Shortened Tuberculosis Treatment for People with HIV in South Africa. A Model-based Evaluation and Cost-effectiveness Analysis.

Abstract

Rationale: Recent tuberculosis treatment trials failed to show that some 4-month (4m) regimens were noninferior to conventional 6-month (6m) regimens for a composite clinical outcome. Novel shortened regimens may still have important clinical and economic benefits in populations with high loss to follow-up (LTFU) and in subgroups such as people with human immunodeficiency virus.Objectives: To identify scenarios in which a novel 4m regimen would be preferred to a conventional 6m regimen for treatment of drug-susceptible tuberculosis in people with human immunodeficiency virus in South Africa, in terms of short-term and long-term clinical and economic outcomes.Methods: We used the Cost-Effectiveness of Preventing AIDS Complications-International microsimulation model to project outcomes modeled on participants in the OFLOTUB trial. For calibration purposes, we did a base case analysis by applying trial-informed parameters for the 4m/6m regimens, including monthly LTFU during treatment (0.68%/0.83%), average monthly tuberculosis recurrence (0.65%/0.31%), and monthly drug costs (U.S. dollars [USD]25.90/3.70). We then evaluated different scenarios and 4m regimen characteristics, varying key parameters, including LTFU (informed by observational cohort data), recurrence, and cost. We projected outcomes, including 2-year mortality and life expectancy. We conducted a cost-effectiveness analysis, evaluating the incremental cost-effectiveness ratio of a 4m versus 6m regimen.Results: In the base case model analysis, risk of the composite unfavorable outcome in the 4m/6m groups was 19.8%/15.9%, similar to the trial; projected life expectancies were 22.1/22.3 years. In analyses of alternative scenarios and 4m regimen characteristics, a 4m regimen yielded lower risk of the composite unfavorable outcome than the conventional 6m regimen if LTFU increased to greater than 3.5%/mo or if average recurrence after a 4m regimen decreased to less than 0.45%/mo, and it yielded higher life expectancy if LTFU was greater than 3.5%/mo or if recurrence was less than 0.5%/mo. A 4m regimen was not cost-effective in the base case but became cost-effective (incremental cost-effectiveness ratio <USD940/yr of life saved) in two-way sensitivity analysis; for example, if LTFU was greater than or equal to 5.3%/mo and either average recurrence was less than or equal to 0.5%/mo or drug cost was less than or equal to USD15/mo.Conclusions: A novel shortened tuberculosis treatment regimen could improve outcomes such as survival despite conferring a higher recurrence risk, particularly in settings where LTFU is higher than that seen in recent trials.