THE IMPACT OF EXPOSURE GROUP ON THE PROGRESSION RATE TO ACQUIRED-IMMUNODEFICIENCY-SYNDROME - A COMPARISON BETWEEN INTRAVENOUS-DRUG-USERS, HOMOSEXUAL MEN AND HETEROSEXUALLY INFECTED SUBJECTS

The objective was to study the impact of exposure group on the progres sion rate to the acquired immunodeficiency syndrome (AIDS). 289 subjec ts in Oslo, Norway, infected with the human immunodeficiency syndrome (HIV) and without major clinical signs of HIV infection (102 intraveno us drug users, 151 homosexual men and 36 heterosexually infected subje cts) were recruited to the Oslo HIV Cohort Study from 1989 and followe d until 1 January 1995. 15 (14.7%) of the intravenous drug users, 56 ( 37.1%) of the homosexual men and 5 (12.5%) of the heterosexually infec ted subjects developed AIDS during a mean time of 47 months (p < 0.001 , log rank test). When controlling for possible confounding variables (age, number of CD4+ lymphocytes, antiviral therapy at study entry, ge nder and year of HIV diagnosis), the relative risk of AIDS progression was 2.2 [1.1-4.5, 95% confidence interval (CI)] for homosexual men an d 0.5 (0.2-1.3, 95% CI) for heterosexually infected subjects as compar ed to intravenous drug users. In a subgroup with known time of serocon version (n = 60), 47% (18/38) of the homosexual men, 20% (3/15) of the intravenous users and none (0/7) of the heterosexually infected subje cts developed AIDS (p = 0.04, log rank test). The results suggest that homosexual men have more rapid progression to AIDS than intravenous d rug users and heterosexually infected subjects.