TABLE 3.
Overall performance characteristics of Lyra C. difficile assay compared to enhanced toxigenic culturea
| Test site | Platform | No. of results |
Sensitivity (95% CI) | Specificity (95% CI) | PPV (95% CI) | NPV (95% CI) | |||
|---|---|---|---|---|---|---|---|---|---|
| True Pos. | True Neg. | False Pos. | False Neg. | ||||||
| 1 | Cepheid SmartCycler | 20 | 98 | 3 | 4 | 83.3 (61.8–94.5) | 97.0 (90.9–99.2) | 87.0 (65.3–96.6) | 96.1 (89.7–98.7) |
| ABI 7500 Fast DX | 21 | 99 | 2 | 3 | 87.5 (66.5–96.7) | 98.0 (92.3–99.7) | 91.3 (70.5–98.5) | 97.1 (91.0–99.2) | |
| ABI Quant Studio DX | 20 | 101 | 0 | 4 | 83.3 (61.8–94.5) | 100.0 (95.4–100.0) | 100.0 (80.0–100.0) | 96.2 (90.0–98.8) | |
| 2 | Cepheid SmartCycler | 24 | 90 | 4 | 2 | 92.3 (73.4–98.7) | 95.7 (88.8–98.6) | 85.7 (66.4–95.3) | 97.8 (91.6–99.6) |
| ABI 7500 Fast DX | 25 | 90 | 4 | 1 | 96.2 (78.4–99.8) | 95.7 (88.8–98.6) | 86.2 (67.4–95.5) | 98.9 (93.2–99.9) | |
| ABI Quant Studio DX | 24 | 93 | 1 | 2 | 92.3 (73.4–98.7) | 98.9 (93.4–99.9) | 96.0 (77.7–99.8) | 97.9 (91.9–99.6) | |
| 3 | Cepheid SmartCycler | 48 | 286 | 8 | 14 | 77.4 (64.7–86.7) | 97.3 (94.5–98.7) | 85.7 (73.2–93.2) | 95.3 (92.1–97.3) |
| ABI 7500 Fast DX | 54 | 294 | 0 | 8 | 87.1 (75.6–93.9) | 100.0 (98.4–100.0) | 100.0 (91.7–100.0) | 97.4 (94.6–98.8) | |
| ABI Quant Studio DX | 52 | 290 | 4 | 10 | 83.9 (71.9–91.6) | 98.6 (96.3–99.6) | 92.9 (81.9–97.7) | 96.7 (93.8–98.3) | |
| Total | Cepheid SmartCycler | 92 | 474 | 15 | 20 | 82.1 (73.5–88.5) | 96.9 (94.9–98.2) | 86.0 (77.6–91.7) | 96.0 (93.7–97.) |
| ABI 7500 Fast DX | 100 | 483 | 6 | 12 | 89.3 (81.7–94.1) | 98.8 (97.2–99.5) | 94.3 (87.6–97.7) | 97.6 (95.7–98.7) | |
| ABI Quant Studio DX | 96 | 484 | 5 | 16 | 85.7 (77.5–91.4) | 99.0 (97.4–99.6) | 95.0 (88.3–98.2) | 96.8 (94.7–98.1) | |
a
Pos., positive; Neg., negative; CI, confidence interval.