Prevalence, risk factors, and outcomes of systemic sclerosis–associated interstitial lung disease in a Chinese population

Systemic sclerosis-associated interstitial lung disease (SSc-ILD) is a leading cause of mortality among systemic sclerosis (SSc) patients. This multicentre cohort study sought to determine the prevalence of SSc-ILD, identify risk factors for ILD development in SSc patients, and explore poor prognostic factors in SSc-ILD patients. Medical records were retrospectively reviewed for Chinese patients who met the 2013 American College of Rheumatology/European League Against Rheumatism classification criteria for SSc. Univariable and multivariable analyses were performed to compare SSc patients with and without ILD, as well as SSc-ILD patients with and without disease progression. Survival analysis was also conducted. The study cohort comprised 223 SSc patients with a median follow-up duration of 8.1 years. The prevalence of ILD was 49.8%. A history of bibasal crackles (hazard ratio [HR]=2.813; P=0.001) was independently associated with ILD development. Among ILD patients, 64.1% exhibited progressive disease. An elevated C-reactive protein (CRP) level at ILD diagnosis (HR=1.064; P=0.002) constituted an independent predictor of ILD progression. The overall mortality rate was 24.2% and pneumonia was the most common cause of death. Predictors of mortality included age at SSc diagnosis (HR=1.101; P=0.002), history of smoking (HR=5.173; P=0.028), and CRP level at SSc diagnosis (HR=1.103; P=0.009). Interstitial lung disease was prevalent among SSc patients in this cohort and the majority exhibited disease progression. Comprehensive clinical assessment, supported by investigations such as CRP level measurement, is essential to identify predictors of poor prognosis.