Use of mycophenolate mofetil for the treatment of hypersensitivity pneumonitis

Introduction: Chronic hypersensitivity pneumonitis (CHP) is a complex syndrome characterized by inflammation and/or pulmonary fibrosis. The main treatment remains antigen avoidance and corticoids. Immunosuppressants can improve the treatment in patients with corticoids side effects and/or poor response to traditional management, although there is little scientific evidence of its effectiveness. This paper describes a cohort of patients with CHP and analyses the evolution of their PFR according to the type of treatment followed. Methods: Longitudinal study of referred outpatients to ILD consult with the suspected diagnosis of CHP between January 2015 and April 2019. Data were collected retrospectively. Results: A total of 97 patients with a definitive diagnosis of CHP from a total of 150 patients with suspected CHP referred to the ILD consult were analyzed. The clinical and epidemiological characteristics are shown in Figure 1. 62.8% (61 patients) required specific pharmacological treatment, with prednisone (group 1, N = 61) or prednisone + mycophenolate (MMF) (group 2, N= 22), in addition to antigenic avoidance. The median follow-up time was 18.78 months IQR (11.37 - 29.26). The overall analysis and by treatment groups comparing the percentage evolution of FVC and DLCO both before and after the start of the specific treatment are shown in figure 2 showing a positive rate of change in FVC and DLCO in Group 2, without reaching the statistical significance. Conclusions: Immunosuppressive treatment with corticoids and MMF is associated with an improvement in lung function (FVC, DLCO) in patients with CHP, although prospective randomized studies would be necessary to validate its effectiveness.