Evaluating the diagnostic accuracy of GeneXpert MTB/RIF assay for the diagnosis of Tuberculosis

Background: Tuberculosis (TB) is one of the major global public health concern particularly affecting population of low-income countries. Early detection of disease coupled with other parameters help in treatment and reducing disease transmission. Methods: The current study was conducted to assess the sensitivity and specificity of the GeneXpert MTB/RIF (Cepheid Sunnyvale, CA, United States) in comparison to conventional techniques used for the diagnosis of TB. Our study is one of the first ones from Pakistan investigating and assessing the performance of GeneXpert. We recruited eight hundred clinically TB suspects initially and included seven hundred and sixteen clinically TB suspects in the final analysis. Results: The results of GeneXpert were compared with Mycobacteria Growth Indicator Tube (MGIT) and Ziehl-Neelsen (ZN) staining. In comparison to MGIT and ZN staining the sensitivity of GeneXpert with 95 % confidence interval (CI) was (99.7 %, CI 0.98-0.99) and (95.1 %, CI 0.92-0.97) respectively. The positive and negative predictive values with 95 % CI were (97.1 %, CI 0.94-0.98) and (99.7 %, CI 0.98-0.99) when results of GeneXpert were compare with MGIT results. Conclusion: The results of this study confirms the performance of GeneXpert. With high sensitivity and rapid detection, GeneXpert is ready to be considered as preferred diagnostic tool for TB.