Identification of diagnostic criteria for chronic hypersensitivity pneumonitis: An international modified Delphi survey

Rationale: Current diagnosis of chronic hypersensitivity pneumonitis (cHP) involves considering a combination of clinical, radiological, and pathological information in multidisciplinary team discussions. However, this approach is highly variable with poor agreement between centers. Objectives: We aimed to identify diagnostic criteria for cHP that reach consensus among international experts. Methods: A three-round modified Delphi survey was conducted between April and August 2017. A total of 45 experts in interstitial lung disease from 14 countries participated in the online survey. Diagnostic items included in round 1 were generated using expert interviews and literature review. During rounds 1 and 2, experts rated the importance of each diagnostic item on a 5-point Likert scale. The a priori threshold of consensus was 75% or greater of experts rating a diagnostic item as very important or important. In the third round, experts graded the items that met consensus as important and provided their level of diagnostic confidence for a series of clinical scenarios. Measurements and Main Results: Consensus was achieved on 18 of the 40 diagnostic items. Among these, experts gave the highest level of importance to the identification of a causative antigen, time relation between exposure and disease, mosaic attenuation on chest imaging, and poorly formed nonnecrotizing granulomas on pathology. In clinical scenarios, the diagnostic confidence of experts in cHP was heightened by the presence of these diagnostic items. Conclusions: This consensus-based approach for the diagnosis of cHP represents a first step toward the development of international guidelines for the diagnosis of cHP.