Evalution of secular trends in cd4+ lymphocyte loss among human immunodeficiency virus type 1 (HIV-1)-infected men with known dates of seroconversion

The rate at which immunodeficiency develops in untreated human immunodeficiency virus type 1 (HIV-1)- infected persons might be increasing or decreasing over time because of viral evolution or other factors. Beginning in 1984, Multicenter AIDS Cohort Study investigators recruited HIV-1-seronegathve homosexual/ bisexual men from four US metropolitan areas and examined them semiannually for HIV-1 seroconversion. To assess possible secular changes in the natural history of HIV-1 infection, the authors examined CD4+ lymphocyte data from 354 men who seroconverted between 1984 and 1991. To control for measurement differences among centers and over time, the authors adjusted CD4+ lymphocyte values to those of persistently seronegative participants. CD4+ lymphocyte percentage measurements at the first seropositive visit formed a U-shaped pattern, with the lowest values observed in 1988 and 1989. The authors observed no consistent secular pattern of CD4+ percentages at later visit dates, except that mean CD4+ percentages were consistently lowest in men who seroconverted in 1988. In a proportional hazards model, the time to the adjusted CD4+ lymphocyte count of <500 cells/mm³ was not associated with the secular time of seroconversion (relative hazard = 1.05, 95% confidence interval 0.97-1.13). The authors' data do not suggest a major change in the natural history of HIV-1 infection in this population. Am J Epidemiol 1995;142:636-42.