A further prevalence study of multiple sclerosis in north-east Scotland.

A second epidemiological study of multiple sclerosis (MS) in north-east Scotland has confirmed that the area has the highest prevalence rate in the world for any population of comparable size. On 1 December 1973 the prevalence was 144 per 100000 population. The age and sex specific prevalence rates are the highest ever recorded, one in every 306 of the population aged 40 to 59 years being affected. All patients have been tabulated in the National Health Service Central Register to facilitate future studies. The MS mortality rate in north-east Scotland is similar to the rate for the whole of Scotland. Throughout most of Scotland, therefore, MS probably is as prevalent as it is in the north-east.     

The use of standardized incidence and prevalence rates in epidemiological studies on multiple sclerosis. A meta-analysis study

OBJECTIVE: To demonstrate whether or not the age and sex adjustment of incidence and prevalence rates in multiple sclerosis (MS) could allow more reliable comparison between epidemiological studies performed in different areas of the world and to establish if the latitude gradient theory could be confirmed after the standardization for age and sex distribution. METHODS: A meta-analysis of population-based incidence and prevalence studies on MS from 1980 through 1998 using the terms 'multiple sclerosis', 'prevalence' and 'incidence' in the bibliographic databases MEDLINE and EMBASE was performed. We included studies that reported the diagnostic criteria, number of cases and the population studied, the date of the study, the latitude, and the age- and sex-specific crude incidence and prevalence rates. According to the inclusion criteria, 69 of 127 papers on prevalence and 22 of 70 papers on incidence were considered for age adjustment and 27 prevalence and 8 incidence studies for sex adjustment. The mean incidence and prevalencerates and the 95% confidence intervals age- and sex-adjusted to the World and the European standard populations were calculated. RESULTS: The Spearman rank correlation and the multiple regression analyses indicated that age adjustment to standard populations could overcome the limitations in comparing the crude prevalence and incidence rates of different epidemiological studies on MS. When the mean crude and age- and sex-adjusted prevalence and age-adjusted incidence rates were stratified by latitude (from south to north), the latitudinal gradient, which was highly significant for the crude rates, became less remarkable for the age- and sex-adjusted prevalence rates and not significant for the age-adjusted incidence rates. CONCLUSIONS: The crude incidence and prevalence rates in epidemiological studies on MS should be age- and sex-adjusted to a common standard population to permit a more reliable comparison among studies performed in different countries. Our findings support the opinion that the latitude does not play a key role in determining the onset of MS. Whenever possible, the crude incidence and prevalence rates should be adjusted to the ethnic origin and migration characteristics.     

Multiple sclerosis in Istria, Yugoslavia

An epidemiological research of multiple sclerosis (MS) in Istria, Yugoslavia, was made in the period of 1980-1981. After examining all the sources of health care information, 125 potential MS patients were found in the investigated area. According to the diagnostic criteria by Schumacher et al., 47 affected were recognized and accepted as clinically definite MS patients. The MS prevalence rate in Istria on March 31st, 1981 amounted to 25.0/10(5) inhabitants (CI: 19.9-38.9). Such rates classify Istria in the middle between the medium and high risk zones for the disease in Europe and in the world. The onset age of MS in Istria was about 30 years, the female/male sex ratio was 2.13. The average duration of MS in Istria up to the prevalence day was 16.5 years. The average annual incidence rate was 1.5/10(5) inhabitants.     

Analysis of the 'epidemic' of multiple sclerosis in the Faroe Islands. I. Clinical and epidemiological aspects

The claim has been made that British troops introduced multiple sclerosis (MS), a transmissible disease, into the Faroe Islands during World War II, causing a three-tier epidemic which resulted in the appearance of 32 cases from 1943 until 1973. Assumptions underlying this hypothesis include the belief that the disease was absent from the Faroe Islands before 1940, the view that ascertainment of cases was complete and that Faroese patients who had either been born in Denmark or had been away from the Islands for 3 or more years before the onset of the disease had to be excluded. All the calculations were based on the presumed date of appearance of the first symptoms of MS. We reject the hypotheses of an epidemic and of the transmissibility of MS for several reasons. The most important one is that the date of onset of illness bears no relationship to the probable date of acquisition, which is widely believed to occur between the ages of 5 and 15 years. The criteria for exclusion of cases are arbitrary and instead of the accepted 32 cases, we believe that 42 cases should be counted in all analyses, including at least 2 with onset of illness before 1940. Only 15 of these 42 were in the age range 5-14 years during the British occupation. We cannot accept the statement that the disease was unknown in the Faroes before 1940 and believe that case ascertainment was incomplete in the Islands, which share close geographic, ethnic, and environmental similarities with other North Sea countries of high MS incidence. The theory of transmission is unconvincing and the characteristics of the putative agent unrealistic. The extremely high incidence of disease, which has statistical significance, is based on a very small number of cases in a very small population, and is of very doubtful biological significance.     

The prevalence of multiple sclerosis in the north–west Italian province of Genoa

The objective of this study was to assess the prevalence of multiple sclerosis (MS), calculated as point prevalence on 31 December 1997, in the province of Genoa, North–western Italy. Methods The province of Genoa is located in North–western Italy, an area of 1835 km². On the point prevalence day the population consisted of 913,218 inhabitants. MS cases were identified by analysing archives of the hospitals with neurological or rehabilitation wards, neurologists serving the community, files of local chapters of the Italian MS society, all requests for oligoclonal bands analysis on CSF in the studied area. Patients included in the study were MS cases diagnosed before 31 December 1997 according to the Poser criteria resident in the province under study. Results A total of 857 subjects were alive and residing in the province of Genoa on the prevalence day. The overall crude prevalence rate was 94 per 100,000 (95% CI 88–100); 291 were males (34%) with a crude prevalence of 67 per 100,000 (95 % CI 60–76) and 566 were females (66%) with a prevalence of 118 per 100,000 (95% CI 108–128). The female/male ratio was 1.9. When age and sex were adjusted to the Italian standard population of 1991 prevalence was 85 per 100,000. Five hundred and thirty two out of the 857 patients agreed to be interviewed. The interviewed sample was representative of the prevalence sample: sex and gender distributions were identical in the two samples. The overall mean age was 48 (± 13) years (48 ± 12 years in males; 48 ± 14 years in females). Mean disease duration was 15 (± 10) years for males and 16 (± 11) years for females. Two hundred and ninety one (55 %) subjects had a relapsing remitting (RR) clinical course, 150 (28%) were secondary progressive (SP) and 91 (17%) were primary progressive (PP). Mean EDSS score was 5 (± 2; median 5). The mean age at time of onset was 33 (±10) years for males and 32 (± 11) years for females. The disease onset was monosymptomatic in 76% (n = 407) patients and polysymptomatic in 24% (n = 125). The mean length of time between clinical onset and diagnosis was 5 (± 6) years. Conclusion We confirmed that the province of Genoa is a very high risk area for MS. We found a high rate of patients with a PP course; also the proportion of patients with high disability scores is greater compared to previous studies.     

Herpes zoster and multiple sclerosis

BACKGROUND: Clinical experience suggests that young multiple sclerosis patients may have herpes zoster (HZ) earlier and more often than the general population. As there is evidence of a relationship between varicella zoster virus (VZV) and MS, a study of HZ and MS was undertaken. METHODS: Eight hundred and twenty-nine patient-members of the Manitoba Chapter of the Canadian Multiple Sclerosis Society were surveyed by mail. Six hundred and thirty-three (76%) responded. Questions included: age at diagnosis of MS, history of HZ (yes, no, probably), number of episodes of HZ and age at each occurrence, date of birth, and sex of respondent. The controls were consecutive patients with other neurological diseases (OND) attending local neurological or neurosurgical clinics, plus practice-based and population-based surveys of herpes zoster without reference to any other disease. The OND controls were assessed at the time of their outpatient visits. RESULTS: In the MS group with a positive/probable history of HZ, the HZ/MS rate was 106/633 (16.8%); in the practice-based survey the rate was 192/3534 (5.4%); and among the patients with OND it was 42/616 (6.8%). The HZ occurred at an earlier age in the MS group. The majority of male patients had HZ prior to the diagnosis of MS. The date of diagnosis is more likely to be a precise memory as opposed to the onset of symptoms. More than one attack of HZ was also more common in the MS group. CONCLUSIONS: This survey adds to the evidence that patients with MS have a unique relationship with the herpes zoster virus.     

Multiple sclerosis epidemiology in Sardinia: evidence for a true increasing risk

OBJECTIVES: To update prevalence and incidence rates of MS among Sardinians. MATERIALS AND METHODS: The present work is a "spider" kind of population based survey, conducted over the interval 1968-97, on patients with MS (Poser criteria) living in the province of Sassari, Northern Sardinia (454,904 population). RESULTS: A crude total prevalence rate of 144.4 per 100,000, an onset-adjusted prevalence rate of 149.7 per 100,000 and an average annual incidence rate of 8.2 for the period 1993-7 were found. CONCLUSION: Repeated epidemiological assessments of MS in Sardinia over decades have shown that the island is at high risk for MS. The present work highlights that MS incidence in Sardinia has been increasing over time. Although a substantial and widely spread improvement in MS case ascertainment can be postulated as the reason for such observations, a comparison between our data and those recently reported from a more industrialized province in Northern Italy seems to prove an at least partially real increase in MS risk among Sardinians and favours the hypothesis of a MS "Sardinian focus" as related to its latitude.     

Multiple sclerosis in the Bern canton (Switzerland). An epidemiologic study

We conducted a study on the prevalence of multiple sclerosis in the canton of Berne (Switzerland) at the Department of Neurology (inpatient and outpatient sections) of the Inselspital hospital (University of Berne) in Berne. The canton of Berne is a heterogeneous region, geographically speaking, extending from the foot of the Jura mountains to high Alpine regions. There are approximately 920,000 inhabitants in an area of 6,000 square kilometers. Sources of our study were, besides the Department of Neurology of the University and the practising neurologists of Berne, the Association of Swiss Hospitals (VESKA) and the Swiss Multiple Sclerosis Society. For ensuring a safe diagnosis we employed a diagnosis score suggested by C. M. Poser et al (1983). This covered only safely established and probable cases of MS. To make sure of the actual residence of the retrospectively assessed patients we conducted a checkup with the relevant authorities. Besides personal data it was also possible, in a majority of patients, to obtain data on the onset and course of the disease. On 1, 1, 1986 1,016 MS patients were residents in the canton of Berne, according to our investigations. This corresponds to a prevalence rate of 110 MS patients for every 100.000 inhabitants. The sex ratio (female/male) is about 1.8: 1. The average age of the MS patients covered by the study was 50 years with an average duration of the disease of 18 years. From the data concerning the course of the disease our study was able to gain further pointers on the beginning of the disease, on the pattern of symptoms, course of the disease, and progression of multiple sclerosis.     

A comparative study of clinical and paramedical aspects of multiple sclerosis in Tunisia

INTRODUCTION: Tunisia is considered as a low zone of prevalence for multiple sclerosis (MS). Consequently, only very few studies have taken an interest in this disorder in North Africa. The objective of this study was to compare the clinical and paraclinical parameters and the outcome of the disease in patients affected with MS in Tunisia during two periods (1974-1978 and 1996-2000) and to determine the incidence of the disease and the impact of the use of diagnostic criteria, including the MRI. PATIENTS AND METHODS: We report the results of a retrospective study concerning patients classified with MS and followed in the National Institute of Neurology in Tunis between 1974 and 2000, with 1058 records examined. We divided the patients into two groups belonging to two periods: Group I (1974-1978, 125 patients classified according to the McAlpine criteria) and Group II (1996-2000, 247 patients classified according to Poser's criteria. We compared the clinical and paraclinical parameters of the two groups. RESULTS: The incidence of the disease was evaluated at 1.3 per 100,000 individuals, placing Tunisia in the middle zone of prevalence. There was no significant difference in the mean age of onset (32.4+/-10.1 years) between the two groups. A slight male preponderance was observed in Group I (M/F sex ratio=1.25). The clinical outcome factors were age of onset after 40 years, pyramidal signs as the first symptom, and the progressive forms of the disease. Although Group II had an earlier diagnosis of the disease and a more systematic treatment of relapses, the functional outcome was similar between the two groups. CONCLUSION: MS in Tunisia has the same clinical characteristics and disease outcome as in other countries. The use of MRI allowed earlier diagnosis but did not increase the overall proportion of definite MS.     

Sexual habits before multiple sclerosis: a national case-control study

The trigging off agent for multiple sclerosis (MS) is despite intensive epidemiological and biomedical research still unknown. The disease is typically diagnosed in reproductive age and recent findings have suggested that MS could be a sexually transmitted disease. AIM: To assess the influence of different sexual practices in young age on the risk of developing MS, and specifically to explore the possible impact of oral sex and oral sperm exposure on this risk. DESIGN: National case-control study. METHODS: Inclusion: Danish women with a first time MS discharge diagnosis from a neurological department at most 40 years old during the period 1998-2005, and an age and geographically matched control group. The response rate to our postal questionnaires was 75% for cases and 61% for controls. A total of 604/619 completed case/control questionnaires were included in the analysis. Data underwent logistic regression analysis. RESULTS: We found no difference between women with and without MS for years of schooling, oral herpes infections, genital herpes, blood transfusions, age at sexual debut, age at coital debut, number of sexual partners before and after age 20 years, anal sex, condyloma attack or chlamydia infections. Family disposition with an affected father, mother or sibling, increased the risk of MS 9.1, 6.9 and 4.1 times, respectively. A total of 68% of cases and of 72% of controls had oral sex sometimes or often before their 20th year. Among women entertaining oral sex, 53%, respectively, 54% had experienced oral sperm exposure. Also oral sex after 20 years was similar in women with and without MS. CONCLUSION: Neither oral sex in early reproductive age, oral sperm exposure, oral sex after 20 years, sexual debut, nor number of sexual partners had any association to the risk of later developing MS. This study does not support the hypothesis that MS is a sexually transmitted or acquired disease.     

Essential tremor in Rochester, Minnesota: a 45-year study.

A 45-year (1935-79) retrospective study of essential tremor based on original medical records on residents of Rochester, Minnesota, is presented. The age and sex adjusted incidence for the most recent 15 year period was 23.7 per 100 000 for US white population. The prevalence rate, age and sex adjusted to 1970 US white population on January 1, 1979 was estimated at 305.6 per 100 000. Survival after diagnosis of essential tremor is comparable to age and sex matched population of West North Central United States. Mean age at diagnosis was 58 (range 2-96) years. Age adjusted annual incidence rate was not different in males (18.3/100 000) and females (17.1/100 000). Functional handicap was reported by four (1.5%) of the 266 incidence cases in school, 13 (5%) cases at work and five cases (2%) retired prematurely. Excessive use of alcohol was noted in 16% and 6% were diagnosed as alcoholic. Torticollis was diagnosed in 3% cases and an additional diagnosis of Parkinson's disease after the index date was made in 2% of incidence cases. Subsequent emergence of Parkinsonism was regarded as incidental. Diagnosis of hypertension was made at some time in 30% of incidence cases during the period (mean 37 years) for which the medical records were available. Risk of hypertension after onset of essential tremor in the cases was not different from that in a control group.     

A population-based study of multiple sclerosis in twins: Update

This study is a 7.5 year follow-up of a population-based series of twins with multiple sclerosis (MS) whose mean age now exceeds 50 years. The twin pairs were identified through the Cabadian nationwide system of MS clinics and were drawn from a population of 5,463 patients. After 7.5 years, the monozygotic concordance rate increased from 25.9 to 30.8 an the dizygotic-like sex concordance rate from 2.4 to 4.7%. These results are very similar to those of other population-based studies and to our own modified replication twin date reported here. We interpret the data to mean that MS susceptibility is genetically influenced, and a single dominant or even a single recessive gene is unlikely to account for this effect. The difference in concordance rates suggests that at least two or more genes are operative. These date also have importatnt implications for the nature of the environmental effect(s) in MS susceptibility. Most monozygotic twins are discordant even after a correction for age and magnetic resonance imaging findings. This unabiguously demonstrates the powerful effect of nonberitable factors.     

An epidemiological study of motor neuron disease in Hong Kong.

Worldwide, the incidence of motor neuron disease (MND) has been increasing steadily over recent decades. We reported a follow-up epidemiology study of MND in this locality. We identified the subjects from the computer database of the government hospital system between 1 January 1997 and 31 January 2002 by searching the ICD code starting from 335.xx. Every retrieved case or their records were reviewed and validated by neurologist(s) of the responsible regional hospitals which the patients attended. One hundred and twenty cases from seven regional hospitals (serving 48.05% of the HKSAR population) were identified, validated and confirmed to be MND or related diseases. Ninety-eight new cases were diagnosed during the study period. Average age of onset was 58.76 years; SD 14.12 (28-89) years. Male to female ratio was 1.72:1. Peak age of onset was 60-64 years without sex difference. The adjusted incidence rate was 0.60/100,000/year. The adjusted point prevalence at the prevalence date (31 January 2001) was 3.04/100,000. Despite the incidence and prevalence of MND among Hong Kong Chinese, it remained low compared to worldwide figures, and our data suggested a significant rise of MND or related disease in the last decade. A territory-wide prospective epidemiological study is indicated.     

Incidence and prevalence of multiple sclerosis in southeastern Iran

Background

Based on data available, Iran is located in a low risk area for multiple sclerosis (MS). The objective of the current study is to determine the age and sex adjusted prevalence and incidence of MS in southeastern Iran.

Methods

This cross-sectional case register study was conducted from January to August 2010. Considering that MS affects people aged between 16 and 50 years, we intended to find the incidence and prevalence of MS during this age range. Since all cases in this area are referred to our university hospital for confirmation of diagnosis, misdiagnosis is rare. Population data, based on the censuses carried out in 1996 and 2006, were obtained from the Iranian Bureau of Statistics to determine the number of people at risk.

Results

Totally 206 patients were identified according to the McDonald criteria. In 2009 the age-adjusted prevalence and incidence rates of MS for 16–50 year-old adults were 13.96 and 2.67 per 100,000 persons, respectively. Based on those values; the female to male ratio was 2.18. Between 2006 and 2009, the incidence rates increased 2.4 and 2.7 times in women and men, respectively. In 2009, the prevalence rates among the age ranges of <15, 16–35, 36–50 and ≥51 years were 1.44, 14.34, 12.24 and 1.45 per 100,000 persons, respectively, and the relapsing-remitting type of MS was the most prevalent form (65.8%).

Conclusion

According to the Kurtzke geographical distribution, the authors conclude that the prevalence of MS in southeastern Iran is in the intermediate range, and the incidence rate is showing a faster growth rate, compared to previous years.     

Prevalence of stroke in a district of Copenhagen

From the city center of Copenhagen, almost 20,000 people, 20 years of age and older, were randomly selected for examination after age and sex stratification. The participation rate was 72%. 231 persons responded affirmatively to a questionnaire concerning cerebrovascular disease. After neurological examination the diagnosis was confirmed in 115 cases. Adjusted on the basis of the age distribution of the Danish population (1976) the prevalence rate was calculated to be 651/100,000 for men and 385/100,000 for women.
The frequency of myocardial infarction and hypertension was significantly higher in the stroke patients than in the study population. The risk factors: cigarette smoking, serum-cholesterol, and high-density-lipoprotein concentration, showed no significant differences between the patients and the study population. 44% of the patients had had their stroke more than 5 years before the prevalence date. In 41% of the patients, residual neurological signs could not be demonstrated, while 59% of the patients had neurological deficits of varying severity. 30% of the surviving patients were in gainful work or managed domestic activities as they had done before the stroke. Nearly 1/2 of the severely disabled patients were independent in self care. The age group above 80 years was underrepresented in this study.     

The prevalence and clinical characteristics of MS in northern Japan

In Japan, there is a low prevalence rate (PR) of multiple sclerosis (MS; 0.8-4.0/100,000) but a relatively high frequency of "optic-spinal form" MS (OS-MS). There have been no intensive epidemiologic frequency studies, however, in over 30 years. We performed a province-wide prevalence study of MS in the Tokachi province of Hokkaido, the northernmost island of Japan, and compared the observed clinical features with other populations in Japan and Western countries. Prevalence was determined on March 31, 2001. The primary sources for the case ascertainment were 13 hospitals that treated patients with neurologic diseases including MS in Tokachi. Patients were classified according to Poser's criteria. The prevalence rate of clinically definite or laboratory-supported definite MS (LSDMS) was 8.57 per 100,000 [31/361,726; male/female ratio=1:2.9, and age at onset=29.1+/-14.2 (mean+/-SD) years]. Out of the 31 patients, 5 (16%) were classified as OS-MS. The prevalence rate of MS in the Tokachi province was the highest reported in Orientals to date, although still low in comparison with Western communities at a similar latitude. In contrast to the previous reports in Japan, there was a relatively low frequency of OS-MS in Hokkaido.     

Multiple sclerosis: changing times

Multiple sclerosis (MS) is distributed about the world in three zones of high, medium, and low frequency. All high- and medium-risk areas are among predominantly white populations. Migration studies indicate MS is already acquired by age 15 in high-risk endemic areas and that low-to-high migrants increase their risk from age 11 years. Therefore MS is an environmental disease ordinarily acquired in adolescence with a long incubation before symptom onset. Susceptibility is limited to the period from about age 11 to 47. In general, MS death rates have been declining over time while prevalence rates have increased. Incidence rates have also increased, however, in: northeastern Scotland; Turku, Finland; Hordaland, Norway; Rochester, Minn.; Lower Saxony; several areas of Italy. Incidence was unchanged in northernmost Norway. Conversely, incidence and prevalence rates have decreased in the Shetland-Orkneys; there was a cyclical pattern in incidence in Rostock, GDR; and there was a transient doubling of incidence in Iceland in the post-World War II decade. In the Faroe Islands, MS was absent before 1943 when a major point-source epidemic began, reaching an incidence rate of 10 per 100,000 population in 1945. This was followed by two consecutively smaller epidemics with respective peaks each about 12 years later, and there is now a new epidemic IV on these islands. Explanations for changing incidence of MS over time should bring us closer to solving the etiology of this disease.     

The prevalence and clinical correlates of metabolic syndrome in patients with schizophrenia: findings from a cohort in Turkey

Most studies point to an increased prevalence of metabolic syndrome (MS) and an increased risk of coronary heart disease (CHD) in schizophrenia patients with MS. The aims of this study were to compare the prevalence of MS in schizophrenia patients with the general population, to explore the clinical correlates and predictors of MS and to evaluate the risk for CHD within 10 years. Consecutive 319 patients, aged 18–75 years, with a diagnosis of schizophrenia according to the DSM-IV were enrolled. The ATP-III, the ATP-IIIA and the IDF criteria were used to define MS. 10-year risk of CHD events was calculated with the Framingham score. One hundred nine (34.2%) patients met the ATP-III criteria, 118 (37%) the ATP-IIIA and 133 (41.7%) the IDF criteria for MS. Patients with MS were older, had a later onset of illness and an older age at first hospitalization. The prevalence of MS in schizophrenia patients was higher from the general population only within the 20–29 age group. Patients with MS had a higher age and sex-corrected 10-year risk of CHD events. The only predictor of MS was the age of illness onset. In conclusion, countries where the general population prevalence of MS is already too high, schizophrenia patients younger than 30 years of age might be under higher risk of morbidity and mortality related with MS. This study points to the necessity for aggressive interventions to correct MS in schizophrenia as early as possible, within the first 10 years of post detection.     

Multiple sclerosis in Móstoles,central Spain

Objectives– Until relatively recently southern Europe was regarded as having a medium to low multiple sclerosis prevalence, of about 20 or less per 100,000. However, recent studies in Sardinia, Sicily, continental Italy, Cyprus and Spain have yielded higher MS prevalence rates, between 32 and 102.6 per 100,000. We present the results of a prevalence study of MS in the municipality of Móstoles, central Spain. Material and methods– To ascertain the prevalence of multiple sclerosis in Móstoles (195,979 inhabitants), an intensive study was undertaken using several sources of information. We used the Poser criteria in diagnosis. Results– There were 85 patients (53 women and 32 men) classified as definite or probable, prevalence 43.4/100,000 (95% CI, 34.7 to 53.7). The incidence rate was 3.8/100,000/year (95% CI, 2.7 to 5.3) in the last 5 years. Mean age on prevalence day was 38.8±10.9 years. Mean age at onset was 31.7±9.3 years. Mean interval between initial symptoms and diagnosis was 1.7 years. Mean duration of disease was 7.6±6.1 years. Overall, 70.6% had a relapsing–remitting course, 18.8% had a primary progressive and 10.5% had a secondary progressive. Mean EDSS score was 2.7±1.9. Conclusion– The Móstoles study confirms the conclusions of previous smaller population studies that Spain is a moderately high or medium MS risk zone.