Cost-effectiveness of novel diagnostic tools for the diagnosis of tuberculosis.

SETTING The potential cost-effectiveness of improved diagnostic tests for tuberculosis (TB) in resource-limited settings is unknown. OBJECTIVE To estimate the incremental cost-effectiveness of a hypothetical new point-of-care TB diagnostic test in South Africa, Brazil and Kenya. DESIGN Decision-analysis model, adding four diagnostic interventions (sputum smear microscopy, new test, smear plus new test and smear plus TB culture) to a baseline of existing infrastructure without smear. RESULTS Adding sputum smear was estimated to be more cost-effective (incremental cost per disability-adjusted life year [DALY] of $86 [South Africa], $131 [Brazil], $38 (Kenya]) than a new TB diagnostic with 70% sensitivity, 95% specificity and price of $20 per test ($198 [South Africa], $275 [Brazil], $84 [Kenya]). However, compared to sputum smear, smear plus new test averted 46-49% more DALYs per 1000 TB suspects (321 vs. 215 [South Africa], 243 vs. 166 [Brazil], 790 vs. 531 [Kenya]), at an incremental cost of $170 (Kenya) to $625 (Brazil) per DALY averted. Cost-effectiveness was most sensitive to the specificity and price of the new test, the baseline TB case detection rate and the discount rate. CONCLUSION Novel diagnostic tests for TB are potentially highly cost-effective. Cost-effectiveness is maximized by high-specificity, low-cost tests deployed to regions with poor infrastructure.