%0 Journal Article %A Vera van Kampen %A Julia Engel %A Olaf Hagemeyer %A Thomas Brüning %A Monika Raulf %A Rolf Merget %T Does the measurement of exhaled nitric oxide before and after specific inhalation challenges improve the diagnosis of occupational asthma? %D 2019 %R 10.1183/13993003.congress-2019.OA3281 %J European Respiratory Journal %P OA3281 %V 54 %N suppl 63 %X Elevated levels of exhaled nitric oxide (FeNO) represent a marker of eosinophilic airway inflammation. Increases of FeNO have been described after specific inhalation challenges (SIC) with occupational allergens.The aim of this study was to assess whether FeNO measurements before and after SIC provide additional information for the diagnosis of occupational asthma (OA) and to define a significant increase of FeNO after SIC.148 patients with suspected OA were examined by SIC with various occupational allergens. Subjects were classified according to standard pulmonary function criteria as pulmonary responders, non-responders or doubtfuls. FeNO was measured before SIC (baseline) and 24 h afterwards. Receiver-operating characteristic curves were used to determine the cut-off for a significant FeNO increase. Subjects with negative or doubtful SIC but a significant increase of FeNO were evaluated individually by an overall expert rating taking into account all available information.31 patients (21%) were classified as pulmonary responders, 105 (71%) as non-responders and 12 (8%) as doubtful. A FeNO increase ≥ 13 ppb after SIC was found to be significant (specificity 0.9 and sensitivity 0.5). Out of 17 subjects with negative or doubtful pulmonary responder status but with a significant FeNO increase the overall rating yielded 13 subjects with OA.By considering the results of FeNO measurements before and after SIC, the number of false-negative diagnoses of OA could be decreased in our study. Because of the low sensitivity, it should not be used as a single tool, but be combined with lung function and further available information.FootnotesCite this article as: European Respiratory Journal 2019; 54: Suppl. 63, OA3281.This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only). %U