Trends in sexual behaviour and the incidence of sexually transmitted diseases and HIV among drug-using prostitutes, Amsterdam 1986–1992

Abstract

To determine trends in commercial sexual risk behaviour among drug-using prostitutes in Amsterdam after local and national prevention campaigns began in 1987. A subgroup of 281 drug-using prostitutes was selected from a comprehensive, open cohort study of drug users in Amsterdam. Cross-sectional (at intake) and within-person trends in sexual behaviour were evaluated. Person-time analysis was used to determine trends in incidence of sexually transmitted disease (STD). From 1986 to 1992, 'always' use of condoms in the 6 months preceding intake increased from 21 to 58% (P < 0.001) and the number of commercial contacts declined from 84 to 64 per month (P = 0.06). Consequently, the mean number of unprotected commercial contacts declined from 26 to nine per month (P < 0.001). Temporal trends within individual prostitutes from visits 1 to 8 (mean interval between visits, 4 months) showed a somewhat larger risk reduction than the cross-sectional trends. From 1989 to 1992, the STD incidence declined from 61 to 40 episodes per 100 person-years (P = 0.06). Prostitutes residing in Amsterdam for shorter time periods reported more STD and a relatively small core group reported the majority of STD episodes. At intake, when < 10% of all participants knew their HIV serostatus, HIV-positive prostitutes reported significantly lower levels of condom use and more STD than HIV-negatives, while, after learning their serostatus, levels of condom use and the STD-incidence were comparable. Prevalent and incident HIV infections were not observed among non-injecting prostitutes. Drug-using prostitutes have reduced sexual risk behaviour. There is evidence for the effectiveness of HIV testing and counseling. At present, new infections among clients of drug-using prostitutes are expected to occur, although not on a large scale. Since the incidence of STD continues to be high, it is important to monitor the spread of HIV among heterosexuals, including prostitutes and their clients, closely.