Goals for Adherence With Low-cost Incentives

Low ART adherence among youth living with HIV threatens positive treatment outcomes. Increasingly incentive interventions have targeted low adherence, yet little is known about how to best structure the incentives and associated eligibility criteria. A particular concern is that for those with low baseline performance, the often relatively high, fixed eligibility thresholds may be perceived as too difficult to reach and be demotivating for the most vulnerable. Our study tests a novel incentive design that permits even those with low initial adherence to qualify for incentives aimed at increasing ART adherence by allowing participants to win prizes for smaller subgoals that build towards a higher goal. This design is based on applications of behavioral economics' Prospect Theory to the psychological literature on goal setting and motivation, which suggests that distant goals can exert a demotivating effect on the individual compared to more proximal goals.

The study is separated into two parts. Study 1 will monitor ART adherence using Wisepill devices for three months among an expected 1,049 individuals aged 15-30 years who have been on ART for three or more months and have regular access to a mobile phone. Monitoring baseline adherence will ensure that individuals being randomized to the interventions in Study 2 are indeed those in need of adherence support, i.e. have low baseline mean adherence of less than 90%.

Study 2 will randomize an expected 560 participants with low adherence from Study 1 into one of four equal-sized intervention arms. In the three treatment arms, participants will be eligible for a prize drawing to win small amounts of mobile airtime of either 500, 5,000 or 10,000 Ugandan Shillings (approximately $0.15, $1.5 and $3) if they reach the adherence goal required in the respective treatment arm. The goals will be set as follows:

• Assigned sub-goals: the study coordinator will choose an ART adherence target for the participant based on their baseline adherence and gradually increase the target every three months, working towards 90% adherence at the end of year 1.
• Participatory sub-goals: the participant will choose their own adherence target every three months, working towards 90% adherence at the end of year 1.
• Fixed goal: the study participant must reach a target adherence level of 90% every three months.
• Control group: will receive the usual standard of care offered at Mildmay. All treatment groups will receive weekly motivational messages and a reminder of their upcoming prize drawing. Weekly SMS messages will help maintain contact with study participants and enable them to become accustomed to receiving messages from the study for potential remote prize drawings. In contrast, the control group will only receive the motivational portion of the text messages (without the reminders of the possibility of winning prizes) as an attention control due to the potential beneficial effects of the messages.

Year 1 of the three-year RCT will evaluate the relative effectiveness of the three incentive approaches for improving adherence. Participants in the three treatment arms will be eligible to enter an in-person or remote prize drawing for a mobile airtime reward every three months if they meet their target adherence. In-person prize drawings will be done if the date of the drawing coincides with the participants' regularly scheduled clinic visits; otherwise, they will be done remotely. Participants will also be eligible to enter a larger prize drawing at the end of year 1 if they reach 90% adherence. Year 2 will test the relative effectiveness of the interventions for maintaining at least 90% mean adherence. Participants will be eligible for a prize drawing every three months if they maintain 90% adherence and a larger prize drawing at the end of the year if viral suppression is attained. Participants that did not reach 90% adherence by the end of year 1 will be allocated to the treatment arm that showed the highest effectiveness in year 1. Follow-up surveys will be conducted every six months after enrolment into Study 2, and prize drawing surveys will be done at every prize drawing to understand cognitive and motivational factors that the intervention may influence. Year 3 will investigate the effectiveness of the three treatment arms on long-term adherence once incentives are removed. A cost-effectiveness analysis will also be performed to help determine the intervention design's potential for sustainability and scale-up.

Inclusion criteria

• If the participant is between 15 and 30 years of age (inclusive),
• has received ART from Mildmay for at least three months,
• exhibits Wisepill-measured adherence of under 90%,
• and has regular access to a mobile phone (at least five days per week)

Exclusion criteria

• If the participant is not within the age range specified above,
• has not received ART from Mildmay for at least three months,
• cannot use a Wisepill device when taking ART medication,
• cannot follow the consenting procedures
• does not have regular access to a mobile phone (at least five days per week)
• or shows Wisepill-measured adherence of over 90%