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.

Idiopathic pulmonary fibrosis has a median survival time after diagnosis of 2-5 years. The main goal of treating IPF is to stabilize or reduce the rate of disease progression. Nintedanib and Pirfenidone have been a breakthrough in the management of IPF. Here we evaluated the effectiveness of Pirfenidone and Nintedanib in a population of IPF patients diagnosed in the last 12 months at Florence ILD Referral Centre. In the last 12 months, 82 IPF patients (66 male, mean age 78.3±23.8 years) were diagnosed and started antifibrotic therapy with Pirfenidone or Nintedanib. Their clinical and functional details were analyzed retrospectively at time 0 and after 6 and 12 months of therapy. The median age of the patients treated with Nintedanib was higher than that of the Pirfenidone group (p0.05). After 1 year, lung function test parameters of patients treated with Pirfenidone had remained stable from baseline. This study emphasizes that both antifibrotic drugs appeared to be a good therapeutic choice in terms of functional stabilization, also in older patients.