INCIDENCE OF HIV-INFECTION IN A COHORT OF HOMOSEXUALLY ACTIVE MEN

The purpose of this study was to estimate the incidence of human immun odeficiency virus (HIV) in a cohort of homosexually active men in Sydn ey. In 1984-85 the Sydney AIDS Prospective Study enrolled homosexually active men, who were followed by six-monthly visits, although regular contact with most participants ceased in the early 1990s. In 1993-94 a major effort was made to establish the HIV status of all participant s who had attended more than once. Of the 1075 men enrolled, 528 (49 p er cent) were negative at enrolment and had at least one further docum ented HIV test. The annual incidence rate of HIV infection was highest in the early years of the study, 1984 (9.6 per cent) and 1986 (5.0 pe r cent), and remained low from 1987 (1.9 per cent) to 1994 (0.0 per ce nt). The incidence of HIV infection was higher among men aged under 34 years at enrolment and men who reported more than four sexual partner s in the six months before enrolment, but these associations disappear ed by 1987. The decrease in HN incidence is consistent with findings f rom other cohorts followed for this length of time.