Population impact of output-based aid on STI treatment in Uganda

Sexually transmitted infections (STIs) represent a major disease burden in western Uganda. Beginning in 2006, the Ministry of Health initiated an output-based aid (OBA) program contracting providers to treat STI patients bearing a subsidized and socially marketed voucher. Venture Strategies and Mbarara University designed and implemented a population-based evaluation to measure the impact of the program on STI prevalence and healthcare utilization. Two quasi-experimental cross-sectional surveys were conducted: a 2006 baseline and a 2007 follow-up. Control populations were selected from comparable areas without voucher distributors. Surveys assessed respondents' socioeconomic status (SES), healthcare utilization, STI risks, use of STI treatment services, and knowledge of voucher program. Diagnostic (TPHA) and confirmatory (VDRL) syphilis tests were administered. Regression models estimated correlations between independent variables (SES, high-risk sexual behaviors, demographics) and outcomes of interest (syphilis, STI-like symptoms past 6 months, STI treatment). At baseline, 2.9% (95% CI= 2.2- 3.5%) of the surveyed population had syphilis with no significant difference between control and intervention areas. 16 months later, syphilis prevalence fell to 2.3% (95% CI 1.4- 2.9%) of the surveyed population, with lower prevalence in intervention compared to control areas, however, the difference was not statistically significant. Nearly 40% of respondents in the baseline survey reported having STI-like symptoms in previous six months and one-third of those respondents sought treatment. In the follow-up survey, fewer respondents reported STI-like symptoms (31%) but among those reporting symptoms, significantly greater numbers sought treatment (41% in 2007 compared to 33% in 2006). High-risk behaviors (unprotected sex and transactional sex) were associated with having syphilis. SES and demographics were not associated with having syphilis. However, among those reporting STI symptoms, SES variables (not high-risk sex or demographics) were associated with STI treatment. Among those reporting STI symptoms, ‘lacking funds' was the most frequent reason to not seek treatment. Populations exposed to vouchers had lower syphilis prevalence compared to controls. The difference, however, was not statistically significant. Populations exposed to vouchers had significantly higher use of STI treatment services compared to controls. OBA vouchers were effectively targeted to individuals reporting STI-like symptoms and individuals with low SES. In our analysis, OBA is an effective strategy to treat populations using targeted subsidies.