TABLE 3.
Performance of the FIA across groups of RT-PCR Ct-valuesa
| Ct-value | |||
|---|---|---|---|
| < 25 | 25–30 | > 30 | |
| Sensitivity | 100.00 (92.29–100.00) | 92.31 (66.69–99.61) | 31.82 (13.87–54.87) |
| Specificity | 88.74 (83.90–92.25) | 76.86 (71.31–81.62) | 73.98 (68.03–79.35) |
| LR+ | 8.88 (6.14–12.85) | 3.99 (3.04–5.24) | 1.22 (0.64–2.34) |
| LR– | 0.00 | 0.10 (0.02–0.66) | 0.92 (0.69–1.24) |
| PPV | 77.11 (69.96–82.97) | 16.90 (9.94–27.26) | 31.69 (19.54–46.98) |
| NPV | 100 (98.09–100.00) | 99.49 (97.18–99.97) | 74.15 (68.74–78.91) |
| Accuracy | 91.72 (87.76–94.73) | 80.96 (75.74–85.48) | 62.81 (56.72–68.61) |
| AUC | 0.94 (0.91–0.97) | 0.85 (0.80–0.89) | 0.53 (0.47–0.59) |
a
LR+/–: positive and negative likelihood ratio; PPV: positive predictive value; NPV: negative predictive value; AUC= area under the curve; FIA = SD Biosensor Standard F COVID-19 Ag Test.