TABLE 4.
Comparative sensitivities, specificities, and Youden index for diagnosis of symptomatic laboratory-confirmed pertussisa
| Method of diagnosis (cutoff) | % Sensitivity (95% CIc) | % Specificity (95% CI) | Youden index |
|---|---|---|---|
| ptxA-Pr PCR | 15.9 (10.8-21.0) | 97.3 (95.1-99.5) | 0.13 |
| IS481 PCR | 45.1 (38.1-52.1) | 85.0 (80.0-90.0) | 0.30 |
| Single serology (≥125 EU/ml) | 64.6 (57.9-71.3) | 92.0 (88.2-95.8) | 0.57 |
| Paired serology (×4b) | 15.9 (10.8-21.0) | 89.4 (85.1-93.7) | 0.05 |
| Combination of single serology (≥125 EU/ml) with: | |||
| Paired serology, (×4) | 80.4 (74.8-86.0) | 89.4 (85.1-93.7) | 0.70 |
| ptxA-Pr PCR | 75.6 (69.6-81.6) | 98.2 (96.3-100) | 0.74 |
| IS481 PCR | 89.0 (84.6-93.4) | 79.6 (73.9-85.3) | 0.69 |
a
Subjects are contacts of infant pertussis cases for whom there is complete laboratory data (n = 195). Complete data include symptoms, serology, and PCR (IS481 and ptx-Pr) at enrollment and symptoms and serology at follow-up visit 1 month later.
b
×4, fourfold change in titer.
c
CI, confidence interval.