Accuracy of GeneXpert in Diagnosis of Smear Negative Tuberculosis: A Cross-Sectional Study

Abstract

Objective: This study was aimed to compare the diagnostic accuracy of GeneXpert in smear negative as compared to smear positive pulmonary tuberculosis patients. Methods: This comparative cross sectional study was undertaken at Health Research Institute (National Institute of Health) TB Research Centre, Pulmonology King Edward Medical University Lahore, Pakistan. A total of 101 patients in each smear negative and positive groups were included. After taking the informed consent a predesigned questionnaire was used to collect the data. Results: A total of 202 patients consisting of 94 (46.5%) male and 108 (53.5%) females with mean age of patients as 39.83±18.14 years were included in this study. Highest proportion of 45% patients remained to be in age range of 18-35 years. Culture presented the highest accuracy of 96.1% with sensitivity, specificity and positive predictive value of 95.9%, 100%, and 100% respectively while GeneXpert remained to be 94.6%, 94.9%, 80%, and 99.5% respectively in this study. Conclusion: Accuracy of GeneXpert is excellent in diagnosis of smear positive pulmonary tuberculosis patients and very well in diagnosing smear negative pulmonary TB patients and a great addition in early and definite diagnosis of TB and keeps the ability to confirm around 75% smear negative pulmonary tuberculosis.