Long-term effects of condom promotion programmes for vaginal and oral sex on sexually transmitted infections among sex workers in Singapore

Abstract

To evaluate the long-term impact of condom promotion programmes for vaginal and oral sex among female brothel-based sex workers in Singapore. A pre-test/post-test comparison group followed by a time series design was used to compare trends in condom use for vaginal sex and cervical gonorrhoea incidence from 1990 to 2002 across cross-sectional samples of sex workers before and after programme implementation in 1995. The subsequent condom promotion programme for oral sex was evaluated using the interrupted time series with a retrospective pre-test to post-test matched control group design. Sex workers completed a questionnaire before and 6 months after participation in educational sessions. Cervical and pharyngeal swabs were taken monthly for cultures for Neisseria gonorrhoeae. Consistent condom use for vaginal sex increased significantly from 30 to 2/1000 person-months. Adjustment for temporal changes in sociodemographic characteristics did not materially alter the trends. Consistent oral condom use increased significantly from 12 to 4.7/1000 person-months. The interventions produced sustained high levels of condom use for vaginal and oral sex with corresponding declines in cervical and pharyngeal gonorrhoea incidence.