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

Objectives The objective of this study was to test whether an airtime reward increased tuberculosis (TB) Check screening uptake. This served as a feasibility study for the planned Phase 2, which aimed to test behavioural messaging to boost take-up of TB testing among users who were advised to get tested by TB Check. Design The study was a randomised controlled trial with a parallel design. Setting This study assessed mHealth support to boost TB testing in high-burden Cape Town clinics. Intervention Patients aged 18 or above with a valid mobile phone number that had been added within the last 5 years were invited by the Western Cape Department of Health and Wellness through unsolicited text messages to screen for TB using TB Check. Participants Patients in the intervention group (n=1250) were additionally offered R15 airtime for completing the screening and participating in the research study. Patients were allocated to the intervention or control group through parallel randomisation with equal group size. Primary outcome measures The primary outcome was the number of TB Check screenings completed within 1week of the SMS invitation being sent. Results Messages were successfully delivered to 616 patients in the control group and 633 patients in the intervention group. Uptake of the invitation by the intended recipients was very low. Eight users in the control group and 20 users in the intervention group initiated a self-screening (1.3% vs 3.2% of delivered messages; 95%CI of difference (0.2 to 3.5)), but only three users in the control group and seven users in the intervention group successfully completed a self-screening (0.49% vs 1.11% of delivered messages; 95%CI of difference (−0.4 to 1.6)). Low delivery of text message invitations (50.0%) and low completion of users who started the screening (35.7%) posed additional challenges. No adverse events were recorded. Conclusions 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 5days 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.