Multiple sclerosis incidence and prevalence in Poland: Data from administrative health claims

Background: The detailed data concerning multiple sclerosis (MS) epidemiology in Poland are based on studies from few and less populated provinces. Therefore, we evaluated MS incidence and prevalence in Poland using electronic administrative health claims (AHCs) from the National Health Fund. Methods: We retrospectively analyzed the AHC financial database collected from 2009 to 2019, encompassing all patients using public health resources. Three different algorithms for identification of MS cases were used: based on studies performed in German population (type 1), tested in the United States (type 2), and one created for the purpose of this study (type 3) that required at least 3 AHCs since 2009 with G35 ICD-10 diagnosis in outpatient specialist care, during hospitalization, and/or at rehabilitation service in any combination within maximally 3 years between the first and the last AHC, and provided that at least one AHC was either in neurological outpatient care or during hospitalization at a neurological ward or prescription of disease-modifying therapy. The American algorithm (type 2) required 3 AHCs within the analyzed year, while the German algorithm (type 1) required only one AHC in the analyzed year. Results: According to the type 3 algorithm, age-adjusted MS incidence and prevalence in 2019 was 6.6 and 131.2 / 100,000 inhabitants, respectively. From 2014 to 2019, the significant trend in increasing prevalence and decreasing incidence of MS was observed (p<0.001). Median age of prevalent MS patients was 50 years (interquartile range, IQR 39-61) whereas median age of incident MS cases was 37 years (IQR 28-48). Female-to-male ratio in MS patients was 2.4. According to the type 1 algorithm, age-adjusted MS incidence and prevalence in 2019 was 11.6 and 244.9 / 100,000 inhabitants, respectively. Use of the type 2 algorithm resulted in estimated age-adjusted MS incidence and prevalence values in 2019 of 6.2 and 120.1 / 100,000 inhabitants, respectively. Conclusions: Multiple sclerosis incidence and prevalence in Poland are higher than previously reported and similar to the numbers shown for central European countries.