Population-level impact of Avahan in Karnataka state, south India using multilevel statistical modelling techniques.

OBJECTIVE: To assess the population-level impact of "Avahan," the India AIDS Initiative of the Bill & Melinda Gates Foundation, between 2003 and 2008 in Karnataka state, India. DESIGN: Secondary data analysis using all consistent data collection sites from antenatal clinic (ANC) sentinel surveillance data from 2003 to 2008 in Karnataka. METHODS: A multilevel logistic regression model considering individual- and district-level variables was developed to compare time trends in HIV prevalence among young ANC women (younger than 25 years of age) between Avahan (18) and non-Avahan (9) districts. District-level random effects were considered for the intercept and time. The impact was assessed using interaction terms between district type (Avahan vs. non-Avahan) and time. The number of cases averted was estimated, comparing predicted ANC HIV prevalence in the presence versus the absence of Avahan. Data from the National Family Health Survey Round 3 (2006) were used to extrapolate these numbers to the general population. RESULTS: HIV prevalence among young ANC women declined from 1.46% (2003) to 0.83% (2008). The HIV prevalence trend was significantly different between Avahan and non-Avahan districts (P = 0.046). Overall, 87,035 cases of HIV infection were estimated to have been averted in the Karnataka general population because of Avahan during the 2003-2008 period (range under varying assumptions: 55,160-150,784). CONCLUSIONS: Our results suggest that Avahan has had a significant impact on the HIV epidemic in the general population of Karnataka. These results suggest that targeted interventions similar to Avahan should be implemented and scaled up in all concentrated and mixed HIV epidemics.

Is HIV prevalence declining in southern India? Evidence from two rounds of general population surveys in Bagalkot District, Karnataka.

OBJECTIVES: To assess the levels and trends in the prevalence of HIV and sexually transmitted infections in the general population in Bagalkot district using 2 cross-sectional surveys undertaken in 2003 and 2009. METHODS: In both surveys, a target sample of 6600 adult males and females was selected systematically from a sample of 10 rural villages and 20 urban blocks in 3 of the 6 talukas (subdistrict units) in the district. Urine and blood samples were collected from all consenting participants for HIV and sexually transmitted infection testing. Changes in HIV prevalence in age subgroups were determined by logistic regression, taking into account the survey design. RESULTS: HIV prevalence fell not significantly from 3.2% to 2.5% during the 6-year study period. It decreased significantly (P = 0.023) among persons aged 15 to 24 years, from 2.4% in 2003 (95% confidence interval [95% CI]: 1.2-3.7) to 1.3% in 2009 (95% CI: 0.6 -2.0). However, among males aged 35 and above, HIV prevalence increased significantly (P = 0.008), from 3.0% (95% CI: 1.1-4.8) to 4.2% (95% CI: 1.8-6.6), a level similar to that found in the younger age-group in 2003. CONCLUSIONS: We observed a significant decline in HIV prevalence among people aged 15 to 24 years, where HIV prevalence more closely reflects incidence. The increase in HIV prevalence among older males may have been because of the aging of a cohort of men among whom HIV prevalence was highest in the 2003 survey. It may also have in part reflected increased survival, as a result of the scaling up of antiretroviral treatment programs throughout the district and state.