Incidence and prevalence of juvenile SSc in the United States: An analysis by age group.

Objectives: Systemic sclerosis is a rare autoimmune connective tissue disease characterized by progressive skin and organ fibrosis, and diffuse fibro-proliferative vascular modifications. Roughly 2%-10% of systemic sclerosis cases develop during juvenile years (under 18 years of age); however, there are limited data on the incidence and prevalence of juvenile systemic sclerosis. This analysis assessed the incidence and prevalence of juvenile systemic sclerosis in the United States, overall and by age group. Methods: Juvenile systemic sclerosis patients with ⩾2 medical diagnostic claims for systemic sclerosis within a 1-year period were identified from the Optum de-identified Clinformatics® Data Mart Database between 2007 and 2021, using International Classification of Diseases diagnostic codes. Incidence and prevalence rates were estimated in the overall population and in a subgroup of patients with at least one filled prescription or infusion of methotrexate, mycophenolate mofetil or cyclophosphamide. Estimates were sex- and/or age-adjusted according to the 2020 US census. Results: Forty-eight incident and 103 prevalent cases were identified. Overall, the age- and sex-adjusted incidence and prevalence of juvenile systemic sclerosis were 2.4 per million person-years and 12.0 per million, respectively. When stratified by age group, incidence and prevalence rates increased with age in the overall and subgroup analyses. Conclusion: In this analysis, incidence and prevalence rates of juvenile systemic sclerosis increased with age. Increasing incidence and prevalence were observed from 10 years old and from 6 years old, respectively. While the overall data are broadly consistent with previous reports, these data provide new information on the estimated incidence and prevalence of juvenile systemic sclerosis by age group.