Is introducing rapid culture in the diagnostic algorithm of smear-negative tuberculosis cost-effective?

Setting: In 2007, WHO recommended introducing rapid Mycobacterium tuberculosis (MTB) culture in the diagnostic algorithm of smear-negative pulmonary tuberculosis (TB). Objective: To assess the cost-effectiveness of the introduction of rapid non-commercial culture method (Thin Layer Agar) together with Löwenstein Jensen culture to diagnose smear-negative TB at a district hospital in Kenya. Design: Effectiveness data (number of true TB cases treated) were obtained from a prospective study evaluating the effectiveness of a clinical and radiological algorithm (conventional) with and without (culture-based) MTB culture in 380 smear-negative TB suspects. The costs of each algorithm were calculated using a “micro-costing” or “ingredient-based” method. The cost and effectiveness was compared between conventional and culture-based algorithms and the incremental cost-effectiveness ratio (ICER) was estimated. Results The cost of conventional and culture-based algorithms (per smear-negative TB case) was 15,026€ (39.5€) and 54,931€ (144€), respectively. The cost per TB confirmed and treated case was 455.3€ and 915.5€, respectively. The culture-based algorithm allowed to diagnose and treat 27 more cases for an additional cost of 39,905€ (1478€ per case). Conclusion MTB culture is cost-effective to diagnose smear-negative pulmonary TB according to WHO standards but did not reduce the cost of overtreatment due to long delay of culture results.