Variation in Effectiveness of HIV Assisted Partner Services by Region, Rural Location and Gender in Kenya: A Cluster Randomized Trial

Abstract

Introduction Assisted partner services (aPS), a strategy to test and link to care the sexual partners of HIV infected persons, is effective in finding new HIV cases. This study assessed whether the effectiveness of aPS differs by region, rural location and gender in a cluster-randomized controlled trial in Kenya. Methods Eighteen HIV testing sites were randomized to provide immediate aPS or aPS delayed for 6 weeks. Generalized estimating equations with a Poisson link, robust standard errors and exchangeable correlation structure were used to assess whether the effectiveness of receiving immediate aPS in getting a sexual partner tested, newly diagnosed with HIV, and linked to care was modified by region (Nairobi/Central vs. Nyanza), testing location (urban vs. rural/peri-urban),and gender. Results We enrolled 1119 index clients and 1286 partners between August 2013 and June 2015.The effectiveness of aPS in getting a sexual partner tested for HIV was modified by region (p=0.001), location (p=0.018), and gender (p=0.061).Comparing the immediate and the delayed arm, partner testing increased 7 fold in Nyanza compared to a 3 fold increase in Nairobi (Incidence Rate Ratio (IRR) 7.2; 95% Confidence Interval (CI) 5.4, 9.6 vs IRR 3.4 95%CI 2.3, 4.8), a 7-fold increase in rural/peri-urban sites compared to a 4-fold increase in urban sites (IRR 6.6; 95%CI 4.5, 9.6 vs. IRR 3.54 95%CI 2.5, 5.0), and a 6-fold increase among female index clients compared to a 4-fold increase among male index clients (IRR 5.8 95%CI 4.2, 7.9 vs IRR 3.7; 95% CI 2.4, 5.8)). In addition, there was a 9-fold increase in newly diagnosing a partner with HIV among female index clients compared to a 3-fold increase among male index clients (IRR 9.1; 95% CI 4.0, 20.9 vs IRR 3.2 95% CI 1.7, 6.0). Conclusions While aPS was effective among the overall study population in Kenya, the size of the effect differed by region, location, and gender. These differences can help to guide the target populations and geographies for aPS as it is rolled out in Kenya. Attribution of support: This abstract was made possible through grants from the US National Institutes of Health (NIH), R01 A1099974-04 and the Fogarty International Center (FIC) D43 TW009580.