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 (*F*_{eNO}) change of less than or the same as the cut-off value (*e.g.*-40%) associated with a positive event.*F*_{eNO}exhibited similar operating characteristics in both the nonsmoking and smoking group. In particular, a high NPV was observed.