Meta-analysis of relation between cigarette smoking and stroke

[Smoking and mortality from cerebrovascular disorders in Brazil: comparative study of capital cities of metropolitan regions, 1988]

AIM

The role of smoking as risk factor for stroke is controversial. An ecological design study was performed to test the association between stroke mortality and smoking in Brazil. Lung cancer mortality was used as a surrogate for smoking habit.

METHODS

The mortality rate for stroke (ICD-9:430-438) and lung cancer (ICD-9: 162) were determined in the following metropolitan areas: Belém, Recife, Salvador, Belo Horizonte, Rio de Janeiro, São Paulo, Curitiba and Porto Alegre for males and females between 30 years-old and 69 years-old. ANOVA test was used to compare both age-adjusted mortality rates.

RESULTS

A negative association by ANOVA was determined between age-adjusted rates and age-specific rates, except among males with 40-49 years-old.

CONCLUSION

These results may be on account of three causes: the different smoking role as a risk factor in the distinct stroke subtypes analyzed; the competitive risk between coronary heart disease and stroke; and the high prevalence of arterial hypertension in the Brazilian metropolitan areas.

Community-based stroke incidence trends from the 1970s through the 1980s in East Germany

BACKGROUND AND PURPOSE

Stroke mortality has declined in most industrialized countries, but incidence rates have increased in some populations while they remained stable or even decreased in others. This study reports stroke incidence trends in East Germany over the past decades.

METHODS

Prospective community-based stroke registers were run in East Germany over two different time periods: 1972 through 1973 in the Berlin-Lichtenberg district and 1985 through 1988 in 14 districts in the central and southern part of the country. Stroke cases were collected and validated in a uniform way using both the World Health Organization (WHO) recommendations for community stroke registers and the guidelines of the WHO MONICA protocol.

RESULTS

Annual age-adjusted incidence rates of first-ever strokes rose among men aged 25 to 64 years from 48.4 per 100,000 in 1972 through 1973 to 88.0 per 100,000 in 1985 through 1988 (P < .05); incidence rates remained unchanged among women in this age range (52.6 and 52.5 per 100,000, respectively). Age-specific incidence rates increased among men in all age groups up to 74 years. Rising stroke rates were also observed in women under 55 years and between the ages of 65 and 74 years, whereas in women aged 55 to 65 years incidence rates declined by more than a third (P < .05). During the period from 1985 through 1988, stroke rates did not change.

CONCLUSIONS

An increase in stroke incidence was detected that can be associated with a deteriorating risk factor profile in the East German population and, in particular, with hypertension in men.

Scoring system to identify men at high risk of stroke: a strategy for general practice

BACKGROUND

The major risk factors for stroke are well described and there is good evidence that the risks associated with hypertension and cigarette smoking are reversible by appropriate interventions. However, if disease prevention measures are to be efficient, it is important that a system which can identify individuals at high risk of stroke be available for use in general practice.

AIM

A study was therefore undertaken to design an effective and practical system for detecting men aged 40 to 59 years at high risk of stroke in primary care.

METHOD

Stroke incidence and risk factor data were examined in a cohort of 7735 men aged 40 to 59 years who had taken part in the British regional heart study. Analysis was performed using data from initial entry into the study and then from five and 11.5 years of follow up. Subjects were randomly selected from the age-sex register of one general practice in each of 24 different towns throughout the United Kingdom, representing the full range of cardiovascular mortality rates.

RESULTS

A simple scoring system derived from logistic regression using age, systolic blood pressure, current cigarette consumption, and evidence of anginal chest pain was able to detect more than 80% of all strokes occurring within five years in the top fifth of the score distribution. The inclusion of other risk factors for stroke did not increase the score's predictive ability. The combination of smoking and hypertension, while much less sensitive than the scoring system, was a better indicator of risk than any single risk factor, all of whose predictive values were poor.

CONCLUSION

Based on readily measured variables, this scoring system could be used in general practice to identify men at high risk of stroke who would benefit from further intervention. Effective identification of high risk individuals requires assessment of the combined effects of multiple risk factors.

Recent alcohol consumption, cigarette smoking, and cerebral infarction in young adults

BACKGROUND AND PURPOSE

The role of recent heavy drinking of alcohol as a risk factor for ischemic brain infarction is unclear. We investigated this problem in young adults, in whom even a thorough workup often fails to reveal any predisposing factor.

METHODS

This was a hospital-based case-control study comprising 75 consecutive subjects aged 16 to 40 years with first-ever ischemic brain infarction and 133 control subjects from the same hospital who were group-matched with the case patients for age, sex, day of the onset of symptoms, and acuteness of disease onset.

RESULTS

Multiple logistic regression analysis showed that alcohol intake exceeding 40 g of ethanol within the 24 hours preceding disease onset was a significant independent risk factor for brain infarction among both men (odds ratio [OR], 6.0; 95% confidence interval [CI], 1.8 to 20.3) and women (OR, 7.8; 95% CI, 1.0 to 60.8). Cigarette smoking was not found to be an independent risk factor in the model, whereas among men arterial hypertension was (OR, 6.2; 95% CI, 1.5 to 24.7).

CONCLUSIONS

We conclude that very recent alcohol drinking, particularly drinking for intoxication, may trigger the onset of brain infarction in young adults and that there might be a variety of mechanisms behind this effect.

Relation of smoking with carotid artery wall thickness and stenosis in older adults. The Cardiovascular Health Study. The Cardiovascular Health Study (CHS) Collaborative Research Group

BACKGROUND

Cigarette smoking has been associated with increased risk of atherosclerotic diseases in hospital-based studies and in studies of middle-aged populations but not in population-based studies of older adults with and without clinical cardiovascular disease.

METHODS AND RESULTS

We investigated the relation of smoking to carotid artery atherosclerotic disease, expressed as intimal-medial wall thickness and arterial lumen narrowing (stenosis) measured by ultrasound. Subjects were 5116 older adults participating in the baseline examination of the Cardiovascular Health Study, a community-based study of cardiovascular diseases in older age. With increased smoking there was significantly greater internal and common carotid wall thickening and internal carotid stenosis: current smokers > former smokers > never-smokers; for instance, the unadjusted percent stenosis was 24%, 20%, and 16%, respectively (P < .0001). A significant dose-response relation was seen with pack-years of smoking. These findings persisted after adjusting for other cardiovascular risk factors and were also confirmed when analyses were restricted to those without prevalent cardiovascular disease. The difference in internal carotid wall thickness between current smokers and nonsmokers was greater than the difference associated with 10 years of age among never-smoking participants (0.39 mm versus 0.31 mm). Among all participants, the prevalence of clinically significant (> or = 50%) internal carotid stenosis increased from 4.4% in never-smokers to 7.3% in former smokers to 9.5% in current smokers (P < .0001).

CONCLUSIONS

These findings extend previous reports of a positive relation between smoking and carotid artery disease to a population-based sample of older adults using several different indicators of atherosclerotic disease.

Oral contraception and stroke. Evidence from the Royal College of General Practitioners' Oral Contraception Study

BACKGROUND AND PURPOSE

A nested case-control analysis of data collected during the prospective Royal College of General Practitioners' Oral Contraception Study was performed to examine the relation between use of oral contraception and risk of stroke.

METHODS

The 253 women who had a first-ever stroke (International Classification of Diseases, eighth revision, codes 4300 to 4389) or amaurosis fugax (code 3791) between 1968 and 1990 (case subjects) were compared with 759 women who did not have this diagnosis (control subjects).

RESULTS

Smoking, social class, and history of hypertension were found to be important risk factors for stroke. Women who had ever used oral contraceptives had an increased risk of all stroke (odds ratio, 1.5; 95% confidence interval, 1.1 to 2.0, adjusted for smoking and social class) and of a fatal event (adjusted odds ratio, 2.3; 95% confidence interval, 1.2 to 4.4). A significant doubling of all stroke risk was observed among current users, an effect that was apparent in both smokers and nonsmokers. Former users had a small nonsignificant elevation in risk of all stroke but a stronger risk of a fatal event. The effects in former users appeared to be restricted to women who smoked.

CONCLUSIONS

Current users of oral contraceptives appeared to be at increased risk of stroke. There is some evidence that former users may also have a persisting effect, although further research is needed to confirm these observations.

The role of risk factors and trigger factors in cerebrovascular events after mitral valve replacement: implications for antithrombotic management

To determine the effect of risk factors and trigger factors on cerebrovascular events, 622 patients who survived mitral valve replacement between December 1979 and December 1992 were analyzed. Ninety-six patients suffered 139 nonhemorrhagic cerebrovascular events. Data were available on 138 events in 95 patients. There were 32 transient ischemic attacks (TIAs), 57 reversible ischemic neurological deficits (RINDs), and 49 strokes. Age, sex, atrial fibrillation, left atrial size, systemic hypertension, and abnormal body mass index did not discriminate between patients who suffered events and those who did not. In contrast, smoking status differed significantly between patients who suffered events and those who did not. Among current or recent ex-smokers, the risk of stroke or RIND was significantly higher than in non-smokers (p < < 0.001). The odds ratio of suffering any type of event in patients who smoked at any time postoperatively versus those who did not smoke was 2.9 (95% confidence interval: 1.8 to 4.6). Of 61 patients contacted directly, 30% recalled an infective episode immediately prior to their event. A diurnal and seasonal influence on events was also detected with peaks in the morning and in the winter months, respectively (both p < 0.001). It is concluded that there is persuasive evidence for the involvement of several nonprosthetic factors in the incidence of cerebrovascular events after mitral valve replacement. This has implications for patient management and for future analysis of prosthetic heart valve series.

Stroke incidence and case fatality in Australasia. A comparison of the Auckland and Perth population-based stroke registers

BACKGROUND AND PURPOSE

Population-based studies are crucial for identifying explanations for the decline in mortality from stroke and for generating strategies for public health policy. However, the present particular methodological difficulties, and comparability between them is generally poor. In this article we compare the incidence and case fatality of stroke as assessed by two independent well-designed incidence studies.

METHODS

Two registers of acute cerebrovascular events were compiled in the geographically defined metropolitan areas of Auckland, New Zealand (population 945,369), during 1991-1992 for 12 months and Perth, Australia (population 138,708), during 1989-1990 for 18 months. The protocols for each register included prospective ascertainment of cases using multiple overlapping sources and the application of standardized definitions and criteria for stroke and case fatality.

RESULTS

In Auckland, 1803 events occurred in 1761 residents, 73% of which were first-ever strokes. The corresponding figures for Perth were 536 events in 492 residents, 69% of which were first-ever strokes. Both studies identified a substantial proportion of nonfatal strokes managed solely outside the hospital system: 28% in Auckland and 22% in Perth of all patients registered. The age-standardized annual incidence of stroke (all events) was 27% higher among men in Perth compared with Auckland (odds ratio, 1.27; P = .016); women tended to have higher rates in Auckland, although these differences were not statistically significant. In both centers approximately a quarter of all patients died within the first month after a stroke. There were significant differences in the prevalence of hypertension among first-ever strokes.

CONCLUSIONS

These two studies emphasize the importance of identifying all patients with stroke, both hospitalized and nonhospitalized, in order to measure the incidence of stroke accurately. The incidence and case fatality of stroke were remarkably similar in Auckland and Perth in the early 1990s. However, there are differences in the sex-specific rates that correspond to differences in the pattern of risk factors.

Therapy of carotid arteriosclerosis

Carotid arteriosclerotic disease is the most readily treatable type of lesion leading to stroke. Its management involves lowering those risk factors over which the patient has control. Patients should regulate hypertension, quit smoking, seek medical attention for treatable cardiac abnormalities, and take steps to reduce increased blood lipids. For symptomatic carotid disease, regardless of whether surgery is offered, platelet inhibitors are obligatory. The recommended dose is 650 mg aspirin per day (or up to 1300 mg, if tolerated). For patients whose symptoms continue despite aspirin therapy or who are aspirin intolerant, ticlopidine is the only recommended platelet inhibitor. Cerebral arterial bypass surgery is not an effective treatment for carotid arteriosclerosis. Carotid endarterectomy helps patients with > or = 70% stenosis as determined by strict arteriographic measurements. We do not yet have sufficient data to determine whether endarterectomy would benefit patients with lower levels of carotid stenosis or asymptomatic patients with any degree of stenosis.

The prevention of cardiovascular disease. Emphasis on secondary prevention

Atherosclerosis is a progressive disease affecting all major arteries. Clinical evidence of atherosclerosis increases the risk of subsequent morbid and mortal events fivefold to sevenfold over the next 5 to 10 years. The same risk factors contribute to the initial development of CVD events as to their recurrence. Both coronary and noncoronary events, such as stroke or PAD, reflect the severity of the underlying atherosclerotic process and strongly predict future excess CVD morbidity and mortality. Short-term and long-term survival depends on modifying the risk factors that contribute to CVD events. Although absolute proof of benefit for secondary prevention does not exist for all risk factors, the data from primary prevention trials and the secondary prevention trials that have been done argue strongly for aggressive intervention. Benefit has been demonstrated for smoking cessation, cholesterol reduction, and blood pressure control. Selected patients may benefit from additional medical, procedural, or surgical interventions to prolong life, such as beta-blocking agents, aspirin, or carotid endarterectomy. Many secondary prevention measures are a cost-effective way to reduce the substantial morbidity and mortality due to CVD. Contrary to primary prevention, even modest treatment effects from secondary prevention efforts can benefit large numbers of patients. Finally, secondary prevention may be more successful because patients with clinical evidence of CVD may be more highly motivated than their healthy counterparts to make and maintain lifestyle changes.

Stroke prevention. An opportunity for efficient utilization of health care resources during the coming decade

BACKGROUND

Stroke is unique among neurological diseases, since it has a high prevalence and burden of illness, high economic cost, and is preventable. Epidemiological approaches to stroke prevention include the "high-risk" and "mass" approaches. In this review we discuss these preventive strategies, target host and discretionary risk factors that are amenable to these measures, and discuss potential cost savings.

SUMMARY OF REVIEW

Projected numbers of strokes prevented for specific stroke risk factors were estimated by using the population-attributable risk estimation for hypertension, cigarette smoking, atrial fibrillation, and heavy alcohol consumption. The projected numbers of strokes that could be prevented were substantial and highest for hypertension and cigarette smoking. Projected yearly cost of stroke associated with these two treatable factors was also substantial.

CONCLUSIONS

The prevention of stroke can be accomplished by the high-risk or mass approach or a combination of these approaches. The high-risk approach prevents strokes but is also expensive. The mass approach may be more cost-effective, which could lead to substantial savings, but this needs to be investigated.

The role of lifestyle factors in the etiology of stroke. A population-based case-control study in Perth, Western Australia

BACKGROUND AND PURPOSE

We sought to examine risk factors for all strokes and for ischemic stroke and primary intracerebral hemorrhage separately.

METHODS

This was a population-based case-control study. Each case subject meeting World Health Organization criteria for stroke (n = 536) from a population-based register of acute cerebrovascular events compiled in Perth, Western Australia, in 1989 to 1990 was matched for age and sex with up to five control subjects drawn from the same geographical area. Objective confirmation of the type of stroke was available from computed tomography, magnetic resonance imaging, or necropsy for 86% of the case subjects. Data on medical history and lifestyle factors were collected from case and control subjects by interview of the subject or a proxy informant.

RESULTS

Current smoking, consumption of meat more than four times weekly, and a history of hypertension or intermittent claudication were each associated with increased risk in multivariate models for all strokes and for all first-ever strokes. Consumption of 1 to 20 g/d alcohol in the preceding week was associated with a significant reduction in the risk of all strokes, all ischemic strokes, and of primary intracerebral hemorrhage, while eating fish more than two times per month appeared to protect against first-ever stroke and against primary intracerebral hemorrhage. Diabetes mellitus was associated with a significantly increased risk of ischemic stroke but a decreased risk of hemorrhagic stroke.

CONCLUSIONS

Risk factors for ischemic and hemorrhagic stroke are not exactly the same. Changes in lifestyle relating to tobacco and diet might make important contributions to further reductions in the incidence of stroke.

Lifestyle factors and risk of cerebrovascular disease in women. The Copenhagen City Heart Study

BACKGROUND AND PURPOSE

The purpose of the present analysis was to determine how lifestyle influences the risk of cerebrovascular disease in women participating in the Copenhagen City Heart Study.

METHODS

A random sample of a white, lower and middle-class, urban population selected in 1976 was invited to two cardiovascular examinations at 5-year intervals. The present analysis was based on 7060 women invited to an initial examination from 1976 through 1978, aged 35 years or more, and without previous stroke or transient ischemic attack. At the initial examination, potential risk factors were recorded. The 265 first cases of stroke and transient ischemic attack were ascertained at a second examination 5 years later and through hospital records and death certificates through 1988. The Cox regression model was used to estimate the influence of the factors recorded on the risk of cerebrovascular disease.

RESULTS

The relative risks of cigarette smoking and lack of physical activity were 1.4 and 1.45; 95% confidence limits, 1.02 to 1.94 and 1.01 to 2.08, respectively). The relative risk of daily consumption of tranquilizers was 1.25 (95% confidence limits, 0.96 to 1.62). No significant influence was found for number of cigarettes, body mass index, or alcohol intake. In postmenopausal women, there was a statistically significant interaction (P < .041) between smoking and hormone replacement therapy. Smokers receiving this therapy had a 28% lower risk of cerebrovascular disease than smokers not receiving it.

CONCLUSIONS

The statistically significant and equally potent effects on the risk of cerebrovascular disease were found for cigarette smoking and lack of physical activity. The risk associated with smoking seemed to be influenced by hormonal replacement therapy.

Risk factors of stroke incidence and mortality. A 12-year follow-up of the Oslo Study

BACKGROUND AND PURPOSE

The objective of this study was to determine the risk factors of stroke incidence and mortality.

METHODS

Our data are based on a prospective cohort study of men aged 40 to 49 years after 12 years of follow-up.

RESULTS

In age-adjusted Cox proportional-hazards regression analysis of 14,403 healthy men, diastolic blood pressure was a stronger predictor for stroke incidence and mortality than systolic blood pressure. Smoking was a stronger predictor of mortality than of incidence. However, there was no dose-response relation among smokers by increased cigarette consumption. Total serum cholesterol was a significant (P < .05) risk factor for stroke mortality and of borderline significance (P = .08) for stroke incidence. Increased physical activity at leisure was associated with reduced stroke incidence but not mortality. The myocardial infarction risk score comprising systolic blood pressure, total serum cholesterol, and daily cigarette smoking was a strong predictor of mortality and incidence. Body mass index, triglycerides, blood glucose, and physical activity at work were not found to be risk factors for stroke.

CONCLUSIONS

Reduction of blood pressure, cessation of smoking, lowered cholesterol, and increased physical activity at leisure are individual measures to reduce the risk of stroke.

Antiplatelet therapy in the treatment of cerebrovascular disease

Aspirin and the new agent ticlopidine have been the most thoroughly evaluated of the platelet-antiaggregating drugs used for the prevention of stroke and other vascular events. Numerous trials have shown aspirin to be effective in reducing the risk of myocardial infarction (MI), recurrent transient ischemic attacks, stroke, and vascular death in men at high risk for these events. Primary prevention trials have shown that aspirin reduces the risk of MI in healthy men over 50 years of age but does not reduce the risk of stroke. Two large, multicenter trials have shown that ticlopidine is effective in reducing the risk of fatal and nonfatal stroke in both men and women. Ticlopidine may also be effective in reducing the risk of recurrent stroke in patients who have had a completed thromboembolic stroke.

The role of stroke attack rate and case fatality in the decline of stroke mortality. The Minnesota Heart Survey

The Minnesota Heart Survey is a population-based study designed to monitor and explain trends in cardiovascular mortality, morbidity, and risk factors in the Minneapolis-St. Paul (Twin Cities) metropolitan area. Trends in stroke mortality were examined from 1960 to 1991; stroke morbidity trends were examined in 50% samples of patients discharged with an acute stroke diagnosis in 1970, 1980, and 1985. Stroke mortality in Twin Cities residents aged 30 to 74 years declined by more than 70% from 1960 to 1991 in both men and women. The decline occurred at a rate of 2.5% per year until 1972, accelerated between 1972 and 1984 (7.9% per year), and slowed considerably thereafter (1.8% per year). Hospitalized acute-stroke discharge rates among those aged 30 to 74 years declined substantially between 1970 and 1985 in both sexes (P < 0.01), but there was no change in definite stroke rates defined by standardized clinical criteria. Both short-term (28 days) and long-term (5 years) survival of definite-stroke patients improved significantly between 1970 and 1985. These improvements, however, were not found in the entire samples of unverified acute-stroke discharges. The proportion of hospitalized acute-stroke patients who had computed tomography performed increased from 0% in 1970 to 75% in 1985. There were also improvements in hospital records pertaining to the documentation of stroke symptoms and signs. These data indicate that the impressive declines in stroke mortality observed in the 1970s and early 1980s have slowed dramatically in the latter half of the 1980s. The decline in stroke mortality likely reflects both a decline in attack rate and improved survival after stroke.(ABSTRACT TRUNCATED AT 250 WORDS)

Trends in stroke risk factors in the United States

Favorable trends in risk factors have contributed to the decline in stroke mortality. Risk factors for stroke include older age, male sex, black race, low socioeconomic status, heart disease, hypertension, diabetes mellitus, certain medications, cigarette smoking, alcohol, and diet. Improvements in economic and living conditions may have contributed to the decline in stroke mortality. However, increasing longevity, growth in population size, and increased survival with coronary heart and other cardiovascular diseases are likely to increase the numbers of strokes in the future. Effective treatment of hypertension is credited with accelerating the decline in stroke death rates since the 1970s. Reductions in cigarette smoking since the 1960s and in alcohol consumption in the 1980s may have contributed to the more recent decline in stroke mortality, especially among men. Dietary changes possibly related to improvements in stroke rates include lower saturated fat and salt intake. Primary prevention through reductions in highly prevalent risk factors is an important strategy for continuing the decline in stroke mortality.

Natural history of unruptured intracranial aneurysms: a long-term follow-up study

To investigate the natural history of unruptured aneurysms and predictive risk factors determining subsequent rupture, the authors followed 142 patients with 181 unruptured aneurysms until death or subarachnoid hemorrhage intervened, or for at least 10 years after the unruptured aneurysm was diagnosed. Six patients had a symptomatic aneurysm, five had an incidentally discovered aneurysm, and 131 had multiple aneurysms, of which the ruptured lesion was clipped at the beginning of the follow-up study. The median follow-up time was 13.9 years (range 0.8 to 30.0 years). During 1944 patient-years of follow-up study there were 27 first episodes of hemorrhage from a previously unruptured aneurysm, giving an average annual rupture incidence of 1.4%. Fourteen of these bleeding episodes were fatal. The cumulative rate of bleeding was 10% at 10 years, 26% at 20 years, and 32% at 30 years after the diagnosis. The only predictor for the rupture was the size of the aneurysm (p = 0.036). However, in patients with multiple aneurysms (the main subgroup) the only variable that tended to predict rupture was the age of the patient: risk of rupture was inversely associated with age (p = 0.080). The median diameter of the aneurysms was 4 mm at the beginning of the follow-up period, both in those with and those without a later hemorrhage. During the angiographic monitoring period, a ruptured aneurysm significantly (p < 0.001) increased in size in 17 patients with hemorrhage but aneurysms did not increase significantly in 14 patients without hemorrhage. In addition, a new aneurysm was found in six of 31 patients. The authors conclude that an unruptured aneurysm should be operated on, irrespective of its size, if it is technically possible and the patient's age and concurrent diseases are not contraindications to surgery.

Benefits of stopping smoking

This article launches a special WESTERN JOURNAL OF MEDICINE effort to help prevent disease and disability. Erica Frank, MD, MPH, an Assistant Professor in the Department of Community and Preventive Medicine and Department of Medicine, Emory University School of Medicine, and Adjunct Professor at the Emory University School of Public Health, Atlanta, Georgia, will head the endeavor. The goals are to present scientific foundations for prevention and to provide practical ways to improve patients' lives. This first article addresses smoking cessation. We may think that we know it all, but we may not, and patients do not: about 25% of Americans smoke, and more than half of persons who ever smoked began their fatal habit before they were 18 years old. Side-stream smoke affects adults and children adversely, too, causing inflammation, infection, and cancer. Smokers need to stop smoking, and young people need to not start. Dr Frank's review is accompanied by a page for patients. It debunks myths and is designed to be duplicated so patients can leave their physician's office with a new lease on life in hand. Look for future prevention-oriented articles in this series that feature science and patient education.

Heart disease in patients with stroke: incidence, impact, and implications for rehabilitation. Part 1: Classification and prevalence

Heart disease is found in about 75% of patients who have suffered a stroke. Cardiovascular diseases can be risk factors, etiologic mechanisms, associated conditions, or direct consequences of stroke. Cardiac comorbidity may delay initiation of rehabilitation, complicate the course and care of the patient with stroke, inhibit participation in a therapeutic exercise program, limit functional outcomes, and contribute to early mortality in the individual with cerebrovascular disease. Part 1 of this two-part article describes the various forms of heart disease that may be seen in stroke patients, and reviews the incidence figures for each type of associated cardiac condition.

Pattern of cerebral atherosclerosis in Hong Kong Chinese. Severity in intracranial and extracranial vessels

BACKGROUND AND PURPOSE

The clinical pattern of stroke and the angiographic distribution of cerebral atherosclerosis in Chinese are different from those in Caucasians. Pathological data from autopsy studies are lacking.

METHODS

The intracranial and extracranial arteries supplying the brains of 114 consecutive Chinese patients undergoing autopsy in a regional general hospital were examined by computer-assisted morphometric analysis under a microscope as well as by macroscopic grading for atherosclerotic narrowing. The severity was correlated with various atherosclerosis-related factors.

RESULTS

Atherosclerosis of the intracranial cerebral vessels was more severe than that of the extracranial vessels. The distal branches of the intracranial vessels were also commonly involved. Hypertension and diabetes mellitus were identified as factors associated only with intracranial atherosclerosis (p < 0.001), whereas ischemic heart disease was associated with atherosclerosis in both the intracranial (p < 0.001) and extracranial (p = 0.012) vessels. Smoking was associated with narrowing of the extracranial vessels only (p = 0.0054).

CONCLUSIONS

Compared with figures from Caucasian and Japanese populations, the extent of intracranial atherosclerosis is much more severe in Hong Kong Chinese, whereas atherosclerotic narrowing of the extracranial carotid artery is less severe in Hong Kong Chinese than in Caucasians.

Cigarette smoking and alcohol consumption as risk factors for aneurysmal subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Aneurysmal subarachnoid hemorrhage is a serious disease despite recent improvements in medical and surgical treatment. Hence, identification of modifiable risk factors for subarachnoid hemorrhage is important.

METHODS

We compared the smoking and drinking habits of 278 consecutive patients with aneurysmal subarachnoid hemorrhage, aged 15-60 years (145 men and 133 women) with those of 314 hospitalized control patients (164 men and 150 women) who did not differ in regard to age, day of onset of symptoms, and acuteness of disease onset.

RESULTS

Multiple logistic regression analysis showed that recent alcohol intake and smoking, but not hypertension, were significant independent risk factors for hemorrhage. After adjustment for age, hypertension, and smoking status, men who had consumed 1-40, 41-120, or > 120 g of alcohol within the 24 hours preceding the onset of illness had a relative risk of hemorrhage of 0.3 (95% confidence interval [CI], 0.1-0.8), 2.5 (95% CI, 1.1-5.5), and 4.5 (95% CI, 1.5-12.9), respectively, compared with men who had consumed 0 g. Women who had consumed 1-40 or > 40 g of alcohol had a risk of hemorrhage of 0.4 (95% CI, 0.2-0.8) and 6.4 (95% CI, 2.3-17.9), respectively, compared with women without use of alcohol. Heavily smoking (> 20 cigarettes per day) men and currently smoking women had adjusted relative risks of hemorrhage of 7.3 (95% CI, 3.8-14.3) and 2.1 (95% CI, 1.2-3.6), respectively, compared with men who had never smoked and with women who were not current smokers. Higher levels of erythrocyte mean corpuscular volume in patients with subarachnoid hemorrhage than in control subjects supported the notion of different smoking and drinking habits.

CONCLUSIONS

Recent heavy alcohol intake and current smoking seem to be independent risk factors for aneurysmal subarachnoid hemorrhage.

Cigarette smoking and risk of primary intracerebral haemorrhage. A population-based case-control study

From September 1985 to December 1989 a total of 158 patients had primary intracerebral haemorrhage in the population of 116,000 in the Jyväskylä Region, Central Finland. All had the diagnosis confirmed by either computerised tomography or necropsy, and information on cigarette smoking habits was available in 155 patients, 20% of whom were current cigarette smokers. One control was selected for each of the 155 patients matched on sex, age, and residence from the census of Central Finland. The odds ratio of primary intracerebral haemorrhage of current cigarette smokers compared with current non-smokers was estimated on basis of the number of discordant pairs as 1.4 (95% confidence interval 0.7 to 2.8). Adjustment for hypertension or diabetes did not change this estimate. Our data did not show evidence of an positive association of cigarette smoking and risk of primary intracerebral haemorrhage. This assumption was strengthened when the results of previous studies and the present study were pooled giving an odds ratio of 1.0 (95% confidence interval 0.8 to 1.3).

Prevalence and risk factors of asymptomatic extracranial carotid artery atherosclerosis. A population-based study

To evaluate the prevalence and risk factors of asymptomatic carotid artery disease, we analyzed a sample of 909 men and women (aged 40-79 years) drawn from the community-based Bruneck Ischemic Heart Disease and Stroke Prevention Study. For the four decades of age (40-49, 50-59, 60-69, and 70-79 years), respective prevalence rates as assessed by duplex scanning were found to be 8.2%, 39.7%, 66.4%, and 82.5% in men and 3.3%, 22.3%, 48.7%, and 76.7% in women. High-grade stenosis (> 80%) classified by Doppler criteria was twice as frequent in men (2.4%) as in women (1.1%). Age and sex were found to be particularly strong and independent predictors of asymptomatic carotid artery disease. Accordingly, separate logistic regression models were developed for both men and women in the elderly (65-79 years) and middle-aged (50-64 years) groups. Systolic blood pressure turned out to be the only attribute with independent significance in all subgroups examined. Cigarette smoking, recorded as pack-years, emerged as the leading risk factor of carotid atherosclerosis in men. Serum fibrinogen levels were found to be highly indicative of carotid artery disease in elderly men and women. For apolipoprotein B predictive significance was observed in the middle-aged populations, whereas apolipoprotein A-I had a protective effect in elderly women. Diabetes mellitus completed the risk factor profile for elderly men. In summary, the relation between cardiovascular risk factors and asymptomatic carotid artery disease showed a dynamic dependence on sex and age. These findings may help to improve the efficacy of risk prediction in the general population and facilitate well-directed preventive measures.

Cost-effective intervention in stroke

A rigorous assessment of current practice in all branches of medicine is necessary to ensure that we are minimising the costs and maximising the effectiveness of management and treatment. This is especially important in cerebrovascular disease which imposes a large burden of death; it is the third commonest cause of death after cancer and heart disease in most developed countries, and the commonest cause of long term disability on society. Stroke consumes up to 5% of healthcare expenditure in developed countries, and costs can be expected to remain static or increase with an increase in the proportion of elderly (who are at high risk of stroke) in the community over coming decades. This article reviews the epidemiology of stroke (risk factors, incidence, prevalence and the burden of disability and handicap), the various studies dealing with the community and individual costs of stroke, and the cost-effectiveness of interventions to prevent stroke such as control of hypertension, reduction in cigarette intake, encouragement of a healthy lifestyle, antiplatelet or anticoagulant therapy, and carotid endarterectomy. Acute treatment of stroke remains an area of major potential therapeutic benefit, but no widely applicable therapy currently exists, although many treatments are being investigated. Rehabilitation after stroke is costly, but may result in significant reduction in disability and handicap with reduced need for long term institutional care. The clinical implications of these studies and the potential for future research are also discussed.

Cigarette smoking, alcohol use, and subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Subarachnoid hemorrhage remains a devastating disease. Identification of etiologic risk factors would allow the possibility of prevention.

METHODS

We conducted a population-based case-control study in King County, Washington. Patients whose bleeds originated from a source other than an aneurysm were excluded. Two age- and gender-matched control subjects were identified for each case through random digit telephone dialing. A standardized in-person interview was conducted with the patient whenever possible, a proxy respondent for the case in all instances, the two control subjects, and their proxies. Analyses involved conditional logistic regression taking into account matching on age, gender and respondent type.

RESULTS

Over 2 years, 169 cases were identified, and 149 participated in the case-control study. Compared with those who never smoked, the odds ratio for current heavy smokers (greater than 20 cigarettes/day) was 11.1 (95% confidence interval [CI], 5.0-24.9); for current light smokers (less than or equal to 20 cigarettes/day), 4.1 (95% CI, 2.3-7.3); and for former smokers, 1.8 (95% CI, 1.0-3.2). The risk associated with smoking was greatest in the 3 hours after a cigarette (odds ratio [OR] = 7.0; 95% CI, 3.7-13.1) and then fell, not reaching the risk in those who had never smoked until more than 10 years had passed since the last cigarette. Heavy alcohol use (greater than 2 drinks/day) was also associated with bleeds (OR = 2.2; 95% CI, 0.9-5.1, after adjusting for smoking status). These associations were not substantially altered after adjusting for several possible confounding factors, including a history of hypertension.

CONCLUSIONS

Cigarette smoking and heavy alcohol use are associated with the occurrence of subarachnoid hemorrhage.

Prevention of ischemic stroke: the role of carotid endarterectomy in symptomatic patients

Carotid endarterectomy (CE) has recently been proved to be beneficial in symptomatic patients with severe (70-99%) appropriate carotid stenosis. After discussing the historical evolution of CE as a possible preventive treatment of ischemic stroke, we review the results of North American and European trials in order to give practical information for the management of cerebrovascular patients.

Transient ischaemic attacks: which patients are at high (and low) risk of serious vascular events?

The aims of this study were to determine the important prognostic factors at presentation which identify patients with transient ischaemic attacks (TIA) who are at high risk (and low risk) of serious vascular events and to derive a prediction model (equation) for each of the major vascular outcome events. A cohort of 469 TIA patients referred to a University hospital, without prior stroke, were evaluated prospectively and followed up over a mean period of 4.1 years (range 1-10 years). The major outcome events of interest were 1) stroke 2) coronary event and 3) stroke, myocardial infarction or vascular death (whichever occurred first). Prognostic factors and their hazard ratios were identified by means of the Cox proportional hazards multiple regression analysis. The significant adverse prognostic factors (in order of strength of association) for stroke were an increasing number of TIAs in the three months before presentation, increasing age, peripheral vascular disease, left ventricular hypertrophy and TIAs of the brain (compared with the eye); the prognostic factors for coronary event were increasing age, ischaemic heart disease, male sex, and a combination of carotid and vertebrobasilar TIAs at presentation; and for stroke, myocardial infarction or vascular death they were increasing age, peripheral vascular disease, increasing number of TIAs in the three months before presentation, male sex, a combination of carotid and vertebrobasilar TIAs at presentation, TIAs of the brain (compared with the eye), left ventricular hypertrophy and the eye), left ventricular hypertrophy and the eye), left ventricular hypertrophy and the presence of residual neurological signs after the TIA. Prediction models (equations) of both the relative risk and absolute risk of each of the major outcome events were produced, based on the presence or level of the significant prognostic factors and their hazard. Before it can be concluded that our equations accurately predict prognosis and can be generalised to other populations, their predictive power needs to be validated in other, independent samples of TIA patients (which we are currently doing).

Lifestyle factors and risk of cerebral infarction

BACKGROUND AND PURPOSE

We evaluated the impact of lifestyle factors on the risk of ischemic stroke.

METHODS

We used a nested case-control design. The cases comprised 163 persons (median age 69 years) admitted to a stroke unit and diagnosed with acute cerebral infarction. All cases had earlier participated in the North Trøndelag Health Survey. The controls comprised 567 participants from the North Trøndelag Health Survey, matched by sex and year of birth.

RESULTS

Raised systolic (p less than 0.001) and diastolic (p = 0.02) blood pressure, antihypertensive treatment (p less than 0.001), previous myocardial infarction (p less than 0.001), prior stroke (p = 0.002), diabetes (p less than 0.001), and former daily smoking (p = 0.02) were identified as significant risk factors by univariate conditional logistic regression. No difference in risk was detected at different levels of alcohol consumption, salt intake, physical activity, or body mass index. Current smokers had virtually the same risk as nonsmokers. No association was found between stroke and the number of cigarettes smoked per day or the number of years of smoking. Multivariate conditional logistic regression identified diabetes (p = 0.002), raised systolic blood pressure (p less than 0.001), and former daily smoking (p = 0.01) as significant and independent risk factors. Previous myocardial infarction (p = 0.07), previous stroke (p = 0.1), and current daily smoking (p = 0.1) were of marginal significance.

CONCLUSIONS

The established medical risk factors for stroke are confirmed. With the possible exception of smoking, we have not identified any lifestyle factor with a significant impact on the risk of ischemic stroke.

The risk of subarachnoid and intracerebral hemorrhages in blacks as compared with whites

BACKGROUND

Stroke is an important cause of death among blacks, and intracerebral and subarachnoid hemorrhages account for nearly half of all early deaths from stroke. The present study investigates whether blacks and whites differ in their risk of having either intracerebral or subarachnoid hemorrhage.

METHODS

We reviewed the medical records, autopsy reports, and CT scans of all patients suspected of having had an intracerebral or subarachnoid hemorrhage during 1988 among the nearly 1.3 million people in the Greater Cincinnati metropolitan area.

RESULTS

There were 221 cases of first spontaneous intracranial hemorrhage among 1,086,462 whites (159 intracerebral and 62 subarachnoid hemorrhages), and 45 cases among 171,718 blacks (27 intracerebral and 18 subarachnoid hemorrhages). Blacks had 2.1 times the risk of subarachnoid hemorrhage of whites (95 percent confidence interval, 1.3 to 3.6) and 1.4 times the risk of intracerebral hemorrhage (95 percent confidence interval, 0.9 to 2.1). In those under the age of 75, the risk of intracerebral hemorrhage among blacks was 2.3 times that of whites (95 percent confidence interval, 1.5 to 3.6), whereas the risk among blacks 75 or older was one fourth that of whites (95 percent confidence interval, 0.1 to 0.8). Deaths within 30 days of intracerebral or subarachnoid hemorrhage accounted for 1.9 years of life lost per 1000 blacks under 65 years of age, as compared with 0.5 year per 1000 whites.

CONCLUSIONS

Young and middle-aged blacks have a substantially higher risk of subarachnoid or intracerebral hemorrhage than whites of similar age. These types of stroke are important causes of excess mortality among young and middle-aged blacks.

The health benefits of smoking cessation

Extensive evidence has now accumulated on the health benefits of smoking cessation. With few exceptions, disease risks are reduced following smoking cessation and continue to drop as abstinence is maintained. The review of the evidence in the 1990 Report of the Surgeon General led to major conclusions that establish smoking cessation as a clear priority for health care providers.

Meta-analysis of observational epidemiological studies: a review

Meta-analyses (integration of findings by quantitative analyses of results of individual studies) are already widely used in the psychological and educational sciences and in the pooling of clinical trial results. Examples of the application of such techniques to the results of observational epidemiological studies are now proliferating. In this paper meta-analysis of the results of observational epidemiological studies is reviewed. Uncritical adoption of techniques used in pooled analyses of clinical trial results may be inappropriate. Some alternative approaches, including meta-regression techniques, are discussed, and illustrated with reference to examples of meta-analyses of studies of breast cancer risk following oral contraceptive use and of patterns of post-bereavement mortality. Although substantial difficulties beset the use of meta-analysis in epidemiology, many of these problems are also implicit in the execution of traditional, narrative reviews. Foremost among these difficulties are those associated with publication bias and with making due allowance for the quality of the studies being combined. Unlike traditional narrative reviews, meta-analyses require explicit statement of the criteria for the review and hence highlight these difficulties. Nonetheless, careful and critical application of appropriate meta-analytical techniques facilitates quantitative exploration of inhomogeneities in, and (where appropriate) synthesis of study results.

Cost-effective investigation of patients with suspected transient ischaemic attacks

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Acute stroke outcome: effects of stroke type and risk factors

We studied 925 consecutive patients hospitalised with acute stroke to determine how stroke type, age, gender and risk factors influence acute, in-hospital outcome. Stroke types included carotid territory cortical or large subcortical infarction (52%), vertebrobasilar infarction (12%), lacunar infarction (11%), intracerebral haemorrhage (16%), and subarachnoid haemorrhage (9%). Mean age (mean +/- 1 SD) was 66 +/- 15 years, but patients with cerebral infarction were older than those with cerebral haemorrhage. The prevalence of hypertension, diabetes mellitus and cardiac disease increased with age across all stroke types, while the prevalence of smoking decreased with age. Mortality was 19% overall, but varied significantly between stroke types, highest in intracerebral haemorrhage (34%), and lowest in lacunar infarction (1%). Age had a marked adverse effect on mortality, independent of stroke type, the probability of death increasing by 3 +/- 0.5% per year from 20-92 years, whereas gender had no effect. Cardiac disease and diabetes were independent adverse prognostic factors (Odds Ratios 1.6 and 1.5 respectively). Cerebral haemorrhage, age, cardiac disease and diabetes all independently worsen acute stroke outcome.