Use of mycophenolate mofetil for the treatment of fibrotic hypersensitivity pneumonitis.

Introduction: The optimal treatment of fibrosing hypersensitivity pneumonitis (fHP) is not well understood. The aim of the study was to obtain information about the usefulness of mycophenolate mofetil (MMF) in its treatment.

Material and methods: Quasi-experimental analysis of patients diagnosed with fHP and treated with MMF for one year, in a single centre. From the start of treatment, data collection was prospective.

Results: 73 were included and 58 completed the study. FVC% and DLCO% decreased until starting MMF (year -1 to year 0). After completion of treatment (year 1), FVC% stabilised (p=0.336) and DLCO% improved significantly (p=0.004) compared to year 0. Dyspnoea, number of patients without corticosteroids and mean corticosteroid dose also improved significantly (p<0.001 in all cases). Being male and having a history of tuberculosis were predictors of poor drug response [AUC = 0.89 (95% CI: 0.80-0.98)]. 45 adverse effects were observed in 34 patients (46.6%). In 4 cases (5.5%), the adverse effect was severe and required discontinuation of treatment.

Conclusions: In patients with fHP, MMF improves lung function and dyspnoea and reduces both the number of patients requiring oral corticosteroids and their mean dose in those who completed 1 year of treatment. The model constructed predicts which patients will respond poorly to treatment, with good discriminative ability and only a small percentage of patients will not tolerate treatment. Further prospective, randomised clinical trials are needed to define the role of this treatment in fHP.