Citations

Background and Purpose —There is scant information available on the incidence of transient ischemic attack (TIA) in a defined population. This study defines incidence rates of first TIA and subtypes of TIA during 1985–1989 and compares the incidence to that obtained from a 1960–1972 cohort study. Methods —Medical records of all residents of Rochester with potential diagnosis of TIA during 1985–1989 were screened to determine whether the case met the criteria for TIA. All available data were used to determine the vascular distribution of the TIA. Average annual age- and sex-adjusted incidence rates were calculated for 1985–1989, and results were compared with incidence rates determined in a Rochester-based 1960–1972 cohort study. Results —Two hundred two cases of first TIA or amaurosis fugax occurred among Rochester residents during 1985–1989. The age- and sex-adjusted incidence rate for any TIA was 68/100 000 population. Incidence of amaurosis fugax was 13/100 000; anterior circulation (cerebral) TIA, 38/100 000; and vertebrobasilar distribution TIA, 14/100 000. Rates were similar to those determined from a 1960–1972 cohort study. Conclusions —The incidence rate of TIA is 41% that of stroke incidence. TIA incidence in Rochester, Minn, is higher than has been previously reported for other sites throughout the world. Although comparison with prior time periods is difficult because of ascertainment issues, it appears that there has been no significant change in TIA incidence since the decade of the 1960s or earlier. This suggests that the most common mechanism for TIA (atherosclerosis) has not changed in prevalence, nor have risk factors leading to this mechanism.

Background and Purpose —This study was conducted to determine the risk factors for ischemic stroke in a defined Russian population. Methods —Our data are based on a population-based case-control study of 237 patients with first-ever ischemic stroke and 237 age- and sex-matched controls. Logistic regression methods for matched pairs were used to estimate the relative risk for the variables studied. Results —In a multivariate analysis, hypertension, left ventricular hypertrophy on electrocardiography, ischemic heart disease, mitral valve disease, current cigarette smoking, and high body mass index were significant and independent risk factors for ischemic stroke in this Russian community. Conclusions —The significant risk factors for ischemic stroke in Novosibirsk are similar to those from other populations and cohorts. This study, the first of stroke risk factors in Russia, has implications for clinical practice and the planning of stroke prevention in the population.

Background and Purpose The present study was conducted to investigate the incidence of stroke and 30-day case-fatality rates for stroke in a defined Russian population. Methods This is a population-based study that was established in 1982. All residents of an administratively defined and typical district of Novosibirsk (approximately 150 000 subjects) who had an incident (first-ever) stroke from January 1, 1982, through December 31, 1992, were registered. Results During an 11-year study period, 3406 incident stroke patients were registered, for an overall crude average annual incidence rate of 202/100 000 population. The rates were higher with increasing age and were significantly higher for men than for women. The age- and sex-adjusted annual incidence rate of stroke declined from 271/100 000 in 1982 to 232/100 000 in 1992. Slowing of the decline in stroke incidence was observed after 1988, and stroke incidence increased slightly in 1992. No significant differences in 30-day stroke case-fatality rates were noted from 1982 through 1992, but a slight trend toward decreasing rates was observed after 1988. There was no major change in patient age at stroke onset. Conclusions Stroke incidence rates in Novosibirsk are among the highest in the world. We observed a decline in stroke incidence but little change in 30-day case-fatality rates in Novosibirsk from 1982 through 1992.

Background and Purpose The purpose of this study was to clarify whether mitral valve prolapse increases the subsequent risk of stroke. Methods A historical cohort study was conducted on 1079 residents of Olmsted County, Minnesota, who had an initial echocardiographic diagnosis of mitral valve prolapse between 1975 and 1989 without prior stroke or transient ischemic attack and who were followed up for first stroke occurrence. Results There was an overall twofold increase in the incidence of stroke among individuals with mitral valve prolapse relative to the reference population (standardized morbidity ratio, 2.1; 95% confidence interval, 1.3 to 3.2). Sex, duration of follow-up from the diagnosis of mitral valve prolapse, or calendar year of initial diagnosis did not modify the association. Within the cohort of patients who were at least 35 years old at diagnosis of mitral valve prolapse, a time-dependent proportional-hazards multivariate model and a person-years analysis revealed that age, ischemic heart disease, congestive heart failure, and diabetes mellitus were important determinants for stroke when person-years of observation after mitral valve replacement were excluded. Among seven persons with mitral valve replacement, three strokes occurred in 24 person-years of follow-up. For those with an auscultatory diagnosis of mitral valve prolapse only as the indication for echocardiography (44%), the risk of stroke relative to the population was 1.0 (95% confidence interval, 0.2 to 2.9); for those with another cardiac diagnosis, the standardized morbidity ratio was 2.5 (95% confidence interval, 1.5 to 4.0). Conclusions Individuals with uncomplicated mitral valve prolapse did not have an increased risk of stroke, although a small increase in the risk may not have been detected.

This is a study of cardiac diseases associated with the 1,382 cases of first cerebral infarction in residents of Rochester, Minn., during 1960-1984. This is a population-based study in Rochester, Minn., for which the medical record-linkage system was used to identify cardiac disease among patients with first cerebral infarction. There were 318 patients (23%) who had at least one major potential cardiac source of emboli. The proportion of patients with a cardiac source of emboli was significantly higher among patients older than age 75 years (29%) than among younger patients (17%). The 30-day stroke recurrence rate among patients with a cardiac source of emboli (2%) was not significantly different than that among those without a cardiac source of emboli (2%). Among patients with a cardiac source of emboli, there was no difference in the probability of stroke at 30 days and at 90 days for those treated or not treated with anticoagulants. During the first 30 days after cerebral infarction, the risk of death in patients with a cardiac source of emboli (23%) was 14 times that of recurrent stroke. The risk of death at 30 days in patients without a cardiac source of emboli was 8%. Significant independent predictors of death (Cox proportional-hazards analysis) were age, prior myocardial infarction, atrial fibrillation present at onset of stroke, congestive heart failure before the stroke, and an age x congestive heart failure interaction. The only significant independent predictors of recurrent stroke were cardiac valve disease and congestive heart failure.

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. 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. 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. 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.

This study is a prospective analysis of the predictive value of diffuse and localized carotid bruit. Patients with asymptomatic carotid bruits are compared with a population-based age- and sex-matched control group known not to have carotid bruit, in regard to subsequent transient ischemic attack, stroke, and death. Each person was followed until death or for 5 years. Among the 566 patients with asymptomatic carotid bruit, the annual stroke rate given survival was 1.5%/yr or 7.5% at 5 years by actuarial analysis. The annual stroke rate given survival for the 428 patients in the population-based cohort was 0.5%/yr or 2.4% at 5 years. Patients with localized carotid bruit were not significantly different from those with diffuse carotid bruits in regard to subsequent cerebral ischemic events (p = 0.11). These data indicate that patients with asymptomatic diffuse or localized carotid bruit are approximately three times more likely to have ischemic stroke than an age- and sex-matched population sample known not to have carotid bruit.

The effect of cigarette smoking on extracranial carotid atherosclerosis was studies by obtaining cigarette smoking histories and information on other potential risk factors from consecutive patients undergoing carotid arteriography. At least on extracranial carotid artery was visualized in 752 patients in whom the extent of carotid atherosclerosis was assessed. The total years of cigarette smoking was the most significant independent predictor of the presence of severe carotid atherosclerosis. Other independent predictors, in order of significance, were age, hypertension, diabetes mellitus, male sex, and current systolic blood pressure. By age 60 years, the risk of having severe carotid atherosclerosis for a person who had smoked for 40 years was approximately 3.5 times that for a never smoker. The major benefit of smoking cessation is in limiting the accumulation of smoking years.

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.

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.