Table 1.
Clinical performance characteristics of LFA in serum to detect SARS-CoV-2 antibodies
| IgM and/or IgG | MedTest | EcoTest | Camtech | Wondfo | ||||
|---|---|---|---|---|---|---|---|---|
| value | 95% CI | value | 95% CI | value | 95% CI | value | 95% CI | |
| Group PCR+/PCR– | ||||||||
| TP | 69 | 67 | 76 | 71 | ||||
| Sensitivity, % | 84.15 | 74.42; 91.28 | 81.71 | 71.63; 89.38 | 92.68 | 84.75; 97.27 | 86.59 | 77.26; 93.11 |
| Specificity, % | 100.00 | 90.51; 100.00 | 78.38 | 61.79; 90.17 | 78.38 | 61.79; 90.17 | 100.00 | 90.51; 100.00 |
| LR (+) | 32.50 | 4.68; 225.50 | 3.78 | 2.03; 7.04 | 4.29 | 2.31; 7.94 | 33.43 | 4.82; 231.85 |
| LR (−) | 0.16 | 0.10; 0.26 | 0.23 | 0.14; 0.38 | 0.09 | 0.04; 0.21 | 0.13 | 0.08; 0.23 |
| DOR | 203.00 | 46.80; 867.00 | 16.43 | 14.5; 18.53 | 47.67 | 57.75; 37.81 | 257.15 | 60.25; 1,008 |
| Youden's index | 0.84 | 0.65; 0.91 | 0.60 | 0.33; 0.80 | 0.71 | 0.47; 0.87 | 0.87 | 0.68; 0.93 |
| CUI+ | 0.84 | 0.77; 0.92 | 0.73 | 0.64; 0.83 | 0.84 | 0.77; 0.91 | 0.87 | 0.80; 0.94 |
| CUI– | 0.74 | 0.66; 0.82 | 0.52 | 0.40; 0.63 | 0.65 | 0.54; 0.76 | 0.77 | 0.69; 0.85 |
| PPV, % | 100.00 | − | 89.33 | 81.81; 93.98 | 90.48 | 83.68; 94.62 | 100.00 | − |
| NPV, % | 74.00 | 63.35; 82.41 | 65.91 | 54.28; 75.90 | 82.86 | 68.71; 91.41 | 77.08 | 66.00; 85.36 |
| Accuracy, % | 89.08 | 82.04; 94.05 | 80.67 | 72.42; 87.34 | 88.24 | 81.05; 93.42 | 90.76 | 84.06; 95.29 |
| MCC | 0.79 | − | 0.57 | − | 0.72 | − | 0.82 | − |
| Group PCR+ | ||||||||
| TP | 68 | 65 | 69 | 69 | ||||
| Sensitivity, % | 97.14 | 90.06; 99.65 | 92.86 | 84.11; 97.64 | 98.57 | 92.30; 99.96 | 98.57 | 92.30; 99.96 |
| Specificity, % | 100.00 | 90.51; 100.00 | 78.38 | 61.79; 90.17 | 78.38 | 61.79; 90.17 | 100.00 | 90.51; 100.00 |
| LR (+) | 37.37 | 5.40; 258.87 | 4.29 | 2.32; 7.96 | 4.56 | 2.47; 8.43 | 37.92 | 5.48; 262.56 |
| LR (−) | 0.03 | 0.01; 0.11 | 0.09 | 0.04; 0.22 | 0.02 | 0.00; 0.13 | 0.01 | 0.00; 0.10 |
| DOR | 1,245 | 540; 2,353 | 47.66 | 58.00; 36.18 | 228 | 0.00; 64.85 | 3,792 | 0.00; 2,625 |
| Youden's index | 0.97 | 0.81; 1.00 | 0.71 | 0.46; 0.88 | 0.77 | 0.54; 0.90 | 0.99 | 0.83; 1.00 |
| CUI+ | 0.97 | 0.94; 1.00 | 0.83 | 0.75; 0.91 | 0.88 | 0.82; 0.95 | 0.99 | 0.96; 1.00 |
| CUI– | 0.95 | 0.91; 0.99 | 0.67 | 0.56; 0.78 | 0.75 | 0.66; 0.86 | 0.97 | 0.94; 1.00 |
| PPV, % | 100.00 | − | 89.04 | 81.43; 93.77 | 89.61 | 82.35; 94.10 | 100.00 | − |
| NPV, % | 94.87 | 82.52; 98.64 | 85.29 | 71.02; 93.21 | 96.67 | 80.44; 99.51 | 97.37 | 84.09; 99.62 |
| Accuracy, % | 98.13 | 93.41; 99.77 | 87.85 | 80.12; 93.37 | 91.59 | 84.63; 96.08 | 99.07 | 94.90; 99.98 |
| MCC | 0.96 | − | 0.73 | − | 0.81 | − | 0.98 | − |
| Group PCR– | ||||||||
| TP | 01 | 02 | 07 | 02 | ||||
| Sensitivity, % | 8.33 | 0.21; 38.48 | 16.67 | 2.09; 48.41 | 58.33 | 27.67; 84.83 | 16.67 | 2.09; 48.41 |
| Specificity, % | 100.00 | 90.51; 100.00 | 78.38 | 61.79; 90.17 | 78.38 | 61.79; 90.17 | 100.00 | 90.51; 100.00 |
| LR (+) | 5.57 | 0.55; 56.78 | 0.77 | 0.19; 3.14 | 2.70 | 1.24; 5.87 | 8.36 | 0.95; 73.88 |
| LR (−) | 0.92 | 0.77; 1.09 | 1.06 | 0.78; 1.44 | 0.53 | 0.27; 1.06 | 0.83 | 0.65; 1.07 |
| DOR | 6.05 | 0.71; 52.02 | 0.73 | 0.24; 2.18 | 5.09 | 4.59; 5.54 | 10.07 | 1.46; 69.05 |
| Youden's index | 0.08 | −0.09; 0.39 | −0.05 | −0.36; 0.39 | 0.37 | −0.11; 0.75 | 0.17 | −0.07; 0.48 |
| CUI+ | 0.08 | 0.00; 0.55 | 0.03 | 0.00; 0.31 | 0.27 | 0.00; 0.60 | 0.17 | 0.00; 0.61 |
| CUI– | 0.77 | 0.69; 0.84 | 0.58 | 0.47; 0.70 | 0.67 | 0.56; 0.78 | 0.79 | 0.71; 0.87 |
| PPV, % | 100.00 | − | 20.00 | 5.77; 50.49 | 46.67 | 28.67; 65.57 | 100.00 | − |
| NPV, % | 77.08 | 73.93; 79.96 | 74.36 | 68.14; 79.72 | 85.29 | 74.41; 92.04 | 78.72 | 74.18; 82.65 |
| Accuracy, % | 77.55 | 63.38; 88.23 | 63.27 | 48.29; 76.58 | 73.47 | 58.92; 85.05 | 79.59 | 65.66; 89.76 |
| MCC | 0.25 | − | −0.05 | − | 0.34 | − | 0.36 | − |
LFA, lateral flow immunochromatographic assay; TP, true positive; PPV, positive predictive value; NPV, negative predictive value; LR, likelihood ratio; DOR, diagnostic odds ratio (the higher the DOR value, the better the test); CUI, clinical utility index; MCC, Matthews correlation coefficient.