Cost-effectiveness analysis of implementing a medication monitor and differentiated care approach among people with TB in South Africa

BACKGROUND: Digital Adherence Technologies (DATs) are being investigated for use in many countries. In this study we evaluated the cost-effectiveness of a technology-enabled Differentiated Care Approach (DCA), where a medication monitor (Wisepill evriMED 1000 device) provided daily reminders and identified missed doses to guide SMS, phone call, and home visit interventions within the TB Monitoring Adherence to Treatment Endpoints (TB MATE) cluster-randomised trial in South Africa. METHODS: We conducted a cost-effectiveness analysis from a societal perspective in one intervention clinic and one standard-of-care (SoC) clinic in each of three selected provinces between June 2019 and August 2020. Health system costs were collected using a bottom-up activity-based costing approach involving time and motion studies. People with Tuberculosis (PWTB) were interviewed on costs related to accessing the intervention. The primary efficacy outcome used in the trial was proportion of patients with ≥ 80% adherence, measured using medication monitor opening as a proxy for adherence. Unit costs were calculated as cost per patient treated for TB while incremental cost-effectiveness ratio (ICER) was calculated as cost per additional adherent PWTB. RESULTS: From a total of 2757 enrolled (62% male, median age 36 years IQR (27-45 years), adherence data was available for 1306 PWTB in the intervention arm and 1278 PWTB in the SoC arm, where effectiveness was 81% and 50.8% in the intervention and SoC arms respectively. The total cost per patient treated for TB was $103.93-$199.87 (intervention) and $44.89 - $131.22 (SoC), resulting in a societal incremental cost of $49.73 (mean). Patient costs were $38.98 - $117.94 (intervention) and $35.92-$91.94 (SoC) per patient with indirect costs (foregone income) contributing to a large proportion of total costs at three intervention (56.7% - 69.8%) and two SoC (69% and 77.4%) clinics. The ICER of achieving an additional adherent PWTB was $166.33. CONCLUSION: Medication monitors and DCA can be considered a cost-effective option for investment and scale-up if we reduce health systems costs.