Quantity, not frequency, of alcohol use moderates the association between multiple sexual partners and Trichomonas vaginalis among women attending an urban STD clinic.

objectiveThe purpose of this study is to investigate alcohol use, sexual risk behaviour and trichomoniasis in a sample of low-income, largely minority, women patients at a publicly funded sexually transmitted disease (STD) clinic in the USA.

methodsBaseline data, collected as part of a clinical trial, were used. Patients (688 women, 46% of the overall sample) completed an audio computer-assisted self-interview that included questions about their alcohol use and sexual behaviours. Trichomoniasis was determined from vaginal swab specimens obtained during a standard clinical exam.

resultsWomen (n=580; 18-56 years of age; 64% African-American) who reported that they had consumed alcohol at least once in the past year were included in the analyses. Of the 580 women, 157 were diagnosed with an STD and 80 tested positive for trichomoniasis. Trichomoniasis was associated with having multiple sexual partners (OR=1.09; 95% CI 1.01 to 1.17) but not with the number or proportion of unprotected sex events (p>0.05) in the past 3 months. Quantity of alcohol use (drinks per drinking day, drinks per week, and peak consumption) moderated the association between the number of sexual partners and trichomoniasis.

conclusionsThe number of sexual partners predicted the probability of trichomoniasis when women reported drinking large quantities of alcohol. Because having multiple sexual partners increases the risk for STD transmission, interventions designed for at-risk women should address the quantity of alcohol consumed as well as partner reduction to reduce the risk for trichomoniasis.