Background: Adverse drug reactions (ADRs) are common during standard, long-course treatment for multidrug-resistant and rifampicin-resistant tuberculosis (MDR-/RR-TB). In particular, second-line injectables (SLIs) are associated with permanent hearing loss, acute renal injury and electrolyte imbalance. We adapted an established Markov model for ambulatory treatment to estimate the impact of the toxicity profile on the incremental cost-effectiveness ratio (ICER) for a proposed MDR-/RR-TB regimen replacing the SLI with bedaquiline (BDQ).
Methods: Treatment effectiveness was evaluated in disability-adjusted life-years (DALYs). Clinical outcomes and ingredient costs from a provider perspective were derived from the South African public-sector treatment program or extracted from the literature. Costs and effectiveness were discounted at 3% per year over 10 years.
Results: A BDQ-based MDR-/RR-TB regimen compared with the SLI regimen had a mean ICER of US$516 per DALY averted using the standard Markov model. Costs for both regimens increased and effectiveness decreased for the SLI regimen once adjusted for toxicity. The resulting ICER for the BDQ-based regimen was cost saving (US$96/patient) and more effective (0.96 DALYs averted) after adjusting for ADRs.
Conclusion: Decision-analysis models of treatment for MDR-/RR-TB, including new drug regimens, should consider the costs of managing ADRs and their sequelae.