Assessment of a change from uncontrolled(Asthma Control Questionnaire (ACQ) score of ≥1.5) to controlled (ACQ score <1.5) asthma
| Nonsmokers | Smokers | |
| Total events n | 283 | 52 |
| Positive cases n | 133 | 17 |
| Prevalence | 47 | 33 |
| Cut-off | -30 | -20 |
| Sensitivity | 68 | 71 |
| Specificity | 71 | 66 |
| PPV | 68 | 50 |
| NPV | 72 | 82 |
| Accuracy | 70 | 67 |
| p-value# | <0.001 | 0.016 |
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 uncontrolled (ACQ score of ≥1.5) to controlled (ACQ score <1.5) asthma. A true-positive case was defined as exhaled nitric oxide fraction (FeNO) change of less than or the same as the cut-off value (e.g. -40%) associated with a positive event. FeNO exhibited similar operating characteristics in both the nonsmoking and smoking group. In particular, a high NPV was observed.