Characterizing Network-Based HIV Testing Interventions to Guide HIV Testing and Contact Tracing at STI Clinics in Lilongwe, Malawi.

BACKGROUND: Understanding heterogeneity across patients in effectiveness of network-based HIV testing interventions may optimize testing and contact tracing strategies, expediting linkage to therapy or prevention for contacts of persons with HIV (PWH). SETTING: We analyzed data from a randomized controlled trial of a combination intervention comprising acute HIV testing, contract partner notification (cPN), and social contact referral conducted among PWH at 2 STI clinics in Lilongwe, Malawi, between 2015 and 2019. METHODS: We used binomial regression to estimate the effect of the combination intervention vs. passive PN (pPN) on having any (1) contact, (2) newly HIV-diagnosed contact, and (3) HIV-negative contact present to the clinic, overall and by referring participant characteristics. We repeated analyses comparing cPN alone with pPN. RESULTS: The combination intervention effect on having any presenting contact was greater among referring women than men [prevalence difference (PD): 0.17 vs. 0.10] and among previously vs. newly HIV-diagnosed referring persons (PD: 0.20 vs. 0.11). Differences by sex and HIV diagnosis status were similar in cPN vs. pPN analyses. There were no notable differences in the intervention effect on newly HIV-diagnosed referrals by referring participant characteristics. Intervention impact on having HIV-negative presenting contacts was greater among younger vs. older referring persons and among those with >1 vs. ≤1 recent sex partner. Effect differences by age were similar for cPN vs. pPN. CONCLUSION: Our intervention package may be particularly efficacious in eliciting referrals from women and previously diagnosed persons. When the combination intervention is infeasible, cPN alone may be beneficial for these populations.