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Table 3 Per patient diagnostic accuracy of Xpert MTB/RIF assay using centrifuged and uncentrifuged pleural fluid to diagnose pleural tuberculosis

From: Comparison of same day diagnostic tools including Gene Xpert and unstimulated IFN-γ for the evaluation of pleural tuberculosis: a prospective cohort study

Assay

Definite-TB vs. Non-TB

Sensitivity% (95% CI)

Specificity% (95% CI)

PPV% (95% CI)

NPV% (95% CI)

Pleural fluid (uncentrifuged)

22.5% (12.4, 37.6) 9/40

98% (89.2, 99.7) 48/48

90% (59.6, 98.3) 9/10

60.3% (49.2, 70.4) 48/78

Centrifuged pellet

23.7% (13.0, 39.3) 9/38

100% (91.7, 100) 42/42

100% (70.1, 100) 9/9

59.2% (48.2, 70.3) 42/71

p-value

ns*

ns*

ns*

ns*

  1. A median volume of 20 ml of pleural fluid was centrifuged at 3000 × g for 15 min with the pellet resuspended in sterile PBS, followed by Xpert MTB/RIF. A positive MTB (Mycobacterium tuberculosis) fluid culture and/or positive MTB biopsy culture and/or histology in keeping with MTB infection used as a reference. PPV: positive predictive value, NPV: negative predictive value, CI: confidence interval, *: Chi squared.