A 60-year follow-up of the incidence and prevalence of multiple sclerosis in Hordaland County, Western Norway

Abstract

ObjectiveInvestigate the incidence of multiple sclerosis during 1953–2013 and estimate the prevalence rate of MS on 1 January 2003 and 2013 in Hordaland County, Western Norway.MethodsAll patients with onset of disease in Hordaland 1953–2013 were identified in files from previous studies until 2003 and from patient records at the departments of Neurology, Haukeland University Hospital and Haugesund Hospital during 2003–2013. 1558 patients were assessed and 1402 of these were included, of whom 1035 were alive and living in Hordaland at prevalence day 1 January 2013. Annual incidence rates were calculated for 1953–2013.ResultsOn 1 January 2003, the crude prevalence rate was 191/100 000 population and on 1 January 2013, the crude prevalence rate was 211.4 (95% CI 198.3 to 224.2) per 100 000; 270.9 (95% CI 250.6 to 292.3) for women and 151.8 (95% CI 136.8 to 167.9) for men. Prevalence peaked at ages 55–59 years for women and 60–64 years for men. The annual incidence rate increased from 1.9 (95% CI 1.2 to 2.6) per 100 000 during 1953–1957 to 7.2 (95% CI 6.0 to 8.5) during 1978–1982 and to 8.5 (95% CI 7.3 to 9.7) during 2003–2007, thus indicating a stabilising incidence over the past 35 years. The female/male ratio ranged from 1.2:1 to 1.8:1 (p=0.381) during the period.ConclusionsStabilising rather than increasing incidence combined with the stable female/male ratio are indicative of non-fluctuating environmental factors in a geographical area otherwise characterised by lack of vitamin D effective sun exposure. The rising prevalence of MS could result from improved survival and follow-up methodology.

Multiple sclerosis prevalence in 2000 and 2010 in Western Finland

“…Epidemiological observations in multiple sclerosis (MS) have consistently pointed at globally increasing prevalence . At the same time, MS mortality has decreased, and analyses on incidence have shown both stability and increase . The highest age‐standardized estimates have been observed in northern latitudes where prevalence among women and in relapsing‐remitting MS is high.…”

“…1,2 At the same time, MS mortality has decreased, and analyses on incidence have shown both stability and increase. [2][3][4][5] The highest age-standardized estimates have been observed in northern latitudes where prevalence among women and in relapsing-remitting MS is high. The relationship between socioeconomic determinants and increase in MS occurrence is observed, occurrence being higher in areas of higher socioeconomic level.…”

Can environmental factors increase the risk of multiple sclerosis? A narrative review

“…In different studies, while introducing cigarettes as a factor in preventing MS 43 , smoking has been identified as a factor in the accelerated process of MS and its symptoms 36 . We have mentioned the impact of infection on MS with various bacterial and viral pathogens, especially the EBV virus, which can be essential to contribute to the pathogenesis of this disease 23,25,29 . It is worth noting that some studies also referred to the effects of parasites on the onset of the disease and its impact on the process 16 .…”

“…Since sun exposure induces vitamin D3 synthesis from the skin 21 , it is assumed that exposure to the sun in early childhood is associated with a reduction in the risk of MS 19 . Studies have indicated that vitamin D is also essential in improving regulatory function for autoimmune disease control 22,23 .…”

“…There are different assumptions about which infectious agents, and how they are involved in the process of occurrence and progression of the disease. In studies that were carried out, different microorganisms involving in the incidence and development of MS include Human Type-6 herpesvirus, Human Type-4 herpesvirus, Chlamydia pneumonia, torque teno virus, and Epstein-Barr viruses (EBV) 23,25 . Meanwhile, EBV is important in the development of this disease.…”