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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.