Background Interventions incorporating constructs from behavioral economics and psychology have the potential to enhance HIV 'treatment as prevention' (TasP) strategies. To test this hypothesis, we evaluated an intervention to improve antiretroviral therapy (ART) adherence based on the concepts of social norms and priming. Methods We used tools from marketing research and patient-centered design to develop a combination intervention that included visual feedback about clinic-level retention in care, a self-relevant prime, and useful take-home items with the priming image. The intervention was implemented at two HIV primary clinics in Shinyanga, Tanzania in 2-week intervals for six months. We conducted a quasi-experimental pilot study with a random sample of exposed and unexposed adult patients living with HIV infection (PLHIV) to compare retention and the proportion of patients with medication possession ratio (MPR) ≥95% after six months. Intervention acceptability was determined with a convenience sample of 405 PLHIV at baseline (n = 189) and endline (n = 216). Results Medical records were reviewed for 438 PLHIV (320 intervention, 118 standard of care). In adjusted analyses, PLHIV exposed to the intervention were significantly more likely to be in care after 6 months (87% vs. 79%, adjusted odds ratio (ORa) = 1.73, 95% CI: 1.08, 2.78, p<0.05) and were more likely to achieve MPR≥95% (70% vs. 59%, OR = 1.51, 95% CI: 0.96, 2.37, p = 0.07). The intervention was associated with increases in staff support of treatment goals (100% vs. 95%, p = 0.01) and life goals (66% vs. 50%, p<0.01), the perceived likelihood of other patients' adherence (54% vs. 32%, p<0.01), support from other patients (71% vs. 60%, p = 0.03), and being very satisfied with care (53% vs. 35%, p<0.01). Conclusions This novel intervention has the potential to improve the clinic experience, short-term retention in care, and ART adherence. Future studies are needed to expand the generalizability of the approach and evaluate effectiveness on clinical outcomes.
