Characteristics, mortality, and risk factors in patients with systemic sclerosis-associated interstitial lung disease

Abstract

Abstract Background Systemic sclerosis (SSc) is a heterogeneous autoimmune disease characterized by the dysregulation of fibroblast function, causing multi-organ damage, which often involves the lungs. Combined interstitial lung disease (SSc-ILD) is a major cause of death among patients with SSc. Our study aimed to identify the risk factors for mortality and compare the clinical characteristics of patients with SSc-ILD. Methods Patients were retrospectively enrolled between 2010 and 2018 in a tertiary hospital in Korea. Patients with SSc-ILD were classified into two groups depending on the first pulmonary function test or radiologic findings: extensive (n = 46, forced vital capacity [FVC] < 70% or > 20% disease extent on CT scan) or limited (n = 60, FVC ≥ 70% or < 20% disease extent on CT scan). Results Patients in the extensive group were younger (mean age ± SD 49.3 ± 11.5) than those in the limited group (53.9 ± 12.5, p = 0.067). The extensive group showed frequent pulmonary hypertension (43.5% vs. 16.7%, p = 0.009), higher erythrocyte sedimentation rate (61.3 ± 33.7 vs 42.1 ± 26.0, p = 0.003), and mortality (32.6% vs. 10.0%, p = 0.011). ILD was detected within five years from the first visit (mean number of years 3.2 ± 3.9 vs. 4.3 ± 5.5, survivors vs. non-survivors), and mortality occurred in 19.8% of all patients during a 15-year follow-up. Older age, lower FVC, and combined malignancy were associated with mortality, but FVC decline was similar in the limited and extensive groups, such as 15–20% in the first year and 8–10% in the next year, regardless of the initial extent of the disease. Conclusions Patients with SSc-ILD had a heterogeneous disease course. Approximately 10% of the patients in the limited group showed progression, which was similar to the proportion of patients in the extensive group. ILD was detected within the first five years of the total follow-up period; therefore, it is necessary to carefully monitor patients’ symptoms and signs from the early stage. Long-term surveillance is also required.