Has there been a decline in subarachnoid hemorrhage mortality?

We studied subarachnoid hemorrhage in the population of Rochester, Minnesota, for the 40-year period from 1945 through 1984. The average annual incidence rate of subarachnoid hemorrhage in Rochester has remained constant at approximately 11 per 100,000 population. Age-specific incidence rates increased with age. However, the average annual mortality rate for subarachnoid hemorrhage in Rochester has shown a decreasing trend, from 6.8 per 100,000 population in 1955-1964 to 4.3 in 1975-1984. It is likely that this is due to a decrease in case-fatality rates from 57% in 1945-1974 to 42% in 1975-1984 (p = 0.10). This decreasing trend was also evident in annual mortality rates from subarachnoid hemorrhage for US white men and women. The reason for the improved case-fatality rate is unclear, but it may be related to changes in management. The interval from onset of subarachnoid hemorrhage to surgery decreased from a median of 12 days in 1975-1979 to 2 days in 1980-1984, and of those who survived to receive medical attention, more patients received some form of medical treatment in 1980-1984. Whether either or both of these changes have led to the decrease in the case-fatality rate is uncertain.     

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.     

Mortality after a First Episode of Status Epilepticus in the United States and Europe

Summary:  Objective: In the last decade several studies have been published on incidence, etiology, and prognosis of status epilepticus (SE) with population-based data from the United States and Europe. The aim of this review is to summarize the available information on the epidemiology of SE and to outline the sources of the variability in reported mortality after SE.
Methods: Comparison of mortality studies in SE from the United States and Europe.
Results: The incidence of SE is lower in Europe (9.9–15.8/10,000) than in the United States (18.3–41/100,000). The overall mortality after SE is similar in the two U.S. studies: the case fatality is 21% in Rochester, and 22% in Richmond. All European studies excluded SE after anoxic encephalopathy following cardiac arrest. This exclusion may partly explain the lower case fatality (around 10%) found in two of the European studies. The study from Bologna showed the highest case fatality (33%) even after exclusion of anoxic encephalopathy. The mortality in acute symptomatic SE was higher than for other forms of SE across all studies.
Conclusions: Short-term mortality after SE occurs mainly in the acute symptomatic group. Based on published data, it is not clear if differences in early management and medical treatment have any impact on prognosis or whether the differences can be attributed only to differences in distribution of the underlying causes in acute symptomatic SE. Future studies should address this issue.     

Incidence of Acute Symptomatic Seizures in Rochester, Minnesota, 1935-1984

Summary We determined the incidence of seizures due to acute CNS insults for residents of Rochester, Minnesota, U.S.A., from 1935 though 1984. The age-adjusted incidence rates for 1955–1984, the period of most complete case ascertainment, was 39.0/100,000 person-years (United States 1970 population as standard). The age-adjusted incidence was considerably higher in men: 52.0 as compared with 29.5 in women. The 3.6% risk of experiencing an acute symptomatic seizure in an 80-year lifespan approaches that of developing epilepsy. The major causes of acute symptomatic seizures were traumatic brain injury, cerebrovascular disease, drug withdrawal, and CNS infections. Each type of acute symptomatic seizure has age, gender, and time period patterns that reflect the occurrence of the underlying cause.     

Incidence, treatment, and case-fatality of non-traumatic subarachnoid haemorrhage in the Netherlands

Background

Non-traumatic subarachnoid haemorrhage (SAH) is a devastating disorder and in the majority of cases it is caused by rupture of an intracranial aneurysm. No actual data are available on the incidence of non-traumatic SAH and aneursymal SAH (aSAH) in the Netherlands and little is known about treatment patterns of aSAH. Our purpose was therefore to assess the incidence, treatment patterns, and case-fatality of non-traumatic (a)SAH within the Dutch general population.

Methods

Two population based data sources were used for this retrospective cohort study. One was the nationwide hospital discharge registry (National Medical Registration, LMR). Cases were patients hospitalized for SAH (ICD-9-code 430) in 2001-2005. The second source was the Integrated Primary Care Information (IPCI) database, a medical record database allowing for case validation. Cases were patients with validated non-traumatic (a)SAH in 1996-2006. Incidence, treatment, and case-fatality were assessed.

Results

The incidence rate (IR) of non-traumatic SAH was 7.12 per 100,000 PY (95%CI: 6.94-7.31) and increased with age. The IR of aSAH was 3.78 (95%CI: 2.98-4.72). Women had a twofold increased risk of non-traumatic SAH; this difference appeared after the fourth decade. Non-traumatic SAH fatality was 30% (95%CI: 29-31%). Of aSAH patients 64% (95%CI: 53-74%) were treated with a clipping procedure, and 26% (95%CI: 17-37%) with coiling.

Conclusion

Non-traumatic SAH is a rare disease with substantial case-fatality; rates in the Netherlands are similar to other countries. Case-fatality is also similar as well as age and sex patterns in incidence.     

50-year trends in the incidence of anorexia nervosa in Rochester, Minn.: a population-based study

OBJECTIVE: The aim of the study was to determine incidence and prevalence rates and long-term trends in incidence of anorexia nervosa by identifying all persons residing in the community of Rochester, Minn., during the 50-year period 1935 through 1984 who had the disorder. METHOD: From a community-based epidemiologic resource, 13,559 medical records with diagnoses of amenorrhea, starvation, weight loss, anorexia nervosa, or other conditions were screened to identify true cases of anorexia nervosa determined by using standard diagnostic criteria. RESULTS: One hundred eighty-one residents (166 female and 15 male) fulfilled the diagnostic criteria for anorexia nervosa; these were the incidence cases. Due to a quadratic trend in the rates for girls 10-19 years old, the incidence rate among female residents fell from 16.6 per 100,000 person-years in the 1935-1939 period to a low of 7.0 in 1950-1954 and increased to 26.3 in 1980-1984. The incidence rates for women 20 years old and older and for males remained constant. For females 15-24 years old, there was a linear increase. The overall age-adjusted incidence rate per 100,000 person-years was 14.6 for females and 1.8 for males. The prevalence rate per 100,000 population was 269.9 for females and 22.5 for males. CONCLUSIONS: Anorexia nervosa is more common than previously recognized. Among girls 15-19 years old it is a very common chronic illness. Its incidence has increased among females 15-24 years old but not among older women or among males.     

The impact of ageing on stroke subtypes, length of stay and mortality: study in the province of Teruel, Spain

BACKGROUND AND PURPOSE: During the last three decades, there have been important advances in the diagnosis and treatment of stroke leading to a decline in mortality rates in western countries. However, the longer life expectancy and the higher proportion of elderly people in the structure of the population may partially counteract this positive trend in stroke-related mortality. The purpose of this study was to analyse the impact of a high ageing index of the population on stroke-related variables such as stroke subtypes, length of hospital stay and mortality from stroke. METHODS: We analysed the data of 1850 consecutive patients with first-ever stroke retrieved from a prospective registry over a period of 8 years (1994-2001) in the province of Teruel, Spain, with two public hospitals in the catchment area. The mean age was 75.5 years (SD: 9.4) and the sex was male in 62% of cases. The variables included in the study were vascular risk factors, stroke subtypes, fatality rate, length of stay and mortality. Mortality was assessed from 1990 to 2000. RESULTS: Arterial hypertension and atrial fibrillation were the most frequent risk factors, with an observed high frequency of cardioembolic stroke. The mean 28-day case fatality rate was 16.6%, ranging from 11.9% in 1994 to 23.4% in 1999. We found complications in 38% of patients, especially in the elderly. Fatality occurred in 20.3% of elderly subjects (65 or over) in comparison to 7.25% for those younger (Relative risk: 2.8; 95% CI: 1.475.3). Crude mortality rates were higher than for the general population in Spain and ranged from 169 in 1991 to 139/100,000 in 2000 with higher rates for women. However, the age-adjusted mortality rate to the standard European population was 56.6/100,000 (95% CI: 4664) in 1999, which was similar to that found in Spain (61/100,000). CONCLUSIONS: The impact of ageing on case fatality and mortality by stroke was substantial. Whereas mortality by stroke stabilized after decreasing in our province and in Spain in the last decade, fatality rates have significantly increased in our province because of the high proportion of elderly people and to the high rate of post-stroke complications.     

Incidence and mortality of generalized convulsive status epilepticus in California

BACKGROUND: Few population-based studies of status epilepticus have been performed in the United States. OBJECTIVE: To determine the incidence, case fatality, and demographics of generalized convulsive status epilepticus (GCSE) in the state of California. METHODS: Using a state-wide hospital discharge database, the authors identified all hospitalizations from 1991 through 1998 with a discharge diagnosis of convulsive status epilepticus. They identified the first admission for each individual to estimate the incidence of GCSE. In-hospital case fatality rates were calculated, and multivariate analysis was performed to determine predictors of death during hospitalization. Secondary diagnoses were analyzed by retrieving all discharge diagnoses accompanying the diagnosis of GCSE. RESULTS: The incidence rate of GCSE was 6.2/100,000 population and fell by 42% between the years 1991 and 1998 from 8.5 to 4.9/100,000. The rate of GCSE was highest among children under the age of 5 (7.5/100,000) and among the elderly (22.3/100,000). Blacks also demonstrated a relatively high incidence of GCSE (13.4/100,000). The case fatality for incident admissions was 10.7%, with increasing age being the only significant predictor in multivariate analysis. Case fatality was highest in patients who also carried a diagnosis of anoxia, CNS infection, or stroke. CONCLUSIONS: The incidence of GCSE requiring hospitalization has fallen over the last decade and is lower than that reported in previous studies. The case fatality is also lower than that reported previously. Further studies are needed to determine the cause of this decline in incidence and mortality of GCSE.     

Secular Trends and Birth Cohort Effects in Unprovoked Seizures: Rochester, Minnesota 1935-1984

Summary: The incidence of idiopathic/lcryptogenic epilepsy and isolated unprovoked seizures has been relatively stable in the population of Rochester, Minnesota, for the 50-year period 1935 through 1984. In each decade, the age-specific rates exhibited a consistent U-shaped pattern of decreasing rates from infancy to age 40–49 and a progressive increase thereafter to a second peak at age 70 years. Males had a 15% higher incidence of cryptogenic unprovoked seizures than females. The most pronounced secular trend was a decrease in the incidence in children aged <10 years for the first 4 decades of the study; however, this trend was interrupted by a slight rebound in the decade 1975–1984. There has been a progressive decrease in the incidence of cryptogenic unprovoked seizures in individuals aged 350 from 1965 through 1984. This decrease paralleled the decrease in cerebrovascular disease in the community. The decrease in idiopathic unprovoked seizures may be related to a concurrent trend in "silent stroke." Plots and Poisson regression analysis did not show patterns in the incidence of idiopathic unprovoked seizures related to successive birth cohorts. However, significantly lower incidence rates were observed for the 1930–1934 birth cohort, about half that of all others, between the ages of 5 and 54 years.     

Trends in the incidence rates of stroke in Rochester, Minnesota, since 1935

The Mayo Clinic medical records system and records-linkage system have been used to study trends in the incidence of stroke in Rochester, Minnesota, for comparison with U.S. stroke mortality trends. This study extends the observations back through 1935. The average annual incidence rate for the period 1935 to 1944 was 188 and 179 per 100,000 population for men and women, respectively--not significantly different from 200 for men and 178 for women for the period 1945 to 1954. The blood pressure level in these patients did not affect probability of survival or recurrent stroke. The trend in the incidence rate of stroke for women showed no change for the 20 years from 1935 to 1954, after which there was a gradual decline. For men there was little change until 1969, after which there was a sharp decline. We suggest that the gradual decline in U.S. stroke mortality rates for this early period may include an artifact introduced by changing codes and changing fashions of diagnosis.     

Incidence of Status Epilepticus in Adults in Germany: A Prospective, Population-Based Study

PURPOSE: To determine the incidence and case-fatality rate of status epilepticus (SE) in adults in Hessen, Germany, we performed a prospective, population-based study from July 1997 through June 1999. METHODS: All adult patients residing within the zip-code area 35 (area-35) with SE were included. Area-35 had 743.285 adult inhabitants, including 123.353 adult inhabitants of the primary service area of the University Hospital Marburg (PS-area). Patients were reported by 16 hospitals in the area and were prospectively identified and carefully reviewed within 5 days by one of the authors. Based on the crude annual incidence of SE and a rate of underascertainment of 10% determined for the PS-area, the corrected, age-adjusted incidence of SE in area 35, more representative of the population of Germany, was calculated. RESULTS: The crude annual incidence in the PS-area was 15.8/100,000 [95% confidence interval (CI), 11.2-21.6]. The calculated, corrected, age-adjusted incidence of SE in area 35 was 17.1/100,000. It was higher for men compared with women (26.1 vs. 13.7) and for those aged 60 years and older (54.5 vs. 4.2/100,000, p < 0.0001). The etiology was mainly remote symptomatic due to cerebrovascular disease. Epilepsy was previously diagnosed in only 50% of the patients. The case-fatality rate was 9.3%. CONCLUSIONS: Based on our data, at least 14,000 patients would be affected by SE in Germany, associated with approximately 1,300 deaths annually. The incidence of SE in Germany is similar to that found in the white United States population. Furthermore, this study confirms the higher incidence of SE in male patients and in the elderly population. This may be due to a higher incidence of cerebrovascular disease in these subpopulations.     

Incidence, mortality, and case-fatality rate of stroke in northern Israel

We studied the incidence and mortality of stroke in northern Israel to determine possible reasons for the differences previously found in mortality from this condition between the sex and ethnic groups in Israel as a whole. We identified 1,149 cases of stroke during 1984. While the age-standardized incidence was higher in men, the case-fatality rate was twice as high in women. After controlling for ethnic origin, we found that incidence was higher only in men of Western origin, while the female rates were higher in women of Asian and North African extraction. The case-fatality rate was substantially higher in women in all ethnic groups. These differences, especially in relation to the case-fatality rate, have important implications for health services in relation to both possible preventive action and to management of the acute disease phase.     

Incidence of Epilepsy and Unprovoked Seizures in Rochester, Minnesota: 1935–1984

Summary: The incidence of epilepsy and of all unprovoked seizures was determined for residents of Rochester, Minnesota U.S.A. from 1935 through 1984. Ageadjusted incidence of epilepsy was 44 per 100,000 personyears. Incidence in males was significantly higher than in females and was high in the first year of life but highest in persons aged ≥75years. Sixty percent of new cases had epilepsy manifested by partial seizures, and two thirds had no clearly identified antecedent. Cerebrovascular disease was the most commonly identified antecedent, accounting for 11% of cases. Neurologic deficits from birth, mental retardation and/or cerebral palsy, observed in 8% of cases, was the next most frequently identified preexisting condition. The cumulative incidence of epilepsy through age 74 years was 3.1%. The age-adjusted incidence of all unprovoked seizures was 61 per 100,000 person-years. Age-and gender-specific incidence trends were similar to those of epilepsy, but a higher proportion of cases was of unknown etiology and was characterized by generalized onset seizures. The cumulative incidence of all unprovoked seizures was 4.1% through age 74 years. With time, the incidence of epilepsy and of unprovoked seizures decreased in children and increased in the elderly.     

The Third Stroke Registry in Tartu, Estonia, from 2001 to 2003

OBJECTIVES: The main goal of the Third Stroke Registry in Tartu was to determine the incidence and 28-day case-fatality of first-ever stroke in an Estonian population. SUBJECTS AND METHODS: Stroke registry was conducted from 1 December 2001 to 30 November 2003. RESULTS: The registry included 451 patients. The incidence rate of first-ever stroke age-standardized to the European population was 188/100,000. Among younger patients, the rates for men dominated. The incidence among men aged 0-44 years was 18/100,000, for women 9/100,000. In the age group 45-54 years, the corresponding rates were 143/100,000 and 98/100,000 respectively. The overall 28-day case-fatality rate was 26%. CONCLUSIONS: The total stroke incidence in Tartu is comparable with other European studies, but the rates for younger patients are higher. This may be associated with lower quality of life, less attention to public health, high prevalence and/or poor control of stroke risk factors. The 28-day case-fatality is somewhat higher than in other European centres.     

Declining mortality from stroke in Allegheny County, Pennsylvania. Trends in case fatality and severity of disease, 1971-1980

Mortality rates for stroke in 1971, 1974, 1977, and 1980 were obtained for residents of Allegheny County in western Pennsylvania. Hospital case fatality ratios were also obtained in the same 4 years for those discharged with the diagnosis of stroke (ICD 430-438 of the Eighth and Ninth Revisions of the International Classification of Disease) in two large hospitals (greater than 400 beds). Age-adjusted mortality rates per 100,000 population have declined significantly in this period for the whole county as well as for the four sex-race groups. Case fatality ratio in the two hospitals of the study has decreased from 19.6 to 11%. A change in the severity of the disease manifested by a reduction in the number of comatose patients has occurred, and this reduction in comatose patients was responsible for greater than 80% of the decline in case fatality ratio. Coma appears to be the best predictor of mortality among hospitalized stroke cases (r = 0.6, p less than 0.00001). The recent introduction of computed tomography for the diagnosis of stroke in the late 1970s was accompanied by a twofold increase in the survivorship of stroke patients. However, this increase in survivorship may reflect selection bias and is based on ecological association. Further studies are needed to examine the role of computed tomography in improving survival.     

The Epidemiology of Status Epilepticus in the United States

Objective

To summarize trends in status epilepticus (SE) in the United States by age, race, sex, admission source, disposition, incidence rates, and mortality.

Methods

Data from US National Hospital Discharge Survey were used from 1979 to 2010 to identify discharges with SE and common etiologies and complications of SE using International Classification of Diseases, 9th Revision, Clinical Modifications codes. Temporal trends in the incidence and in-hospital mortality of SE were examined with respect to age, sex, and race.

Results

We identified 760,117 discharges with SE over 32 years. The incidence of SE increased from 3.5 to 12.5/100,000 between 1979 and 2010, without a significant change in in-hospital mortality. Higher incidence, earlier age of onset, and higher mortality were observed among males. Age stratification revealed a “U-shaped” distribution with higher incidence at age <10 years (14.3/100,000) and age >50 years (approaching 28.4/100,000). In-hospital mortality, however, was the lowest (2.6 %) at age <10 years and approached 20.2 % with age ≥80 years. The incidence of SE was higher among blacks (13.7/100,000), compared to whites (6.9/100,000) and other races (7.4/100,000). Mortality, however, was lower among blacks (7.2 %) compared to whites and other races (9.8 and 9.2 %, respectively). Black men had the highest incidence (15.0/100,000), relatively younger age of onset (39.3 years) and the lowest mortality (5.6 %). A net temporal decline in the reported prevalence of epilepsy, central nervous system infections, and traumatic brain injury was noted among SE cohort.

Conclusions

The incidence of SE increased nearly fourfold with relatively unchanged mortality. Gender and racial disparities exist in the incidence of SE, and age is an important predictor of mortality.     

Long-term mortality after a first episode of status epilepticus

OBJECTIVE: To evaluate long-term mortality among people with status epilepticus (SE). METHODS: The authors performed a population-based retrospective cohort study to determine long-term mortality after SE. Between January 1, 1965, and December 31, 1984, all first episodes of SE receiving medical attention were ascertained through the Rochester Epidemiology Project Records-Linkage System. Cases surviving the first 30 days (n = 145) were followed until death or study termination (February 1996). RESULTS: At 10 years, cumulative mortality among 30-day survivors was 43%. The standardized mortality ratio (SMR) at 10 years was 2.8 (95% CI, 2.1-3.5). The mortality rate of those with idiopathic/cryptogenic SE was not increased (SMR = 1.1; 95% CI, 0.5-2.3). The following characteristics of SE increased long-term risk for mortality: SE > or = 24 hours in duration vs. SE < 2 hours (relative risk [RR] = 2.3; 95% CI, 1.1-5.1); acute symptomatic etiology vs idiopathic/cryptogenic etiology (RR = 2.2; 95% CI, 1.0-5.1) SE; myoclonic SE vs generalized convulsive SE (RR = 4.0; 95% CI, 1.3-13). CONCLUSION: Forty percent of subjects who survived the first 30 days after an incident episode of SE die within the next 10 years. The long-term mortality rate was threefold that of the general population over the same time period. The long-term mortality rate at 10 years was worse for those with myoclonic SE, for those who presented with SE lasting more than 24 hours, and for those with acute symptomatic SE. The long-term mortality rate was not altered in those with idiopathic/cryptogenic SE. We conclude that SE alone does not modify long-term mortality.     

Temporal trends in the incidence and case fatality of stroke in children and adolescents

A recent study reported that mortality from stroke in children and adolescents decreased by 58% from 1979 to 1998, although it wasn't clear if the case fatality or the incidence of stroke in this age group is decreasing. We report trends of stroke incidence and case fatality in children and adolescents within a large biracial population. The study involved collection of all strokes in the study population between January 1, 1988 and December 31, 1989, July 1, 1993 and June 30, 1994, and January 1, 1999 and December 31, 1999, at all of the regional hospitals serving the Greater Cincinnati/Northern Kentucky population (only the children's hospital in 1988). Study nurses reviewed the medical records of all inpatients with stroke-related discharge diagnoses and abstracted relevant data. A study physician reviewed each abstract to determine whether a stroke or transient ischemic attack had occurred. A total of 54 strokes occurred in children or adolescents younger than 20 years during the three study periods (30% African American, 70% Caucasian, and 56% female). The overall incidence rate of all strokes in children younger than 15 years was 6.4/100,000 in 1999, a nonsignificant increase when compared to 1988. The 30-day case-fatality rates were 18% in 1988-1989, 9% in 1993-1994, and 9% in 1999. We found that the incidence of strokes in children has been stable over the past 10 years. The previously reported nationwide decrease in overall stroke mortality in children might be due to decreasing case fatality after stroke and not decreasing stroke incidence. Based on our data, we conservatively estimated that approximately 3000 children less than 20 years old would have a stroke in the United States in 2004.     

Incidence and case fatality rates of first-ever stroke - comparison of data from two prospective population-based studies conducted in Warsaw

Background and purposeAccording to official statistics, the stroke mortality rate has remained high in Eastern European countries for a few decades. It has been shown that also in Poland stroke mortality failed to decline in the period 1984 to 1992. Since that time, stroke management in our country has changed, especially in the cities, where stroke units have been developed. The aim of the present study was to compare incidence and case fatality rates, estimated on the basis of two prospective population-based studies performed in Warsaw in 1991/1992 and 2005.Material and methodsIncidence rates and case fatality rates for the first-ever-in-a-lifetime stroke have been estimated on the basis of two population-based studies: the Warsaw Stroke Registry (population 182 649) conducted in 1991 and 1992, and the European Register of Stroke (population 120 186) – registration in 2005. In both studies data were standardized to the European population by the direct methods.ResultsContrary to the incidence rates, which did not change significantly between 1991/1992 and 2005, 30-day and 1-year case fatality rates decreased significantly from 43% to 14.9% and from 59.7% to 33.1%, respectively.ConclusionsComparison of data from two population-based prospective stroke registries showed that stroke case fatality and mortality significantly decreased. This may be associated with the better management of patients in the acute phase of stroke and implementation of secondary prevention strategies for stroke.     

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.