TY - JOUR T1 - Are FENO indices useful diagnostic tools in suspected asthma? Experience of a routine lung function laboratory JF - European Respiratory Journal JO - Eur Respir J VL - 38 IS - Suppl 55 SP - p4050 AU - Florence Schleich AU - Raluca Asandei AU - Maité Manise AU - Jocelyne Sele AU - Cédric Graas AU - Renaud Louis Y1 - 2011/09/01 UR - http://erj.ersjournals.com/content/38/Suppl_55/p4050.abstract N2 - Background: Asthma diagnosis is based on symptoms associated with airflow variability. Airway inflammatory component measured by exhaled nitric oxide (FENO50) has been proposed as a diagnostic tool but remains controversial.Aim: To assess the ability of FENO indices to identify bronchial hyperresponsiveness to methacholine (PC20M < 16mg/ml) and to establish which respiratory symptoms relate to FENO indices and PC20M.Methods: We conducted a prospective study on 174 steroid naive patients addressed for PC20M. Patients with respiratory symptoms, FEV1 ≥70% pred and no proof of reversibility to inhaled salbutamol (either not done or response <12%) completed a questionnaire about their symptoms and underwent FENO measurement at different flow rates (50-100-150 and 200ml/sec) and PC20M.Results: 82 had a PC20M <16mg/ml and had significantly higher FENO50, J'awNO and Intercept but did not show significant difference in CAlvNO value. By constructing ROC curve, we found that FENO50 cut-off value of 34 ppb is able to identify bronchial hyperresponsiveness with high specificity (95%) and PPV (88%) but low sensitivity (35%) and NPV (62%). For the whole group, the dose-response slope (DRS) for methacholine weakly correlated with FENO50 but not with CalvNO. Among the positive PC20M, there was no relationship between the magnitude of PC20M and the level of FENO indices. Wheezing was the symptom most convincingly associated with raised FENO50.Conclusion: FENO50 >34 ppb is a good diagnostic criterion in patients with suspected asthma. However FENO50 ≤34ppb clearly does not rule out bronchial hyperresponsiveness and should prompt the clinician for asking methacholine challenge. ER -