Pediatric-onset multiple sclerosis in Poland: A registry-based retrospective cohort study.

Background: Epidemiologic data on pediatric-onset multiple sclerosis (POMS) in Central and Eastern Europe are limited. The aim of this study was to determine the incidence, prevalence and the clinical features of POMS in Poland.

Methods: Registry-based retrospective study was conducted among Polish children population (age ≤ 18 years), between 1 January 2010 and 31 December 2019. A total of 329 pediatric or juvenile patients fulfilled the International Pediatric MS Study Group (IPMSSG) criteria for MS, reported to the Polish Multiple Sclerosis Registry, were considered for estimation of age- and sex-specific prevalence (per 100,000 persons), and incidence rates (per 100,000 person-years). The demographic data, clinical presentation and treatment strategies also were investigated.

Results: On December 31, 2019 in the database were collected data of 329 patients up to 18 years with POMS diagnosis (101 boys and 228 girls; mean age 15.3 ± 3.8 years). The age-adjusted prevalence standardized to the European Standard Population was 5.19/100,000 (95% confidence interval (CI), 4.64-5.78). A significantly higher prevalence was recorded in girls (7.41; 95% CI, 6.48-8.44) than in boys (3.08; 95% CI, 2.50-3.74; P<0.001). The mean annual standardized incidence in Poland between 2015 - 2019 was 0.77 (95%CI, 0.45-1.02) per 100,000 person-years. The highest overall standardized incidence 1.06 (95%CI, 0.82-1.34) was noted in 2018. Most of patients (95.7%) had relapsing-remitting disease with polysymptomatic onset in one-thirds of the cases, and 82.3% were treated with disease-modifying drugs. Family history of MS was reported in 26 cases (7.9%).

Conclusion: In this first report of registry-based study from Poland an increasing prevalence and incidence of POMS was found during the last years. This temporal trend corroborate the findings of studies conducted elsewhere.