A retrospective review of clinical features and treatment outcomes in steroid-resistant interstitial lung disease from polymyositis/dermatomyositis

Introduction: We reviewed our experience with immunosuppressive agents in patients with steroid-resistant Interstitial Lung Disease in the setting of Polymyositis/Dermatomyositis (PM/DM-ILD) to determine whether there were major differences in outcomes. Methods: We identified all patients treated for PM/DM-ILD and assessed cyclophosphamide (CYC), azathioprine (AZA) and mycophenolate (MMF) when used as first-line steroid sparing therapy for effects on pulmonary function variables, dyspnea and tolerance at six and twelve months. Results: Among 46 patients meeting the inclusion criteria, 24 were treated with CYC, 13 with AZA and 9 with MMF. There were no baseline differences between the three treatment groups for any of the demographic or physiologic variables, dyspnea score, the presence of >30% fibrosis on CT, or the baseline steroid dose. At the six months assessment, the overall median change in FVC was 5.0% (25th, 75th percentile -3, 11.5%), corresponding to +.20 L (.09, 0.42 L) and the DLCO increased by 2.93% (-4, 9%), corresponding to 1 mm/ml/Hg (-.58, 2.3). The severity of dyspnea decreased substantially, prednisone dose could be reduced and no important difference in side effects was found in the whole group of patients. This effect was sustained after twelve months of therapy. Conclusions: In patients with PM/DM-ILD related, treatment with CYC, AZA or MMF was associated with stabilization of pulmonary physiology, improved dyspnea, and a reduction of steroid dose.