A table to show the positive test thresholds for objective tests used to diagnose asthma in children and young people (aged 5 years and older)1
| Test | Positive test threshold |
| FeNO | ≥35 ppb |
| BDR test | Improvement in FEV1 of ≥12% |
| Obstructive spirometry | FEV1/FVC ratio <70% |
| Peak flow variability | Variability >20% |
BDR, bronchodilator reversibility; FeNO, fractional exhaled nitric oxide.