Corticosteroid-induced remission and mycophenolate maintenance therapy in granulomatous lymphocytic interstitial lung disease: long-term, longitudinal change in lung function in a single-centre cohort

Aim The aim of the study was to evaluate the response in lung function to different treatment regimens for common variable immunodeficiency patients with granulomatous lymphocytic interstitial lung disease (GLILD). Method A longitudinal retrospective cohort study was carried out. Patients were divided into three groups. To assess the response to different treatments, we compared baseline lung function with post-treatment tests. Results 14 patients with GLILD were included, seven of whom were treated with acute corticosteroids for a mean duration of 132±65 days. Spirometry results were unchanged, but there was a significant improvement in diffusing capacity of the lung for carbon monoxide (DLCO)% and transfer coefficient of the lung for carbon monoxide (KCO)% (median change in DLCO%=7%, p=0.04, and KCO%=13%, p=0.02). Relapse occurred in three out of seven patients. Five patients were treated with long-term mycophenolate mofetil (MMF) with/without corticosteroids for a mean duration of 1277±917 days. No changes were found in spirometry; however, there was a significant increase in DLCO% and KCO% (median change in each of DLCO% and KCO%=10%, p=0.04). Four patients on steroids with MMF successfully weaned the prednisone dose over 12 months. Four patients never received immunosuppression therapy. A significant decline was found in their lung function assessed over 7.5 years. The median reduction in the forced vital capacity (FVC)%, forced expiratory volume in 1 s (FEV1)% and DLCO% was 15%, 7% and 15%, equivalent to 2%, 1% and 2% per year, respectively. Conclusion Corticosteroids improve gas transfer in GLILD, but patients often relapse. The use of MMF was associated with long-term effectiveness in GLILD and permits weaning of corticosteroids. A delay in initiating and continuing maintenance treatment could lead to disease progression.