Respondent-driven sampling is more efficient than facility-based strategies at identifying undiagnosed people who inject drugs living with HIV in India.

ABSTRACT

INTRODUCTION: Injection drug use drives HIV epidemics in many low-resource settings, yet many people who inject drugs (PWID) living with HIV are not diagnosed. We assessed the ability of respondent-driven sampling (RDS) - which uses peer network connections - to identify undiagnosed PWID living with HIV compared to a facility-based strategy in India. METHODS: In six Indian cities from 2014 to 2017, integrated care centers (ICCs) provided HIV testing. From 2016 to 2017, RDS samples of PWID in these same cities were conducted. Using biometric matching, characteristics associated with identification by RDS only and both RDS and ICC, compared to ICC only were explored. Undiagnosed individuals tested positive and did not report a prior diagnosis. The number needed to recruit (NNR) (average number recruited to find one undiagnosed PWID living with HIV) and the identification rate (average number undiagnosed PWID identified per week) assessed the efficiency of RDS vs. ICCs. RESULTS: There were 10,759 ICC clients and 6012 RDS participants; 40% of RDS participants were also ICC clients resulting in 14,397 unduplicated PWID. PWID identified by RDS vs. ICC only were more likely to be male (adjusted odds ratios [aOR] RDS only 6.8, both 2.7) and living with HIV but undiagnosed (aOR RDS only 2.5, both 1.5). Overall, the RDS NNR was 11 and the ICC NNR was 26. The RDS identification rate (18.6/week) was faster than the ICC identification rate (2.7/week) overall and in all cities. CONCLUSIONS: RDS required screening fewer PWID and more rapidly identified undiagnosed PWID living with HIV as compared to ICCs.