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Table 2 Per patient diagnostic accuracy of Xpert MTB/RIF, IFN-γ, and ADA for the diagnosis 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) +LR (95% CI) -LR (95% CI)
Xpert MTB/RIF 22.5% *#□$£ (12.4, 37.6) 9/40 98% (89.2, 99.7) 47/48 90% (59.6, 98.3) 9/10 60.3% (49.2, 70.4) 48/78 10.8 (1.43, 81.65) 0.79¢°¤§¿ (0.67, 0.94)
IFN-γ 92.5%*O (80.2, 97.5) 37/40 95.9% (86.1, 98.9) 46/48 94.9% (83.2, 98.6) 37/39 93.9%†∞ (83.5, 97.9) 46/49 22.20 (5.70, 86.46) 0.08¢ð (0.03, 0.23)
ADA (Clinical cut point) 79% ∆#× (63.7, 89) 30/38 92.7% (80.6, 97.5) 38/41 91% (73.4, 95.4) 30/33 82.7% (69.3, 91.0) 38/46 10.79 (3.59, 32.47) 0.23° (0.12, 0.42)
ADA (Rule-in cut point) 55.3% □O×€¥ (39.8, 69.9) 21/38 95.2% (83.9, 98.7) 39/41 91.4% (73.3, 97.6) 21/23 69 · 7% ∞⌂ (56.7, 80.1) 39/56 11.33 (2.85, 45.1) 0.47¤ðþ (0.33, 0.67)
Xpert MTB/RIF followed by IFN-γ if MTB/RIF-negative 92.5%$€ (80.2, 97.5) 37/40 93.8% (83.2, 97.9) 45/48 92.5% (80.2, 97.5) 37/40 93.8% (83.2, 97.9) 45/48 14.80 (4.93, 44.43) 0.08§þ (0.03, 0.24)
Xpert MTB/RIF followed by ADA (clinical cut-point) if MTB/RIF-negative 81.6%£¥ (66.6, 90.8) 31/38 92.7% (80.6, 97.5) 38/41 91.2% (77.1, 97) 31/34 84.5% (71.3, 92.3) 38/45 11.15 (3.70, 33.49) 0.20¿ (0.10, 0.39)
p-value *; #; $ and £: p < 0.0001 O; ; ×; and ¥: p < 0.05    and : P < 0.0001 ; ; ▪ and : p < 0.05   ¢; °; ¤; §; ¿; ð and þ: non overlapping CI
  1. 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, +LR: positive likelihood ratio, -LR: negative likelihood ratio, CI: confidence interval, IFN-γ: interferon gamma, ADA: adenosine deaminase. IFN- γ cut point of 107.7 pg/ml determined by ROC. ADA clinical cut point of 30 U/L is used for clinical decision-making at Groote Schuur hospital. Rule-in ADA cut point of 48.85U/l determined by ROC.
  2. Superscript symbols: *; #; $; £: O; ; ×; ; ¥; ; ; ; ; ▪; ; ¢; °; ¤; §; ¿; ð and þwere used to indicate which groups were being compared for statistical analysis.