Background: Despite advances in diagnosis and management, the interstitial lung disease (ILD) lexicon is plagued by ambiguous and inconsistent terminology that complicates communication and impedes knowledge generation. The objective of this Fleischner Society Consensus Statement was to produce standardized terminology for ILD multidisciplinary diagnoses and major phenotypes.

Methods: Interviews with 10 experts were used to identify ILD clinical diagnoses and major phenotypes. The preferred term for each entity and potential alternatives were identified, alongside rationale for the preferred term. Entities with >1 potential term were the subject of an online modified Delphi survey posed to the 29 committee members, aiming to achieve consensus. Committee members rated their agreement with the initially preferred term (strongly agree, agree, neutral/unsure, disagree, strongly disagree; scored from 5 to 1, respectively), with the option to provide additional comments. Median score 4 and interquartile range 1 was considered consensus agreement. Terms not reaching agreement were discussed by video conference, followed by an additional survey that incorporated feedback.

Results: From the 60 initial terms, there were 2 root terms that required upfront consensus prior to survey initiation (ILD and interstitial pneumonia) and another 8 terms that had no alternative suggested by the committee or in the literature. Agreement was met by 47/50 terms (94%) in round 1 of the survey. The 3 terms (6%) not reaching agreement met agreement in round 2.

Conclusions: This document provides standardized recommended terms for ILD multidisciplinary diagnoses and major phenotypes that will facilitate communication among clinicians, researchers, patients, and other stakeholders.