Syed Wasib Hussain Shah, Raza Ullah, Sohail Khan Raja, Jamal Ahmed, Shomail Onaiz, Jawad Khaliq Ansari, Sara Naqvi, Zafar Iqbal.
Diagnostic accuracy of GeneXpert and sputum Zeil Nelson Staining in predicting tuberculosis taking Sputum Culture as Gold standard.
Pak J Chest Med Jan ;25(2):68-73.

Background: Tuberculosis (TB) is a highly prevalent infectious disease that can involve any part of the body; the most favored site is lung. Tests used for its diagnosis include sputum Zeil Nelson staining, Gene Xpert, and culture. Objective: Objective of this study was to determine the diagnostic accuracy of GeneXpert and sputum-ZN staining in predicting tuberculosis taking sputum culture as Gold standard. Methodology: This cross sectional validation study was conducted in March 15, 2015 the Pulmonology department, Military Hospital Rawalpindi from September 14, 2015 to 14/09/2015. Patients of both gender aged 18-70 years and pulmonary TB (PTB) suspect were included in the study through consecutive non-probability sampling technique. The sample size was calculated through WHO software, assuming 25% TB prevalence, 95% confidence interval and 10% margin of error. Diagnosed PTB Patients, those on anti-tuberculosis (ATT) treatment, patients with co-morbid like congestive heart failure, Diabetes mellitus, HIV positive and patients on steroids were excluded from the study. Results: Out of 265 patients, 183 (69.1%) were male and 82 (30.9%) female. Mean age was 45.65+-14.91 years. Sensitivity and Specificity of Sputum smear microscopy was 68.48% and 74.07% respectively. While PPV, NPV and diagnostic accuracy of sputum smear microscopy was 85.71%, 50.85% and 70.19% respectively. Sensitivity and Specificity of Gene Xpert was 97.83% and 92.59%. However Positive Predictive Value, Negative predictive Value and diagnostic accuracy of Gene Xpert test was 96.77%, 94.94% and 96.23% respectively. Conclusion: GeneXpert is more accurate and reliable than sputum microscopy in predicting pulmonary TB.

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