Assessment of a change from controlled(Asthma Control Questionnaire (ACQ) score <1.5) to uncontrolled (ACQ score ≥1.5) asthma
| Nonsmokers | Smokers | |
| Total events n | 360 | 40 |
| Positive cases n | 65 | 10 |
| Prevalence | 18 | 25 |
| Cut-off | +50 | +50 |
| Sensitivity | 42 | 68 |
| Specificity | 75 | 87 |
| PPV | 26 | 63 |
| NPV | 86 | 89 |
| Accuracy | 69 | 83 |
| p-value# | 0.001 | 0.017 |
Data are presented as %, unless otherwise indicated. PPV: positive predictive value; NPV: negative predictive value. #: the p-value was defined as the statistical significance of rejecting an area under the curve of 0.5. A positive event was defined as a change from controlled (ACQ score <1.5) to uncontrolled (ACQ score ≥1.5) asthma. A true-positive case was defined as an exhaled nitric oxide fraction (FeNO) change of more than or the same as the cut-off value associated with a positive event. FeNO exhibited similar operating characteristics in both the nonsmoking and smoking group. In particular, a high NPV was observed.