Archive

Posts Tagged ‘AIDS prevention’

Treatment as Prevention: Protecting Individual Autonomy

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.

Expert opinion:

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

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/&gt;.

(3)    http://phe.oxfordjournals.org/content/3/3.toc

(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

iPrEx trial results of Pre exposure prophylaxis – PrEP ,

December 13, 2010 Leave a comment

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 [3], 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.

1:

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.

2:

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.

PrEP: Pre exposure prophylaxis to prevent HIV infection. August 2009

August 11, 2009 Leave a comment

Pre exposure prophylaxis in relation to HIV infection refers to the administration of anti HIV medications to uninfected people as a means of protecting them from becoming infected with HIV.     It is not known if this intervention will succeed in achieving its goal.   Several trials have been underway to test it for safety and efficacy, and many more are planned worldwide.

I have paid little attention to these initiatives but was prompted to do so by notices of a meeting to discuss pre exposure prophylaxis – now known as PrEP – in the coming weeks.   The wording of this notice is quite vague, but the notice suggests that it is urgent to start planning for the implementation of PrEP as the analysis of initial safety and efficacy trials are expected within the next year.

This is quite startling in its implication that PrEP actually works and presumably is safe.  The actual words of the notice are:

“Results and analyses of initial safety and efficacy trials are expected within the next year, which highlights the urgency to beginning to plan now for how PrEP might be used to maximize its public health impact”.

This is a convoluted statement, to the point of being quite unintelligible. It can be misleading in the implication that can easily be drawn from it that PrEP works. Why else begin to plan for how to use it?

I had not been aware of just how extensive the PrEP initiative has been.   To get some idea of the many trials that are underway or planned, take a look at this website:

http://www.prepwatch.org/

Trials are sponsored by several organizations, mainly it seems, Family Health International (FHI).

http://www.fhi.org/en/Topics/preexposure_prophylaxis.htm

FHI has produced a set of slides listing PrEP trials.

http://www.prepwatch.org/pdf/Meetings/Cates_TDF_slides_May.2006.pdf

Among the “research consortia” listed as involved in PrEP research are the Bill and Melinda Gates Foundation, Gilead Sciences, the Centers for Disease Control (CDC), The National Institutes of Health (NIH),  and UCSF. These trials are conducted  in many countries, including Peru, Botswana, Thailand, the US and Malawi.

Organizations listed under “community consortia” are GMHC,  AVAC, Global Campaign for Microbicides, CHAMP, and the IAS.

The websites of these organizations contain information about PrEP.

AVAC :   http://www.avac.org/

Global Campaign for Microbicides:  http://www.global-campaign.org/

CHAMP:  http://www.champnetwork.org/about

The International AIDS Society:  www.iasociety.org

All the trials use a once daily drug, tenofovir, with or without emtricitabine (FTC). Tenofovir is manufactured by Gilead in the US although I believe a generic version is produced in India.

The trials vary in design.   Some require daily tenofovir, some are used intermittently or specifically before sexual intercourse. Some use a gel formulation.

Previous trials had run into difficulties; several were stopped for different reasons.  For example a trial in Cameroon was stopped amid allegations that those who seroconverted did not receive adequate treatment.  A trial in Nigeria was stopped because of inadequate standards in laboratory testing.

A trial of PrEP among Cambodian sex workers was stopped in 2004 by the Cambodian government.  This was perhaps the most publicized of the several PrEP trials that were stopped, because several activist groups brought attention to it at the XV International AIDS Conference in Bakgkok.   Among the many reasons stated for pressure by activist groups to stop the trial were poor HIV prevention counselling, and a lack of medical services to those who seroconverted.    Act Up-Paris was active in stopping PrEP trials both in Cambodia and Cameroon, although it is reported that this organization is supportive of tenofovir trials in general.

These events are described in an article entitled “The Abandoned Trials of Pre-Exposure Prophylaxis for HIV: What Went Wrong?”  The authors are Jerome Singh and Edward Mills.  It can be seen here.

http://www.plosmedicine.org/article/info%3Adoi%2F10.1371%2Fjournal.pmed.0020234

For reasons I will describe I do believe that there is no way to design a trial of the efficacy of PrEP that can meet acceptable ethical standards.   On the other hand, it is perfectly possible to conduct trials to determine the safety of tenofovir for pre exposure prophylaxis.

So maybe an answer to Drs Singh and Mills as to what went wrong with the abandoned trials of pre exposure prophylaxis is that the question of efficacy, unlike that of safety, cannot and should not be tested on human research subjects.

Here are the reasons why this cannot be done, at least regarding the use of tenofovir to prevent sexual transmission of HIV.

No ethically designed and conducted trial can definitely prove that PrEP works.  Definite proof of course may be an unattainable goal, but even credible evidence regarding efficacy  would not be found if the trial were to be conducted in an ethical manner, simply because with the availability of condoms, and the imperative to provide counselling  that they be consistently  used,  such  a trial could not answer the question asked of it. This is essentially because the consistent use of condoms will ensure that insufficient seroconversions occur in participants receiving  placebo.

In any trial that studies the ability of a new intervention to prevent sexual  transmission of HIV, participants must receive persistent counselling about the need to use condoms.  These must be provided, with ongoing support for their continued use.  This is the ethical requirement.

Quite clearly if great care is taken to meet this requirement there will be few infections in people receiving placebo.  The investigators are presented with a conflict of interest that no amount of verbal assurance can resolve.  The conflict is that on the one hand the investigator must always be cognisant of the importance of doing all that’s possible to encourage condom use to prevent the sexual transmission of HIV infection, and on the other hand the investigator has an interest in demonstrating an effect of PrEP in preventing it.

It is only when condom use falls below a certain level that the effect of another preventative measure can be assessed.  We are obliged to do all we can to ensure that this does not happen.

The Centers for Disease Control (CDC) are sponsoring several trials of PrEP[i].  They are very sensitive to the need to provide risk reduction counselling to participants.

Here is an excerpt from material published by CDC:

“One of the greatest risks, as efforts progress to identify new biomedical prevention approaches, is that individuals at risk will reduce their use of existing HIV prevention strategies. It will therefore be crucial to reinforce proven behavioral prevention strategies, both within and beyond these trials. All three trials are taking multiple steps to address this issue during the education and enrolment of trial participants and through ongoing participant counselling.

First, it is critical to ensure that participants understand that trial participation may not protect them from HIV infection—either because they may receive a placebo or because they may receive a study drug, the efficacy of which remains unproven. This and other key aspects of the trial, including the potential risks and benefits of participation, are explained to potential volunteers in the language of their choice, prior to their enrolment. To ensure participants fully understand all aspects of their participation, all volunteers are required to pass a comprehension test prior to providing written informed consent. Study participants are also free to withdraw from the trial at any time and for any reason”.

So there is clear recognition that there may be a falling off in the use of proven prevention approaches, importantly, the use of condoms.

Here is another excerpt:

“To assist participants in eliminating or reducing HIV risk behaviours, extensive counselling is provided at each study visit, and more often if needed. This interactive counselling has proven effective in reducing the risk of HIV and other STDs in multiple populations, including past participants of similar HIV prevention trials. Participants are also offered free condoms and STD testing and treatment to reduce their risk for HIV infection”.

If such counselling is effective, the prevention of sexual transmission of HIV particularly through the consistent use of condoms will make it impossible to detect an effect of PrEP.   As mentioned the investigators are presented with a conflict that it is not possible to resolve.

PrEP is an experimental approach to prevention, while consistent condom use is an established method to substantially reduce the sexual transmission of HIV.

The argument that may be presented by those who are proponents of PrEP is that condom use is not consistent, and that we need an alternative

The implication of such an argument supporting PrEP is that prevention education, essentially the use of condoms, has not been sufficiently effective.  This cannot be known to be true of prevention education in principle.

What is definitely true is that those responsible for prevention education have not been sufficiently effective.

Our efforts  should be focussed on improving prevention education and support for the consistent use of condoms,

There is so much more that can be done with persistent, culturally sensitive, highly targeted prevention education.  In order to improve our efforts at prevention education we have to first confront the fact that we may have not been too successful in this endeavour, understand why,  and absolutely not take the position that the undertaking is an impossible one.

Every new infection today represents a failure, not of prevention education as an undertaking, but a failure to provide it effectively.  The introduction of condom use among gay men in the US in the 1980s originated in this community, it was promoted and effectively advocated for by this community and proved to be effective..   In those early years there was certainly no help from the Government which was to spend enormous sums on a vacuous and ineffective untargeted campaign “ America responds to AIDS” which did absolutely  nothing to stop the advance of this disease into African American communities , although this was happening in plain sight.

What we can learn from this is that different affected communities are best able to understand the  issues specific to their communities that must be emphasized  and  promote prevention education that is most effective for each of them. Their input is therefore  absolutely vital.

The design and implementation of well funded and highly targeted prevention education has been neglected.   These initiatives need to be specifically targeted to different groups, the needs of which must be assessed,  barriers identified, continuing support provided, as well as some instrument developed to evaluate the success of the programs. .   It is an enormous challenge.

We know that gay men were able to make it work for them before the concept of risk reduction had even been articulated. It can work and this is where our efforts must be concentrated.  Not on trials of the efficacy of PrEP that are impossible to conduct in an ethical fashion.

However It is entirely possible  that PrEP may add an additional layer of safety to condom use during sexual intercourse.  This may be of  particular importance in certain circumstances such as among sex workers.  This is also the case among some women who are unable to rely on the use of a condom by their male partners.   Trials of the safety of once daily tenofovir are absolutely possible and even desirable.  Such trials would be unburdened with the ethical problems that make efficacy trials impossible to conduct.  It will be clear that the trials are to determine the safety of tenofovir when used with condoms to provide an additional level of safety.   It is true that we may never be able to firmly establish its efficacy, but if it proves to be safe, there is sufficient – if far from conclusive evidence to justify its use.

It is clear that all that has been written about concerns the sexual transmission of HIV.    For those in whom the risk of infection  is through intravenous drug use there is an entirely different set of considerations.  The only known prophylactic measure, the reliable provision of sterile injecting equipment is probably just unavailable for most, and efficacy trials are therefore not burdened with the same ethical constraints.

One cannot help but note that at least  in two initiatives, pharmacological rather than behavioural approaches to prevention are now being emphasized.  Of course PrEP to prevent  transmission of HIV is one. The other is the attempt to end the HIV epidemic by testing and treating all HIV infected people, whether or not a particular infected individual needs treatment for his or her benefit.  Both are beset with ethical problems.

The use of condoms can significantly reduce the sexual transmission of HIV.  We know this.   Therefore  our greatest efforts should be placed in improving prevention education.  It is a tremendous challenge given the cultural diversity of the populations involved, and the special difficulties experienced by some. This is particularly true where women are disempowered.

We know that untargeted efforts such as “America Responds to AIDS” do not work.  We need to understand the barriers to effective prevention education.

A denial of  the importance of sexual expression to the human experience, stigmatization of those infected, homophobia, racism, bigotry in general and the fact that unlike the use of drugs, prevention education provides no financial return,  are surely amongst them.


[i] [i]    http://www.cdc.gov/hiv/prep/resources/factsheets/index.htm

Treatment as Prevention. A last short postscript

I have written several posts dealing with “Treatment as Prevention”  referring to proposals that the epidemic could be controlled by testing and treating all infected people.   However, as this phrase is also used in a different, although related context, I am adding this last postscript.

Thus,  “treatment as prevention” has a context that concerns populations and considers a strategy to  control and even end the epidemic.    The same phrase  also has a context that deals with prevention of infection at an individual level, and focuses on transmission risks  between two people.

The latter context was brought to attention in 2008 by the Swiss Federal Commission on HIV/AIDS.  Their publication essentially states that, under certain conditions,  with effective antiviral treatment achieving an undetectable viral load, the risk of sexual transmission without condom use is not greater than that with the use of condoms.

Among the conditions stipulated is that there is no sexually transmitted infection, and that the viral load has been undetectable for at least six months.

http://www.aids.ch/e/fragen/pdf/swissguidelinesART.pdf

Now a German voluntary organization, Deutsche AIDS-Hilfe, has added support – with some modifications to the Swiss statement.

http://www.aidshilfe.de/media/de/0904_DAH-Papier_HIV-Therapie_und_Praevention_Englisch.pdf

There was a huge controversy when the Swiss recommendations were first made public in 2008.  Their conclusions were rejected  by groups  in the US,  even by those who promoted the application of the same principle – the reduction in infectivity conferred by treatment – as a means of controlling the epidemic.

I was – and am – absolutely supportive of the Swiss recommendations as applied to individuals.  Here is an excerpt from a letter I wrote when the Swiss document was published:

“The report is absolutely reasonable. There are caveats and cautions in it, and since I can see no reasonable objection to them, we have to look elsewhere to try and understand why the report has provoked such a furious response. I know it is a bit pedantic and pretentious but I’m going to add a quotation that is over 100 years old that recognizes that scientists can be as irrational as anyone else (especially about sex), here it is:

In Man Adapting, Rene Dubos notes that:

“The presuppositions on which medicine operates are thus conditioned by the general philosophy of the social group as a whole” and adds the words of Oliver Wendell Holmes in 1860:

“The truth is that medicine, professedly founded on observation, is as sensitive to outside influences, political, religious, philosophical, imaginative, as is the barometer to the changes in atmospheric density”10
I would bet that some who have commented have not even read the cautious Swiss text, and have allowed their prejudices and squeamishness about sex in general to surface at the very mention of sex without condoms.

The Swiss authors do deserve some recognition for their courage. There are circumstances in which it is not irresponsible to have sex without condoms. And even for those for whom these circumstances do not apply, the knowledge of the possibility of sex without condoms will be an encouragement, in at least two ways.

Firstly, to continue using condoms when this is necessary, and then as a support with treatment adherence and monitoring.

I say these things as someone who had something to do with the original introduction of condom use for AIDS prevention in 1983, – briefly described here:

http://aidsperspective.net/articles/Callen-Berk_collaboration4.pdf

and until now thought – as probably most did, that condom use  would be forever.

Knowing that this is not necessarily so is a tremendous encouragement and I believe this thought alone will help our prevention efforts”.

I have continued to encourage the use of condoms, but I do welcome the Swiss document for pointing out, with appropriate documentation and caution, that there are circumstances when it is not irresponsible to dispense with them.

This also means that there are circumstances when conception is possible. There are also implications in situations where there are laws that criminalize sexual contact with HIV infected people under certain circumstances.

A large part of the irrational responses to the proposal are I believe based on a disparaging attitude towards sex.

For many, the use of condoms is a barrier to intimacy.  The knowledge that if certain circumstances can be met, an infected person is not endangering their sexual partner by dispensing with condoms is in fact a life affirming celebration of sex, one of life’s joys.

Admittedly, dispensing with condoms will not be possible for most individuals.  It is probably most relevant to serodiscordant couples in a stable relationship – that is where only one of the partners is HIV infected.

But knowing that this might be achieved could be a great support to most HIV infected people  who must continue to use condoms   It will also be a greater incentive to remain adherent to one’s treatment regimen.

Of course the diminished infectivity of effectively treated individuals is the basis for the proposals to use treatment of all infected people as a means of controlling the epidemic.

This is a very different situation, most importantly because it will involve treating people who do not need to be treated for their own personal benefit. These healthier people will derive no benefit from the medications and only be exposed to their side effects.  I have written about this in previous posts on treatment as prevention.

Except for the relatively uncommon situations outlined in the Swiss document, and more cautiously and explicitly, in the German document, the consistent use of condoms remains one of the most important measures we have to prevent infection.

HIV TREATMENT AS PREVENTION

March 27, 2009 4 comments

The proposal that testing and treating everyone who is HIV infected would end the epidemic is back in the news.

It is not a new idea. It has been discussed at HIV/AIDS conferences. At the beginning of the year an exercise in mathematical modelling was presented in the Lancet providing some support for this notion of universal testing and treatment. Now some experts in molecular biology and virology have added their personal opinions in favour of this approach; I notice that at least on one web site addressed to HIV and Hepatitis virus infected individuals, the views of these pioneer researchers are reported with, as seems to be usual, no analysis or criticism. http://www.hivandhepatitis.com/recent/2009/032409_a.html

It begins to look almost like an advertising campaign, with the touch of a skilled publicist; an idea is gradually brought to public attention, it is widely endorsed and the hope is that public support will ensure that funders and politicians will move the project forwards.

The merits of the proposal, and the way it is being promoted are two different issues.

Regarding the proposal, in principle it is certainly a worthwhile idea that deserves consideration.
But there are several problems, not mentioned in public reports of this proposal, and barely dealt with in the professional literature, which may constitute insuperable barriers to its implementation.

Leaving aside for the moment the question of whether such a project is even feasible, perhaps the most important problem is that infected people who do not need treatment will be asked to receive it to achieve a social benefit.

This proposal then involves the general concept of a public health intervention on individuals who will not themselves derive any benefit from the intervention, but will only be exposed to its risks.

We have thankfully not yet reached the point where enforced testing and treatment can be seriously proposed. (We may be getting close in the removal of written informed consent for HIV testing).

Certainly the spectre of mandatory testing and treatment is lurking behind this proposal to test and treated everyone infected. This would do wonders for drug and testing equipment sales.

So we would have the situation where some individuals will voluntarily take treatments that despite what we may be told can most certainly not be regarded as absolutely free of possible adverse effects, Many infected people will of course benefit from this. Others however will agree to take risks, with no benefit to themselves but for the benefit of others. Quite apart from many other issues, we can only ask these individuals to participate in the project if there is an overwhelming chance of success. At the moment we do not have this assurance.

It is not a digression to compare this situation with that in which an individual is asked to join a clinical trial and who may be randomly assigned to receive a new treatment of as yet only conjectural benefit. We are absolutely obliged to ensure that the trial design is such that reliable information will be obtained from the study.

Since the testing and treatment of all infected individuals to end the epidemic can in no way be regarded as an undertaking with an assured successful outcome, it really is a trial, based on an hypothesis somewhat supported perhaps by mathematical modelling. As such it will require written informed consent from the participants.

I wonder what such a consent form would look like. It is possible, actually likely, that a consent form outlining possible risks and benefits would dissuade many from participating.
The disincentive would be felt by those infected individuals who do not themselves require antiretroviral treatment.

This inconvenient obstacle can be easily eliminated.

All that is needed is for treatment guidelines to include a recommendation that antiviral treatment should be offered to all infected individuals, even those with greater than 500CD4 lymphocytes. A precedent has now been set where treatment recommendations can be made on the flimsiest of evidence. The inappropriate use of retrospective observations to justify an earlier start to antiretroviral treatment is a good example.

So all one needs to do is to move the goal posts a little further and declare that antiretroviral treatments should be given to all HIV infected individuals, irrespective of CD4 count. There should be no difficulty in selecting retrospective observations that will support this recommendation. In the field of HIV/AIDS you can probably find retrospective data to fit whatever idea you are interested in promoting.

There is another tool available to promote the contention that every HIV infected individual, irrespective of CD4 count will benefit from antiviral therapy. This useful tool is called “expert opinion”. (Actually, people billed as “experts” have already expressed this opinion).

The problem with this is: what does it take to be regarded as an expert?

We may well be in an era where we have “experts” for hire.

Defining what was meant by “expert” was once much easier. Years of experience and significant contributions to the field might have been required attributes. But no longer.

Experts can seemingly be created overnight, at least by commercial entities interested in marketing a product. Their credentials are easily supplied. These instant experts will give talks at conferences, they will appear on educational programs, and even put their names to ghost written articles.

[http://healthcare-economist.com/2008/05/03/ghostwriting-by-pharmaceutical-companies/

Revealed: how drug firms ‘hoodwink’ medical journals Pharmaceutical giants hire ghostwriters to produce articles – then put doctors’ names on them.
http://www.guardian.co.uk/society/2003/dec/07/health.businessofresearch
]

As for the practice of ghost writing , there is a great deal of evidence for this, a little shown above. I’m ashamed to admit that I once (only once many years ago) allowed an employee of a drug company to write an article which carried my name. But I had done the work without their support, and in my defense, I checked every word, changing some, – an experience the writer was evidently not used to. This was my first (and only) personal encounter with this practice

I will hazard a prediction; before the year is out we will have arrived at the point that experts will state that every HIV infected person benefits from treatment, irrespective of CD4 count. If required we will see retrospective observational studies which show that in people who started treatment above a CD4 count of 500, mortality from all causes was reduced as compared to those starting below 500 CD4 cells. It should be just as easy to find retrospective data that shows that starting treatment immediately on diagnosis confers a benefit not seen when treatment is delayed to CD4 count of 350.

Of course these expert views will be very widely disseminated in press reports and on numerous web sites – some will even provide the opportunity for doctors to earn CME credit. In this way conjectures are transformed into established facts.

I don’t know how we might obtain real evidence that testing and treating all infected people is not only feasible, but would achieve its goals. The two are related.

For example, how does one ensure that all people are tested? Or that they will agree to be treated? Or that they will adhere to their treatments?
As imperfect as this is maybe one approach is to test these issues in a limited setting where mobility in and out of the selected areas can be controlled for.

This could more usefully be a trial where two different strategies were compared – the present practice of starting treatment at 350 CD4 cells, and treating everyone infected, while promoting HIV tests in both groups. Despite complications introduced by the movement of people, we might get an idea if this is a feasible and effective approach.

Sadly those bodies that instruct physicians on how to treat HIV infected people, and who tell HIV infected people what is best for them, seem to be averse to calling for prospective studies, designed to shed some light on what may in fact be best for infected people. Those who manufacture the treatments appear to prefer trials that are designed to provide them with the answer most congenial to them. Here is an account of the practice of designing trials to provide the answer most desired.
[http://www.washingtonpost.com/wp-dyn/content/article/2008/07/14/AR2008071402145.html]

They can also rummage in retrospective data collections selecting observations best suited to the outcome they have already decided on. Of course there is always an expert to be created to promote this outcome.

When the mathematical modeling referred to above supporting the idea of a “test and treat everyone infected” approach appeared, I wrote a reply to the Lancet which published the article. Not my letter, which was politely rejected.
I am adding a slightly edited copy of that letter here.

A recent Lancet article suggests that we could end the HIV epidemic by testing and treating all who are infected, irrespective of whether or not the individual would benefit from such treatment (R. Granich et al. 2009 Lancet 373:48).

This represents an intervention on individuals, primarily for a public health benefit. At the present time, ethical considerations make this proposal a completely indefensible approach.
The available drugs are far from benign; for a particular individual, their use is desirable and justified when their benefits clearly outweigh their risks. Treating individuals to achieve a population benefit requires a similar risk benefit assessment. F M Hodges and colleagues have addressed this issue. (EM Hodges, JS Svoboda, RS van Howe
Prophylactic interventions in children: balancing human rights with public health. J Med Ethics 2002; 28: 10-26)

To protect individual liberties they propose six conditions that should be met before for such interventions are taken. All of these are reasonable. I quote a passage from their article that outlines them.

“PROPHYLACTIC INTERVENTIONS FOR PUBLIC HEALTH BENEFIT”
Prophylactic medical interventions are frequently performed on healthy individuals who have given informed consent. …..
The most common example arises when the patient is at significant risk of contracting a life- and public health-threatening illness for which the proposed prophylaxis is a proven preventive. In order to safeguard individual liberties, the situations in which such procedures may be undertaken for public health benefit must meet the following requirements:
1. The danger to public health must be substantial.
2. The condition must have serious consequences if transmitted.
3. The effectiveness of the intervention in safeguarding the majority of the public against the particular malady must be well established.
4. The intervention must be the most appropriate, least invasive, and most conservative means of achieving the desired public health objective.
5. The individual must be provided with appreciable benefit not dependent on speculation about hypothetical future behaviours of the patient.
6. The burden to the individual’s human rights and health must be balanced against and found to be substantially outweighed by the benefit to society in helping prevent a highly contagious disease or other potentially calamitous condition from affecting the public health”.
Clearly the proposal to treat all infected people will include some in whom the fifth consideration will not be met, but the concerns are covered in the sixth one. But here the benefit to society must be assured, or more practically, be considered to be highly probable, with credible evidence produced to support the contention (as stated in the third consideration).

While the first two criteria are very clearly met, the present proposal to treat all who test positive fails utterly on the third point. It is far from well established that antiviral treatment of all who are infected will protect the “majority of individuals” in diverse settings. Among problems acknowledged by the authors are those related to toxicity, adherence and the development of resistance to the antiviral drugs. To this must be added the possible negative effects on behaviour deriving from a perception of being non infectious. The fourth condition is also not met. We cannot state that we have exhausted the utility of prevention education and promotion of condom use.

Let alone the questionable wisdom of mounting an extensive and expensive public health intervention that is based only on mathematical modeling, we are very far from possessing information that would supply the slightest confidence that such a measure would effectively meet its objective.
Regarding adherence, the optimism presented by the authors based on studies in Malawi is hardly justified. Adherence by individuals who may be ill, and certainly know they are receiving medications for their own benefit tells us nothing about adherence by people who feel healthy and know they are not taking the medications to benefit themselves.

The general relationship between viral load and infectivity is well established. The success of the proposed strategy according to the model presented depends on achieving a significant reduction in viral load from the pre-treatment value. The solid evidence of the potent ability of antiviral drugs to very substantially reduce viral loads in a sustained fashion derives predominantly from observations in settings where untreated endemic or concurrent infections are uncommon. The ability to achieve a sustained significant drop in viral load may be more difficult where there is a high prevalence of untreated endemic or associated infections. This is the case in parts of Sub Saharan Africa. Many of these infections are able to activate and enhance HIV replication, through the action of pro inflammatory cytokines. Should these infections be associated with genital ulceration there are additional uncertainties.
HIV disease is characterized by an enormous variability in the rates of disease progression. There is no such thing as a standard course of disease progression that is one of the assumptions used in the modeling. We know very little about the distribution of different rates of disease progression among infected individuals, or about the influence on this of associated untreated infections.
Risking individual harm for a public benefit is a slippery slope. Will we see a proposal to administer (with consent, of course) antiretroviral medication to the whole sexually active population, HIV infected or not?

AIDS is a preventable disease. We have far from exhausted less conjectural, as well as less speculative approaches to its prevention.

Addendum
Apart from this proposed strategy to treat all infected people, there definitely are situations where treatment as prevention is absolutely appropriate and desirable. One is post exposure prophylaxis (PEP), where individuals who have been exposed to HIV attempt to prevent infection by rapidly taking antiretroviral drugs – that is within 72 hours of exposure. This applies to both occupational and sexual exposure. Regarding sexual exposure – where feasible, which is certainly the case in N America Europe and in many other regions, a 3 day supply of drugs should be available 24 hours of the day, given the limited time frame for action. Measures to immediately start PEP immediately should of course be available where occupational exposure is a risk. Emergency departments should be equipped and ready to start the protocols for PEP. People at risk should even be encouraged to keep a 3 day supply of drugs at home to cover times when medical care is not available – at night or weekends. .Very importantly people at risk must be informed of the availability of PEP.

The second is pre exposure prophylaxis. This is taking antiretroviral drugs on specific occasions when there might be a risk of exposure. This absolutely cannot replace the use of condoms, but some individuals may wish to take an additional even if unproven preventative measure. This really is a matter for individual choice. Our obligation is to make it very clear that this is not a substitute for condoms.