Hypersensitivity Pneumonitis (HP) is an immune-mediated disease that manifests as interstitial lung disease after exposure to an inhaled antigen, often unidentified. HP can be classified as non-fibrotic or fibrotic HP. Fibrotic HP is associated with impaired quality of life (QoL) and reduced survival. The value and decline of forced vital capacity (FVC) are predictive factors of mortality in fibrotic HP. In most expert centres worldwide, corticosteroids are chosen as the first-line drug to treat fibrotic HP in clinical practice. However, this strategy has not been validated in a randomized controlled trial and it remains controversial, Moreover, corticosteroids are responsible for potentially serious adverse events. The hypothesis is that prednisolone, as a first-line treatment in fibrotic hypersensitivity pneumonitis (HP), slows down FVC decline compared to placebo.
The main objective is to assess the efficacy of first-line treatment with prednisolone against placebo, on the 6-month change in FVC in percent of predicted value (% pred).The primary endpoint will be the absolute change in FVC (% pred) from baseline (inclusion visit,M0) to 6 months (M6) will be compared between the placebo arm and the prednisolone arm.