TABLE 1.
Threshold values and corresponding diagnostic sensitivity and specificity for the competition ELISA, determined by ROC analysis
| Threshold | Sensitivity (%) (95% CI) | Specificity (%) (95% CI) | PPV (%) | NPV (%) |
|---|---|---|---|---|
| (A) Non‐immune plasma versus CCP | ||||
| >0.183 | 60.8 (49.4–71.1) | 100 (86.2–100) | 100 | 0 |
| >0.159 | 77.3 (66.3–85.1) | 87.5 (69.0–95.7) | 100 | 0 |
| >0.138 | 82.4 (72.2–89.4) | 79.2 (59.5–90.8) | 100 | 0 |
| >0.106 | 94.6 (86.9–97.9) | 62.5 (42.7–78.8) | 100 | 0 |
| (B) Low titer CCP versus high titer CCP | ||||
| >0.505 | 5.26 (0.94–17.3) | 100 (90.4–100) | 100 | 76.0 |
| >0.401 | 18.4 (9.22–33.4) | 97.2 (85.8–99.9) | 68.7 | 78.1 |
| >0.330 | 34.2 (21.2–50.1) | 88.9 (74.7–95.6) | 50.7 | 80.2 |
| >0.233 | 52.6 (37.3–67.5) | 58.3 (42.2–72.9) | 29.6 | 79.7 |
Note: (A) Results for discrimination between non‐immune plasma and CCP. (B) Results for discrimination between low (≤1:80) and high (≥ 1:160) titer CCP. The positive predictive value (PPV) and negative predictive value (NPV) are given in (A) assuming a prevalence of 100%, that is, the donor provides evidence of former SARS‐CoV‐2 infection and (B) assuming a prevalence of 25% ≥ CCP160 in the population.