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

Lida Jouca De Assis Figueredo,Afrânio Lineu Kritski,Maria Cláudia Vater,Caroline Gontijo Gonçalves Manso,Wânia Da Silva Carvalho,Suely Alves,Lucas Benício Dos Santos,Valéria Martins Soares,Cristiane Menezes De Pádua,Isabela Neves De Almeida,Silvana Spíndola De Miranda

doi:10.1590/0037-8682-0314-2020

Abstract

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.

Highlights

Rapid and accurate tuberculosis detection is critical for improving patient diagnosis and decreasing tuberculosis transmission
The Xpert had a mean cost of USD 17.37 with an activity based costing (ABC) of USD 10.86, while smear microscopy had a mean cost of USD 13.31 with an ABC of USD 6.01
The World Health Organization (WHO) estimated that in 2018, approximately 10 million people had developed TB, and that TB was responsible for an estimated 1.2 million deaths among human immunodeficiency virus (HIV) negative patients and an additional 251 thousand deaths among patients living with HIV1

Summary

Introduction

Rapid and accurate tuberculosis detection is critical for improving patient diagnosis and decreasing tuberculosis transmission. Molecular assays can significantly increase laboratory costs; 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. Results: The average turnaround time for smear microscopy was 16.6 hours while that for Xpert was 24.1 hours. 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; the turnaround time and cost of smear microscopy were lower than those of Xpert. The diagnosis of extrapulmonary TB remains a challenge, since the total number of bacteria in extrapulmonary specimens is often lower than that present in pulmonary specimens[2]. The collection of extrapulmonary material requires invasive procedures, and it is usually difficult to obtain additional samples[2]

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