Dec 22, 2003
At the risk of being thought of as of as a bit of a curmudgeon, I am writing in response to your recent posting concerning the patient who had recently begun treatment after being diagnosed with PCP and was attempting to ascertain his life expectency. I think your answer was very sound in suggesting that treatment adherence was crucial to increased lifespan; my question, though, is epidemiological: are there any longitudinal studies that track the increasing life expectencies of individuals on HAART?
It appears to me that most evidence has been anecdoctal up to this point, and that our understandings of "Lazarus" scenerios -- whereby people came back to the living after starting new drug protocols -- are less valuable now that an increasing number of people are diagnosed HIV+ before becoming ill, begin treatment with relatively more intact immune systems, and consequently look forward to their remaining livespans trying to balance possible side effects, quality of life issues, and the economic and social ramifications of chronic illness and treatment. Has anyone that you know of engaged in this kind of work?
Response from Dr. Pierone
You points are very true; we do need studies that track people with HIV infection to determine the future trends and consequences of the HIV pandemic. There are a number of groups doing epidemiological work and attempting to answer basic questions about the effect of HIV infection on future morbidity and mortality.
The general premise is to take several years of longitudinal data on cohorts of HIV-infected people and use this information to develop a model for future predictions on medical complications and ultimate lifespan. For example, one can measure how long the average first regimen lasts before resistance occurs, then the second, third, and salvage. Then based on this data, one can assign rates of viral resistance, impact of resistant virus on CD4 count decline, and mortality based on CD4 count to construct a mathematical model to predict future survival. Another piece of such a model might be to take the average cholesterol increase in a population of HIV-infected patients on therapy and plug this into a Framingham calculation to estimate the future impact of cardiovascular mortality. The challenges of creating these models are formidable. Many of the large cohorts of HIV-infected patients that are underway have large numbers, but are shallow in terms of longitudinal data. Other cohorts have longer follow up, but don't contain data critical to the build these models (resistance data, cholesterol levels, hepatitis status, smoking status, etc) so a best guess has to made. Unless the assumptions are reasonable, and the model is soundly designed, the results may not mean very much. But this work is necessary in order for health planners to predict future needs and trends.
What none of these models can do is to take into account transformational advances in treatment. For example, what if 10 years from now we treat HIV infection by giving once monthly intravenous infusions of antiretroviral cocktails combined with a therapeutic vaccine? For the sake of argument, this new treatment reconstitutes immune function much better than current therapy and almost never leads to resistance. How does one put an advance of this into a model? The 1994 models of HIV survival did not take into account the impact of HAART (how could they, it didn't exist) and the companies buying life insurance policies of HIV-infected patients got creamed (another point for the home team!).
Another thing that none of these models can do is answer one of the most important questions that a newly diagnosed person with HIV infection asks - what does the future hold for me? I believe that the answer for that individual depends largely on how much they want to live and if they have what it takes to survive and thrive with HIV. If one has untreated depression, smokes cigarettes, abuses alcohol and crack cocaine, is in and out of jail, and stays away from doctors, the prognosis of HIV infection is terrible. But for someone else that wants to live, can navigate the healthcare system, has the discipline to take medications without fail, the prognosis is excellent.
The "Lazarus" stories are anecdotal, but essential. For someone who has just been diagnosed with AIDS and come through a near death experience, the natural assumption is that life is basically over. These true stories demonstrate that is not the case, it possible for persons with AIDS, even those in desperate straits, to regain health and resume a high quality life. GP
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