immune activation and its effects, including inflammation, are harmful if sustained, there are mechanisms that can dampen it.
But in HIV disease, immune activation persists with continued deleterious consequences.
The reason I’m revisiting this now is that there is a question that continues to be bothersome.
HIV disease is not the only infection associated with long standing immune activation.
Several endemic infections in Africa are also associated with sustained immune activation, certainly not all – some even have a dampening effect on immune responses. TB is another example of an infection associated with chronic immune activation. In none of these conditions is there such a profound loss of CD4 lymphocytes as in HIV disease. While individuals with active pulmonary TB have been reported to have lower CD4 counts than healthy individuals, the numbers were well above 500.
Is the difference between sustained immune activation associated with HIV and that associated with other chronic infections in HIV negative individuals a matter of degree – is it a quantitative difference?
Could the mechanisms that dampen and check immune activation be impaired in HIV disease? These mechanisms include the secretion of cytokines that have anti-inflammatory properties, such as IL-10, IL-13, and TGF-beta, among others. Specialized immune system cells can also dampen immune activation. Tregs, a subset of T lymphocytes, have such a dampening effect. Although there are conflicting reports on the relationship of Tregs to HIV disease, it is known that HIV targets some of these particular T lymphocytes.
This graphic comes from my earlier post on positive feedback characteristics of HIV disease.
In this diagram HIV pathogenesis is represented by a circular process moving in a clockwise direction. It is started by HIV infection and can be propelled by a positive feedback association between HIV replication with immune activation. Immune activation is reinforced by CMV, and in certain settings, by some endemic infections. This is represented by the + sign in the diagram. Immune activation is retarded by those influences that dampen the immune response, including anti-inflammatory cytokines and Tregs, represented by the – sign in the diagram.
Here is a revised version of this diagram:
HIV disease progression is represented as moving clockwise in a circle, reinforced by sources of immune activation other than HIV and retarded by Tregs and other mechanisms that dampen immune responses. Tregs act as brakes, but HIV can directly make the brakes less effective.
Could critical differences between HIV disease and other infectious causes of long standing immune activation where CD4 numbers are relatively preserved, be the preferential targeting of Tregs by HIV and a different pattern of cytokine secretion?
I wonder if this revised representation of HIV disease lends itself to a more formal modelling process.
In this particular model a disease process is represented by a circular motion in a clockwise direction, with forces that both propel and retard it. Some predictions can be made.
The degree of immune activation at the time of HIV seroconversion would favour more rapid HIV disease progression. The set point – the level from which CD4 lymphocytes decline following an acute HIV infection, would be lower, and the subsequent rate of CD4 decline higher when HIV infection occurs in a person where there already is a higher degree of immune activation, compared to an individual where this is not the case. There already is some evidence in support of this possibility.
It’s well established that HIV disease progresses more rapidly with increasing age. Could an explanation for this be that immune activation increases with age – indeed, it’s been suggested that immune activation contributes to the aging process.
HIV disease progresses more rapidly in individuals with active TB. CMV viremia was noted to carry an adverse prognostic significance in HIV disease very early in the epidemic. There are but two examples, but there are many more of of a more rapid course of HIV disease in the setting of other infections caused by bacteria, protozoa, viruses and helminthes. Some are referred to in a previous post.
Are Treg numbers at seroconversion and for a period immediately afterwards related to subsequent disease progression?
Could treatment with anti CMV agents during acute HIV infection retard subsequent disease progression?
There already is some evidence that treatment of HIV during acute infection might slow the subsequent course of HIV disease.
The utility of any model of a disease process lies in its ability to provide a common explanation for disparate observations as well as to make predictions that can be tested by an analysis of available data or by experimentation.
Viewing HIV disease as a process with a positive feedback interaction between HIV replication and immune activation with forces that both enhance and retard this interconnection, provides a useful descriptive framework as well as testable predictions.