Guillain-Barré syndrome. Clinicoepidemiologic features and effect of influenza vaccine

A study of the epidemiologic and clinical features of Guillain-Barré syndrome in the population of Olmsted County, Minnesota, over the 46-year period 1935 through 1980 was conducted through the centralized diagnostic index maintained at Mayo Clinic, Rochester, Minn. A total of 48 cases were identified, giving an age- and sex-adjusted incidence of 1.8 per 100,000 person-years. The rate increased over time from 1.2 in the interval 1935 through 1956 to 2.4 in the interval 1970 through 1980. Males were affected more than females (age-adjusted rates of 2.3 and 1.2, respectively). The rate increased with age from 0.8 in those under 18 years old to 3.2 for those 60 years and older. Antecedent infectious diseases were reported in 65% of the cases. Implications with regard to the incidence of Guillain-Barré syndrome associated with the A/New Jersey/76 (swine flu) vaccine are discussed.     

Follow-up study on amyotrophic lateral sclerosis in Rochester, Minn., 1925 through 1984

The incidence, secular trend and survivorship of amyotrophic lateral sclerosis in the Rochester, Minn., population has been investigated over a 60-year period, 1925 through 1984. The crude average annual incidence rate was 2.0 per 100,000 population. The rate, age- and sex-adjusted to the US 1970 white population, was 2.4 per 100,000 population (3.0 for men and 2.0 for women), with a male to female ratio of 1.5:1. Incidence rates after 1955 showed a small but nonsignificant increase compared to those of the former 30-year period. Median age at onset was 67.5 years; the incidence rates increased significantly with advancing age, but without a peak. Median survivorship was 23.8 months, and younger patients had a better prognosis than patients with an advanced age at onset. No change in duration of survivorship was observed over the period studied. Two of the 44 patients (4.5%) had a family history of amyotrophic lateral sclerosis.     

Incidence and effectiveness of cerebrospinal fluid shunts in Olmsted County, Minnesota, 1956-1981

In the period 1956 through 1981, 129 cerebrospinal fluid (CSF) shunt operations were performed on 50 patients who were residents of Olmsted County, Minn. The overall average annual age- and sex-adjusted incidence of initial CSF shunts during this 26-year period was 2.3 per 100,000 person-years. Within 5-year calendar time intervals, the average annual incidence rates per 100,000 person-years ranged from 0.8 (1956-1960) to 4.6 (1971-1975). There were 4 shunt-related deaths, 1 due to a CSF shunt infection and 3 due to acute increases in intracranial pressure. In this analysis of shunt procedures in a defined population, the diagnostic indications and changes over time in CSF shunting devices are also described.     

Incidence of migraine headache: a population-based study in Olmsted County, Minnesota.

To determine the incidence of clinically detected migraine headache in the defined population of Olmsted County, MN, 1979-1981, we screened over 6,400 patient records from several diagnostic rubrics using the unique resources of the Rochester Epidemiology Project for population-based studies. We identified 629 Olmsted County residents who fulfilled the International Headache Society's 1988 criteria for newly diagnosed migraine headache between 1979 and 1981. The overall age-adjusted incidence was 137 per 100,000 person-years for males and 294 per 100,000 person-years for females. The highest incidence in females was among those aged 20 to 24 years (689 per 100,000 person-years), and in males, the highest incidence was among those aged 10 to 14 years (246 per 100,000 person-years). From 1979 to 1981, there was a striking increase in the age-adjusted incidence in those under 45 years of age: the incidence increased 34% in women and 100% for men. This is the first population-based study of migraine incidence across all ages.     

Reye's syndrome: incidence and time trends in Olmsted County, MN, 1950-1981

Incidence and time trends of Reye's syndrome have been determined in Olmsted County, MN, using the facilities of the Rochester Epidemiology Program Project at Mayo Clinic. Incidence rates in individuals under 18 years of age were 1.1 per 100,000 person-years in the 1970-75 time interval and 1.7 in the 1976-81 interval. Failure to identify any case in the earliest time interval yields a rate of zero, and an incidence higher than 0.6 per 100,000 can be excluded with 95% probability. This finding is consistent with an increasing incidence over time in this community and does not exclude the possibility that Reye's syndrome did not exist in Olmsted County before 1970.     

Prevalence of medically diagnosed dementia in a defined United States population: Rochester, Minnesota, January 1, 1975

Using the centralized diagnostic data resource for the population of Rochester, Minnesota, we determined the prevalence of medically diagnosed dementia for this community. There were 289 individuals with dementia who were residing in Rochester on January 1, 1975: 208 women and 81 men. The overall age- and sex-adjusted rates per 100,000 population were 342 for all dementias and 227 for Alzheimer's disease. Prevalence rates increased with age for both sexes. Limiting the denominator to persons greater than or equal to 65 years, age-adjusted rates per 100,000 population for men and women were 3,452 and 3,466 (or about 3.5%), respectively, for dementia and 2,007 and 2,675 (2.0 and 2.7%), respectively, for Alzheimer's disease.     

Hemifacial spasm in Rochester and Olmsted County, Minnesota, 1960 to 1984

The incidence of hemifacial spasm in residents of Olmsted County, Minnesota, was studied by reviewing the medical records of patients residing in the community between 1960 and 1984. The average annual incidence rate was 0.74 per 100,000 in men and 0.81 per 100,000 in women, age-adjusted to the 1970 US white population. The average prevalence rate was 7.4 per 100,000 population in men and 14.5 per 100,000 in women. The incidence and prevalence rates were highest in those from 40 to 79 years of age.     

Is the prevalence of dementia changing?

We compared the point prevalence rates of dementing illnesses in the population of Rochester, Minnesota, on January 1, 1980, with the previously published rates of January 1, 1975, by using extensive health care records available from all sources of care in the community, in order to identify and classify cases with standard diagnostic criteria derived from DSM-III. The overall age- and sex-adjusted prevalence rate per 100,000 population for dementia on January 1, 1980, was 402.5 compared with 388.4 on January 1, 1975; for Alzheimer's disease it was 259.8 in 1980 and 259.5 in 1975. The stability of the rates suggests no change in the incidence and mortality associated with these conditions. The prevalence rates for Rochester, Minnesota, are similar to many other rates estimated in other North American communities, but they differ from two other population-based estimates from East Boston and California. Case definitions and methods of assessment probably account for the differences in estimated prevalence.     

The increasing incidence and prevalence of MS in a Sardinian province

OBJECTIVE: To verify incidence rates and their temporal trend in a homogeneous, ethnically, and genetically distinct population of central Sardinia (the Nuoro province). BACKGROUND: Intensive epidemiologic studies carried out in Sardinia since the 1970s have suggested that the prevalence and incidence of MS are much higher in this Mediterranean island compared with those found on mainland Italy. METHODS: The study area had a population of approximately 274, 000 people in the 1991 census. The authors adopted a complete enumerative approach by reviewing all possible sources of case collection available in the investigative area. RESULTS: Based on 469 MS patients, the mean annual incidence for 1955 to 1995 was 4.18 per 100,000 (or 4.3 per 100,000 if age- and sex-adjusted to the European population). The incidence, averaging 1.95 per 100,000 during 1955 to 1959, rose progressively over time, reaching rates of 6.6 in the quinquiennium 1985 to 1989 and 6.4 per 100,000 in 1990 to 1995. On December 31, 1994, the crude prevalence, based on 415 MS patients alive in the study area, was 151.9 per 100,000 (156.6 if adjusted to the European population). CONCLUSION: These incidence and prevalence rates are the highest to date that have been estimated for a large community in southern Europe, and they constitute some of the highest rates in the world. Based on other surveys, these results reinforce the position of Sardinia as a higher and rising prevalence area for MS compared with other Mediterranean populations. Genetic and social-historic data strengthen the hypothesis of the environmental role and genetic factors among Sardinians in determining the notable difference in MS frequency between Sardinians and other Mediterraneans.     

Epidemiology and clinical features of idiopathic trigeminal neuralgia and glossopharyngeal neuralgia: similarities and differences, Rochester, Minnesota, 1945-1984.

A comparison of epidemiological and clinical features of trigeminal neuralgia (TN) and glossopharyngeal neuralgia (GN) in Rochester, Minn., reveals several differences. The overall age- and sex-adjusted annual incidence rates were significantly higher for TN than for GN (4.7 vs. 0.8 per 100,000 population). The TN:GN ratio was increased for both men and women and was 5.9:1 for both sexes combined. This ratio is greater than reported in previous non-population-based studies. GN is a milder disease than TN, as indicated by the number of episodes, treatment, and characterization of pain. The right side is affected more often with TN than with GN. Bilaterality was noted less often in TN than in GN cases.     

Presenile dementia in Israel

A nationwide epidemiologic study of presenile dementia of the Alzheimer type (PDAT) with onset through age 60 years was carried out in Israel. The Israeli National Neurologic Disease Register and clinical records of all patients discharged from hospitals between 1974 and 1983 with a neurologic or psychiatric diagnosis suggestive of dementia were reviewed. A total of 71 Jewish patients with onset of PDAT between 1974 and 1978 was ascertained. The age at onset in these patients ranged from 43 to 60 years. The median survival was 8.1 years, with slightly longer survival if onset occurred before age 55 years, even after correction for expected mortality according to age and sex. The average annual incidence rate per 100,000 population at risk was 2.4 in the population aged 40 through 60 years. Although the incidence rates were slightly greater for women, the difference between the rates by sex was not statistically significant. The age- and sex-adjusted incidence of PDAT per 100,000 population was significantly higher in those born in Europe or America (2.9) than in those born in Africa or Asia (1.4). No significant difference in survival was found between these two groups. The curve of the incidence rates by age for PDAT in Israel is continuous with that for senile dementia of the Alzheimer type collected by similar methods elsewhere, which suggests that one disease process may account for both conditions.     

Epidemiological characteristics of lacunar infarcts in a population

BACKGROUND AND PURPOSE: This study evaluated the characteristics and natural history of patients with lacunar (small, deep) cerebral infarcts in a defined population for comparison of these characteristics to those in patients with nonlacunar infarcts. METHODS: This is a population-based study in Rochester, Minnesota, from 1960 to 1984, that used the medical record-linkage system to identify and characterize patients with cerebral infarction. RESULTS: The age- and sex-adjusted average annual incidence rate of lacunar cerebral infarction was 13.4/100,000 persons, accounting for 12% of all first cerebral infarcts. Temporal trends in incidence rates, stroke recurrence rates, prevalence of diabetes mellitus, and causes of death (given survival for 30 days) for cases of lacunar infarction were not significantly different from those for cases of nonlacunar infarction. Hypertension was found in 81% of patients who had a lacunar infarct and in 70% of patients who had a nonlacunar infarct (p = 0.05). A potential cardiac source of embolism was found in 12% of patients who had a lacunar infarct and in 28% of patients who had a nonlacunar infarct (p = 0.002). Survival was significantly better after a lacunar infarct than after a nonlacunar infarct. CONCLUSIONS: Small, deep cerebral infarcts had many of the epidemiological characteristics of other cerebral infarcts but there was a slightly higher frequency of hypertension, significantly lower frequency of a cardiac embolic source, and significantly better survival in patients with lacunar infarction than in those with nonlacunar infarction.     

The trends in incidence of primary brain tumors in the population of rochester,minnesota

A number of reports have suggested an increasing incidence of primary brain tumors, especially malignant astrocytomas, in the elderly population. To investigate this issue, we analyzed the incidence and temporal trends of primary intracranial neoplasms diagnosed in the population of Rochester, Minnesota, over the 40 years between 1950 and 1990. The incidence of symptomatic primary brain tumors (excluding patients diagnosed incidentally at autopsy and by neuroimaging studies) increased from 9.5 per 100,000 population per year in 1950 to 1969 to 12.5 per 100,000 per year in 1970 to 1989; this change was not statistically significant (χ² trend, 1.89; p = 0.17). While the incidence of pituitary adenomas increased significantly between the two periods (χ² trend, 4.44;p = 0.04), the incidence trends of all gliomas, malignant astrocytomas, and meningiomas showed no change among persons younger than 65 years as well as those 65 years and older. The number of patients incidentally found to have neoplasms by neuroimaging studies increased in the recent 20-year period (χ² trend, 4.08;p = 0.04). The average age- and sex-adjusted incidence rates per 100,000 per year during the study period in the population of Roshester, Minnesota, for symptomatic tumors were 5.0 for all gliomas, 3.3 for malignant astrocytomas, 2.0 for meningiomas, and 2.4 for pituitary adenomas. In conclusion, our data indicate that the reported increase in the incidence of primary brain tumors is an artifact of improvement in diagnostic technology and practice.     

Multiple sclerosis in southern Europe: Monreale City, Italy. A twenty-year follow-up incidence and prevalence study

BACKGROUND: Several follow-up studies showed increasing prevalence and incidence rates for multiple sclerosis (MS). OBJECTIVE: To ascertain, throughout a follow-up study, the incidence and prevalence of MS in the city of Monreale, Sicily, southern Italy. METHODS: We calculated crude and age- and sex-specific prevalence rates on December 31, 2000, and determined incidence rates for the period January 1, 1992 to December 31, 2000. RESULTS: The prevalence of MS was 71.2 per 100,000 population (48,5/100,000 in men; 93,0/100,000 in women). The incidence rate of MS for the period 1992-2000 was 4.0/100,000 per year. CONCLUSION: This study showed a nonsignificant increase in MS incidence rates in Monreale city for 1992-2000 compared to 1981-1991. Prevalence rates were similar to those of the previous follow-up study. Intervals between onset of symptoms and diagnosis seemed shorter than in prior studies. There is no evidence that the high prevalence and incidence rates have changed in this interval but numbers are too small for firm statements. These findings indicate that in Monreale city MS prevalence is stable and confirm Sicily as a high-risk area for MS.     

Incidence rates of stroke in the eighties: the end of the decline in stroke?

Studies of the population of Rochester, Minnesota, have provided the only data on temporal trends for the incidence of stroke in North America. Among the residents of Rochester, the average annual incidence rate of stroke declined by 46%, from 213 to 115 per 100,000 population, between 1950-1954 and 1975-1979. The decline occurred in all age and sex groups, but it occurred earlier in women than in men. The rates stabilized in the 1970s, and did so earlier in women. For 1980-1984, the incidence rate of stroke was 17% higher than that for 1975-1979. The onset of the decline in incidence rates coincided with the introduction of effective antihypertensive therapy, but stabilized and increased rates were associated with continuing improvement in the control of hypertension. The increase in the incidence rates of stroke coincided with the introduction of computed tomography, which appeared to increase the detection of less severe strokes.     

Incidence and prevalence of amyotrophic lateral sclerosis in Harris County, Texas, 1985-1988

The incidence of amyotrophic lateral sclerosis was determined in Harris County, Texas, for the period 1985 through 1988. Amyotrophic lateral sclerosis cases were ascertained from four sources: area neurologists, hospitals, death certificates, and the Muscular Dystrophy Association. The age-adjusted incidences of 1.27 per 100,000 person-years in males and 1.03 per 100,000 person-years in females were lower than recent rates in the northern US, Canadian, and northern European studies but higher than rates in southern European studies. Comparisons with other recent incidence studies show less uniformity in occurrence of amyotrophic lateral sclerosis, in both the overall rates and in the age- and sex-specific patterns, than was suggested by mortality studies. The incidence of amyotrophic lateral sclerosis among blacks and whites was similar. Hispanic males had incidences similar to white males, although a deficit of female Hispanic cases was found in Harris County. The prevalence of amyotrophic lateral sclerosis peaked in the 65- to 74-year age group at 33 per 100,000 population among males and 19 per 100,000 population for females.     

Ischemic stroke subtypes: a population-based study of incidence and risk factors

BACKGROUND AND PURPOSE: There is scant population-based information on incidence and risk factors for ischemic stroke subtypes. METHODS: We identified all 454 residents of Rochester, Minn, with a first ischemic stroke between 1985 and 1989 from the Rochester Epidemiology Project medical records linkage system. We used Stroke Data Bank criteria to assign infarct subtypes after reviewing medical records and brain imaging. We adjusted average annual incidence rates by age and sex to the US 1990 population and compared the age-adjusted frequency of stroke risk factors across ischemic stroke subtypes. RESULTS: Age- and sex-adjusted incidence rates (per 100 000 population) were as follows: large-vessel cervical or intracranial atherosclerosis with >50% stenosis, 27; cardioembolic, 40; lacuna, 25; uncertain cause, 52; other or uncommon cause, 4. Sex differences in incidence rates were detected only for atherosclerosis with stenosis (47 [95% CI, 34 to 61] for men; 12 [95% CI, 7 to 17] for women). There was no difference in prior transient ischemic attack and hypertension among subtypes, and diabetes was not more common among patients with lacunar infarction than other common subtypes. CONCLUSIONS: The age-adjusted incidence rate of stroke due to stenosis of the large cervicocephalic vessels is nearly 4 times higher for men than for women. There is no association between preceding transient ischemic attack and stroke mechanism. Diabetes and hypertension are not more common among patients with lacunae. Age- and sex-adjusted incidence rates for ischemic stroke subtypes in this population can be compared with similarly determined rates from other populations.     

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.     

Incidence and prognosis of brain abscess in a defined population: Olmsted County, Minnesota, 1935-1981

The incidence of brain abscess was studied on all cases occurring in residents of Olmsted County, Minn., from 1935 through 1981. Thirty-eight cases (9 cases first diagnosed at autopsy) were identified and followed through the Rochester Olmsted County medical record-linkage system at the Mayo Clinic. The incidence rate was 1.3/100,000 person-years (PY), 1.9 in males and 0.6 in females. Incidence decreased from 2.7 in 1935-44 to 0.9 in 1965-81. Rates were higher in children 5-9 years old (2.4) and after age 60 (2.6 PY). An etiologic agent was identified in 29 cases (76%) with streptococci being the most frequently isolated. Case-fatality ratio was 38% (11/29), stable over time. Concurrent bacterial meningitis was the strongest predictor of death. Neurologic sequelae were observed in 8 (44%) of the 18 surviving patients including epilepsy (5 cases), deafness and motor impairment.     

Amyotrophic lateral sclerosis in Olmsted County,Minnesota, 1925 to 1998

The authors sought to determine trends in the incidence of ALS in Olmsted County from 1925 to 1998. Seventy-seven cases of ALS were identified during the period studied. The incidence rate remained stable at 1.7 cases per 100,000 people per year. Mean age at onset was 63 years. Mean survival was 23 months from diagnosis. Mean survival for patients <60 years old was 31 months; for patients aged >or=60 years, it was 20 months (p = 0.02). Mean time from symptom onset to diagnosis was 13 months. Neither survival nor time to diagnosis changed significantly over time.