Epidemiological aspects of multiple sclerosis: a comparative study of four centres in Europe

Epidemiology of Multiple Sclerosis in Austria

BACKGROUND

To assess the incidence rate and prevalence ratio of multiple sclerosis (MS) in Austria.

METHODS

Hospital discharge diagnosis and MS-specific immunomodulatory treatment prescriptions from public health insurances, covering 98% of Austrian citizens with health insurance were used to extrapolate incidence and prevalence numbers based on the capture-recapture method.

RESULTS

A total of 1,392,629 medication prescriptions and 40,956 hospitalizations were extracted from 2 data sources, leading to a total of 13,205 patients. The incidence rate and prevalence ratio of MS in Austria based on the capture-recapture method were 19.5/100,000 person-years (95% CI 14.3-24.7) and 158.9/100,000 (95% CI 141.2-175.9), respectively. Female to male ratio was 1.6 for incidence and 2.2 for prevalence.

CONCLUSIONS

Incidence rates and prevalence ratios of MS in our study are within the upper range of comparable studies across many European countries as well as the United States.

Prevalence of multiple sclerosis in Csongrád County, Hungary

OBJECTIVE

Recent epidemiological studies were mainly based on the Poser or other diagnostic criteria. There have been no previous data from Hungary, which were assessed with the more up-to-date McDonald criteria and which give comparable standardized data from the region.

MATERIALS AND METHODS

Data were collected from the MS Register of the Department of Neurology at the University of Szeged. All possible and definitive patients with MS living in the county on the prevalence day were included in the study. Direct standardization was based on the European standard population.

RESULTS

On 1 January 2013, 379 registered patients with MS were alive in the county, that is, a crude MS prevalence of 89.8/100,000, 46.6/100,000 in males and 128.6/100,000 in females; standardized prevalence: 83.7/100,000 (42.3/100,000 for males, 122.6/100,000 for females). The distribution of the clinical forms: 11% clinically isolated syndrome, 69% relapsing-remitting form, 14% secondary progressive form, 6% primary progressive form. Patients with no or only mild symptoms comprised 91.9% of the relapsing-remitting population.

CONCLUSIONS

This is the first standardized epidemiological study based on the McDonald criteria in Central Europe. Hungary is a medium-risk country as concerns the prevalence of MS. The crude prevalence appears to have increased relative to previous reports from the county.

Paediatric multiple sclerosis and acute disseminated encephalomyelitis in Germany: results of a nationwide survey

The aim of this study was to evaluate the incidence of paediatric multiple sclerosis (MS) and acute disseminated encephalomyelitis (ADEM) in Germany. In a prospective nationwide survey carried out between 1997 and 1999, all registered new cases of paediatric MS and ADEM with an onset before the age of 16 years were evaluated using a standardised questionnaire. A total of 132 patients with suspected or definite MS and 28 patients with an assumed diagnosis of ADEM were reported. Among these, 82% of the MS patients were 10 years of age or older, as opposed to 18% in the ADEM-cohort. The female-to-male ratio was 1.2:1 in the MS-cohort and 0.8:1 in the ADEM-cohort. Manifestation was polysymptomatic in 67% of the MS patients compared to 86% of the ADEM patients. The most frequent primary symptoms in the MS-cohort were cerebellar (44%), sensory (39%) or visual (36%), followed by brainstem (30%), pyramidal (29%) and cerebromental (22%) complaints.

CONCLUSION

The incidence of paediatric MS in Germany is more than fourfold higher than that of paediatric ADEM; in addition, it shows a strikingly different age-distribution. With an estimated minimum of 50 new cases per year, the incidence of paediatric MS in Germany is much more frequent than previously believed.

Costs and quality of life in multiple sclerosis in The Netherlands

This cost-of-illness analysis based on information from 1.549 patients in The Netherlands is part of a Europe-wide study on the costs of multiple sclerosis (MS). The objective was to analyze the costs and quality of life (QOL) related to the level of disease severity and progression. Patients from three specialized MS centres participated in the survey by answering a mail questionnaire (response rate, 52%). In addition to details on the disease (type of disease, relapses, level of functional disability), the questionnaire asked for information on all resource consumption, medical, non-medical, work absence, early retirement and informal care as well as QOL (expressed as utility). The mean age of the cohort was 47 years, and 7.6% of patients were 65 years of age or more. Forty-eight percent of patients had mild disease [Expanded Disability Status Scale (EDSS) score of 0-3], 40% moderate disease (EDSS score of 4-6.5) and 11% severe disease (EDSS score of 7 and above). The mean EDSS score in the sample was 3.9 (median 4.0), with a utility of 0.61. Costs and utility are highly correlated with disease severity. Workforce participation decreases from around 75 to 80% in early disease to less than 5% in the very late stages. Hospitalization is very infrequent in early disease, representing less than euro 500 per year for patients at EDSS scores below 6, but increases steeply for patients at an EDSS score of 7 and above. Ambulatory care increases fivefold between early and late disease, while services rise from basically no cost to almost euro 8.000 per year at an EDSS score of 7 and euro 19.000 per year at EDSS scores of 8-9. Productivity losses are multiplied by 10 in late disease, while informal care increases from euro 300 per year at EDSS scores of 0-1 to nearly euro 15.000 per year at EDSS scores of 8-9. Hence, total mean costs per patient are driven essentially by the distribution of the severity levels in the sample, increasing from euro 9.300 per year at EDSS scores of 0-1 to euro 50.000 per year at an EDSS score of 7 and euro 78.000 per year at EDSS scores of 8-9. The same is true for utility, which decreases from 0.85 to 0.05 as the disease becomes severe. However, the utility loss compared to the age- and gender-matched general population is high at all levels of the disease (0.25 at an EDSS score of 2 to 0.4 at EDSS scores of 5-6), leading to an estimated annual loss of 0.24 quality-adjusted life-years (QALYs) per patient. Relapses for patients with an EDSS score below 5 are associated with a cost of around euro 2.800 and a utility loss of 0.15 during the quarter in which they occur.

The epidemiology of multiple sclerosis in Europe

Multiple sclerosis (MS) is a chronic and potentially highly disabling disorder with considerable social impact and economic consequences. It is the major cause of non-traumatic disability in young adults. The social costs associated with MS are high because of its long duration, the early loss of productivity, the need for assistance in activities of daily living and the use of immunomodulatory treatments and multidisciplinary health care. Available MS epidemiological estimates are aimed at providing a measure of the disease burden in Europe. The total estimated prevalence rate of MS for the past three decades is 83 per 100,000 with higher rates in northern countries and a female:male ratio around 2.0. Prevalence rates are higher for women for all countries considered. The highest prevalence rates have been estimated for the age group 35-64 years for both sexes and for all countries. The estimated European mean annual MS incidence rate is 4.3 cases per 100,000. The mean distribution by disease course and by disability is also reported. Despite the wealth of epidemiological data on MS, comparing epidemiological indices among European countries is a hard task and often leads only to approximate estimates. This represents a major methodological concern when evaluating the MS burden in Europe and when implementing specific cost-of-illness studies.

Descriptive epidemiology of multiple sclerosis in Europe in the 1980s: a critical overview

The oversimplified but commonly accepted belief, based on the comparison of the prevalence studies conducted until 1980, that the distribution of multiple sclerosis (MS) in Europe is related to latitude has been contradicted by a great number of prevalence and incidence studies carried out since 1980. The most recent studies, based on more appropriate methods, clearly indicate that the MS distribution in Europe is much more complex than supposed in the past. The MS distribution in Europe now appears to be very uneven, with great variations not only between areas at the same latitude, but also within the countries themselves. However, even the most recent European studies cannot be reliably compared because of differences in the denominator characteristics, case ascertainment accuracy, diagnostic criteria, and definitions of prevalence and incidence. Despite these problems, descriptive data since 1980 indicate that ethnicity plays an important role in determining the European MS distribution. Furthermore, variations in both prevalence and incidence rates in ethnically homogeneous populations confirm the i importance of environmental factors in determining the primary acquisition of the disease. Further descriptive studies based on more comparable methods and better control for ethnicity would more precisely define the role of genetic susceptibility as well as suggest more valuable clues regarding environmental factors affecting the primary acquisition of MS.

Epidemiologic evidence for multiple sclerosis as an infection

The worldwide distribution of multiple sclerosis (MS) can be described within three zones of frequency: high, medium, and low. The disease has a predilection for white races and for women. Migration studies show that changing residence changes MS risk. Studies of persons moving from high- to low-risk areas indicate that in the high-risk areas, MS is acquired by about age 15. Moves from low- to high-risk areas suggest that susceptibility is limited to persons between about ages 11 and 45. MS on the Faroe Islands has occurred as four successive epidemics beginning in 1943. The disease appears to have been introduced by British troops who occupied the islands for 5 years from 1940, and it has remained geographically localized within the Faroes for half a century. What was introduced must have been an infection, called the primary MS affection (PMSA), that was spread to and from successive cohorts of Faroese. In this concept, PMSA is a single widespread systemic infectious disease (perhaps asymptomatic) that only seldom leads to clinical neurologic MS. PMSA is also characterized by a need for prolonged exposure, limited age of susceptibility, and prolonged incubation. I believe that clinical MS is the rare late outcome of a specific, but unknown, infectious disease of adolescence and young adulthood and that this infection could well be caused by a thus-far-unidentified (retro)virus.

Incidence of multiple sclerosis: a periodic or stable phenomenon

For diseases of unknown aetiology, the question as to whether the incidence is constant or variable is very important. A study on multiple sclerosis in a defined northern area of the German Democratic Republic showed a prevalence of 68.6 and an incidence rate of 3.0. Retrospective and prospective investigations concerning an observation period of 22 years revealed cyclic periods (6-7 years) of high incidence rates (up to 4.5) interrupted by shorter intervals (4-5 years) with low rates (about 1.8). The differences (1963-1968 vs. 1969-1973, 1974-1978 vs. 1979-1983) are significant. In accordance with the findings of Kurtzke et al. on a cyclic outbreak of multiple sclerosis in the Faroes and Iceland, our results are considered to be a consequence of environmental factors, such as epidemic viral infections.