TABLE 3.
Performance of all assay systems for the detection of CDAD using the final diagnosis based on clinical and laboratory criteria as the gold standard
| Assay method | Result | Specimens from patients for whom CDAD status was determined to be (n = 193a):
|
Performance characteristics (%)
|
||||
|---|---|---|---|---|---|---|---|
| Positive (n = 56) | Negative (n = 137) | Sensitivity | Specificity | PPVb | NPVc | ||
| Cytotoxin | Positive | 55 | 2 | 98 | 99 | 96 | 99 |
| Negative | 1 | 135 | |||||
| ImmunoCard Toxin A | Positive | 30 | 2 | 54 | 99 | 94 | 84 |
| Negative | 26 | 135 | |||||
| Oxoid Toxin A | Positive | 28 | 3 | 50 | 98 | 91 | 83 |
| Negative | 28 | 134 | |||||
| TechLab Toxin A/B | Positive | 44 | 3 | 79 | 98 | 94 | 92 |
| Negative | 12 | 134 | |||||
| Premier Toxin A&B | Positive | 45 | 3 | 80 | 98 | 94 | 93 |
| Negative | 11 | 134 | |||||
| Culture | Positive | 32 | 0 | 57 | 100 | 100 | 85 |
| Negative | 24 | 137 | |||||
a
For five patients from whom 7 of 200 specimens were submitted, full clinical details were not accessible. These seven specimens are excluded from the analysis.
b
PPV, predictive value of a positive result.
c
NPV, predictive value of a negative result.