Table 2. Sensitivity, specificity, PPV, and NPV according to carbapenemase type with discrepant analysis.
| Carbapenemase type (N) | % Sensitivity (95% CI) | % Specificity (95% CI) | % PPV (95% CI) | % NPV (95% CI) | |
|---|---|---|---|---|---|
| Total (206)* | At initial analysis | 95.0 (88.8–98.4) | 98.1 (97.7–98.5) | 49.0 (44.0–53.9) | 99.9 (99.8–100) |
| After discrepant analysis | 96.7 (92.3–99.0) | 99.0 (98.7–99.3) | 73.5 (67.8–78.4) | 99.9 (99.7–100) | |
| KPC (120) | At initial analysis | 94.9 (88.6–98.3) | 99.6 (99.3–99.7) | 79.7 (72.4–85.4) | 99.9 (99.8–100) |
| After discrepant analysis | 95.7 (90.3–-98.6) | 99.9 (99.7–99.9) | 93.3 (87.5–96.6) | 99.9 (99.8–99.9) | |
| NDM (61) | At initial analysis | 100 (47.8–100) | 99.0 (98.7–99.2) | 8.2 (6.4–10.3) | 100 |
| After discrepant analysis | 100 (89.4–100) | 99.5 (99.3–99.7) | 54.1 (44.4–63.5) | 99.9 (99.8–99.6) | |
| VIM (10) | At initial analysis | - | 99.8 (99.6–99.9) | - | 100 |
| After discrepant analysis | 100 (29.2–100) | 99.9 (99.7–99.9) | 30.0 (17.0–47.3) | 100 | |
| IMP (9) | At initial analysis | 100 (2.5–100) | 99.8 (99.7–99.9) | 11.1 (5.9–19.9) | 100 |
| After discrepant analysis | 100 (29.2–100) | 99.9 (99.8–99.9) | 33.3 (18.3–52.6) | 100 | |
| OXA-48 (6) | At initial analysis | 100 (2.5–100) | 99.9 (99.8–100) | 16.7 (7.7–32.4) | 100 |
| After discrepant analysis | 100 (29.2–100) | 99.9 (99.8–100) | 50 (24.4–75.6) | 100 | |
| Non-KPC (86)† | At initial analysis | 100 (59.0–100) | 99.6 (99.5–99.7) | 8.1 (6.6–9.9) | 100 |
| After discrepant analysis | 100 (91.6–100) | 99.8 (99.7–99.8) | 48.8 (41.5–56.2) | 100 | |
*The number of positive samples was counted; samples harboring multiple genes were counted as one sample.
†Non-KPC includes NDM, VIM, IMP, and OXA-48.
Abbreviations: CI, confidence interval; PPV, positive predictive value; NPV, negative predictive value; KPC, Klebsiella pneumoniae carbapenemase; NDM, New Delhi metallo-β-lactamase; VIM, Verona integron-mediated metallo-β-lactamase; IMP, imipenem; OXA-48, oxacillinase-48.