Table 5 Sensitivity, specificity, PPV and NPV of CRP as a test for detecting GAS (n = 111)
CRP (mg/l) | No of patients | GAS | No GAS | Sensitivity (95% CI) | Specificity (95% CI) | PPV (95% CI) | NPV (95% CI) | Adjusted PPV* | Adjusted NPV* |
|---|---|---|---|---|---|---|---|---|---|
≥ 0 | 111 | 25 | 86 | 1 (0.86–1) | 0 (0–0.04) | 0.23 (0.23–0.23) | N/A | 0.30 (0.30–0.30) | N/A |
≥ 10 | 61 | 20 | 41 | 0.80 (0.59–0.93) | 0.52 (0.41–0.63) | 0.33 (0.27–0.40) | 0.90 (0.80–0.95) | 0.42 (0.35–0.49) | 0.86 (0.73–0.93) |
≥ 20 | 50 | 19 | 31 | 0.76 (0.55–0.91) | 0.64 (0.53–0.74) | 0.38 (0.30–0.47) | 0.90 (0.82–0.95) | 0.48 (0.38–0.56) | 0.86 (0.75–0.93) |
≥ 30 | 34 | 15 | 19 | 0.60 (0.39–0.79) | 0.78 (0.68–0.86) | 0.44 (0.32–0.57) | 0.87 (0.80–0.92) | 0.54 (0.41–0.67) | 0.82 (0.74–0.88) |
≥ 40 | 26 | 13 | 13 | 0.52 (0.31–0.72) | 0.85 (0.76–0.92) | 0.50 (0.35–0.65) | 0.86 (0.80–0.90) | 0.60 (0.44–0.73) | 0.80 (0.73–0.86) |
≥ 50 | 22 | 11 | 11 | 0.44 (0.24–0.65) | 0.87 (0.78–0.93) | 0.50 (0.33–0.67) | 0.84 (0.79–0.88) | 0.60 (0.42–0.75) | 0.78 (0.72–0.84) |
… | |||||||||
≥ 100 | 10 | 6 | 4 | 0.24 (0.09–0.45) | 0.95 (0.89–0.99) | 0.60 (0.31–0.83) | 0.81 (0.78–0.84) | 0.69 (0.40–0.88) | 0.75 (0.70–0.79) |