Abstract
INTRODUCTION: Interstitial lung disease (ILD) in systemic sclerosis (SSc) is heterogeneous with varied progression rate. This study aimed to identify the baseline clinical characteristics associated with ILD progression within 1, 3 and 5 years of the diagnosis of ILD. METHODS: This was a prospective, multicentre study - Systematic Sclerosis Cohort Singapore - conducted from January 2008 to February 2021, which included SSc patients with ILD diagnosed by high-resolution computed tomography. Progression of ILD was defined by forced vital capacity (FVC) decline ≥10% predicted or FVC decline 5%-9% predicted, with diffusing lung capacity of carbon monoxide decline ≥15% from the time of ILD diagnosis. Multivariable logistic and Cox regression analyses, adjusting for malignancy and treatment, were performed to determine independent risk factors of ILD progression. RESULTS: Of 124 SSc patients with ILD, 47.6% had limited cutaneous SSc, 33.9% had diffuse SSc and 18.5% had SSc-overlap. Progression of ILD was seen in 6%, 15% and 23% of patients within 1, 3 and 5 years, respectively. After adjusting for malignancy and treatment, anti-La was associated with ILD progression within 1 year (odds ratio [OR] 6.94, 95% confidence interval [CI]: 1.14-42.2; P = 0.04) and 3 years (OR 5.98, 95% CI: 1.31-27.4; P = 0.02), and anti-Scl-70 was associated with ILD progression within 5 years (OR 2.54, 95% CI: 1.05-6.12; P = 0.04). Analysing time to ILD progression as an outcome, anti-La was significantly associated with higher risk of ILD progression (hazard ratio 3.47, 95% CI: 1.18-10.2; P = 0.02). Time to ILD progression was 1.4 years in patients with anti-La versus 6.9 years in patients without anti-La ( P = 0.02), and 4.7 years in patients with anti-Scl-70 versus 8.9 years in patients without anti-Scl-70 ( P = 0.12). CONCLUSION: In this Asian cohort of SSc patients, autoantibodies may help to predict ILD progression rates.