Multiple sclerosis epidemiology in Finland: Regional differences and high incidence

Abstract

Objectives Studies on the east‐west gradient of multiple sclerosis (MS) are scarce. In Finland, epidemiological differences have been only partially elucidated, but the MS risk is high, and it has been claimed that the occurrence follows a longitudinal gradient. In this register‐based study, we updated the MS epidemiology in southwest Finland (SwF) and compared it to the easternmost hospital district, North Karelia (NK), for which no previous data exist. Materials and methods Patients with ICD‐10 code G35 were identified from hospital district administrative data. Patient records were reviewed to include only cases with a definitive diagnosis. Incidence period covered 5 years (2012‐2016), and the prevalence date was December 31, 2016. Results were standardized using the direct method. Results A total of 1184 persons had MS in SwF and 253 persons in NK at the end of 2016. The prevalence was 280/100 000 (95% CI 264‐296) in SwF and 168/100 000 (95% CI 148‐190) in NK (age‐standardized for the European standard population 2013). During the incidence period, 211 new MS diagnoses were made in SwF and 49 in NK. The annual age‐standardized (ESP 2013) incidence was 12.1/100 000 person‐years (95% CI 10.5‐13.8) in SwF and 8.6/100 000 person‐years (95% CI 6.4‐11.2) in NK in the age‐group 10‐69 years. Conclusions There are regional differences in MS epidemiology in Finland, possibly related to demographic, social, and genetic circumstances, but the retrospective nature and limited sample size of this study might introduce some uncertainty to the calculations. SwF is a region with a globally very high risk for MS.

Multiple sclerosis prevalence in 2000 and 2010 in Western Finland

“…A special epidemiological feature in Finland observed already in 1970s concerns the regionally high MS prevalence in coastal parts of Western and South‐Western Finland . The difference between South‐Western and Eastern Districts shown already in 1970s prevailed in a study in 2016, where a 5‐year follow‐up from 2012 to 2016 showed age‐standardized rates 280/10 5 (95% CI 264‐296) and 168/10 5 (95% CI 148‐190), respectively . Difference between coastal and inland districts was shown to prevail also in our data.…”

“…Finland is located between latitudes 60° and 70°N, and longitudes 20° and 32°E, and it is one of the world's northernmost countries. Epidemiological data updated in 2016 showed a high nationwide MS crude prevalence estimate of 180‐200/10 5 and east‐west gradient . Incidence trends from 1981 to 2010 in the Province of Western Finland in Tampere University Hospital District showed a significant increase among women and opposite trends in increasing relapsing‐remitting onset MS (RRMS) and decreasing primary progressive (PPMS) .…”

“…Epidemiological data updated in 2016 showed a high nationwide MS crude prevalence estimate of 180-200/10 5 and east-west gradient. 7,8 Incidence trends from 1981 to 2010 in the Province of Western Finland in Tampere University Hospital District showed a significant increase among women and opposite trends in increasing relapsing-remitting onset MS (RRMS) and decreasing primary progressive (PPMS). 9 These trends differed from a tandem increase in RRMS and PPMS reported in a Finnish MS cohort from 1979 to 1993.…”

Environmental and genetic risk factors for MS: an integrated review

“…Routine vitamin D supplementation for pregnant women was introduced in 2004, providing a natural trial of vitamin D supplementation and the impact on MS incidence. Incidence rates for MS in southwest Finland were 5.1, 5.2, and 11.6 per 100 000 for the hospital districts of Uusimaa, Vaasa, and Seinajoki, respectively, from 1979 to 1993, and 12.1 per 100 000 for southwest Finland in 2012–2016 . This is not the dramatic reduction in MS incidence that might have been expected with the advent of vitamin D supplementation.…”

Cost Assessment Modelling of Treatments for Highly Active Relapsing Multiple Sclerosis

“…Finland is a high-risk MS region with a prevalence of 280/100,000 in southwest parts of the country [13], and a nationwide prevalence estimate between 10,000 and 11,000 patients, corresponding to a crude prevalence of 180-200/100,000 [14]. The estimated annual economic burden of MS in Finland using a bottom-up approach of costing was €46,994 per patient on average and increasing from €10,835 to €109,901 in parallel with advancing disability [15].…”