The mortality of motor neuron disease in Sweden

The age-standardized mortality from motor neuron disease in Sweden doubled from 1961 to 1985. The average annual rate during the period was 1.9 per 100,000 population. The male to female ratio was 1.2:1. The age-specific mortality rates had a peak at 70 to 79 years of age. When each birth cohort was followed up separately over time, the peak was less clear and in some cohorts the mortality rates increased continuously with advancing age. A significant increase of motor neuron disease among men was found in one Swedish county.     

A prevalence survey of Parkinson's disease and other movement disorders in the People's Republic of China

A door-to-door survey was conducted in six cities of the People's Republic of China. A total of 63,195 individuals were sampled during 1983 to determine the prevalence of major neurologic disorders. The survey involved a complete census, followed by a pretested interview and brief screening examination with a high level of sensitivity for detecting individuals with frequently occurring neurologic diseases, including movement disorders. Subjects with abnormal responses or findings were examined by a neurologist. There was 100% cooperation among the study subjects. Twenty-eight individuals alive on prevalence day (Jan 1, 1983) were identified as having Parkinson's disease, yielding an age-adjusted (to the 1960 US population) prevalence ratio of 57 per 100,000 population. All subjects were older than the age of 50 years. After the fifth decade of life, the age-specific prevalence ratios increased with age.     

Prevalence and incidence of multiple sclerosis in Catania, Sicily

OBJECTIVE: An epidemiologic survey was conducted to determine the prevalence and incidence of MS in the city of Catania, Sicily, Italy. Prevalence rate was calculated as point prevalence at January 1,1995, and incidence during 1974 to 1995. METHODS: The authors studied the frequency of MS in the community of Catania in a population of 333,075 inhabitants according to the 1991 census. The primary sources for the case ascertainment were the neurologic and motor rehabilitation departments, the MS Center, the Italian MS Association, private neurologists, and family doctors. All patients who satisfied the Poser criteria for clinically definite MS, laboratory-supported definite MS, clinically probable MS, and laboratory-supported probable MS were considered prevalent and incident cases. RESULTS: One hundred ninety-five patients with MS who had had the onset of disease on prevalence day in a population of 333,075 inhabitants were detected. The prevalence rate was 58.5 per 100,000 (95% CI 50.7 to 67.5). Prevalence was higher in women (62.0/100,000) than in men (54.8/100,000). The age-specific prevalence showed a peak in the group aged 35 to 44 (145.1/100,000). From 1975 to 1994, 170 subjects with MS had the clinical onset of the disease. The mean annual incidence was 2.3 per 100,000 (95% CI 2.0 to 2.6). Age-specific incidence showed a peak in the group aged 25 to 34 (6.32/100,000). Incidence for 5-year intervals increased from 1.3 during 1975 to 1979 to 3.9 during 1990 to 1994. CONCLUSIONS: These prevalence and incidence rates are close to those reported in other similar surveys carried out in Italy and southern Europe.     

Neuroepidemiology

Epidemiology is the study of the natural history of disease, which includes its frequency, severity, and course and the identification of “risk factors” that influence these aspects. Neuroepidemiology is that branch of epidemiology dealing with disorders that affect the nervous system. Frequency of disease is best measured by population-based rates, which are ratios of the number of cases to the population at risk, expressed as cases per unit of population. Incidence and mortality rates refer, respectively, to new cases of, and deaths caused by, a disease per unit of time and population. Prevalence rate is the cross-sectional count of cases of a disease present at a given time per unit of population. Comparison of rates often requires consideration of age-specific or age-adjusted rates rather than crude rates, all ages. Course of illness (survival, complications, recurrence) can be measured by life-table methods. The annual incidence for disease and injury of the nervous system is about 2.5% (2,500 per 100,000 population) and the prevalence is about 9.5%. Excluding all traumatic, pain, headache, alcohol, psychiatric, and special-sense disorders, neurological diseases have an annual incidence and prevalence rate, respectively, of 1.1 and 3.6% of the population.     

The incidence of amyotrophic lateral sclerosis in southwestern Ontario, Canada

The incidence, prevalence, and mortality rates of amyotrophic lateral sclerosis in southwestern Ontario, Canada, were determined for the years 1978 through 1982. The average annual incidence rate was 1.63 per 100,000 population. The prevalence rate was 4.9 per 100,000 on January 1, 1983. The average annual mortality rate was 1.52 per 100,000 population and increased with age, reaching a peak in the 70 to 79-year decade in both sexes. The male:female ratio was 1.2:1. The average age at diagnosis was 62.5 years, and the average duration from date of diagnosis was 2.5 years. The distribution of the disease was uneven in 12 counties, with the highest incidence in Perth (3.33) and Essex (2.43) counties. The city of Windsor, in an industrial region, had a high average annual incidence rate of 2.81.     

EPIDEMIOLOGY of PARKINSON''S DISEASE IN FINLAND

This investigation was conducted to clarify the epidemiology of Parkinson's disease in Finland. A community survey was made in a selected area in southwest Finland in addition to an analysis of Finnish mortality statistics for Parkinson's disease. The annual mortality rate from Parkinson's disease was found to average 2 per 100,000 population. Almost 70 per cent of the deaths occurred between 65-79 years of age. The total and age-specific mortality rates for males were greater than those for females whereas the proportionate mortality rates were almost identical. This was considered to indicate that suggestions of greater male prevalence, based on mortality statistics, do not appear justified. On prevalence day, Dec. 31st, 1971, 484 patients with Parkinson's disease (of which 444 were personally examined) lived in the area of investigation (population 402,988), the prevalence rate being 120.1 per 100,000 population. The highest annual incidence rate was 16.6 per 100,000 population. The age-specific prevalence rates showed a rapid increase after the 50th year of age. The greatest prevalence was shown by the age group 70-79 years of age in which almost 0.8 per cent of the population are affected. Age-specific incidence rates also displayed an increase after the 50th year of age. The greatest incidence was observed in the age group 70-79 years of age in which almost 1 per 1,000 of the population are annually affected by the disease. A difference between the sexes was demonstrable in the prevalence and incidence rates showing greater values for females, but in the age-specific frequencies the differences were reduced. This probably reflects the difference between the age structures of the male and female populations, suggesting that both sexes have a similar risk of being affected by the disease. The permanent age structure shown by idiopathic patients in comparison with previous investigations as well as the increased mean age and proportionate decrease of postencephalitic patients was found to be in disagreement with the cohort theory according to which all parkinsonian patients are previously victims of encephalitis lethargica.     

A possible spatial and temporal cluster of multiple sclerosis in the town of Linguaglossa,Sicily

We carried out an epidemiological survey to determine prevalence and incidence of multiple sclerosis in the little town of Linguaglossa in the Province of Catania. We calculated prevalence rate as point prevalence at 1 January 2001 and incidence during 1991–2000.We studied the frequency of multiple sclerosis in the community of Linguaglossa in a population of 5,422 inhabitants in the 2001 census. The primary sources for the case ascertainment were the general practitioners of Linguaglossa, the local Italian Multiple Sclerosis Association and the neurological departments, Multiple Sclerosis Centers and private neurologists of the province of Catania. We considered as prevalent and incident cases all patients who satisfied the Poser’s diagnostic criteria. We detected 11 patients with multiple sclerosis who had had the onset of disease on prevalent day (P.D.). The onset–adjusted prevalence rate was 203/100,000 (95% CI 107–352).Prevalence was higher in women (247/100,000) than in men (154/100,000). From 1991 to 2000, 10 subjects with MS had clinical onset of disease. The mean annual incidence risk was 18.2/100,000 (C. I. 95 % 5.9–42.5).Conversely in the same population prevalence on 1 January 1991 was 37/100,000 while the onset adjusted annual incidence risk during the previous decade (1981–1991) was 3.6/100,000. Prevalence and incidence rates of MS during the last decade in the little town of Linguaglossa are higher than those found in the same area during the previous ten years and also than those reported in other Sicilian and Italian surveys suggesting a possible cluster of MS.     

The prevalence of migraine and tension headache in Saudi Arabia: a community-based study

The prevalence of migraine and tension headache was determined in a 2-stage, door-to-door community survey in Thugbah, Saudi Arabia. Out of 22630 subjects surveyed, 2742 individuals had headaches thus yielding a crude prevalence of 12.1% (95% CI = 11.7–12.5%) and with age-adjustment, it rose to 15.9% (95% CI = 15.4–16.4%). There was female preponderance overall and the peak frequency was in the 3rd decade. The age-specific rates rose from 2.4% in the first decade to 37.2% in the 7th decade. The prevalence of tension-type headache (PR 9.5%; 95% CI = 9.1–9.9%) was higher than migraine (PR = 5.0%; 95% CI = 4.7-5.3%). The low headache prevalence in this community compared to findings in western countries could be ascribed to the young age of the population and/or could possibly reflect the influence of traditional life styles and cultural factors in the Kingdom.     

Incidence and mortality of Parkinson's disease in older Canadians

ObjectiveTo estimate the age-specific incidence of Parkinson’s disease (PD) in elderly persons in the Canadian province of British Columbia (BC). All-cause and injury mortalities and relative risk of death for those persons with PD were also examined.MethodsA historical cohort study was conducted using 5 provincial administrative databases from 1991/92 to 2000/2001. A series of algorithms based on the databases were created for case ascertainment of PD for persons 65 years or older. Crude and age-specific incidence and mortality rates were calculated using person-years of follow-up as the denominator. The impact of PD on all-cause and injury mortalities was examined using multivariate Cox regression models to provide adjusted hazard ratios.Results10,910 incidence cases over 6,051,682 person-years of follow-up were identified. The crude annual incidence rate was 252 per 100,000 person-years. Over the nine year period, age standardized incidence for males ranged from 207 to 396 per 100,000 person-years and 127 to 259 per 100,000 person-years for females. Persons with PD were at a 43% greater risk of all-cause mortality and specifically, 51% greater risk of injury mortality.ConclusionsIncidence of PD is substantially higher in advanced age with age adjusted increases for both all-cause and injury mortalities. These findings also highlight falls as a primary factor for injury mortality in PD.     

Epidemiology of multiple sclerosis in western Herzegovina

OBJECTIVES: To determine epidemiological rates of multiple sclerosis (MS) in western Herzegovina. PATIENTS AND METHODS: We analysed data from 81 MS patients (49 females, 32 males) on the prevalence day, 31 December 2003. Patient information was obtained from a search of all available medical records from the period 1994-2003 in the investigated area. RESULTS: Crude prevalence of MS was 27/100,000 (95% confidence interval (CI) 20-34). Prevalence was highest in the mountainous municipality of Posusje (56/100,000) and lowest in the coastal municipality of Neum (0 incidence). The annual incidence of MS was 1.6/100,000 (95% CI 0-3.3). The female/male ratio of MS was 1.5. The mean age of the patients on prevalence day was 40.0+/-11.6 years, and the mean age at disease onset was 31.0+/-7.1 years. Eight (10%) of the patients had a first-degree relative with MS. The primary progressive (PP) disease course was observed only in females. Visual symptoms were the initial symptom of MS in 6 (7%) of the patients. CONCLUSIONS: Western Herzegovina is an area of moderate risk for MS, and the distribution of MS in western Herzegovina is heterogeneous. PP-MS occurred only in females, and involvement of the visual pathways as the initial symptom of MS was low.     

Epidemiology of primary intracranial neoplasms in Manitoba, Canada

The incidence of primary intracranial tumors in Manitoba, Canada was reviewed. From 1980 through 1985, 657 tumors were diagnosed. The crude incidence rates were 10.2/100,000 for males and 10.8/100,000 for females. The three most common tumors were: astrocytoma 281 (43%), meningioma 145 (22%), and pituitary adenoma 111 (17%). Average annual incidence rates for all tumors showed a bimodal distribution with one peak in the 0-4 age group (4.2/100,000), and the other in the 60-69 age group (27.2/100,000). For malignant astrocytoma, the age-specific annual incidence rate increased to the seventh decade where it reached a peak of 14.3/100,000. The incidence of benign astrocytoma remained relatively constant with age at 1.1/100,000. The annual incidence of meningioma increased with age up to the eighth decade reaching 7.2/100,000. Of the 145 meningiomas, 56 (39%) were meningotheliomatous, 48 (33%) transitional, 10 (7%) malignant, 7 (5%) fibroblastic, 6 (4%) psammomatous, 3 (2%) angioblastic, and 15 (10%) lacked pathologic diagnosis. The annual incidence of pituitary adenoma showed two peaks, the first occurring in the third decade (2.6/100,000) and the second in the eighth decade (3.2/100,000). Although the incidence of meningioma was relatively high, the clinical features and pathologic patterns of these tumors were not unlike those previously reported in the literature.     

Prevalence of neurological disorders in Bangalore, India: a community-based study with a comparison between urban and rural areas

A population-based neuroepidemiological survey of 102,557 individuals in urban and rural Bangalore in Southern India was conducted to determine the prevalence and pattern of neurological disorders. The study population included subjects from urban (51,502) and rural (51,055) areas, identified through a two-stage stratified random sampling method. Trained social workers administered the screening questionnaire, which had been tested and validated in an earlier pilot study and a neurologist examined the individuals who screened positive. Adults, children (<15 years) and elderly adults (>60 years) constituted 61, 34 and 5% of the study group, respectively. There was a distinct difference in education, occupation and income levels between urban and rural areas with all these parameters being lower in the rural population. In the surveyed population, 3,206 individuals with neurological disorders were detected resulting in crude and age-adjusted prevalence rates of 3,126 and 3,355 per 100,000 population, respectively. The prevalence rate among children, middle-aged (31-40 years) and elderly adults was 2,653, 3,932 and 5,012 per 100,000 population, respectively. The prevalence of neurological disorders among women (3,617) was higher compared with men (2,657). The prevalence rate in urban and rural populations was 2,190 and 4,070/1,00,000, respectively, implying that neurological disorders were twice as frequent in rural areas as in urban areas. The prevalence rates per 100,000 population of the most frequent disorders in the descending order of frequency were: headache (1,119), epilepsy (883), febrile convulsions (330), cerebrovascular disorder (150), and mental retardation (142). This large-scale population-based survey provides data that will be crucial for developing hospital and community-based neurological services in India and other developing countries.     

Community-based study of neurological disorders in rural central Ethiopia

Between 1986 and 1988 a door-to-door survey was conducted on a stable rural population of 60,820 in central Ethiopia. Trained lay health workers made a complete census and identified cases with symptoms and signs of neurological disorders, using specially designed questionnaires which, in a previous pilot study, were found to have a sensitivity of 91% and specificity of 85%. Neurological disorders in the rural population were epilepsy, postpoliomyelitis paralysis, mental retardation, peripheral neuropathy (mainly due to leprosy), and deaf-mutism with prevalence rates (cases/100,000 population) of 520, 240, 170, 150 and 130, respectively. The prevalence rates of the other less common neurological disorders were 62 for hemiparesis (15 of which were for cerebrovascular accidents), 20 for cerebral palsy, 16 for optic atrophy, 12 for perceptive deafness, 10 for tropical spastic paraparesis, 7 for Parkinson's disease and 5 for motor neuron disease, ataxia and chorea/athetosis. Among related non-neurological conditions, blindness, locomotor disability and deafness were predominant. The significance and role of such a neuroepidemiological study in laying the strategies for the prevention of neurological disorders and rehabilitation of patients are discussed in the context of a developing country.     

Stroke in the urban population of Calcutta--an epidemiological study

A population-based cluster survey on stroke disorders was conducted for the first time in the city of Calcutta, India. The population surveyed totaled 50,291. The crude prevalence rate of stroke was 147/100,000 (age-adjusted prevalence 334/100,000). The annual incidence rate of stroke for the year 1998-1999 was 36/100,000 (age-adjusted annual incidence rate 105/100,000). Women outnumbered men regarding stroke prevalence in all age groups except in the 50- to 69-year age group. There were relatively more cases of cerebral haemorrhage in our study, compared to those in the western countries. Case-control analysis found hypertension to be the most significant risk factor for stroke.     

Prevalence of Parkinson's disease in the L'Aquila district, central Italy

OBJECTIVE: We estimated the prevalence of Parkinson's disease (PD) in the L'Aquila district. METHODS: Cases of PD were identified screening all available case sources including general practitioners and antiparkinsonian drug-users by means of pharmacy records. Prevalence of PD was computed considering the prevalence day of December 31, 2001. RESULTS: On the prevalence day, 682 patients with PD were alive and residing in the L'Aquila district. A total of 354 patients were women and 328 men. The overall crude prevalence rate was 229.3/100,000 (95% CI 212.7-247.1), without any difference between men (227.4/100,000; 95% CI 200.0-257.5) and women (231.1/100,000; 95% CI 202.2-263.1). Prevalence rates increased with age in both sexes and were higher in urban (244.5/100,000; 95% CI 213.7-278.5) than in rural residents (214.7/100,000; 95% CI 189.0-242.9) (SRR = 1.7; 95% CI 1.3-2.1). CONCLUSIONS: The prevalence of PD in the L'Aquila district was within the range of prevalence rates found in our country and steeply increased with advancing age in both sexes.     

AMYOTROPHIC LATERAL SCLEROSIS IN FINLAND

The prevalence of ALS and its distribution in Finland was investigated on the basis of prevalence numbers by counties. On the prevalence day, 1 January 1973, 168 ALS patients were found alive. They were collected from hospital records and the registers of the National Pension Institute. The prevalence was 3.56 cases per 100,000 population, 4.25/100,000 for men and 1.92/100,000 for women, which gave a male to female prevalence ratio 1.5 to 1. The distribution of the disease was uneven in the country being more frequent in the southeastern counties. The disease was contracted earlier (at 51.9 years of age) and its course was slower (3.7 years up to the prevalence day) in the prevalence material than in cases derived from the mortality statistics (58.0 years at the onset and duration of 2.6 years, respectively). This is explained by the dropping out of some of the younger and/or more benign cases from the mortality statistics. This seems to be true also in other countries.     

Prevalence of movement disorders in men and women aged 50-89 years (Bruneck Study cohort): a population-based study

BACKGROUND: There is emerging awareness that movement disorders rank among the most common neurological diseases. However, the overall burden of these disorders in the general community is not well defined. We sought to assess the prevalence of all common categories of movement disorders in a population, accounting for sex differences and age trends. METHODS: As part of an ongoing prospective population-based study of carotid atherosclerosis and stroke risk (the Bruneck Study), a total of 706 men and women aged 50-89 years underwent a thorough neurological assessment. The diagnosis of movement disorders and ratings for disease severity were based on standard criteria and scales. Prevalences were estimated from logistic regression models (regression-smoothed rates) and standardised to the age and sex structure of the general community. FINDINGS: The prevalence of all common categories of movement disorders was 28.0% (95% CI 25.9-30.1). Proportions in men (27.6% [95% CI 24.5-30.7]) and women (28.3% [25.5-31.2]) were closely similar and sharply increased with age (from 18.5% [15.0-22.0] in 50-59-year olds to 51.3% [44.9-57.7] in 80-89-year olds). Almost half of all patients (90/214) had moderate-to-severe disease expression, but only 7.0% (15/214) received standard drug treatment. Prevalence of tremor was 14.5%, followed by restless legs syndrome (10.8%), parkinsonism (7%), primary dystonia and secondary dystonia (1.8%), and chorea and tics (<1% each). A fifth of all movement disorders were diagnosed to be probably drug-induced. INTERPRETATION: There is a high prevalence of and substantial under-recognition and under-treatment of movement disorders in the general community.     

Epidemiology of amyotrophic lateral sclerosis in Hordaland county, western Norway

The incidence, prevalence and prognosis of amyotrophic lateral sclerosis (ALS) in the county of Hordaland, western Norway were determined for the years 1978 through 1988. The average annual incidence rate was 1.60 per 100,000 population with a male to female ratio of 1.26 (95% confidence interval: 0.76-2.09). The maximal age-specific annual incidence was 8.12 per 100,000 and occurred in the age-group between 61 and 65 years. The prevalence of ALS was 3.67 per 100,000 on December 31, 1988. The average age at the onset of the disease was 60.9 years ranging from 34 to 82 years of age. Survival was studied with life table techniques. Median survival from the onset of symptoms was 28.0 months overall. In patients with bulbar onset the median survival was 24.0 months whereas it was 40 months in patients with spinal onset of disease (log rank test, P = 0.0004). The difference in survival between ALS with bulbar or spinal onset was not explained by age or sex differences in the two groups.