DIFFERENCES IN TIME FROM HIV SEROCONVERSION TO CD4-POINTS AND AIDS INCOHORTS OF HOMOSEXUAL MEN( LYMPHOCYTE END)

Objective: To evaluate the decline in CD4+ counts in relation to the i ncidence of AIDS in different cohorts of homosexual men and to quantif y possible consequences of laboratory variation in CD4+ measurement. M ethods: Our study includes 403 men with well documented dates of HIV s eroconversion originating from five cohort studies among homosexual me n. Differences in time from HIV seroconversion to the first CD4 + coun t dropping < 500 or 200 x 10(6)/l and to AIDS were evaluated using Kap lan-Meier survival analyses. Results: We found considerable difference s between cohorts in CD4+ depletion, but not in the incidence of AIDS (1987 definition). Conclusions: Variation in CD4+ depletion appears to be mainly the result of laboratory differences. Policy recommendation s on a basis of CD4+ counts probably requires a calibration of measure ment. The 1993 AIDS case definition leads to a site-specific shortenin g of the incubation time, which complicates the study of the natural h istory of HIV infection and of trends in the AIDS epidemic.