Posted on April 13th, 2009 2 comments
“Starting HIV Therapy Earlier Saves Lives”
“Study: Treatment for HIV Should Start Earlier”
“Starting Therapy Earlier Found to Improve Survival”
“Earlier HIV Treatment Boosts Survival”
With headlines like these you would think that there is a clear answer to the question of when is it best for HIV infected people to start antiretroviral treatment. There can be no doubt at all that starting antiviral therapy early – in this case at a CD4 count above 500 improves survival. These headlines, addressed to HIV infected individuals their physicians and the public are a unanimous response to a study that just appeared in the New England Journal of medicine (NEJM). http://content.nejm.org/cgi/content/full/NEJMoa0807252
But is this confidence justified?
Unfortunately, despite these headlines, the study which occasioned them was absolutely unable to justify the conclusion ; we still do not know when it’s best to start treatment.
The study examined data that had been previously collected. It was a retrospective observational study with all the problems inherent in such studies. These have been outlined in a previous post.
About a week after this study appeared in the NEJM, another large retrospective observational study was published in the Lancet (April 9th 2009
While both studies support the desirability of not delaying a start to antiviral therapy to a CD4 count below 350, they do differ with respect to the reported benefits of starting above that number. The Lancet study, whose lead author is Jonathan Sterne, finds a decreasing benefit at start times increasing above a CD4 count of 350, with nothing at starting around 400.
The authors of both reports agree that prospective randomized studies are the best way to approach a resolution of the “when to start” question – a question that might have already received a reliable general answer had we begun these studies in 1997, as some of us suggested we do at that time.
Obviously we cannot just wait for the results of randomized prospective studies. We do need guidelines now, but any recommendation based on available information must be regarded as provisional, until the results of prospective randomized studies are in. It is important that this be clearly stated. If we are ever going to be able to enrol a prospective randomized study then we cannot afford to delude ourselves that the answer to the when to start question is already known.
While the lead author of the New England Journal of Medicine did pay homage to prospective randomized trials – and a kind of ritualized homage is exactly what it sounded like, this gesture most certainly did not inhibit her from unreservedly recommending an earlier start to treatment, a start even at a CD4 count above 500, without conducting such a prospective study. Her conclusion:
“The early initiation of antiretroviral therapy before the CD4+ count fell below two
prespecified thresholds significantly improved survival, as compared with deferred
One of these prespecified thresholds was a count 500 CD4 lymphocytes.
This categorical statement, arrived at by the kind of study that cannot possibly justify such confidence, will have a negative effect on enrolment in proposed randomized trials, which are in fact the kind of study that can provide conclusions in which we can have justified confidence.
This study may well be the last coffin nail in any hopes there may have been for the completion of prospective randomized trials designed to address the “when to start” issue. It may now be impossible to enrol, and will never get off the ground. This difficulty is made so much worse by the kind of uncritical headlines shown above
I wonder how the commentators who rushed so uncritically to announce Dr Kitahata’s conclusion on the benefits of starting treatment at CD4 counts even greater than 500 will respond to the Lancet report, which did not find a benefit with starting at such high CD4 numbers? I hope I’m wrong in suspecting that this study will be largely ignored; the headlines trumpeting the survival benefit of starting treatment early – even above a CD4 count of 500 will not be marred by any doubt introduced by the study reported in the Lancet.
Among the problems with the New England Journal of Medicine study is that a significant number of people were left out of the analysis, because their HIV disease failed to cooperate with preconceived notions about the course of this disease.
This is a significant criticism and I will try to explain why. The study examined two groups of people, one with over 500 CD4 lymphocytes, and one with CD4 counts between 351 and 500.
Let’s just take the 351 to 500 group. Here, deaths in those starting at counts between 351 and 500 were compared with deaths in those starting below 350. Sounds reasonable? Maybe, until we learn that significant numbers of people with 351 – 500 CD4 cells who did not start treatment also did not progress to below 350 CD4 cells. So the authors just left these people out of their calculations. They in effect did not exist for the investigators.
The recommendations the authors make are meant for all people, including those who did not progress and were left out of the analysis. These people are also going to be treated with drugs they don’t need, as they cannot be identified.
I suppose this will do wonders for drug sales, but there will be individuals taking drugs for no reason and some may only suffer their ill effects as well as cost while deriving no benefit.
Here is another serious problem with this study.
Among those people with CD4 counts between 351 and 500, it is important to know just how long treatment was delayed in those who waited until their counts fell below 350. This information was provided; the median count at the time of starting treatment among all who waited was 286. But what was the CD4 count at starting treatment among those in this group who died?
This information was not given – at least I was unable to find it.
Could there have been those starting treatment with counts below 100, below 50 – maybe even below 20. In an extreme example, if a person waited to start treatment to a point close to death, there would not be much surprise that delaying treatment initiation is associated with a worse outcome.
Many physicians are proud that the field has abandoned uncritical authority as a guide to practice and has now embraced evidence based medicine. David Sackett, one of its originators, has stated that one pillar of evidence based medicine is the use of the best external evidence in making clinical decisions.
All too frequently physicians, while priding themselves on practising evidence based medicine, somehow are still able to make decisions based solely on their unproven beliefs, as if they have a private source to the truth, some special access to an oracle. I have heard one physician state that anyone with a viral load should be treated, another saying essentially the same thing in stating that he would treat every HIV infected patient no matter what the CD4 count. How on earth have they arrived at these conclusions? Patients might just as well seek advice from a palm reader.
As always you can’t beat the truth. No matter what the private sources of information to which some physicians and patients apparently have access, the truth remains that apart from people with under 200 CD4 cells the best time to initiate antiviral therapy is unknown.
I have once before faced this kind of opposition to conducting a randomized prospective study to address the question of when is it best to start treatment. In the early 1990s I participated in an effort to conduct a trial of early versus deferred treatment with AZT. A pilot study was initiated, and I participated with some statisticians in describing the study to numbers of physicians in New York City, with the hope of encouraging them to enrol patients. Despite expressions of enthusiasm, the response was so dismal that the trial could never take place. However there was one physician – just a single physician in San Jose who was able to recruit many more patients than all the others combined. He was so successful that we asked him to come to New York City to explain how he was able to enrol so many patients. His answer was simple. He told patients the truth. He did not know when it was best to start treatment, so he and his patients let the toss of a coin determine this, as a means of finding out what was best by participating in a study.
This means that the other doctors were unable to say they did not know. Maybe, as is the case today some actually felt that they did know, as they had complete faith in their intuition, or perhaps had some private access to the truth. For these physicians the practice of medicine is more akin to a faith based activity. Maybe other physicians did not know when it was best to start treatment, but might have felt unable to admit this; maybe some patients felt they knew and physicians acceded to their wishes.
The rational response to uncertainty – having first overcome the hurdle of being able to admit that there is uncertainty – is to try to resolve this by the best means available.
I fear we are not even close to recognizing that there is uncertainty about when to start treatment in people with over 200 CD4 cells. The NEJM article exacerbates the problem with its assumption of certainty, an assumption very sadly shared by some health care providers, some journalists and community commentators to whom HIV infected people turn to for advice.
In conclusion I cannot lose an opportunity to yet again bring attention to the need to individualize therapy. The rate of HIV disease progression is so widely variable that there are limitations in setting a fixed CD4 count as a guide to start therapy. A prospective appropriately designed trial can tell us if on average it is better to start above rather than below a certain CD4 count, or on average it is better to start treatment immediately or to defer it.
It is the “on average” limitation that needs fine tuning for each individual patient.
Not only will the rate of disease progression vary widely between patients, but there are other individual considerations that impact the decision to start treatment. For example, adequate housing, mental health issues, co morbidities and many other factors need to be considered.
These two aspects, the general and the particular, fit so very neatly into David Sackett’s description of evidence based medicine that I will quote a passage:
“The practice of evidence based medicine means integrating individual clinical expertise with the best available external clinical evidence from systematic research. By individual clinical expertise we mean the proficiency and judgment that individual clinicians acquire through clinical experience and clinical practice“.
BMJ 1996;312:71-72 (13 January) : Evidence based medicine: what it is and what it isn’t. David L Sackett, William M C Rosenberg, J A Muir Gray, R Brian Haynes, W Scott Richardson
The best available external evidence will be the results of a prospective randomized trial; these will provide general guidance. Individual clinical expertise will apply this to particular patients, taking into account many factors, not least of which is the patient’s rate of disease progression.
A previous post discusses the issue of individualization of treatment.
If we took individualization of treatment seriously, we could in fact come some way to identifying rapid and slow/non progressors. See previous post on individualization of treatment.