Table 3.
Diagnostic accuracy measures for QIAstat-Dx Respiratory SARS-CoV-2 Panel and laboratory PCR in the point-of-care testing group (n=469)
|
QIAstat-Dx SARS-CoV-2 assay |
Laboratory PCR |
||||
|---|---|---|---|---|---|
| n/N | % (95% CI) | n/N | % (95% CI) | ||
| Positive results | 180/469 | 38·4% (34·0–42·9) | 155/469 | 33·0% (28·8–37·5) | |
| True (positive predictive value) | 176/180 | 97·8% (94·3–99·2) | 152/155 | 98·1% (94·3–99·4) | |
| False | 4/180 | 2·2% (0·6–5·6) | 3/155 | 1·9% (0·4–5·6) | |
| Negative results | 289/469 | 61·6% (57·1–66·0) | 314/469 | 67·0% (62·5–71·2) | |
| True (negative predictive value) | 288/289 | 99·7% (97·6–99·9) | 289/314 | 92·0% (88·5–94·8) | |
| False | 1/289 | 0·3% (0·0–1·9) | 25/314 | 8·0% (5·2–11·5) | |
| Sensitivity | 176/177 | 99·4% (96·9–100·0) | 152/177 | 85·9% (79·9–90·7) | |
| Specificity | 288/292 | 98·6% (96·5–99·6) | 289/292 | 99·0% (97·0–99·8) | |
| Positive likelihood ratio | .. | 72·6% (27·4–192·1) | .. | 83·6% (27·1–258·1) | |
| Negative likelihood ratio | .. | 0·01% (0·0–0·04) | .. | 0·14% (0·1–0·21) | |
| Overall accuracy | 464/469 | 98·9% (97·5–99·7) | 441/469 | 94·0% (91·5–96·0) | |
Results from each assay were compared against a composite reference standard (PCR assay with confirmation by a second assay), which showed 177 positive cases (prevalence 37·7% [33·3–42·3]) and 292 negative cases.