Expert Consensus on Chronic Hypersensitivity Pneumonitis Diagnostic Criteria

An international modified Delphi survey identified 18 items as important in the diagnosis of chronic hypersensitivity pneumonitis (cHP), according to an article published in the American Journal of Respiratory and Critical Care Medicine.

cHP is a fibrotic interstitial lung disease (ILD) that results from exposure to a sensitizing antigen over time. However, it can be difficult to differentiate cHP from idiopathic pulmonary fibrosis. There are no accepted guidelines or criteria to aid the practitioner in the diagnosis of cHP and, as a result, the diagnostic process varies considerably from one ILD center to another.

To assist clinicians in the cHP diagnostic process, Julie Morisset, MD, of the Département de Médecine, Centre Hospitalier de l’Université de Montréal in Quebec, Canada, and colleagues conducted an online, 3-round, modified Delphi survey between April and August 2017 in 45 experts in ILD from 14 countries. 

Experts rated the importance of each diagnostic item on a 5-point Likert scale during rounds 1 and 2. A threshold of 75% of experts constituted consensus in rating a diagnostic item as important or very important. In round 3, experts graded the items that met consensus as important and established a level of diagnostic confidence for a series of clinical scenarios.

The HP Delphi Collaborators reported that consensus was reached on 18 of the 40 diagnostic items. The 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 pathologic examination. The experts felt that the presence of these diagnostic criteria created greater confidence in a diagnosis of cHP.

The researchers noted that the study has important limitations, including having only pulmonologists on the expert panel. Although pulmonologists are usually the medical professionals who arrive at a diagnosis of cHP, this could have biased the results or limited the discussion in some ways. Another issue was that although there was good response for each round of Delphi, it was not complete for all 3 rounds. It also was not possible to include all possible combinations of diagnostic criteria in the round 3 clinical scenarios, limiting the options of the expert panel vote. In addition, the wording of the survey questions could have biased the results.

Nonetheless, the authors believe that this study is an essential first step toward establishing international guidelines for the diagnosis of cHP.

Reference

Morisset J, Johannson KA, Jones KD, et al. Identification of diagnostic criteria for chronic hypersensitivity pneumonitis. An international modified Delphi survey. Am J Respir Crit Care Med. 2018;197:1036-1044.