RESUMO
BACKGROUND: In adults, measurement of FENO has been recently suggested as a substitute for the methacholine challenge test (MCT) for diagnosis of asthma. This study aimed to evaluate whether FeNO is a substitute for MCH also in children with suspicious asthma. METHODS: During a single visit steroid naive children (5-17 years) with suspicious asthma underwent skin prick test (SPT), FENO measurement and spirometry prior and during MCT (one concentration procedure). Results of the SPT (atopy/non-atopy) and MCT (asthma/non-asthma) were used for categorization. ROC analysis in atopy non-atopy subgroups yielded sensitivity, specificity, positive and negative predictive value (PPV and NPV) for FENO. RESULTS: The SPT revealed atopy in 134 out of 222 children (age 9.7⯱â¯3.2 years) investigated and asthma was diagnosed in 114 (77/37 atopy/non-atopy) patients. FENO values in patients with atopic asthma were significantly higher compared to those with either non-atopic asthma or atopia without asthma (18â¯ppb (5-89) vs 7â¯ppb (5-36); pâ¯<â¯0.001; 18â¯ppb (5-89) vs 11â¯ppb (5-98); pâ¯<â¯0.05). Sensitivity and specificity of FENO for diagnosing atopic asthma (FENO≥15.5â¯ppb; AUCâ¯=â¯0.635, pâ¯<â¯0.01) were 61.1% and 64.9% and non-atopic asthma (FENO≥ 6.5â¯ppb; AUCâ¯=â¯0.445, pâ¯=â¯0.382) 54.1% and 39.2%, respectively. The PPV/NPV for FENO were 0.70/0.55 in atopy and 0.39/0.54 in non-atopy patients, respectively. CONCLUSION: In children, FENO is not appropriate to substitute for the MCT. However, in patients with a negative SPT a FENO in the normal range makes the presence of atopic asthma unlikely.