• Effectiveness of Antiretroviral Therapy in the Elderly Compared to a Younger Cohort (Poster 340)
  Authored by A. Chakroborty, V. Waring, and I. E. Salit
  View the original abstract

Several studies have shown that older age is an important risk factor for accelerated HIV-disease progression. And this is independent of the duration of HIV infection, the clinical stage of HIV-disease, or CD4+ cell counts. The presence of co-morbidities (other diseases) affecting older patients could play a significant role in the increased frequency of complications in HIV-infected individuals as age advances.

In sharp contrast with the above-mentioned studies, other studies have demonstrated that virologic response to highly active antiretroviral therapy may be superior in older persons (like it happened in ACTG 320). We do not know if there is a biological reason for this, or it is the trivial explanation that older people tend to be more adherent to therapies.

As we age it is not only our eyesight and hair that declines. Our immune system takes a hit too. There is an increase of memory cells and a decrease of naive T cells (probably because the thymus does not work as well as it did when we were younger), so we might not be able to fight new infections as well as when we were younger.

The normal thymic function decreases with age (NOTE for the uninitiated: the thymus is the organ where the final differentiation of T-cell lymphocytes takes place, it is inside the chest, and as we age it tends to become smaller and smaller). It has been suggested that older individuals would have a harder time recovering a "complete" immune system after HAART.

In this study, the group from Toronto looked at their "old" clinic population and compared it to "matched" controls among the younger patients in their clinic. They did not see very many differences between them. Older people were as likely as younger patients to be on antiretrovirals, to have a nice antiretroviral response, and to have a similar CD4 response. In summary, they behaved pretty much the same after antiretroviral therapy is started. This is good news for our elders. In spite of all the theoretical considerations that would make them less likely to respond to antiretrovirals, they did just as well as the young.

Case controls studies like this one are limited because of the retrospective nature of them, and because of the fact that one can not control for all the variables that might be important (cases and controls did not receive the same antiretroviral regimen, so it is possible that the lack of difference has nothing to do with age and was more related to treatment)

Prospective trials are a better tool to use to answer these type of questions. In this kind of trial, one can control for all the variables and get a "cleaner" answer to a question. ACTG 5015 is currently looking at the immunologic and virologic responses in HIV-positive individuals less than thirty years of age and older than forty-five. All of the patients are receiving a combination of d4T, FTC, and Kaletra. Patients will be followed for a prolonged period of time. That study will allow us to answer definitely the question if there is a difference in the antiretroviral response and the immunologic recovery between the young and people who are "less young." The final answer maybe in a year or two.