Variability of HIV Assisted Partner Services by Region, Urbanicity and Gender in Kenya: A Cluster Randomized Trial

Background: We previously reported results of a cluster randomized trial demonstrating that immediate assisted partner services (aPS) increases HIV testing and case-finding among partners of persons newly diagnosed with HIV. Here we present the variability of aPS effectiveness by demographic factors. Methods: Eighteen HIV testing sites were randomized to immediate versus 6-week delayed aPS. Participants were HIV- infected index clients and their partners. The primary outcomes were the number of partners per index participant who 1) tested for HIV, 2) tested HIV-positive and 3) enrolled in HIV care. We used generalized estimating equations to assess differences in aPS effectiveness by region (medium/low vs high prevalence), testing location (urban vs rural/peri-urban), and gender. Findings: From August 2013-August 2015, the study enrolled 1119 index participants, 625 of whom were in the immediate group and 1286 sexual partners. Immediate aPS was more effective than delayed aPS across regions, gender and locations, being 7·2-fold more effective in promoting testing among partners in high HIV prevalence regions compared to a 3·4-fold increase in medium/low prevalence regions (Nyanza incidence rate ratio [IRR] 7·2; 95% confidence interval [CI] 5·4, 9·6 vs Nairobi IRR 3·4 95%CI 2·3, 4·8). Differences were also seen comparing rural/peri-urban and urban sites (IRR 6.6; 95%CI 4.5, 9.6 vs IRR 3.5 95%CI 2.5, 5.0, respectively), and female versus male index participants (IRR 5.8 95%CI 4·2, 7·9 vs IRR 3·7; 95%CI 2·4, 5·8, respectively). Providing aPS to female versus male index participants also resulted in more newly diagnosed HIV cases (IRR 9·1; 95%CI 4·0, 20·9 vs IRR 3·2 95%CI 1·7, 6·0, respectively). Interpretation: APS is effective in promoting HIV testing and case-finding across populations in Kenya and has higher effectiveness when provided in higher HIV prevalence settings, rural areas and for female index cases. These populations and locations can be prioritized when resources are constrained. Clinical Trial Registry: ClinicalTrials.gov registration number is NCT01616420. Funding: This study was funded by grants from the US National Institutes of Health (NIH), R01 A1099974-04 and Fogarty International Center (FIC) D43 TW009580. Author Disclosure Statement: We declare no conflicts of interest. Ethics Statement: This trial was approved by the Kenyatta National Hospital/University of Nairobi Ethics Review Committee (P523/10/2012) and the University of Washington Human Subjects Institutional Review Board Committee (43628 C).