Diagnosis of Hypersensitivity Pneumonitis in Adults: An Official ATS/JRS/ALAT Clinical Practice Guideline

Abstract

Background: This guideline addresses the diagnosis of hypersensitivity pneumonitis (HP). It represents a collaborative effort among the American Thoracic Society, Japanese Respiratory Society, and Asociación Latinoamericana del Tórax. Methods: Systematic reviews were performed for six questions. The evidence was discussed, and then recommendations were formulated by a multidisciplinary committee of experts in the field of interstitial lung disease and HP using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach. Results: The guideline committee defined HP, and clinical, radiographic, and pathological features were described. HP was classified into nonfibrotic and fibrotic phenotypes. There was limited evidence that was directly applicable to all questions. The need for a thorough history and a validated questionnaire to identify potential exposures was agreed on. Serum IgG testing against potential antigens associated with HP was suggested to identify potential exposures. For patients with nonfibrotic HP, a recommendation was made in favor of obtaining bronchoalveolar lavage (BAL) fluid for lymphocyte cellular analysis, and suggestions for transbronchial lung biopsy and surgical lung biopsy were also made. For patients with fibrotic HP, suggestions were made in favor of obtaining BAL for lymphocyte cellular analysis, transbronchial lung cryobiopsy, and surgical lung biopsy. Diagnostic criteria were established, and a diagnostic algorithm was created by expert consensus. Knowledge gaps were identified as future research directions. Conclusions: The guideline committee developed a systematic approach to the diagnosis of HP. The approach should be reevaluated as new evidence accumulates.

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“…HP can be categorized by disease duration into acute, subacute, and chronic subtypes ( 60 ). Raghu et al recently proposed categorization based on the presence or absence of radiological and/or histopathological fibrosis into either fibrotic HP or non-fibrotic HP, which has been widely accepted ( 61 ).…”

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“…The authors pointed to the frequent misdiagnosis of HP and emphasised the need for more clinical studies aimed at a more solid diagnosis and better management of HP. A recently presented guideline for the diagnosis of HP classifies the disease into nonfibrotic and fibrotic phenotypes [ 53 ]. According to the authors, this guideline represents the first clinical practice guideline for clinicians to recognise nonfibrotic and fibrotic HP in adult patients with newly diagnosed interstitial lung disease (ILD).…”

“…Because of undiagnosed, misdiagnosed or delayed diagnosed cases of HP, the differentiation to diseases with similar symptoms including COPD, allergic asthma, flu or flu-like infections and interstitial pneumonia should be stand in focus. When applied successively, diagnostic methods including anamnesis, physical examination, serology, chest radiography or HRCT, lung biopsy, bronchoalveolar lavage (BAL) and specific inhalation challenges with qualifying antigens can lead to a possible diagnosis of HP [ 36 , 38 , 48 , 53 , 60 – 63 ]. For correct diagnosis and successful therapy, multidisciplinary expertise including pulmonologists, radiologists, pathologists and occupational physicians, to name a few, is helpful [ 53 , 55 , 64 ].…”

Establishing content-validity of a disease-specific health-related quality of life instrument for patients with chronic hypersensitivity pneumonitis

“…We are now at the cusp of an ever-expanding field of CHP research. This includes the establishment of diagnostic criteria [ 20 , 21 ], efforts to improve methods for antigen detection and avoidance, and therapeutic clinical trials [ 2 , 3 , 22 , 23 ]. As such, there is a need for a reliable and valid HRQOL measure for use in CHP.…”