Cost analysis of smear microscopy and the Xpert assay for tuberculosis diagnosis: average turnaround time.

Introduction: Rapid and accurate tuberculosis detection is critical for improving patient diagnosis and decreasing tuberculosis transmission. Molecular assays can significantly increase laboratory costs; therefore, the average time and economic impact should be evaluated before implementing a new technology. The aim of this study was to evaluate the cost and average turnaround time of smear microscopy and Xpert assay at a university hospital.

Methods: The turnaround time and cost of the laboratory diagnosis of tuberculosis were calculated based on the mean cost and activity based costing (ABC).

Results: The average turnaround time for smear microscopy was 16.6 hours while that for Xpert was 24.1 hours. The Xpert had a mean cost of USD 17.37 with an ABC of USD 10.86, while smear microscopy had a mean cost of USD 13.31 with an ABC of USD 6.01. The sensitivity of smear microscopy was 42.9% and its specificity was 99.1%, while the Xpert assay had a sensitivity of 100% and a specificity of 96.7%.

Conclusions: The Xpert assay has high accuracy; however, the turnaround time and cost of smear microscopy were lower than those of Xpert.