Table 1.
Performance characteristics (with 95% confidence intervals) of anti‐SARS‐CoV‐2 antibodies IgM and IgG at different cutoff values as determined by CLIA method
| Anti‐SARS‐CoV‐2 IgM antibodies | |||||||
|---|---|---|---|---|---|---|---|
| Cutoff value | 6.7 AU/mL | 7.5 AU/mL | 9.4 AU/mL | 10.0 AU/mL | 11.3 AU/mL | 12.2 AU/mL | 13.4 AU/mL |
| Sensitivity | 76.7% (59.7‐89.2) | 73.3% (56.0‐86.8) | 73.3% (56.0‐86.8) | 73.3% (56.0‐86.8) | 70.0% (52.4 ‐ 84,3) | 66.7% (48.9‐81.7) | 66.7% (48.9‐81.7) |
| Specificity | 90.6% (81.9‐96.2) | 90.6% (81.9‐96.2) | 92.2% (84.0‐97.1) | 92.2% (84.0‐97.1) | 92.2% (84.0 ‐ 97,1) | 92.2% (84.0‐97.1) | 93.7% (86.1‐98.0) |
| PPV | 79.3% (62.5‐91.2) | 78.6% (61.3‐90.9) | 81.5% (64.3‐92.9) | 81.5% (64.3‐92.9) | 80.8% (63.1‐92.6) | 80.0% (61.8‐92.3) | 83.3% (65.4‐94.5) |
| NPV | 89.2% (80.2‐95.2) | 87.9% (78.6‐94.3) | 88.1% (78.9‐94.4) | 88.1% (78.9‐94.4) | 86.8% (77.4‐93.4) | 85.5% (76.0‐92.5) | 85.7% (76.3‐92.6) |
| LR+ | 8.18 | 7.82 | 9.39 | 9.39 | 8.96 | 8.53 | 10.7 |
| LR− | 0.26 | 0.29 | 0.29 | 0.29 | 0.33 | 0.36 | 0.36 |
| OR | 31.8 | 26.6 | 32.5 | 32.5 | 27.5 | 23.6 | 30.0 |
| Anti‐SARS‐CoV‐2 IgG antibodies | |||||||
|---|---|---|---|---|---|---|---|
| Cutoff value | 5.4 AU/mL | 7.1 AU/mL | 8.9 AU/mL | 10.0 AU/mL | 10.7 AU/mL | 12.6 AU/mL | 15.9 AU/mL |
| Sensitivity | 83.3% (67.5‐93.7) | 83.3% (67.5‐93.7) | 80.0% (63.6‐91.5) | 76.7% (59.7‐89.2) | 76.7% (59.7‐89.2) | 73.3% (56.0‐86.8) | 70.0% (52.4‐84.3) |
| Specificity | 98.45 (93.3‐99.9) | 100% (94.3‐100) | 100% (94.3‐100) | 100% (94.3‐100) | 100% (94.3‐100) | 100% (94.3‐100) | 100% (94.3‐100) |
| PPV | 96.2% (84.1‐99.8) | … | … | … | … | … | … |
| NPV | 92.6% (84.9‐97.3) | 92.8% (85.1‐97.3) | 91.4% (83.4‐96.5) | 90.1% (81.8‐95.6) | 90.1% (81.8‐95.6) | 88.9% (80.3‐94.8) | 87.7% (78.9‐93.9) |
| LR+ | 53.3 | … | … | … | … | … | … |
| LR− | 0.17 | 0.17 | 0.20 | 0.23 | 0.23 | 0.27 | 0.30 |
| OR | 315 | … | … | … | … | … | … |
Abbreviations: CLIA, chemiluminescence immunoassay; LR + , positive likelihood ratio; LR−, negative likelihood ratio; NPV, negative predictive value; OR, odds ratio; PPV, positive predictive value.