Objectives: To determine baseline HIV prevalence in a trial of improved sexually transmitted disease (STD) treatment, and to investigate risk factors for HIV. To assess comparability of intervention, and comparison communities with respect to HIV/STD prevalence, and risk factors. To assess adequacy of sample size.
Setting: Twelve communities in Mwanza Region, Tanzania: one matched pair of roadside communities, four pairs of rural communities, and one pair of island communities. One community from each pair was randomly allocated to receive the STD intervention following the baseline survey.
Methods: Approximately 1000 adults aged 15-54 years were randomly sampled from each community. Subjects were interviewed, and HIV, and syphilis serology performed. Men with a positive leucocyte esterase dipstick test on urine, or reporting a current STD, were tested for urethral infections.
Results: A total of 12 534 adults were enrolled. Baseline HIV prevalences were 7.7% (roadside), 3.8% (rural), and 1.8% (islands). Associations were observed with marital status, injections, education, travel, history of STD, and syphilis serology. Prevalence was higher in circumcized men, but not significantly after adjusting for confounders. Intervention, and comparison communities were similar in the prevalence of HIV (3.8 versus 4.4%), active syphilis (8.7 versus 8.2%), and most recorded risk factors. Within-pair variability in HIV prevalence was close to the value assumed for sample size calculations.
Conclusions: The trial cohort was successfully established. Comparability of intervention, and comparison communities at baseline was confirmed for most factors. Matching appears to have achieved a trial of adequate sample size. The appartent lack of a protective effect of male circumcision contrasts with other studies in Africa.
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