Posttuberculosis Consequences on Tuberculosis Prevention Effectiveness and Cost-effectiveness among New Immigrants, Canada

Abstract

Cost-effectiveness analyses of tuberculosis (TB) preventive treatment rarely consider long-term TB consequences. We examined how long-term TB consequences influence the effectiveness and cost-effectiveness of TB prevention among persons who immigrate to Canada. By using a Markov microsimulation model of 400,000 persons immigrating to Canada in 2025, we compared current postarrival TB infection screening levels (0.5%) with a screening level of 68% among new immigrants. Modelling scenarios included acute TB consequences and long-term TB-related death, illness, and healthcare costs (25-year horizon, 1.5% discount rate). Including long-term TB-related consequences increased the estimated TB-related quality-adjusted life years (QALYs) lost by 2.1-fold (95% uncertainty range 1.7–2.5-fold). When long-term TB-related consequences were included, estimated QALYs gained from expanded screening increased 2.4-fold (95% uncertainty range 1.6–4.4-fold), reducing the cost per QALY from $235,088 to $100,742 CAD. Ignoring long-term TB consequences substantially underestimates the effectiveness and cost-effectiveness of preventive interventions; such consequences should be incorporated into future evaluations.