Integration of a Geospatially Targeted Community-Based Testing Approach with Respondent-Driven Sampling to Identify People Who Inject Drugs Living with HIV and HCV in Patti and Gorakhpur, India.

Background: Respondent-driven sampling (RDS), a network recruitment approach, is effective at reaching people who inject drugs (PWID), but other strategies may be needed to reach PWID at risk or living with HIV and/or Hepatitis C (HCV). We examined the impact of integrating geospatially targeted community-based HIV/HCV testing with an RDS survey.Methods: PWID were recruited between 2019 and 2021 in Patti and Gorakhpur, India, in a two-phased approach for identifying PWID living with HIV/HCV. Phase 1 was an RDS survey, in which participants reported injection venues. Venues with the highest prevalence of HIV/HCV viremia were selected for Phase 2: community-based testing. All participants underwent rapid HIV and HCV testing and viral load quantification. Using Pearson's chi-squared test, two-sided exact significance tests, and t-tests, we compared prevalence and identification rates for each of the primary outcomes: the number of PWID 1) living with HIV/HCV, 2) undiagnosed, and 3) viremic.Results: Both approaches identified large numbers of PWID (n similar to 500 each; N=2011) who were living with HIV/ HCV and had transmission potential (i.e., detectable viremia). The community-based approach identified a higher proportion of individuals living with HCV (76.4% vs. 69.6% in Gorakhpur and 36.3% vs. 29.0% in Patti). Community-based testing was also faster at identifying PWID with detectable HIV viremia. Both approaches identified PWID with varying demographic characteristics.Conclusions: Community-based testing was more efficient than RDS overall, but both may be required to reach PWID of varying characteristics. Surveillance should collect data on injection venues to facilitate community -based testing and maximize case identification.