NUMBER OF SEXUAL PARTNERS, CONDOM USE AND RISK OF HUMAN-IMMUNODEFICIENCY-VIRUS INFECTION

Background. To analyse the relation between number of sexual partners, selected sexual habits and the risk of human immunodeficiency virus ( HIV) infection. Methods. We conducted a case-control study nested in a cross-sectional survey conducted among subjects attending sexually tr ansmitted diseases (STD) clinics in Northern Italy. Eligible for the s tudy were 1711 subjects (1259 males, 452 females) who referred themsel ves for the first time between September 1988 and March 1993 to three STD clinics in Northern Italy for suspected STD or STD treatment. A to tal of 145 subjects (113 males and 32 females) were HIV positive. Resu lts. In comparison with subjects reporting no or one sexual partner ov er the 3 years before the interview, the estimated odds ratios (OR) of HIV serum positivity were 1.2 (95% confidence interval [CI] : 0.6-2.3 ), 0.8 (95% CI : 0.4-1.8) and 0.3 (95% CI : 0.4-2.5) in subjects repor ting 2-3, 4-5, and greater than or equal to 6 partners, respectively. The results were similar considering separately males and females and in men reporting only homosexual partners. Regular condom use decrease d the risk of HIV infection: in comparison with subjects reporting no or occasional use of condoms, the OR of HIV infection was 0.5 (95% CI : 0.4-0.8) for regular users. Considering men only, compared with men with no homosexual intercourse, the OR of HIV infection was 2.3 (95% C I : 1.4-3.9) in those reporting bisexual intercourse and 2.2 (95% CI : 1.2-4.2) in men reporting only homosexual intercourse (among homosexu als), There was no relation between HIV infection risk and receptive a nal sex. Conclusions. The risk of HIV infection does not increase line arly with the number of sexual partners in this population. This is re asonable, as the prevalence of HIV infection in this population is ess entially determined by drug use. Caution is needed in the interpretati on of these results since the analysis of role of number of sexual par tners in male intravenous drug users is impaired by low statistical po wer.