The Natural History of Untreated HIV Infection in Lima, Peru: Implications for Clinical Trial Endpoints for HIV Vaccines

HIV vaccines are being developed to both reduce acquisition of infection as well as to reduce post-acquisition viral replication and disease progression. Most efficacy trials of HIV-1 vaccines are being initiated in areas of the world with high HIV incidence, yet there is little published data on the characterization of the clinical course of HIV-1 infection in these regions. 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 candidate HIV-1 vaccines are being tested. We examined 92 consecutive patients with untreated HIV-1 in calendar year 2002 seen at the specialty HIV clinic and evaluated the CD4⁺ T cell count and frequency of opportunistic infections over time. Over the course of follow-up, CD4 count decreased by a mean of 31 cells/mm3/yr 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 and the median time to CD4 count <200 cells/mm3 was 4.5 years. The most frequent observed OIs were TB, candidiasis, Pneumocystis pneumonia, Cryptococcus, and nonHodgkins lymphoma. If clinical endpoints are required to evaluate the clinical effectiveness of HIV-1 vaccines, extended clinical follow-up of subjects enrolled in such trials will be required.