TABLE 1.
Performance characteristics of A/B EIA and the LF-A/B assay compared with those of a two-step algorithm using C. Diff Chek-60 and C. difficile toxin B assays
| Test and result | No. of specimens with the following two-step algorithm result:
|
Sensitivity (%) | Specificity (%) | NPVa (%) | PPVb (%) | |
|---|---|---|---|---|---|---|
| Positive | Negative | |||||
| A/B-EIA | 59.5 (43.5-73.7)c | 99.4 (97.8-99.8) | 95.6 | 91.7 | ||
| Positive | 22 | 2 | ||||
| Negative | 15 | 329 | ||||
| LF-A/B assay | 43.2 (28.7-59.1) | 98.5 (96.5-99.4) | 93.9 | 76.2 | ||
| Positive | 16 | 5 | ||||
| Negative | 21 | 326 | ||||
a
NPV, negative predictive value (predictive value of a negative test result).
b
PPV, positive predictive value (predictive value of a positive test result).
c
Values in parentheses are the 95% confidence limits, determined by the “score” method.