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