The natural history of untreated HIV infection in Lima, Peru: implications for clinical trial endpoints for HIV vaccines.

Abstract

Most candidate HIV vaccines are directed at priming memory T cell responses and are being evaluated on their effects on post acquisition viremia and/or disease progression. These vaccines are being studied in areas of high HIV-1 prevalence. As such, we evaluated the frequency of CD4+ T cell decline and time course of opportunistic infections of patients presenting at a major metropolitan hospital in Lima, Peru, an area where such candidate vaccines are being tested. We examined 92 patients with untreated HIV-1 in calendar year 2002: 35% presented with CD4+ T cell counts of <200, 25% between 201 and 400, and 17% with >400 cells/mm3, 30 of 92 patients presented with overt AIDS, 6 were without an AIDS defining OI but CD4 counts <200. Over the course of follow-up, CD4 count decreased by a mean of 31 cells/mm3/year in women and 28 in men (p>0.5). Among persons presenting with CD4 counts >250 cells/mm3, the median time to first OI was 3.5 years. If clinical endpoints are required to evaluate the clinical effectiveness of T cell based vaccines, extended clinical follow-up of subjects enrolled in such trials will be required.