Table 3.
Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV)
| Multiplex real-time PCR | Culturea | Total | |
|---|---|---|---|
| Positive | Negative | ||
| Positive | 11 | 4 | 15 |
| Negative | 1 | 86 | 87 |
| Total | 12 | 90 | 102 |
| Sensitivity (95% CI)b | 91.7% (59.7–99.5%) | ||
| Specificity (95% CI)b | 95.5% (88.4–98.6%) | ||
| PPV (95% CI)b | 73.3% (44.8–91.1%) | ||
| NPV (95% CI)b | 98.9% (92.9–99.9%) | ||
aStandard routine culture of vaginal-rectal swab specimen collected from pregnant women at 35–37 weeks of gestation; bValues calculated with 95% confidence interval (CI) using the program available at http://faculty.vassar.edu/lowry/clin1.html