Predictive factors for interstitial lung disease progression in a Singapore systemic sclerosis cohort: a multicentre study.

Abstract

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. 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. 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). In this Asian cohort of SSc patients, autoantibodies may help to predict ILD progression rates.