India has an estimated 177,000 injection drug users (IDU) with a national HIV prevalence of 7.14%. Reliable estimates of HIV incidence are not available for this population.
We report HIV incidence in a cohort of male, HIV-negative IDUs recruited through peer-referral, targeted outreach and as walk-in clients in Delhi from May to October, 2011. Fourth-generation Antigen–Antibody tests were used to diagnose new infections and results were confirmed using Western blot tests. HIV incidence based on HIV seroconversion was calculated as number of events/person-years. Cox regression was used to identify significant (p<0.05) seroconversion predictors.
A total of 2790 male HIV-negative IDUs were recruited at baseline; 67.4% (n=1880) returned for their first follow-up visit and 96% (n=1806) underwent HIV testing. Participants were followed for a median of 9.7 months. A total of 112 new HIV infections occurred over a cumulative 1398.5 person-years of follow-up resulting in an incidence rate of 8.01 new infections/100 person-years (95% CI: 6.65–9.64); 74% of these participants reported risky injection practices in the past month. In multivariate analysis, moderate-high risk injection behaviors (Adjusted Hazard Ratio [AHR] 2.59; 95% CI 1.45–4.62) were associated with a higher risk of new infections.
Male IDUs in Delhi continue to practice unsafe injection practices leading to high sero-incidence despite the availability of HIV prevention services offered through targeted intervention programs.