Table 3. The BD GeneOhm Cdiff assay and the multiplex real-time PCR assay results compared to toxigenic culture as the reference method.
| Assay | Toxigenic culture | Assay performance (95% confidence interval) | ||||
|---|---|---|---|---|---|---|
| Negative | Positive | Sensitivity (%) | Specificity (%) | PPV (%) | NPV (%) | |
| BD GeneOhm Cdiff | ||||||
| Negative | 298 | 1 | 97.8 (87.0-99.8) | 97.7 (95.1-98.9) | 86.5 (73.5-93.9) | 99.6 (97.8-99.9) |
| Positive | 7 | 45 | ||||
| Total | 305 | 46 | ||||
| Real-time PCR | ||||||
| Negative | 301 | 2 | 95.6 (83.9-99.2) | 98.6 (96.4-99.5) | 91.6 (79.1-97.2) | 99.3 (97.3-99.8) |
| Positive | 4 | 44 | ||||
| Total | 305 | 46 | ||||
| P value* | 0.361 | > 0.999 | > 0.999 | 0.413 | ||
*P value for the comparison of sensitivity, specificity, PPV, and NPV of BD GeneOhm Cdiff and Real-time PCR assays.
Abbreviations: PPV, positive predictive value; NPV, negative predictive value.