Drug injection and sexual mixing patterns of drug-using male sex workers

Background: Drug-using male sex workers (DUMSWs) are known to have large numbers of drug injection and sex partners. Goals: The purpose of this study was to describe the assortative and disassortative drug injection and sexual mixing patterns of DUMSWs. Implications of the high rates of disassortative mixing patterns of DUMSWs for HIV infection are discussed. Implications of disassortative mixing of DUMSWS with regard to DUMSWs bridging disparate HIV risk groups are evaluated. Study Design: Data were collected from 89 DUMSWS. Data on up to six drug injection and six sex partners were collected from respondents. One hundred drug injection and 169 sex respondent/partner pairs were analyzed for the proportions of pairs that were concordant (like) or discordant (unlike) in gender, trading sex for money, race/ethnicity, and age cohort. For race/ethnicity and age, within-group differences were assessed with chi-square statistics. Results: Data showed high proportions of discordant respondent/partner pairs for both drug injection and sex by gender, trading sex for money, race/ethnicity, and age. Significant within-group differences in rates of discordant pairs were found for both behaviors in relation to race/ethnicity and age. Minority persons and respondents 19 years of age or younger were more likely to be in discordant pairs. Conclusions: Direct assessment of HIV risk posed by the mixing patterns was not possible. Elaborating the mechanisms by which DUMSWs might act as an epidemiologic bridge is complex and involves more variables than were explored in this study. Nevertheless, such a study would be worthwhile.