INDEX CHARACTERISTICS ASSOCIATED WITH PARTNER HEPATITIS C (HCV) SEROPOSITIVITY AMONG PEOPLE WHO INJECT DRUGS AND LIVING WITH HIV IN KENYA

Abstract

BackgroundHepatitis C virus (HCV) infection disproportionately burdens people who inject drugs (PWID), with global HCV antibody prevalence estimated at 52.3% in this population. In Kenya, HCV prevalence among PWID ranges from 11.9% to 36.4%, with the highest burden concentrated in coastal counties. HIV coinfection, prevalent among Kenyan PWID, accelerates HCV disease progression and complicates treatment. Assisted Partner Services (APS)—a structured model in which HIV-positive index participants disclose contact information for their sexual and injecting partners, who are then notified, tested, and linked to care, has demonstrated effectiveness for HIV case finding. However, its potential for identifying undiagnosed HCV infection within PWID networks remains under-explored. MethodologyWe conducted a cross-sectional secondary data analysis that utilized the Study of HIV/Hepatitis C, APS, and Phylogenetics for Persons Who Inject Drugs (SHARP) cohort, enrolling PWID living with HIV across Nairobi, Mombasa, and Kilifi counties from March 2018. Peer educator–mediated APS was used to recruit index participants and trace their named sexual and injecting partners for rapid HCV antibody testing. APS efficiency was quantified using the number of indexes needed to interview (NNTI) to identify one HCV-positive partner. Univariate and multivariable Poisson regression models assessed associations between index-level sociodemographic, behavioral, and clinical characteristics and partner HCV positivity. ResultsAmong 989 index participants, 51% were men and median age was 36–45 years. 4,700 partners were named and tested of which 822 (18%) were positive for HCV antibody at enrollment, and 48% of indexes had at least one HCV-positive partner identified. The overall NNTI was 2.1 (95% CI: 1.9–2.3). APS efficiency was substantially higher among indexes in the Coastal region versus Nairobi (NNTI: 0.81 vs. 2.06; p<0.001), those with ≥5 years of injecting experience (NNTI: 0.95 vs. 1.47; p<0.001), those reporting ≥3 injecting partners (NNTI: 1.03 vs. 1.85; p<0.001), indexes aware of their HCV status (NNTI: 0.84 vs. 1.27; p<0.001), and HCV-positive indexes (NNTI: 0.76 vs. 1.36; p<0.001). In adjusted analyses, geographic region and injecting duration remained independently associated with APS efficiency, while the sex difference was no longer significant after controlling for age, region, and injecting history. ConclusionAPS is a high-yield strategy for HCV case finding among PWID living with HIV in Kenya. Its efficiency is greatest in high-burden geographic regions and among indexes with more established injecting networks and HCV awareness. These findings support integrating HCV-focused APS into existing HIV care and harm reduction platforms to accelerate progress toward WHO 2030 HCV elimination targets. Keywords: Hepatitis C virus; people who inject drugs; assisted partner services; HIV; Kenya; case finding; harm reduction; sub-Saharan Africa