Increasing prevalence and incidence of multiple sclerosis in South East Wales.
ABSTRACT Epidemiological studies of multiple sclerosis suggest a trend of increasing disease prevalence in susceptible populations. The reasons for this are unclear and may be the results of methodological differences between studies, incomplete ascertainment or advances in technologies that allow the increased identification of early or mild disease. In addition, direct comparison of cross sectional prevalence estimates performed in different epochs in ethnically and geographically distinct populations may be inappropriate.
Using detailed phenotypic information and standardised methodology, a geographically defined Welsh population was resurveyed after a significant interval, establishing contemporary prevalence rates and examining demographic and clinical data to determine causes of changing disease frequency.
Disease prevalence increased 45% from 101 to 146 per 100,000 population over 20 years. The greatest increase was observed in women between the ages of 45 and 54 years. No significant increase in disease frequency was observed in the male population overall, or within specific age groups. There was no demographic evidence for a pattern of earlier age at onset or diagnosis to explain increased disease frequency or decrease in mean age of the prevalent population. In addition, we failed to identify a pattern of recognition of patients with less severe disability. Although there was a modest 13% increase of 2.2 years in mean disease duration, and eight new previously prevalent patients were identified, the main cause of rising disease frequency was related to a 2.8-fold increase in disease incidence for women over 23 years from 2.65 to 7.30/100,000/year increasing the sex ratio of incident patients from 1.8 to 4.3 (women:men).
Recent change in disease incidence and prevalence in this population is likely to be the result of environmental factors that have been operative in the past few decades in women alone and infers avoidable risk factors. Modelling of current overall incidence suggests a further increase in prevalence to 260 per 100 000 population within the next 20-40 years. Further studies are needed in order to identify recent changes in sex specific environment and lifestyle that confer susceptibility.
Article: Sex ratio of multiple sclerosis in persons born from 1930 to 1979 and its relation to latitude in Norway.[show abstract] [hide abstract]
ABSTRACT: A remarkable increase in female to male ratio of multiple sclerosis (MS) is recognised in high incidence areas. Norway is a high-risk area for MS, spanning latitudes 58-71°N. We studied whether the sex ratio has changed over time and whether it differs by clinical phenotype or by latitude. Population-based epidemiological data and data from the Norwegian MS Registry on patients born from 1930 to 1979 were combined in this study. Place of birth was retrieved from the Norwegian Population Registry and information on clinical subtypes was obtained from the Norwegian MS Registry. The female to male ratio ranged from 1.7 to 2.7 (median 2.0) in 5,469 patients born in Norway, and increased slightly by 5-year blocks of year of birth (p = 0.043). The sex ratio was 2.6:1 in 825 patients born 1970-1979, which is significantly higher than in those born 1930-1969 (p < 0.001). In patients with relapsing remitting onset, the sex ratio was 2.4:1, while it was 1.1:1 in those with primary progressive disease. The sex ratio did not differ between the south, the middle and the north of the country. The overall sex ratio of MS is strongly determined by cases with relapsing remitting onset. We did not observe the remarkable increase in sex ratios of MS reported from other high-risk areas. The high sex ratio in the youngest birth cohorts may change as an increasing proportion of cases in this age group is being diagnosed. Sex ratio was not associated with latitude.Journal of Neurology 01/2013; · 3.47 Impact Factor
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ABSTRACT: The lack of complete concordance of autoimmune disease in identical twins suggests that nongenetic factors play a major role in determining disease susceptibility. In this review, we consider how epigenetic mechanisms could affect the immune system and effector mechanisms in autoimmunity and/or the target organ of autoimmunity and thus affect the development of autoimmune diseases. We also consider the types of stimuli that lead to epigenetic modifications and how these relate to the epidemiology of autoimmune diseases and the biological pathways operative in different autoimmune diseases. Increasing our knowledge of these epigenetic mechanisms and processes will increase the prospects for controlling or preventing autoimmune diseases in the future through the use of drugs that target the epigenetic pathways.Biologics: Targets & Therapy 01/2012; 6:307-27.