Systemic sclerosis: comparison of efficacy of oral cyclophosphamide and azathioprine on skin score and pulmonary involvement—a retrospective study

The aim of this study was to evaluate efficacy of azathioprine (AZA) and cyclophosphamide (CYC) as a therapeutic regimen for interstitial lung disease associated with systemic sclerosis (SSc). Thirty-six selected patients included in this retrospective cohort and received one of the two drugs; the first group consists of 15 patients who were treated with AZA (1.5–2 mg/kg/day) and the second group with 21 patients received oral CYC (up to 2 mg/kg/day). Both groups received additional low dose of prednisolone (≤10 mg) for 6 months. Forced vital capacity (FVC), diffusion lung capacity for carbon monoxide (DLCO) and skin score were assessed as outcome measures. Modified Rodnan skin score (mRSS), pulmonary function test and DLCO were evaluated at entry and at the end of study after 12 months. The mean (SD) FVC percentages obtained at baseline and post-treatment in AZA-treated patients were 62.8 ± 9.8 and 71.1 ± 20.9 with mean difference of FVC% +7.6 ± 13.1, p = 0.05, and in CYC-treated patients 59.5 ± 10.7, 63.1 ± 16.2 and +2.9 ± 11.5, respectively, p = 0.19. Baseline and post-treatment DLCO% in AZA-treated patients were 61.4 ± 25.8 and 76.7 ± 24.0 with mean difference of +15.0 ± 14.5, respectively, p = 0.01. In CYC-treated patients, those measures were 67.7 ± 27.5 and 60.0 ± 22.9 with mean difference of −8.0 ± 23.7 (p = 0.12). Following 12 months of treatment in AZA-treated patients, mean difference of changes in mRSS was −2.9 ± 3.7 and −1.4 ± 4.5 in CYC-treated patients. Our results indicated that AZA can be effective in ameliorating or stabilizing lung function in selected SSc patient groups.