Effectiveness and Costs of Identification Pathways for Tuberculosis: Modelling the Impact of Dual Energy X-Ray Technology

Background Existing screening methods for TB involve trade-offs among sensitivity, specificity and cost. Recent advances mean that dual-energy X-ray is more sensitive and only slightly more costly than conventional chest X-ray and could be a high-performing alternative for TB screening, particularly if associated computer-aided diagnostic (CAD) software were developed. Methods Existing data on sensitivity,specificity and cost were used for six screening methods (sputum testing, conventional chest X-ray with and without CAD software, dual-energy X-ray with and without CAD software, and nucleic acid amplification testing (NAAT), used in various sequences. Cost and effectiveness of 20 different screening pathwayswere examined using data for Pakistan. Monte-carlo based sensitivity analysis focused on parameters for dual-energy X-ray. Results Sputum followed by NAAT is the best pathway when government budgets are low, and NAAT alone is the best when budgets are unlimited. With intermediate budgets, pathways including dual-energy X-ray dominate those including conventional X-rays, particularly if CAD software is developed for dual-energy X-ray. Conclusions Dual-energy X-ray can be a valuable addition to the screening options for TB. Our study provides different TB screening options for policy makers and TB program managers, which could be used as a guide for planning and implementation of TB screening programs.