Prevalence and mortality of systemic sclerosis-associated interstitial lung disease (SSc-ILD) using the French national health insurance system (SNDS) database in France

Aims: Interstitial lung disease (ILD) is frequent in patients with systemic sclerosis (SSc). It is characterized by progressive decline in lung function and is the leading cause of death in patients with SSc. In Europe, the prevalence and annual incidence of SSc-ILD have been estimated at 1.7-4.2 per 100,000 and 0.1-0.4 per 100,000 per year, respectively. This study aimed at assessing the epidemiology and mortality of patients with SSc-ILD in a real life nationwide setting in France. Methods: A longitudinal retrospective cohort study was conducted in the French administrative health care database. SSc-ILD patients were identified using an algorithm based on ICD-10 codes of SSc and of lung fibrosis between January 2010 and December 2017. Results: Among 9817 SSc patients identified, 3460 had associated ILD (35.0%). In 2017, the prevalence and incidence of SSc-ILD were respectively 4.5 per 100,000 (4.3-4.7) and 0.4 per 100,000 per year (0.3-0.5). Patients were predominantly females (75.6%) with a mean age of 60.7 years (±14.5). 73.6% and 20.8% of patients respectively had at least one claim of systemic corticosteroids and mycophenolate mofetil treatments during the study period. The overall survival rate was estimated to be 92.9%, 81.8%, 70.5%, and 65.1% 1, 3, 5, and 8 years, respectively. Median survival was better in women. Conclusion: This study demonstrated that SSc-ILD is a rare disease with significant mortality.