Table 3.
Predictive Accuracy of FENO50 and Blood Eosinophil Measurements for Assessing Airway Eosinophilia in Stable COPD Patients
| FENO50 | ||||||||
|---|---|---|---|---|---|---|---|---|
| Sputum Eosinophils | AUC | 95% CI | P value | Cut Point (ppb) | Sensitivity (%) | Specificity (%) | PPV (%) | NPV (%) |
| >3% (n=8) | 0.69 | 0.45–0.93 | 0.097 | 29.5 | 63 | 91 | 56 | 93 |
| >2% (n=13) | 0.59 | 0.39–0.79 | 0.350 | 20.6 | 50 | 75 | 44 | 79 |
| Blood Eosinophils (absolute count) | ||||||||
| Sputum Eosinophils | AUC | 95% CI | P value | Cut Point (cells ×109/L) | Sensitivity (%) | Specificity (%) |
PPV (%) |
NPV (%) |
| >3% (n=8) | 0.84 | 0.65–1.02 | 0.003 | 0.316 | 75 | 98 | 86 | 95 |
| >2% (n=13) | 0.82 | 0.68–0.96 | <0.001 | 0.204 | 77 | 76 | 53 | 91 |
| Blood Eosinophils (relative percentage) | ||||||||
| Sputum Eosinophils | AUC | 95% CI | P value | Cut Point (%) | Sensitivity (%) | Specificity (%) | PPV (%) | NPV (%) |
| >3% (n=8) | 0.80 | 0.58–1.01 | 0.008 | 3.5 | 75 | 84 | 46 | 95 |
| >2% (n=13) | 0.78 | 0.63–0.93 | 0.003 | 2.5 | 77 | 63 | 42 | 89 |
Abbreviations: AUC, area under the receiver operating characteristic curve; CI, confidence interval; FENO50, fractional exhaled nitric oxide measured at an exhalation flow rate of 50 mL/s; ppb, parts per billion; PPV, positive predictive value; NPV, negative predictive value.