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Table 2 Diagnostic performance of plasma IS6110- and IS1081- dPCR assay for TB

From: Evaluation of digital PCR assay in detection of M.tuberculosis IS6110 and IS1081 in tuberculosis patients plasma

  Cut-off point (copies/20 μl) AUC Sensitivity(%) Specificity(%) LR+ LR- PPV (%) NPV (%)
Total TB (n = 155) compared with HC (n = 106)
 IS6110-dPCR 7 0.79 (0.74–0.85) 40.6 (32.8–42.8) a,b 93.4 (86.9–97.3) 6.2 (2.9–12.9) 0.6 (0.6–0.7) 90.0 (80.4–95.9) 51.8 (44.5–59.1)
 IS1081-dPCR 5.5 0.72 (0.66–0.78) 27.1 (20.3–34.8) 93.4 (86.9–97.3) 4.1 (1.9–8.8) 0.8 (0.7–0.9) 85.7 (72.8–94.1) 46.7 (39.8–53.7)
 Joint detection IS6110 & IS1081-dPCR 0.67 (0.60–0.73) 42.6 (34.7–50.8) 90.6 (83.3–95.4) 4.5 (2.4–8.4) 0.6 (0.5–0.7) 86.8 (77.1–93.5) 51.9 (44.4–59.3)
Disseminated TB (16) compared with HC (n = 106)
 IS6110-dPCR 7 0.98 (0.97–1.00) 100.0 (79.4–100.0) c,d 93.4 (86.9–97.3) 15.1 (7.4–31.0) 0.0 (−) 69.6 (46.5–87.1) 100.0 (96.3–100.0)
 IS1081-dPCR 5.5 0.95 (0.91–0.99) 68.8 (41.3–89.0) e,f 93.4 (86.9–97.3) 10.4 (4.7–22.9) 0.3 (0.2–0.7) 61.1 (35.0–83.2) 95.2 (89.1–98.4)
Extrapulmonary TB (56) compared with HC (n = 106)
 IS6110-dPCR 7 0.83 (0.77–0.90) 50.0 (36.3–63.7) 93.4 (86.9–97.3) 7.6 (3.5–16.2) 0.5 (0.4–0.7) 80.0 (62.8–91.7) 78.0 (69.7–84.8)
 IS1081-dPCR 5.5 0.81 (0.74–0.88) 39.3 (26.5–53.5) 93.4 (86.9–97.3) 4.2 (2.1–8.2) 0.7 (0.5–0.8) 68.7 (49.7–84.1) 73.8 (65.4–81.2)
Bilateral TB (111) compared with HC (n = 106)
 IS6110-dPCR 7 0.82 (0.76–0.87) 43.2 (33.9–53.0) 93.4 (86.9–97.3) 6.6 (3.1–13.8) 0.6 (0.5–0.7) 87.3 (75.4–94.8) 61.1 (53.1–68.7)
 IS1081-dPCR 5.5 0.75 (0.68–0.81) 33.3 (24.7–42.9) 93.4 (86.9–97.3) 5.1 (2.4–10.8) 0.7 (0.6–0.8) 84.1 (69.7–93.4) 57.2 (49.5–64.7)
  1. AUC area under receiver operating characteristic (ROC) curve, LR+ positive likelihood ratio, LR- negative likelihood ratio, PPV positive predictive value, NPV negative predictive value
  2. a sensitivity comparison between IS6110- and IS1081- dPCR in total TB patients (p < 0.001, McNemar test)
  3. b sensitivity comparison between IS6110- and IS6110- or IS1081- positive dPCR in total TB patients (p = 0.250, McNemar test)
  4. c sensitivity comparison of IS6110-dPCR between Disseminated TB and Extrapulmonary TB patients (p < 0.001, Pearson Chi-Square test)
  5. d sensitivity comparison of IS6110-dPCR between Disseminated TB and Bilateral TB patients (p < 0.001, Pearson Chi-Square test)
  6. e sensitivity comparison of IS1081-dPCR between Disseminated TB and Extrapulmonary TB patients (p = 0.037, Pearson Chi-Square test)
  7. f sensitivity comparison of IS1081-dPCR between Disseminated TB and Bilateral TB patients (p = 0.006, Pearson Chi-Square test)