Seropositivity for HIV and the development of AIDS or AIDS related condition: three year follow up of the San Francisco General Hospital cohort.

The three year actuarial progression rate to the acquired immune deficiency syndrome (AIDS) in a cohort of men in San Francisco who were seropositive for the human immunodeficiency virus (HIV) was 22%. An additional 26 (19%) developed AIDS related conditions. Beta 2 Microglobulin concentration, packed cell volume, HIV p24 antigenaemia, and the proportion and number of T4 lymphocytes each independently predicted progression to AIDS. Beta 2 Microglobulin was the most powerful predictor. The 111 subjects tested who were normal by all predictors (40%) had a three year progression of 7%, and the 68 subjects who were abnormal by two or more predictors (24%) had a progression rate of 57%. Two thirds of all men who progressed to AIDS were in the last group. The median T4 lymphocyte count in subjects who did not progress to AIDS fell from 626 x 10(6) to 327 x 10(6)/l. HIV p24 antigenaemia developed in 7% of the subjects per year. The proportion who were abnormal by two or more predictive variables rose to 41%. At three years an estimated two thirds of the seropositive subjects showed clinical AIDS, an AIDS related condition, or laboratory results that were highly predictive of AIDS. It is concluded from the observed rates and the distribution of predictive variables at three years that half of the men who were seropositive for HIV will develop AIDS by six years after the start of the study, and three quarters will develop AIDS or an AIDS related condition.