Use of mycophenolate mofetil and azathioprine for the treatment of chronic hypersensitivity pneumonitis-A single-centre experience

Introduction The optimal pharmacological management of chronic hypersensitivity pneumonitis (cHP) is unknown. Corticosteroids are often used as first line therapy but can be associated with side effects. There is a paucity of data examining the role of steroid-sparing agents in cHP. We aimed to determine the effect of mycophenolate mofetil (MMF) and azathioprine (AZA) on lung function and prednisolone dose in cHP patients. Methods Retrospective analysis of patients initiated on either MMF or AZA following a multidisciplinary team diagnosis of cHP. Changes in lung function and prednisolone dose up to 12 months before and after MMF/AZA initiation were analysed. Results Twenty two out of 30 patients remained on treatment at 12 months (18 MMF, 4 AZA). Steroid-sparing therapy resulted in a significant reduction in prednisolone dose from 16.2 +/- 9.7 to 8.2 +/- 4.2 mg daily (P = 0.002). Treatment with MMF or AZA for 12 months was associated with a significant improvement in carbon monoxide diffusing capacity (TLCO) (-0.55 +/- 0.96 vs. +0.31 +/- 0.58 mmol/kPa/min, P = 0.02). Although treatment reduced the rate of forced vital capacity decline (-111 +/- 295 vs. +2.3 +/- 319 mL), it was not significant (P = 0.22). Conclusion MMF or AZA therapy in cHP is associated with an improvement in TLCO and reduction in prednisolone dose. There is a need for prospective trials.