This protocol addresses Bird fancier's lung in patients with hypersensitivity pneumonitis presenting with radiological and/or histopathological pulmonary fibrosis — the fibrotic phenotype of HP. International diagnostic guidelines now distinguish fibrotic from nonfibrotic HP because the presence of pulmonary fibrosis carries distinct prognostic and treatment implications.
In fibrotic HP, the primary aim is stabilization of lung function — specifically slowing the decline of FVC. Unlike predominantly inflammatory disease, meaningful improvement in clinical parameters is a less realistic expectation in the fibrotic phenotype; halting or slowing progression is the target.
When both inflammatory and fibrotic clinical features are present, immunosuppressive therapy may be appropriate. The benefit in fibrotic HP is expected to be more modest than in predominantly inflammatory disease, and agent selection is tailored accordingly.
DOI: 10.1111/resp.14847
Recently published international diagnostic guidelines recommend HP classification into fibrotic or nonfibrotic phenotypes based on the presence or absence of radiological and/or histopathological fibrosis, supported by the observation that pulmonary fibrosis conveys important prognostic and treatment implications.
Patients with fibrotic HP who progress despite antigen remediation, with or without immunosuppression, are considered to have PPF disease behaviour.
Despite this uncertainty, when both inflammatory and fibrotic clinical features are present, immunosuppressive therapy may still be reasonable, albeit with a lower expected magnitude of benefit than predominantly inflammatory lung disease.
For nonfibrotic HP, improvement in clinical parameters with therapy may be expected, whereas disease stabilization (or slowing of progression) may be more realistic goals in patients with predominantly fibrotic HP.
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