Impact of financial incentives on viral suppression among adults initiating HIV treatment in Tanzania: a hybrid effectiveness-implementation trial.

Background: Small incentives could improve engagement in HIV care. We evaluated the short-term and longer-term effects of financial incentives for visit attendance on viral suppression among adults initiating antiretroviral therapy (ART) in Tanzania.

Methods: In a type 1 hybrid effectiveness-implementation study, we randomised (1:1) 32 primary care HIV clinics in four Tanzanian regions to usual care (control group) or the intervention (usual care plus ≤6 monthly incentives [22 500 Tanzanian Shillings, about US$10, each], conditional on visit attendance). Adults (aged ≥18 years) initiating ART (<30 days) who owned a mobile phone and had no plans to transfer to another facility were eligible. The primary outcome was retention on ART with viral suppression (<1000 copies per mL) at 12 months. Secondary outcomes included retention on ART with viral suppression at 6 months and viral suppression at 6 months and 12 months using a lower threshold (<50 copies per mL). Intent-to-treat analysis and a cluster-based permutation test were used to evaluate the effect of financial incentives on outcomes. This trial is registered with ClinicalTrials.gov, NCT04201353, and is completed.

Findings: Between May 28, 2021, and March 8, 2022, 1990 participants (805 male and 1185 female) were enrolled in the study. 1059 participants were assigned to the intervention group and 931 participants were assigned to the control group. Overall, 1536 (88%) participants at 6 months and 1575 (83%) at 12 months were on ART with viral suppression. At 12 months, 6 months after the intervention ended, 866 (85%) participants in the intervention group compared with 709 (81%) in the control group had viral loads less than 1000 copies per mL (adjusted risk difference [aRD] 4·4 percentage points, 95% CI -1·4 to 10·1, permutation test p=0·35). At 6 months, 858 participants (90%) in the intervention group were on ART with viral loads less than 1000 copies per mL compared with 678 (86%) in the control group (aRD 5·1 percentage points, 95% CI 1·1 to 9·1, permutation test p=0·06). Effects were larger at 6 months and 12 months with the lower threshold for viral suppression, and there was significant effect heterogeneity by region. Adverse events included 106 deaths (56 in the control group and 50 in the intervention group), none related to study participation.

Interpretation: Short-term incentives for visit attendance had modest, short term benefits on viral suppression and did not harm retention or viral suppression after discontinuation. These findings suggest the need to understand subgroups who would most benefit from incentives to support HIV care.

Funding: National Institute of Mental Health.

Translation: For the Swahili translation of the abstract see Supplementary Materials section.