The purpose of this study 'SMS as an Incentive To Adhere' (SITA) is to test two novel approaches of using SMS messages (provision of information about electronically measured own adherence, as well as in combination with group adherence level) to improve adherence to anitretroviral (ART) and pre-ART prophylaxis among youth age 15-24 at an HIV clinic in Uganda.

SITA addresses two behavioral biases observed in people living with HIV/AIDS (PLWHA). The growing field of behavioral economics (BE) suggests that people display behavioral biases (i.e. systematic decision making errors) that among patients can contribute to suboptimal adherence. Investigators observed two important such biases in our own work in Uganda: first, investigators found that patients to a large degree overestimate their own adherence, i.e. think that they adhere better than they actually do. Second, a patient's social environment matters: PLWHA clearly care about their peers and their peers' attitudes and behavior.

SITA is based on Social Cognitive Theory (SCT) and adapts two traditional interventions to mHealth. The first intervention is that of self-monitoring, i.e. providing participants with feedback about their adherence performance. Traditionally this involves clinic visits that take up provider and patient time and resources; SITA instead suggests providing objective, real-time information measured by electronic monitoring (Wisepill) devices sent to patients by weekly SMS. Such feedback builds self-efficacy, a key SCT concept and thereby may improve adherence. The second intervention is based on the SCT concept of social learning. Perceived group norms, and interventions that affect those perceptions, are a key influence on health behavior among youths, providing a substitute for direct learning. Investigators adapt this approach to a mHealth environment by providing PLWHA not only with their own adherence information but also that of a reference (peer) group.

SITA will use mixed methods research techniques and focus on knowledge transfer within a multidisciplinary team. In formative Phase 1 investigators will conduct qualitative focus groups with key stakeholders to elicit information about the use of wisepill devices, and acceptance, feasibility and locally appropriate adaptation of SITA. In Phase 2, investigators will implement a nine-months, three-arm (with 50-60 participants each) randomized controlled trial: youths in intervention group 1 will receive information about their wisepill-measured adherence level by weekly SMS. Intervention group 2 will in addition be sent the adherence level of a reference group that investigators hypothesize to exert normative influence. The control group will receive the usual standard of care. Throughout the study investigators will focus on capacity building and knowledge transfer to the Ugandan collaborators through workshops and mentoring.

Inclusion Criteria:

• have been in HIV care at the clinic for at least three months
• are currently taking HIV-related medication (ART or co-trimoxazole)
• either own a phone or have regular access to one
• intend to stay at the clinic for the study period
• are not in boarding school (where phones are forbidden)

Exclusion Criteria:

• does not speak or understand either English or Luganda
• does not have the cognitive capacity to consent and/or understand the study procedures