The NAb concentrations of the tested 37 positive samples from NIBSC
| Result | Control | |||
|---|---|---|---|---|
| Positive | Negative | Sum | ||
| Study | Positive | 22 (a) | 2 (b) | 24 (a+b) |
| Negative | 0 (c) | 100 (PM) (d) | 113 (c+d) | |
| 13 (<3.8, NIBSC) (d) | ||||
| Sum | 22 (a+c) | 115 (b+d) | 137 (a+b+c+d) | |
The evaluation of relative clinical sensitivity (positive percent agreement; PPA) and specificity (negative percent agreement; NPA) of the recombinant RBD antigen applied LFA kits compared to a previously marketed NAb detection kit (confidence interval; CI=95%).
Agreement is assessed in terms of Cohen’s kappa; Kappa statistic must be at or in excess of 80%.
∙PPA (%)=100×a/(a+c): 100%. ∙NPA (%)=100×d/(b+d): 98.3%. ∙Overall rate of Agreement (%)=100×(a+d)/(a+b+c+d): 98.5%.
