TABLE 4.
The comparison of the distinct positive bands and the trace bands in LFIAs by visual reading in compliance to the index of LFIA by fluorescence-based automated reading.
| SDQ |
P4D |
|||
| IgM | IgG | IgM | IgG | |
| Confirmed as positive, N | 218 | 214 | 194 | 186 |
| Distinct positive band | ||||
| N | 176 | 200 | 140 | 165 |
| % | 80.7 | 93.5 | 72.2 | 88.7 |
| SDF index (COI), mean ± SD | 7.12 ± 3.37 | 15.01 ± 4.83 | 7.99 ± 3.11 | 16.31 ± 3.11 |
| Trace band | ||||
| N | 42 | 14 | 54 | 21 |
| % | 19.3 | 6.5 | 27.8 | 11.3 |
| SDF index (COI), mean ± SD | 2.29 ± 1.23 | 3.80 ± 5.13 | 3.41 ± 1.82 | 9.50 ± 6.44 |
| p-value | < 0.0001 | < 0.0001 | < 0.0001 | < 0.0001 |
| By reclassifying “trace” as “negative” | ||||
| Sensitivity, % | 45.2 | 51.4 | 36 | 42.4 |
| Specificity, % | 99.7 | 100 | 100 | 99.8 |
COI, cut-off index; LFIA, lateral flow immunoassay; N, n, number; P4D, P4DETECT COVID-19 IgM/IgG (PRIME4DIA); SD, standard deviation; SDF, STANDARD F COVID-19 IgM/IgG Combo FIA (SD BIOSENSOR); SDQ, STANDARD Q COVID-19 IgM/IgG Combo (SD BIOSENSOR).