Usefulness of new diagnostic criteria for chronic hypersensitivity pneumonitis established on the basis of a Delphi survey: A Japanese cohort study

Background: Chronic hypersensitivity pneumonitis (CHP) is a fibrotic interstitial lung disease (ILD) caused by repeated exposure to a variety of organic particles. In November 2017, new criteria for CHP diagnosis were proposed by Morisset et al. based on a modified Delphi survey of ILD experts. However, it remains unclear whether these criteria are useful to accurately diagnose CHP. We aimed to evaluate the newly proposed CHP diagnostic criteria. Methods: We retrospectively applied Morisset's CHP diagnostic criteria to consecutive Japanese patients who underwent surgical lung biopsy for diagnosis of ILD from 2008 to 2015. All patients underwent bronchoalveolar lavage and pulmonary function testing. Patients who had connective tissue disease complications or showed an acute or subacute disease onset were excluded. Results: A total of 251 patients were included. The diagnoses based on multidisciplinary discussion (MDD) were CHP (n = 27), idiopathic pulmonary fibrosis (n = 117), unclassifiable interstitial pneumonia (IP) (n = 65), and other diagnoses (n = 42). Of the 27 MDD-CHP patients, 14 were classified as a CHP group with diagnostic confidence >50% and 13 were not categorized (sensitivity, 51.9%; specificity, 77.7%). Morisset's CHP diagnostic criteria could help avoid SLB for the diagnosis of CHP in seven patients. Of the 13 MDD-CHP patients who were not categorized in the CHP group with diagnostic confidence >50%, the reason for the exclusion was an inconsistent with UIP pattern without CHP features. Conclusions: Half of the MDD-CHP patients were diagnosed with CHP using Morisset's CHP diagnostic criteria. Further investigation will be important for developing improved diagnostic criteria for CHP. (C) 2019 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.