Incidence and prevalence of systemic sclerosis and systemic sclerosis with interstitial lung disease in the United States

BACKGROUND: Although systemic sclerosis (SSc) with interstitial lung disease (SSc-ILD) is a serious condition and incurs a substantial clinical burden, the epidemiology has not been well characterized. OBJECTIVE: To estimate the incidence and prevalence of SSc and SSc-ILD among commercially insured adults in the United States. METHODS: Adults with medical claims between 2011 and 2016 for SSc or SSc-ILD with and without high-resolution computed tomography scans were identified from the Optum Clinformatics Data Mart. Incidence and prevalence were calculated as rates per 100,000 person-years and 100,000 people, respectively. The crude and age- and sex-adjusted prevalence and incidence of SSc and SSc-ILD were estimated and stratified by year and geography. Sensitivity analyses were conducted based on different cohort identification algorithms. RESULTS: Overall, the crude incidence rates of SSc and SSc-ILD were 16.4 and 1.2 per 100,000 person-years, respectively, and the crude prevalence was 24.4 and 6.9 per 100,000 people, respectively. Patient characteristics were generally similar between the SSc and SSc-ILD groups. Mean age range was 59.2-59.9 years and 61.8-62.9 years in the SSc and SSc-ILD groups, respectively. SSc had an age- and sex-adjusted incidence rate of 15.1 per 100,000 person-years and an adjusted prevalence of 25.9 per 100,000 people. The adjusted incidence rate of SSc-ILD was 1.1 per 100,000 person-years and the adjusted prevalence was 7.3 per 100,000 people. CONCLUSIONS: This study provides current estimates of the national incidence and prevalence of SSc and SSc-ILD, which have not been previously well characterized. Further research in the future may help to support health management strategies and resource allocation for adults with SSc and SSc-ILD in the United States.