Diagnostic accuracy of FeNO testing (≥35 ppb) in diagnosing asthma compared with traditional methods3 4
| Test | Population | Sensitivity (95% CI) | Specificity (95% CI) | NPV (95% CI) | PPV (95% CI) | Quality of evidence |
| FeNO | Children | 57% | 87% | 49% | 90% | High—no risk of bias, inconsistency or indirectness |
| Adults | 43% to 88% | 60% to 92% | 65% to 93% | 54% to 95% | Moderate—no risk of bias, serious indirectness | |
| Spirometry | Children | 52% | 73% | 49% | 75% | |
| Adults | 23% to 47% | 31% to 100% | 18% to 73% | 45% to 100% | Moderate—no risk of bias, serious indirectness | |
| Peak flow | Children | 50% | 72% | 74% | 48% | High—no risk of bias, inconsistency or indirectness |
| Adults | 46% | 80% | 10% | 97% | ||
| Bronchodilator reversibility | Children | 50% | 86% | |||
| Adults | 17% to 69% | 55% to 81% | 22% to 68% | 53% to 82% | Very low—serious risk of bias, inconsistency and indirectness |
FeNO, fractional exhaled nitric oxide; NPV, negative predictive value; PPV, positive predictive value.