The incidence of interstitial lung disease in patients with systemic sclerosis: rate, risk factors and prognostic implications in a EUSTAR cohort analysis (CP 133)

OBJECTIVES: Interstitial lung disease (ILD) carries significant morbidity and mortality risk in systemic sclerosis (SSc). We aimed to estimate the incidence of new-onset SSc-ILD and the associated risk factors, as well as its impact on the prognosis. METHODS: Patients classified as having SSc, with the absence of ILD signs on high-resolution computed tomography (HRCT) at baseline and having at least 1 follow-up visit with available HRCT data, were selected. SSc-ILD incidence was calculated as a rate per 100 person-years. Predictors of new-onset ILD and risk factors for ILD progression and mortality were chosen according to the literature and expert opinion. Risk factors for new-onset ILD, as well as its prognostic impact on ILD progression and mortality, were tested by generalised logistic estimating equation and Cox regression models, respectively. RESULTS: Among 5331 patients with SSc with negative baseline HRCT, the incidence of new-onset ILD was 3.83 cases per 100 person-years. Notably, there was a continuous detection of new ILD onset up to 10 years from baseline. Risk factors for new-onset ILD included New York Heart Association stage ≥2, muscle weakness, high inflammatory markers, and SSc-specific autoantibodies, but not disease duration. Despite a lower risk of ILD progression compared with prevalent ILD diagnosed at baseline, incident ILD still carried an increased risk for mortality, which was almost double when compared with ILD-negative cases. CONCLUSIONS: Patients with SSc should be considered for regular screening following a negative baseline HRCT, in particular when carrying high-risk features for new ILD onset, given its incidence and prognostic implications.