Diagnosis of Hypersensitivity Pneumonitis in Adults - Clinical Practice Guideline

The American Thoracic Society offers official clinical practice guidelines for the diagnosis of hypersensitivity pneumonitis (HP) in adults.

In this document, a review committee considered six questions from which recommendations were formulated by a multidisciplinary committee of experts in the field using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach.

The recommendations include, but are not limited to:

• HP must be considered in the differential diagnosis for patients with newly identified interstitial lung disease (ILD).
• HP can be categorized into two clinical phenotypes - nonfibrotic HP and fibrotic HP - with separate recommendations made for each type.
• For both types, the following recommendations are made:
  • A thorough history should be taken to identify potential environmental causes associated with HP.
  • Serum IgG testing targeting potential antigens association with HP is suggested.
  • Bronchoalveolar lavage (BAL) fluid can be obtained and analysed for lymphocytes.
  • Surgical lung biopsy is suggested only when all other diagnostic testing has failed.
• For nonfibrotic HP, transbronchial forceps lung biopsy is also suggested.
• For fibrotic HP, transbronchial lung cryobiopsy is also suggested.