Diagnostic accuracy of the biomarkers in the complete group
| Test | AUC (95% CI) | Positivity threshold | Sensitivity (95% CI) | Specificity (95% CI) | PPV (95% CI) | NPV (95% CI) | True positive | False positive | False negative | True negative |
| FeNO | 0.82 (0.77–0.87) | ≥12.2 ppb | 0.96 (0.90–0.99) | 0.28 (0.22–0.34) | 0.41 (0.35–0.47) | 0.92 (0.82–0.97) | 108 | 154 | 5 | 59 |
| ≥64.5 ppb | 0.39 (0.30–0.49) | 0.95 (0.92–0.98) | 0.81 (0.68–0.90) | 0.75 (0.69–0.80) | 44 | 10 | 69 | 203 | ||
| Blood eosinophils | 0.83 (0.78–0.87) | ≥0.09×109 cells·L−1 | 0.96 (0.90–0.99) | 0.26 (0.20–0.33) | 0.40 (0.34–0.46) | 0.92 (0.81–0.97) | 108 | 161 | 5 | 57 |
| ≥0.41×109 cells·L−1 | 0.36 (0.27–0.46) | 0.95 (0.91–0.97) | 0.79 (0.65–0.88) | 0.74 (0.69–0.79) | 41 | 11 | 72 | 207 | ||
| Total IgE | 0.69 (0.63–0.75) | ≥13.5 kU·L−1 | 0.96 (0.90–0.99) | 0.28 (0.22–0.34) | 0.41 (0.35–0.47) | 0.92 (0.82–0.97) | 110 | 157 | 5 | 60 |
| ≥763.5 kU·L−1 | 0.08 (0.04–0.14) | 0.95 (0.92–0.98) | 0.47 (0.25–0.71) | 0.66 (0.61–0.71) | 9 | 10 | 106 | 207 | ||
| FeNO + blood eosinophils | 0.87 (0.83–0.91) | ≥0.095# | 0.95 (0.90–0.99) | 0.39 (0.32–0.46) | 0.45 (0.39–0.52) | 0.94 (0.86–0.98) | 106 | 129 | 5 | 82 |
| ≥0.70# | 0.46 (0.36–0.56) | 0.95 (0.91–0.98) | 0.84 (0.71–0.91) | 0.77 (0.71–0.82) | 51 | 10 | 60 | 201 |
Data are presented as n, unless otherwise stated. n=336. AUC: area under the curve; PPV: positive predictive value; NPV: negative predictive value; FeNO: fraction of exhaled nitric oxide; Ig: immunoglobulin. #: All test combinations were log transformed; these values correspond to an individual's probability of sputum eosinophilia, as determined by the formula provided in online supplementary figure E3.