Effects of small airtime rewards linked to unsolicited text messages on uptake of a tuberculosis self-screening app in South Africa: a randomised trial

The addition of a small airtime participation reward to unsolicited text message invitations did not appear to be an effective tool to reach targeted individuals in this context. The results of Phase 1 reported here suggested that Phase 2 would not be feasible, so we did not proceed with the planned Phase 2. However, uptake of incentivised self-screening was unexpectedly high among users who were not originally invited (presumably known contacts of the original invitees). Within 5 days of the invitations being sent, 1962 unique self-screenings had taken place using the incentive code; only 7 of these users were originally invited. The lessons learnt from this study can help to inform future efforts to promote TB self-screening, mHealth initiatives and attempts to engage with patients via text message. TRIAL REGISTRATION: The study was pre-registered with the South African National Clinical Trials Registry (Phase 1 trial no DOH-27-112023-9045, Phase 2 trial no DOH-27-112023-4944) and the Pan African Clinical Trials Registry (Phase 1 trial no PACTR202311529334858).