Incidence, prevalence and regional distribution of systemic sclerosis and associated interstitial lung disease: a nationwide cohort study

Objective: To investigate incidence, prevalence and patterns of diagnosis in Systemic Sclerosis (SSc) and SSc-associated interstitial lung disease (SSc-ILD) in a nationwide population-based study.Methods: Patients with an incident diagnosis of SSc in 2000 - 2016 were identified in the Danish National Patient Registry and categorised based on diagnosis of ILD. Incidence- and prevalence proportions were calculated based on the annual population estimates. A cox proportional hazards model was used to evaluate the association between age, sex, region and marital status and presence of ILD.Results: In total, 1,869 patients with SSc were identified; 275 patients (14.7%) had SSc-ILD. The majority of patients were females (75.5%). The percentage of males was higher in SSc-ILD than in SSc alone (30.9% and 23.4%, p=0.008). Median time between SSc and ILD diagnosis was 1.4 years (range 0 – 14.2); 53.8% of patients with ILD were diagnosed within one year, and 74.5% within three years from the SSc diagnosis. Development of ILD was associated with male gender (HR 1.75, 95% CI 1.15-2.66) and residency in the North Denmark Region (HR 1.95, 95% CI 1.12-3.40). The mean annual incidence proportion of SSc was 2.9/100,000 and the mean annual prevalence proportion was 16.8/100,000. The incidence remained stable, but the prevalence proportion increased from 14.1 – 16.5/100,000 in 2000 – 2008 to 17.9 – 19.2/100,000 in 2009 – 2016.Conclusion: The prevalence of SSc increased during the study period, while the incidence remained stable. The prevalence of SSc-ILD was 14.7% and thus less frequent than expected.FootnotesCite this article as Eur Respir J 2022; 60: Suppl. 66, 1499.This article was presented at the 2022 ERS International Congress, in session “-”.This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only).