Bedaquiline-based treatment for extensively drug-resistant tuberculosis in South Africa: A cost-effectiveness analysis

Abstract

Background: The treatment success rate of conventional anti-tuberculosis (TB) regimens for extensively drug-resistant TB (XDR-TB) is low, resulting in high morbidity and healthcare cost especially in the high TB burden countries. Recent clinical findings reported improved treatment outcomes of XDR-TB with the bedaquiline (BDQ)-based regimens. We aimed to evaluate the cost-effectiveness of BDQ-based treatment for XDR-TB from the perspective of the South Africa national healthcare provider.

Methods: A 2-year decision-analytic model was designed to evaluate the clinical and economic outcomes of a hypothetical cohort of adult XDR-TB patients with (1) BDQ-based regimen and (2) injectable-based conventional regimen. The model inputs were retrieved from literature and public data. Base-case analysis and sensitivity analysis were performed. The primary model outputs included TB-related direct medical cost and disability-adjusted life years (DALYs).

Results: In the base-case analysis, the BDQ group reduced 4.4152 DALYs with an incremental cost of USD1,606 when compared to the conventional group. The incremental cost per DALY averted (ICER) by the BDQ group was 364 USD/DALY averted. No influential factor was identified in the sensitivity analysis. In probabilistic sensitivity analysis, the BDQ group was accepted as cost-effective in 97.82% of the 10,000 simulations at a willingness-to-pay threshold of 5,656 USD/DALY averted (1× gross domestic product per capita in South Africa).

Conclusion: The BDQ-based therapy appeared to be cost-effective and showed a high probability to be accepted as the preferred cost-effective option for active XDR-TB treatment.

Fig 1. Simplified decision-analytical model for XDR-TB treatment with BDQ-based regimen versus injectable-based conventional regimen.

BDQ: Bedaquiline; SAE: Serious adverse event; XDR-TB: Extensively drug-resistant tuberculosis.

Fig 2. Tornado diagram of influential factors identified in one-way sensitivity analysis on ICER of the BDQ group versus the conventional group.

BDQ: Bedaquiline; DALY: Disability adjusted life year; ICER: Incremental cost per DALY averted; XDR-TB: Extensively drug-resistant tuberculosis.

Fig 3. Scatter plot of the incremental cost against DALY averted by the BDQ group versus the conventional group in 10,000 Monte-Carlo simulations.

BDQ: Bedaquiline; DALY: Disability-adjusted life-year; WTP: Willingness-to-pay.

Fig 4. Acceptability curves of the BDQ group and the conventional group to be cost-effective against willingness-to-pay.

BDQ: Bedaquiline; WTP: Willingness-to-pay.