Background Systemic sclerosis (SSc) is a connective tissue disease characterized by fibrosis of the skin and internal organs. Although interstitial lung disease (ILD) is a major cause of death in this disease, pulmonary function remains stable in a subset of SSc patients with ILD without any treatment. However, clinical characteristics in this subset of patients are not well characterized.
Objectives To investigate clinical characteristics of SSc patients with ILD who do not require additional immunosuppressive treatment for ILD.
Methods A total of 151 SSc patients with ILD who received medical care at Seoul National University Hospital between 1978 and 2013 were enrolled in this study. ILD was diagnosed based on chest computed tomography (CT) and the extent of ILD was semi-quantitatively graded into 1-4 (grade 1, <25%; grade 2, 25–50%; grade 3, 50–75%; grade 4, >75% of lung involvement). Detailed baseline clinical characteristics were obtained from medical record review. Mortality was ascertained from medical record review and data from the Statistics Korea. After confirming survival benefit of untreated group versus treated group with Kaplan Meier analysis, clinical characteristics of untreated group were defined by comparison with treated group (chi-square test or Student t-test). Sensitivity test was performed by proving survival benefit of patients with the defined characteristics in the untreated group (log-rank test).
Results The mean (standard deviation) age at diagnosis of 151 patients was 48.7 (12.9) years and 88.7% were women. Eighty (52.9%) patients did not receive immunosuppressive treatment for ILD, while 71 (47.0%) patients required immunosuppressive treatment, which includes cyclophosphamide (n=46), azathioprine (n=8), glucocorticoids (n=14) and others (n=3). Interestingly, median survival of non-treatment group was significantly better than treatment group during the follow-up of 1300.80 person-years (p=0.029 by log-rank test). Compared with treatment group, non-treatment group had higher baseline predicted % of forced vital capacity (FVC, 79.2±16.8% vs. 68.0±18.2, p<0.001), predicted % of diffusion capacity of carbon monoxide (DLCO, 66.4±20.5 vs. 52.0±17.9, p<0.001), lower CT grade (Grade 1: 89.6% vs. 54.7%, p<0.001), absence of pulmonary arterial hypertension (83.8% vs. 64.8%, p=0.013) and absence of gastrointestinal involvement (60.0% vs. 39.0%). Other baseline characteristics were not different, which include age at diagnosis, duration of disease, skin subset, profile of autoantibodies, involvement of heart or kidney and subtypes of ILD on CT. Among the non-treatment group, patients with the defined characteristics showed significant survival benefit than those without the characteristics (p=0.0047 by log-rank test).
Conclusions Watch and wait approach may be applied to patients with SSc-associated ILD with minimal pulmonary infiltrates on CT scan and absence of pulmonary arterial hypertension at ILD diagnosis.
Disclosure of Interest None declared