Change in stroke incidence, mortality, case-fatality, severity, and risk factors in Oxfordshire, UK from 1981 to 2004 (Oxford Vascular Study)

A prospective community-based study of stroke in Kolkata, India

BACKGROUND AND PURPOSE

Information on essential stroke parameters are lacking in India. This population-based study on stroke disorder was undertaken in the city of Kolkata, India, to determine the subtypes, prevalence, incidence, and case fatality rates of stroke.

METHODS

This was a longitudinal descriptive study comprising 2-stage door-to-door survey of a stratified randomly selected sample of the city population, conducted twice per year for 2 successive years from March 2003 to February 2005.

RESULTS

Out of the screened population of 52,377 (27 626 men, 24 751 women), the age standardized prevalence rate of stroke to world standard population is 545.10 (95% CI, 479.86 to 617.05) per 100,000 persons. The age standardized average annual incidence rate to world standard population of first-ever-in-a-lifetime stroke is 145.30 (95% CI, 120.39 to 174.74) per 100,000 persons per year. Thirty-day case fatality rate is 41.08% (95% CI, 30.66 to 53.80). Women have higher incidence and case fatality rates. Despite divergence on socioeconomic status between the slum and nonslum dwellers, stroke parameters were not significantly different.

CONCLUSIONS

The age standardized prevalence and incidence rates of stroke in this study are similar to or higher than many Western nations. The overall case fatality rate is among the highest category of stroke fatality in the world. The women have higher incidence and case fatality rates compared with men.

Lipid-Altering Therapies and the Progression of Atherosclerotic Disease

Lipids play a key role in the progression of atherosclerosis, and lipid-lowering therapies have been studied for 30 years in coronary disease. Measurement of the progression of atherosclerosis through carotid intima-media thickness, coronary mean lumen diameter, and, mostly recently, intravascular ultrasound is generally accepted. This article reviews the role of lipid-lowering therapies in changing the rate of atherosclerosis progression in the coronary and carotid circulations. Statins are the primary therapy used to reduce atherosclerosis and cardiovascular events, including strokes and transient ischemic attacks, and have benefits in reducing events in patients undergoing carotid endarterectomy. In contrast, data for other agents, including fibrates and nicotinic acid, in reducing the progression of atherosclerosis are less extensive and not as well known. There is increasing interest in optimizing the whole lipid profile, as this might deliver extra benefits over and above statin therapy alone. Initial proof of this concept has recently come from studies that measured the progression of atherosclerosis and showed that adding nicotinic acid to statin therapy and, more directly, infusion of high-density lipoprotein-like particles reduced progression and indeed might induce regression of the disease. It is likely that the management of significant carotid stenosis will become ever more drug focused and will be customized to the lipid profile of each patient with intervention reserved only for late-stage symptomatic disease.

Épidémiologie des accidents vasculaires cérébraux

The development of several population stroke registries has improved our knowledge of the epidemiology of strokes, their natural history, and their trends over time and place. In Europe, stroke incidence decreases from east to west and from north to south. Incidence and mortality have also been decreasing regularly over time. The diagnostic tools created with the arrival of computed tomography (CT), magnetic resonance imaging (MRI), and other forms of vascular and cardiac imaging have improved the identification of risk factors for stroke according to its mechanism--hemorrhagic or ischemic--and according to the subtype of ischemic stroke. Hypertension is the leading risk factor for both ischemic and hemorrhagic strokes. New independent stroke risk factors have been confirmed, including elevated cholesterol and homocysteine levels. The regular decline of the incidence of some types of stroke and of mortality is partly due to the positive effects of prevention and confirms the usefulness of screening and early treatment of stroke risk factors. Development of new treatments during the acute phase and in the field of primary and secondary stroke prevention (such as statins) is necessary to improve prognosis, which remains too serious, especially in women.

Trend in mortality after stroke with atrial fibrillation

PURPOSE

To evaluate trend in mortality in stroke associated with atrial fibrillation, we examined mortality trend after stroke with atrial fibrillation by calendar year period (1980-1984, 1985-1989, 1990-1994, 1995-1999, and 2000-2002). We estimated trends separately for each sex in unadjusted analyses. We also adjusted for age, comorbid conditions, and general trend in mortality in the background population.

METHODS

We identified all individuals, aged 40-89 years, with an incident diagnosis of stroke of any nature (ischemic or hemorrhagic) and no history of heart valve disease and a previous or concomitant diagnosis of atrial fibrillation or flutter in the Danish National Registry of Patients. Subjects were followed in the Danish Civil Registration System for emigration and vital status. We used multivariate Cox proportional hazards regression analysis to estimate trend in mortality.

RESULTS

Incident stroke with a previous or concomitant diagnosis of nonvalvular atrial fibrillation or flutter was diagnosed in 24,470 subjects (11,554 men and 12,916 women). During 34,405 years of observation, 9237 men died, and during 35,381 years of observation, 10,827 women died. The hazard ratio for mortality after stroke in the last 3-year period compared with the first 5-year period was .65 (95% confidence interval [CI], .61-.71) in men and .69 (95% CI, .64-.74) in women.

CONCLUSIONS

We observed a substantially better survival in men and women after stroke associated with atrial fibrillation or flutter in Denmark during the years 1980 to 2002. However, we could not control for changes in admission practice, diagnostic performance, or treatment.

Risk of stroke in people with type 2 diabetes in the UK: a study using the General Practice Research Database

AIMS/HYPOTHESIS

Risk estimates for stroke in patients with diabetes vary. We sought to obtain reliable risk estimates for stroke and the association with diabetes, comorbidity and lifestyle in a large cohort of type 2 diabetic patients in the UK.

MATERIALS AND METHODS

Using the General Practice Research Database, we identified all patients who had type 2 diabetes and were aged 35 to 89 years on 1 January 1992. We also identified five comparison subjects without diabetes and of the same age and sex. Hazard ratios (HRs) for stroke between January 1992 and October 1999 were calculated, and the association with age, sex, body mass index, smoking, hypertension, atrial fibrillation and duration of diabetes was investigated.

RESULTS

The absolute rate of stroke was 11.91 per 1,000 person-years (95% CI 11.41-12.43) in people with diabetes (n = 41,799) and 5.55 per 1,000 person-years (95% CI 5.40-5.70) in the comparison group (n = 202,733). The age-adjusted HR for stroke in type 2 diabetic compared with non-diabetic subjects was 2.19 (95% CI 2.09-2.32) overall, 2.08 (95% CI 1.94-2.24) in men and 2.32 (95% CI 2.16-2.49) in women. The increase in risk attributable to diabetes was highest among young women (HR 8.18; 95% CI 4.31-15.51) and decreased with age. No investigated comorbidity or lifestyle characteristic emerged as a major contributor to risk of stroke.

CONCLUSIONS/INTERPRETATION

This study provides risk estimates for stroke for an unselected population from UK general practice. Patients with type 2 diabetes were at an increased risk of stroke, which decreased with age and was higher in women. Additional risk factors for stroke in type 2 diabetic patients included duration of diabetes, smoking, obesity, atrial fibrillation and hypertension.

Impact of Carotid Endarterectomy on Medical Secondary Prevention After a Stroke or a Transient Ischemic Attack

Background and Purpose— Whether a history of carotid endarterectomy influences patient compliance with medical treatments and physician attitude toward treatments after ischemic stroke or transient ischemic attack (TIA) is not well known.

Methods— We studied the baseline data of 18 467 ischemic stroke and TIA patients from the international REduction of Atherothrombosis for Continued Health (REACH) Registry and investigated the impact of a history of endarterectomy on the secondary medical prevention measured by the use of antiplatelet agents and statins, and by the control of cholesterol level, glucose level, and blood pressure.

Results— Among the patients with a history of ischemic stroke or TIA, those with a history of endarterectomy (n=1474) were more likely to receive antiplatelet agents and statins, to have a blood pressure <140/90 mm Hg, and a fasting total cholesterol <200 mg/dL. In diabetic patients, endarterectomy was associated with lower fasting blood glucose levels. In multivariate logistic regression analyses, endarterectomy was significantly associated with the use of antiplatelet agents (odds ratio [OR], 1.6; 95% CI, 1.3 to 1.9; P <0.0001) and statins (OR, 1.8; 1.6 to 2.0; P <0.0001), and with a cholesterol level <200 mg/dL (OR, 1.3; 1.2 to 1.5; P <0.0001). By contrast, the associations with blood pressure and blood glucose levels were no longer significant. There was no heterogeneity across the world regions or among the specialists who enrolled the patients.

Conclusions— Carotid endarterectomy is associated with a higher use of antiplatelet agents and statins in stroke/TIA patients. The absence of such an association with blood pressure and blood glucose control suggests that the individual determinants of the quality of the secondary medical prevention vary from one risk factor to another and from one class of drugs to another.

Central nervous system involvement in diabetes mellitus

Diabetic complications result in much morbidity and mortality and considerable consumption of scarce medical resources. Thus, elucidation of the risk factors and pathophysiologic mechanisms underlying diabetic complications is important. The effects of diabetes on the central nervous system (CNS) result in cognitive dysfunction and cerebrovascular disease. Treatment-related hypoglycemia also has CNS consequences. Advances in neuroimaging now provide greater insights into the structural and functional impact of diabetes on the CNS. Greater understanding of CNS involvement could lead to new strategies to prevent or reverse the damage caused by diabetes mellitus.

Type 1 diabetes as a risk factor for stroke in men and women aged 15-49: a nationwide study from Sweden

AIMS

The main objective was to determine premature stroke risk in men and women in Sweden with previous hospital admission for Type 1 diabetes or without previous hospital admission.

METHODS

All individuals in Sweden aged 15-34 years at first hospital admission for Type 1 diabetes and aged 15-49 years at first hospital admission for stroke during the study period (1987-2001) were identified. Standardized incidence ratios (SIRs) were calculated to compare premature stroke risk between individuals admitted to hospital with Type 1 diabetes and individuals without hospital admission, after controlling for age, time period, occupation and geographical region. SIRs were also calculated for individuals with diabetic complications.

RESULTS

The overall SIRs for premature stroke in men and women with hospital admission for Type 1 diabetes were 17.94 [95% confidence interval (CI) 12.87, 24.36] and 26.11 (95% CI 18.81, 35.32), respectively. Men and women with diabetic nephropathy had the highest significant SIRs of premature stroke: 48.87 and 73.53, respectively.

CONCLUSIONS

Our data indicate that young to middle-aged individuals with Type 1 diabetes had a considerably higher risk of premature stroke than those without Type 1 diabetes. This underscores the need to implement vigorous interventions in healthcare settings in order to decrease the risk of premature stroke in individuals with Type 1 diabetes.

Medium-Term Variability of Blood Pressure and Potential Underdiagnosis of Hypertension in Patients With Previous Transient Ischemic Attack or Minor Stroke

Background and Purpose— Blood pressure (BP) is a major risk factor for stroke. However, the variability of systolic and diastolic BP (SBP and DBP) means that single measurements do not provide a reliable measure of usual BP. Although 24-hour ambulatory BP monitoring can correct for the effects of short-term variation, there is also important medium-term variability. The extent of medium-term variability in BP is most marked in patients with a previous transient ischemic attack (TIA) or stroke. We studied the potential impact of this variability on the likely recognition of hypertension.

Methods— We analyzed multiple repeated measurements of BP in 3 large cohorts with a TIA or minor stroke: the UK-TIA trial (n=2098), the Dutch TIA trial (n=2953), and the European Carotid Surgery Trial (ECST; n=2646). Regression dilution ratios and coefficients of variation were calculated for SBP and DBP from baseline and repeated measurements during the subsequent 12 months. Categorization based on single baseline measurements was also compared with categorization based on the subsequent “usual” BP.

Results— The correlation between measurements of BP at baseline and 3 to 5 months later was poor ( R 2 from 0.17 to 0.31 for SBP and from 0.10 to 0.20 for DBP). Categorization of patients by baseline values resulted in substantial misclassification in relation to usual BP. For example, of patients with an SBP <140 mm Hg at baseline, the percentage with a usual SBP ≥140 mm Hg was 31.6% in the UK-TIA trial, 48.2% in the Dutch TIA trial, and 57.7% in the ECST. At least 3 consecutive measurements of SBP <120 mm Hg were required to be >90% certain that subsequent usual SBP would not be ≥140 mm Hg.

Conclusions— Given the greater medium-term variability of BP in patients with a previous TIA or stroke than in the general population, single measurements of “normal” or “low” BP will substantially underestimate the true prevalence of hypertension.

The evidence for carotid stenting versus carotid endarterectomy in symptomatic patients

Large randomized trials have demonstrated the value of surgical intervention for symptomatic carotid artery disease in stroke prevention. More recently trials have also demonstrated benefit in asymptomatic patients. However, the benefit of surgery comes with significant burden in terms of a risk of both stroke at the time of procedure and other complications. Less invasive endovascular techniques might reduce this complication rate whilst proving as effective as surgery. At the time of writing conclusive evidence is still being sought but a Cochrane meta-analysis has indicated that with the current knowledge based on randomised trials the neuro-embolic complication rate at 30 days is equivalent between the two therapies. Endovascular techniques have fewer non-neuroembolic complications.

Population-Based Study of Determinants of Initial Secondary Care Costs of Acute Stroke in the United Kingdom

BACKGROUND AND PURPOSE

To determine the cost-effectiveness of specific interventions to prevent or treat acute stroke, it is necessary to know the costs of stroke according to patient characteristics and stroke subtype and etiology. However, very few such data are available and none from population-based studies. We determined the predictors of resource use and acute care costs of stroke using data from a population-based study.

METHODS

Data were obtained from the Oxford Vascular study, a population-based cohort of all individuals in nine general practices in Oxfordshire, UK, which identified 346 patients with a first or recurrent stroke during April 1, 2002, to March 31, 2004. Univariate and multivariate analyses were performed to identify the main predictors of resource use and costs.

RESULTS

Acute care costs ranged from 326 pounds sterling (lower decile) to 19,901 pounds sterling (upper decile). There were multiple important univariate interrelations of patient characteristics, stroke subtype, and stroke etiology with hospital admission, length of stay, and 30-day case-fatality. For example, patients with primary intracerebral hemorrhage were more likely to be admitted than patients with partial anterior circulation ischemic stroke and less likely to survive without disability, but length of stay was reduced as a result of high early case-fatality such that cost was substantially less. However, the majority of univariate predictors of resource use, cost, and outcome were confounded by initial stroke severity as measured by the National Institutes of Health Stroke Scale score, which accounted for approximately half of the predicted variance in cost. Cost increased approximately linearly up to an National Institutes of Health Stroke Scale score of 18 and then fell steeply at higher scores as a result of rising early case-fatality.

CONCLUSIONS

Several patient and event-related characteristics explained the wide range of initial secondary care costs of acute stroke, but stroke severity was by far the most important independent predictor.

Underinvestigation and undertreatment of carotid disease in elderly patients with transient ischaemic attack and stroke: comparative population based study

OBJECTIVE

To identify any underinvestigation of older patients with transient ischaemic attack (TIA) and stroke.

DESIGN

Comparative population based studies.

SETTING

Routine clinical practice in all secondary care services in Oxfordshire and a nested population based study of incidence of transient ischaemic attack and stroke (the Oxford vascular study-OXVASC). PARTICIPANTS/POPULATION: All patients undergoing carotid imaging for ischaemic retinal or cerebral transient ischaemic attack or stroke from 1 April 2002 to 31 March 2005 in the Oxford vascular study (n = 91,105) and from 1 April 2002 to 31 March 2003 in routine clinical practice (n = 589,899).

MAIN OUTCOME MEASURES

Age specific rates of carotid imaging, diagnosed >or= 50% symptomatic carotid stenosis, and subsequent endarterectomy, in patients with recent transient ischaemic attack or stroke.

RESULTS

Of patients with recent carotid territory transient ischaemic attack or ischaemic stroke, 575 in routine clinical practice and 402 in the Oxford vascular study had carotid imaging, with similar rates up to the age of 80. The incidence of >or= 50% symptomatic stenosis increased steeply with age, particularly in those aged >or= 80. Compared with investigations in patients in the Oxford vascular study, the rates of carotid imaging (relative rate 0.36, 95% confidence interval 0.28 to 0.46, P < 0.0001), diagnosis of >or= 50% symptomatic stenosis (0.33, 0.16 to 0.69, P = 0.004), and carotid endarterectomy (0.19, 0.06 to 0.63, P = 0.007) in this age group in routine clinical practice were all substantially lower.

CONCLUSIONS

Incidence of symptomatic carotid stenosis increases steeply with age, but, despite good evidence of major benefit from endarterectomy in elderly patients and a willingness to have surgery, there is substantial underinvestigation in routine clinical practice in patients aged >or= 80 with transient ischaemic attack or ischaemic stroke.

Modulation of thrombin-induced neuroinflammation in BV-2 microglia by carbon monoxide-releasing molecule 3

Carbon monoxide-releasing molecules are emerging as a new class of pharmacological agents that regulate important cellular function by liberating CO in biological systems. Here, we examined the role of carbon monoxide-releasing molecule 3 (CORM-3) in modulating neuroinflammatory responses in BV-2 microglial cells, considering its practical application as a novel therapeutic alternative in the treatment of stroke. BV-2 microglia cells were incubated for 24 h in normoxic conditions with thrombin alone or in combination with interferon-gamma to simulate the inflammatory response. Cells were also subjected to 12 h of hypoxia and reoxygenated for 24 h in the presence of thrombin and interferon-gamma. In both set of experiments, the anti-inflammatory action of CORM-3 was evaluated by assessing its effect on nitric oxide production (nitrite levels) and tumor necrosis factor (TNF)-alpha release. CORM-3 (75 microM) did not show any cytotoxicity and markedly attenuated the inflammatory response to thrombin and interferon-gamma in normoxia and to a lesser extent in hypoxia as evidenced by a reduction in nitrite levels and TNF-alpha production. Inactive CORM-3, which does not liberate CO and is used as a negative control, failed to prevent the increase in inflammatory mediators. Blockade of endogenous CO production by tin protoporphyrin-IX did not change the anti-inflammatory activity of CORM-3, suggesting that CO liberated from the compound is responsible for the observed effects. In addition, inhibition of the mitogen-activated protein kinases phosphatidyl inositol 3 kinase and extracellular signal-regulated kinase amplified the anti-inflammatory effect of CORM-3. These results suggest that the anti-inflammatory activity of CORM-3 could be exploited to mitigate microglia activity in stroke and other neuroinflammatory diseases.

The unchanging incidence and case-fatality of stroke in the 1990s: a population-based study

BACKGROUND AND PURPOSE

Many advances were made in stroke prevention strategies during the 1990s, and yet temporal trends in stroke incidence and case-fatality have not been reported in the United States. Blacks have a 2-fold higher risk of stroke; however, there are no data over time showing if any progress has been made in reducing racial disparity in stroke incidence. The objective of this study was to examine temporal trends in stroke incidence and case-fatality within a large, biracial population during the 1990s.

METHODS

Within a biracial population of 1.3 million, all strokes were ascertained at all local hospitals using International Classification of Diseases, 9th Revision codes during July 1993 to June 1994 and again in 1999. A sampling scheme was used to ascertain cases in the out-of-hospital setting. Race-specific incidence and case-fatality rates were calculated and standardized to the 2000 US Census population. A population-based telephone survey regarding stroke risk factor prevalence and medication use was performed in 1995 and 2000.

RESULTS

There were 1954 first-ever strokes in 1993-1994 and 2063 first-ever strokes in 1999. The annual incidence of first-ever hospitalized stroke did not significantly change between study periods: 158 per 100,000 in both 1993-1994 and 1999 (P=0.97). Blacks continue to have higher stroke incidence than whites, especially in the young; however, case-fatality rates continue to be similar between races and are not changing over time. Medication use for treatment of stroke risk factors significantly increased in the general population between study periods.

CONCLUSIONS

Despite advances in stroke prevention treatments during the 1990s, the incidence of hospitalized stroke did not decrease within our population. Case-fatality also did not change between study periods. Excess stroke mortality rates seen in blacks nationally are likely the result of excess stroke incidence and not case-fatality, and the racial disparity in stroke incidence did not change over time.

Stable Stroke Incidence Rates but Improved Case-Fatality in Dijon, France, From 1985 to 2004

BACKGROUND AND PURPOSE

With the progress in stroke prevention, it is important to evaluate the epidemiological trends of strokes over a long period and from a nonselected population-based perspective.

METHODS

We estimated changes in incidence, case-fatality rates, severity, risk factors and prestroke use of preventive treatments for first-ever strokes, from a continuous 20-year well-defined population-based registry, from 1985 to 2004.

RESULTS

We recorded 3142 ischemic strokes, 341 primary cerebral hemorrhages and 74 subarachnoid hemorrhages. During the 20-year study, the age at first stroke onset increased by 5 years in men and 8 years in women. Comparing the 1985 to 1989 and the 2000 to 2004 periods, age- and sex-standardized incidences of first-ever strokes were stable except for lacunar strokes whose incidence significantly increased (P=0.01) and for cardioembolic stroke whose incidence significantly decreased (P=0.01). Twenty-eight-day case-fatality rates decreased significantly mainly for lacunar strokes (P=0.05) and for primary cerebral hemorrhages (P=0.03). The proportion of hypercholesterolemia and diabetes significantly increased (P<0.01). In contrast, the proportion of myocardial infarction significantly decreased (P=0.02). Prestroke antiplatelets and anticoagulants treatment significantly increased (P<0.01).

CONCLUSIONS

The age- and sex-standardized incidences of first strokes in Dijon have been stable over the past 20 years and were associated with an increase in age at stroke onset, a decrease in case-fatality rates, and an increased use of antiplatelet treatments.

Risk-corrected impact of mechanical versus bioprosthetic valves on long-term mortality after aortic valve replacement

OBJECTIVE

Choice of a mechanical or biologic valve in aortic valve replacement remains controversial and rotates around different complications with different time-related incidence rates. Because serious complications will always "spill over" into mortality, our aim was to perform a meta-analysis on overall mortality after aortic valve replacement from series with a maximum follow-up of at least 10 years to determine the age- and risk factor-corrected impact of currently available mechanical versus stented bioprosthetic valves.

METHODS

Following a formal study protocol, we performed a dedicated literature search of publications during 1989 to 2004 and included articles on adult aortic valve replacement with a mechanical or stented bioprosthetic valve if age, mortality statistics, and prevalences of well-known risk factors could be extracted. We used standard and robust regression analyses of the case series data with valve type as a fixed variable.

RESULTS

We could include 32 articles with 15 mechanical and 23 biologic valve series totaling 17,439 patients and 101,819 patient-years. The mechanical and biologic valve series differed in regard to mean age (58 vs 69 years), mean follow-up (6.4 vs 5.3 years), coronary artery bypass grafting (16% vs 34%), endocarditis (7% vs 2%), and overall death rate (3.99 vs 6.33 %/patient-year). Mean age of the valve series was directly related to death rate with no interaction with valve type. Death rate corrected for age, New York Heart Association classes III and IV, aortic regurgitation, and coronary artery bypass grafting left valve type with no effect. Included articles that abided by current guidelines and compared a mechanical and biologic valve found no differences in rates of thromboembolism.

CONCLUSION

There was no difference in risk factor-corrected overall death rate between mechanical or bioprosthetic aortic valves irrespective of age. Choice of prosthetic valve should therefore not be rigorously based on age alone. Risk of bioprosthetic valve degeneration in young and middle-aged patients and in the elderly and old with a long life expectancy would be an important factor because risk of stroke may primarily be related to patient factors.

Factors associated with geographic variations in stroke incidence among older populations in four US communities

BACKGROUND AND PURPOSE

In the Cardiovascular Health Study (CHS), we previously observed lower stroke incidence in Allegheny County, PA compared with the other 3 study sites. The purpose of this study was to study possible reasons for the lower stroke incidence in Allegheny County.

METHODS

CHS participants 65 years or older who were stroke-free at baseline (n=5639) were followed between 1989 to 1990 and 2000 for the development of stroke. Risk factors at baseline and their subsequent control were compared among both groups. Site-specific hazard ratios for stroke incidence were calculated using Cox regression models.

RESULTS

The unadjusted hazard ratio for total stroke incidence in Forsyth County, NC; Sacramento County, CA; and Washington County, MD combined compared with Allegheny County, PA was 1.74 (95% CI: 1.42, 2.14). After adjustment for age and other traditional risk factors, there was modest reduction of the excess hazard in non-Allegheny sites compared with Allegheny County (hazard ratio=1.52, 95% CI: 1.17, 1.98). Between baseline and the seventh-year visits, control of hypertension, diabetes, lipids, smoking, atrial fibrillation and transient ischemic attack were similar across sites. White matter grade > or = 3 on the baseline brain MRI was less common in Allegheny County (25.8% versus 36.3%, respectively; P<0.001) and accounted for 25% of the excess hazard in non-Allegheny sites compared with Allegheny County.

CONCLUSIONS

Site differences in stroke risk factors at baseline and subsequent control only partially explain site differences in stroke incidence. White matter grade as a possible integrated measure of exposure and control of risk factors may help in explaining geographic variations in stroke incidence.

Primary Prevention of Ischemic Stroke

Background and Purpose— This guideline provides an overview of the evidence on various established and potential stroke risk factors and provides recommendations for the reduction of stroke risk.

Methods— Writing group members were nominated by the committee chair on the basis of each writer’s previous work in relevant topic areas and were approved by the American Heart Association Stroke Council’s Scientific Statement Oversight Committee. The writers used systematic literature reviews (covering the time period since the last review published in 2001 up to January 2005), reference to previously published guidelines, personal files, and expert opinion to summarize existing evidence, indicate gaps in current knowledge, and when appropriate, formulate recommendations based on standard American Heart Association criteria. All members of the writing group had numerous opportunities to comment in writing on the recommendations and approved the final version of this document. The guideline underwent extensive peer review before consideration and approval by the AHA Science Advisory and Coordinating Committee.

Results— Schemes for assessing a person’s risk of a first stroke were evaluated. Risk factors or risk markers for a first stroke were classified according to their potential for modification (nonmodifiable, modifiable, or potentially modifiable) and strength of evidence (well documented or less well documented). Nonmodifiable risk factors include age, sex, low birth weight, race/ethnicity, and genetic factors. Well-documented and modifiable risk factors include hypertension, exposure to cigarette smoke, diabetes, atrial fibrillation and certain other cardiac conditions, dyslipidemia, carotid artery stenosis, sickle cell disease, postmenopausal hormone therapy, poor diet, physical inactivity, and obesity and body fat distribution. Less well-documented or potentially modifiable risk factors include the metabolic syndrome, alcohol abuse, drug abuse, oral contraceptive use, sleep-disordered breathing, migraine headache, hyperhomocysteinemia, elevated lipoprotein(a), elevated lipoprotein-associated phospholipase, hypercoagulability, inflammation, and infection. Data on the use of aspirin for primary stroke prevention are reviewed.

Conclusion— Extensive evidence is available identifying a variety of specific factors that increase the risk of a first stroke and providing strategies for reducing that risk.

Stroke incidence and prevalence in Europe: a review of available data

Reliable data on stroke incidence and prevalence are essential for calculating the burden of stroke and the planning of prevention and treatment of stroke patients. In the current study we have reviewed the published data from EU countries, Iceland, Norway, and Switzerland, and provide WHO estimates for stroke incidence and prevalence in these countries. Studies on stroke epidemiology published in peer-reviewed journals during the past 10 years were identified using Medline/PubMed searches, and reviewed using the structure of WHO's stroke component of the WHO InfoBase. WHO estimates for stroke incidence and prevalence for each country were calculated from routine mortality statistics. Rates from studies that met the 'ideal' criteria were compared with WHO's estimates. Forty-four incidence studies and 12 prevalence studies were identified. There were several methodological differences that hampered comparisons of data. WHO stroke estimates were in good agreement with results from 'ideal' stroke population studies. According to the WHO estimates the number of stroke events in these selected countries is likely to increase from 1.1 million per year in 2000 to more than 1.5 million per year in 2025 solely because of the demographic changes. Until better and more stroke studies are available, the WHO stroke estimates may provide the best data for understanding the stroke burden in countries where no stroke data currently exists. A standardized protocol for stroke surveillance is recommended.

Aspirin plus dipyridamole versus aspirin alone after cerebral ischaemia of arterial origin (ESPRIT): randomised controlled trial

BACKGROUND

Results of trials of aspirin and dipyridamole combined versus aspirin alone for the secondary prevention of vascular events after ischaemic stroke of presumed arterial origin are inconsistent. Our aim was to resolve this uncertainty.

METHODS

We did a randomised controlled trial in which we assigned patients to aspirin (30-325 mg daily) with (n=1363) or without (n=1376) dipyridamole (200 mg twice daily) within 6 months of a transient ischaemic attack or minor stroke of presumed arterial origin. Our primary outcome event was the composite of death from all vascular causes, non-fatal stroke, non-fatal myocardial infarction, or major bleeding complication, whichever happened first. Treatment was open, but auditing of outcome events was blinded. Primary analysis was by intention to treat. This study is registered as an International Standard Randomised Controlled Trial (number ISRCTN73824458) and with (NCT00161070).

FINDINGS

Mean follow-up was 3.5 years (SD 2.0). Median aspirin dose was 75 mg in both treatment groups (range 30-325); extended-release dipyridamole was used by 83% (n=1131) of patients on the combination regimen. Primary outcome events arose in 173 (13%) patients on aspirin and dipyridamole and in 216 (16%) on aspirin alone (hazard ratio 0.80, 95% CI 0.66-0.98; absolute risk reduction 1.0% per year, 95% CI 0.1-1.8). Addition of the ESPRIT data to the meta-analysis of previous trials resulted in an overall risk ratio for the composite of vascular death, stroke, or myocardial infarction of 0.82 (95% CI 0.74-0.91). Patients on aspirin and dipyridamole discontinued trial medication more often than those on aspirin alone (470 vs 184), mainly because of headache.

INTERPRETATION

The ESPRIT results, combined with the results of previous trials, provide sufficient evidence to prefer the combination regimen of aspirin plus dipyridamole over aspirin alone as antithrombotic therapy after cerebral ischaemia of arterial origin.

Update on intracerebral haemorrhage

Intracerebral haemorrhage (ICH) is a common and serious disease. About 1 to 2 out of 10 patients with stroke have an ICH. The mortality of ICH is higher than that of ischaemic stroke. Only 31% are functionally independent at 3 months. Only 38% of the patients survive the 1(st) year. The cost of ICH is high. Hypertension is the major risk factor, increasing the risk of ICH about 4x. Up to half of hypertensive patients who suffer a ICH are either unaware of their hypertension, non-compliant with the medication or fail to control periodically their blood pressure levels Microbleeds and white matter changes are MRI markers of the risk of ICH. ICH has 3 main pathophysiological phases: arterial rupture and haematoma formation, haematoma enlargement and peri-haematoma oedema. Up to 40% of the haematomas grow in the first hours post-rupture. ICH growth is associated with early clinical deterioration. Two randomised clinical trials (RCTs) demonstrated that treatment with rFVIIa limited haematoma growth and improved outcome, but was associated with a increase in thromboembolic complications. Ventricular drainage with thrombolytics might improve outcome for patients with intraventricular bleeding. A large RCT and meta-analysis failed to show a benefit of surgery over conservative treatment in acute ICH.

The use of neurovascular imaging for triaging tia and minor stroke: Implications for therapy

Nondisabling cerebrovascular events (minor stroke or transient ischemic attack) are not benign; a significant proportion of these patients will suffer a new disabling stroke or develop stroke progression in hospital, resulting in dependence or death. With the exception of the modest benefits of aspirin, there are currently no effective acute medical therapies to prevent early progression or recurrence in such patients. Early carotid revascularization appears to be the most efficacious treatment available for patients with symptomatic (> 50%) internal carotid artery stenosis. More acute treatment and acute prevention trials are needed. MRI, CT bolus techniques, and transcranial Doppler emboli detection represent tools for detection of patients at high risk for deterioration and should be incorporated into the development of effective therapies by targeting the most appropriate patients for intervention.

Patient Behavior Immediately After Transient Ischemic Attack According to Clinical Characteristics, Perception of the Event, and Predicted Risk of Stroke

Background and Purpose— Little research has been done on patients’ behavior after transient ischemic attack (TIA). Recent data on the high early risk of stroke after TIA mean that emergency action after TIA is essential for effective secondary prevention. We therefore studied patients’ behavior immediately after TIA according to their perceptions, clinical characteristics, and predicted stroke risk.

Methods— Consecutive patients with TIA participating in the Oxford Vascular Study or attending dedicated hospital clinics in Oxfordshire, UK, were interviewed. Predicted stroke risk was calculated using 2 validated scores.

Results— Of 241 patients, 107 (44.4%) sought medical attention within hours of the event, although only 24 of these attended the emergency department. A total of 107 (44.4%) delayed seeking medical attention for ≥1 day. Correct recognition of symptoms (42.2% of patients) was not associated with less delay. However, patients with motor symptoms or duration of symptoms ≥1 hour were more likely to seek emergency attention (hazard ratio, 2.1; 95% CI, 1.4 to 3.2; P =0.00005), as were those at higher predicted stroke risk ( P =0.001). The other main correlate with delay was the day of the week on which the TIA occurred ( P <0.001), with greater delays at the weekend. Delay was unrelated to age, sex, or other vascular risk factors.

Conclusions— Many patients delay seeking medical attention after a TIA irrespective of correct recognition of symptoms, although patients at higher predicted risk of stroke do act more quickly. Public education about both the urgency and nature of TIA is required.

Protocol for the 'e-Nudge trial': a randomised controlled trial of electronic feedback to reduce the cardiovascular risk of individuals in general practice [ISRCTN64828380]

Background

Cardiovascular disease (including coronary heart disease and stroke) is a major cause of death and disability in the United Kingdom, and is to a large extent preventable, by lifestyle modification and drug therapy. The recent standardisation of electronic codes for cardiovascular risk variables through the United Kingdom's new General Practice contract provides an opportunity for the application of risk algorithms to identify high risk individuals. This randomised controlled trial will test the benefits of an automated system of alert messages and practice searches to identify those at highest risk of cardiovascular disease in primary care databases.

Design

Patients over 50 years old in practice databases will be randomised to the intervention group that will receive the alert messages and searches, and a control group who will continue to receive usual care. In addition to those at high estimated risk, potentially high risk patients will be identified who have insufficient data to allow a risk estimate to be made. Further groups identified will be those with possible undiagnosed diabetes, based either on elevated past recorded blood glucose measurements, or an absence of recent blood glucose measurement in those with established cardiovascular disease.

Outcome measures

The intervention will be applied for two years, and outcome data will be collected for a further year. The primary outcome measure will be the annual rate of cardiovascular events in the intervention and control arms of the study. Secondary measures include the proportion of patients at high estimated cardiovascular risk, the proportion of patients with missing data for a risk estimate, and the proportion with undefined diabetes status at the end of the trial.

Improvement in stroke mortality in Canada and the United States, 1990 to 2002

BACKGROUND

In the United States and Canada, folic acid fortification of enriched grain products was fully implemented by 1998. The resulting population-wide reduction in blood homocysteine concentrations might be expected to reduce stroke mortality if high homocysteine levels are an independent risk factor for stroke.

METHODS AND RESULTS

In this population-based cohort study with quasi-experimental intervention, we used segmented log-linear regression to evaluate trends in stroke-related mortality before and after folic acid fortification in the United States and Canada and, as a comparison, during the same period in England and Wales, where fortification is not required. Average blood folate concentrations increased and homocysteine concentrations decreased in the United States after fortification. The ongoing decline in stroke mortality observed in the United States between 1990 and 1997 accelerated in 1998 to 2002 in nearly all population strata, with an overall change from -0.3% (95% CI, -0.7 to 0.08) to -2.9 (95% CI, -3.5 to -2.3) per year (P=0.0005). Sensitivity analyses indicate that changes in other major recognized risk factors are unlikely to account for the reduced number of stroke-related deaths in the United States. The fall in stroke mortality in Canada averaged -1.0% (95% CI, -1.4 to -0.6) per year from 1990 to 1997 and accelerated to -5.4% (95% CI, -6.0 to -4.7) per year in 1998 to 2002 (P< or =0.0001). In contrast, the decline in stroke mortality in England and Wales did not change significantly between 1990 and 2002.

CONCLUSIONS

The improvement in stroke mortality observed after folic acid fortification in the United States and Canada but not in England and Wales is consistent with the hypothesis that folic acid fortification helps to reduce deaths from stroke.

Increasing rates of dementia at time of declining mortality from stroke

BACKGROUND AND PURPOSE

Stroke is associated with increased risk of dementia. There has been a decline in mortality from stroke among persons 65 and over in recent decades in the US. It is not clear, however, how this process has affected incidence of various dementias.

METHODS

We evaluated over time changes in stroke admission rates and survival, and in rates of newly diagnosed dementias (Alzheimer disease, senile, and cerebrovascular disease-related dementia) in persons with and without stroke aged 65 and over, using Medicare inpatient records, 1984 to 2001, linked to the National Long-Term Care Survey (about 380,000 person-years totally).

RESULTS

Age-adjusted stroke rate increased from 0.0066 to 0.008 (P=0.08) from 1984-1990 to 1991-2001. One-year survival after stroke improved from 53% in 1984 to 1990 to 65% in 1991 to 1996 (P<0.0001). Age-standardized rate of diagnosed dementias increased from 0.0062 in 1984 to 1990 to 0.0095 in 1991 to 2000 (P=0.001). Among stroke patients the rate rose from 0.043 to 0.080. The relative increase in risk was largest for cerebrovascular disease-related dementia (3.68). For senile dementia, the increase was small and not significant. Rates of dementia among persons without stroke rose mainly attributable to Alzheimer disease.

CONCLUSIONS

Mortality from stroke declined mainly because of declining stroke case-fatality. In parallel, the rate of diagnosed dementia increased. The increase was larger for persons with stroke compared with stroke-free population. Improved survival from stroke may contribute to this trend. Other contributing factors may include better diagnostics, an increased propensity to make the diagnosis, and increasing dementia risk attributable to factors other than stroke.

Recent advances in management of transient ischaemic attacks and minor ischaemic strokes

The risk of recurrent stroke during the first few days after a transient ischaemic attack or minor stroke is much higher than previously estimated. However, there is substantial variation worldwide in how patients with suspected transient ischaemic attack or minor stroke are investigated and treated in the acute phase: some health-care systems provide immediate emergency inpatient care and others provide non-emergency outpatient clinical assessment. This review considers what is known about the early prognosis after transient ischaemic attack and minor ischaemic stroke, what factors identify individuals at particularly high early risk of stroke, and what evidence there is that urgent preventive treatment is likely to be effective in reducing the early risk of stroke.

Applicability to primary care of national clinical guidelines on blood pressure lowering for people with stroke: cross sectional study

OBJECTIVE

To compare the characteristics of patients with cerebrovascular disease in primary care with those of the participants in the PROGRESS trial, on which national guidelines for blood pressure lowering are based.

DESIGN

Population based cross sectional survey of patients with confirmed stroke or transient ischaemic attack.

SETTING

Seven general practices in south Birmingham, England.

PARTICIPANTS

All patients with a validated history of stroke (n = 413) or transient ischaemic attack (n = 107).

PATIENT CHARACTERISTICS

age, sex, time since last cerebrovascular event, blood pressure, and whether receiving antihypertensive treatment.

RESULTS

Patients were 12 years older than the participants in PROGRESS and twice as likely to be women. The median time that had elapsed since their cerebrovascular event was two and a half years, compared with eight months in PROGRESS. The systolic blood pressure of 315 (61%) patients was over 140 mm Hg, and for 399 (77%) it was over 130 mm Hg. One hundred and forty seven (28%) patients were receiving a thiazide diuretic, and 136 (26%) were receiving an angiotensin converting enzyme inhibitor.

CONCLUSIONS

Important differences exist between the PROGRESS trial participants and a typical primary care stroke population, which undermine the applicability of the trial's findings. Research in appropriate populations is urgently needed before the international guidelines are implemented in primary care.

Improving the management and referral of patients with transient ischaemic attacks: a change strategy for a health community

PROBLEM

Rapid referral and management of patients with transient ischaemic attacks is a key component in the national strategy for stroke prevention. However, patients with transient ischaemic attacks are poorly identified and undertreated.

DESIGN AND SETTING

Before and after evaluation of quality improvement programme with controlled comparison in three primary care trusts reflecting diverse populations and organisational structures in an urban district in the North of England.

KEY MEASURES FOR IMPROVEMENT

The proportion of patients receiving antiplatelet drugs and safe driving advice on referral to a specialty clinic, and the numbers of referrals, adjusted for age, to the specialist clinic before and after the improvement programme.

STRATEGIES FOR CHANGE

Interviews with patient and professionals to identify gaps and barriers to good practice; development of evidence based guidelines for the management of patients with transient ischaemic attacks; interactive multidisciplinary workshops for each primary care trust with feedback of individual audit results of referral practice; outreach visits to teams who were unable to attend the workshops; referral templates and desktop summaries to provide reminders of the guidelines to clinicians; incorporation of standards into professional contracts.

EFFECTS OF CHANGE

A significant improvement occurred in identification and referral of patients with transient ischaemic attacks to specialist clinics, with a 41% increase in referrals from trained practices compared with control practices. There were also significant improvements in the early treatment and safety advice provided to patients before referral.

LESSONS LEARNT

A strategic approach to effective quality improvement across a diverse health community is feasible and achievable. Careful planning with patient and professional involvement to develop a tailored and multifaceted quality improvement programme to implement evidence based practice can work in very different primary care settings. Key components of the effectiveness of the model include contextual analysis, strong professional support, clear recommendations based on robust evidence, simplicity of adoption, good communication, and use of established networks and opinion leaders.

Secular stroke trends: early life factors and future prospects

Stroke mortality rates have declined during the second half of the 20th century in developed countries. Possible reasons for this include preventive measures, recent environmental changes impacting on adult health risks, and more distant environmental influences on childhood health. Data from a number of populations in Europe and the USA suggest that a decrease in early life blood pressure, occurring since the beginning of the 20th century, may have been an important determinant of declining stroke incidence rates and cardiovascular disease mortality in general. Advances in stroke epidemiology are increasing the accuracy of case ascertainment, and neuroimaging refinements (particularly MRI) are improving the accuracy of stroke type and subtype diagnoses. Although some risk factors are common to ischaemic and haemorrhagic stroke, there is accumulating evidence of differing aetiology. There is also an increasing recognition that early life factors may influence stroke risk. Despite the encouraging decline in stroke incidence, there is evidence of a recent increase in mean blood pressure in young people observed in the USA and UK, prompting concern that favourable trends in stroke risk may not be maintained. Reducing early life blood pressure in a population and delaying the onset of hypertension, along with effective measures to combat obesity, are required to avoid a reversal in stroke incidence trends in developed countries, and to prevent the anticipated increase in the burden of stroke in developing countries.

Family History of Stroke Does Not Predict Risk of Stroke After Transient Ischemic Attack

BACKGROUND AND PURPOSE

Animal models suggest a genetic contribution to cerebral susceptibility to ischemia. Family history of stroke (FHxstroke) is a risk factor for ischemic stroke, but there is significant confounding by heritability of hypertension and other intermediate phenotypes, and it is uncertain whether genetic factors have a direct independent influence on cerebral susceptibility to ischemia in man.

METHODS

We related detailed FHxstroke to baseline characteristics and subsequent risk of stroke in 2 population-based incidence studies and a consecutive hospital-referred series of patients with recent transient ischemic attack (TIA).

RESULTS

In none of the cohorts or the pooled data (757 patients; 5515 patient years follow-up; 200 ischemic strokes; 126 myocardial infarctions [MIs]) did FHxstroke predict ischemic stroke (odds ratio [OR], 0.87; 95% CI, 0.57 to 1.32). No associations were revealed by analyses stratified by age or hypertension in the proband, FHx(stroke) in parents versus siblings, number of affected relatives, or their age at stroke. FHxstroke was unrelated to presence of ischemic lesions on baseline computed tomography (OR, 0.96; 0.52 to 1.76) or risk of MI during follow-up. There was no bias attributable to any relationship between FHxstroke and risk factor control or medication.

CONCLUSIONS

Family history of stroke does not predict risk of ischemic stroke after TIA.

Ethnic disparities in incidence of stroke subtypes: Auckland Regional Community Stroke Study, 2002–2003

BACKGROUND

Limited population-based data exist on differences in the incidence of major pathological stroke types and ischaemic stroke subtypes across ethnic groups. We aimed to provide such data within the large multi-ethnic population of Auckland, New Zealand.

METHODS

All first-ever cases of stroke (n=1423) in a population-based register in 940 000 residents (aged 15 years) in Auckland, New Zealand, for a 12-month period in 2002-2003, were classified into ischaemic stroke, primary intracerebral haemorrhage (PICH), subarachnoid haemorrhage, and undetermined stroke, according to standard definitions and results of neuroimaging/necropsy (in over 90% of cases). Ischaemic stroke was further classified into five subtypes. Ethnicity was self-identified and grouped as New Zealand (NZ)/European, Maori/Pacific, and Asian/other. Incidence rates were standardised to the WHO world population by the direct method, and differences in rates between ethnic groups expressed as rate ratios (RRs), with NZ/European as the reference group.

FINDINGS

In NZ/European people, ischaemic stroke comprised 73%, PICH 11%, and subarachnoid haemorrhage 6%, but PICH was higher in Maori/Pacific people (17%) and in Asian/other people (22%). Compared with NZ/European people, age-adjusted RRs for PICH were 2.7 (95% CI 1.8-4.0) and 2.3 (95% CI 1.4-3.7) among Maori/Pacific and Asian/other people, respectively. The corresponding RR for ischaemic stroke was greater for Maori/Pacific people (1.7 [95% CI 1.4-2.0]), particularly embolic stroke, and for Asian/other people (1.3 [95% CI 1.0-1.7]). The onset of stroke in Maori/Pacific and Asian/other people began at significantly younger ages (62 years and 64 years, respectively) than in NZ/Europeans (75 years; p<0.0001). There were ethnic differences in the risk factor profiles (such as age, sex, hypertension, cardiac disease, diabetes, hypercholesterolaemia, smoking status, overweight) for the stroke types and subtypes.

INTERPRETATION

Compared to NZ/Europeans, Maori/Pacific and Asian/other people are at higher risk of ischaemic stroke and PICH, whereas similar rates of subarachnoid haemorrhage were evident across ethnic groups. The ethnic disparities in the rates of stroke types could be due to substantial differences found in risk factor profiles between ethnic groups. This information should be considered when planning prevention and stroke-care services in multi-ethnic communities.

Multidisciplinary Vascular Screening Program Modestly Improves the Medical Treatment of Vascular Risk Factors

PURPOSE

This study investigated whether recommendations given to the treating vascular specialist and the GP by a multidisciplinary team of vascular specialists concerning the medical treatment of risk factors, based on international guidelines, led to an increased medication use in a high-risk population.

METHODS

Data were obtained from 618 patients enrolled in the SMART study, an ongoing single-center prospective cohort study of patients referred to the University Medical Center Utrecht for atherosclerotic vascular diseases. All patients underwent a vascular screening and their physicians received recommendations concerning the medical treatment of newly detected or not yet sufficiently treated vascular risk factors. After a median follow-up of 29 months, questionnaires about medication use were sent to 618 patients; 534 (86%) questionnaires were returned. Actual use of medication was compared with medical treatment recommendation given at baseline.

RESULTS

The proportion of patients on antihypertensive medication with hypertension (> or =140/90 mmHg) and not diagnosed with coronary heart disease increased from 56% to 68% (95% confidence interval (95% CI) 2 - 23). The frequency of lipid-lowering medication use increased substantially from 47% to 69% (95% CI 17 - 28). The frequency of glucose-lowering medication use increased slightly from 11% to 14% (95% CI 1 - 7). The use of folic acid increased from 2% to 14% (95% CI 9 - 15) in patients with hyperhomocysteinaemia.

CONCLUSIONS

Medical treatment recommendations, formulated by a multidisciplinary team, led to a significant increase in medication use. The increase is marginal compared with trends in medication use without this intervention in usual care.

Trends in Ethnic Disparities in Stroke Incidence in Auckland, New Zealand, During 1981 to 2003

Background and Purpose— Although geographical variations in stroke rates are well documented, limited data exist on temporal trends in ethnic-specific stroke incidence.

Methods— We assessed trends in ethnic-specific stroke rates using standard diagnostic criteria and community-wide surveillance procedures in Auckland, New Zealand (NZ) in 1981 to 1982, 1991 to 1992, and 2002 to 2003. Indirect and direct methods were used to adjust first-ever (incident) and total (attack) rates for changes in the structure of the population and reported with 95% CIs. Ethnicity was self-defined and categorized as “NZ/European,” “Maori,” “Pacific peoples,” and “Asian and other.”

Results— Stroke attack (19%; 95% CI, 11% to 26%) and incidence rates (19%; 95% CI, 12% to 24%) declined significantly in NZ/Europeans from 1981 to 1982 to 2002 to 2003. These rates remained high or increased in other ethnic groups, particularly for Pacific peoples in whom stroke attack rates increased by 66% (95% CI; 11% to 225%) over the periods. Some favorable downward trends in vascular risk factors, such as cigarette smoking, were counterbalanced by increasing age, body mass index, and diabetes in certain ethnic groups.

Conclusions— Divergent trends in ethnic-specific stroke incidence and attack rates, and of associated risk factors, have occurred in Auckland over recent decades. The findings provide mixed views as to the future burden of stroke in populations undergoing similar lifestyle and structural changes.

Phosphodiesterase 4D and 5-lipoxygenase activating protein in ischemic stroke

Risk for ischemic stroke is mediated by both environmental and genetic factors. Although several environmental exposures have been implicated, relatively little is known about the genetic basis of predisposition to this disease. Recent studies in Iceland identified risk polymorphisms in two putative candidate genes for ischemic stroke: phosphodiesterase 4D (PDE4D) and 5-lipoxygenase activating protein (ALOX5AP). A collection of North American sibling pairs concordant for ischemic stroke and two cohorts of prospectively ascertained North American ischemic stroke cases and control subjects were used for evaluation of PDE4D and ALOX5AP. Although no evidence supported linkage of ischemic stroke with either of the two candidate genes, single-nucleotide polymorphisms and haplotypic associations were observed between PDE4D and ischemic stroke. There was no evidence of association between variants of ALOX5AP and ischemic stroke. These data suggest that common variants in PDE4D may contribute to the genetic risk for ischemic stroke in multiple populations.

Potential consequences for recruitment, power, and external validity of requirements for additional risk factors for eligibility in randomized controlled trials in secondary prevention of stroke

BACKGROUND AND PURPOSE

Eligibility criteria determine the external validity (generalizability) of the results of randomized controlled trials. To increase the number of outcome events, and hence statistical power, some recent stroke prevention trials have required additional vascular risk factors for eligibility.

METHODS

To assess the merits of additional eligibility criteria in stroke prevention trials, we analyzed data from 3 trials and 1 hospital-referred series of patients with a transient ischemic attack or minor ischemic stroke. Patients were stratified according to 2 sets of additional risk factors similar to those used in recent trials (MATCH, SPORTIF and PRoFESS); risk of stroke, myocardial infarction, or vascular death was calculated in relation to the number of risk factors.

RESULTS

Although the observed risk during follow-up did increase with the number of risk factors present (P<0.01 for both sets), the risks in patients with > or =1 risk factors were not substantially greater than those in all patients. Consequently, although the proportions of patients with no risk factors in the 4 cohorts differed substantially between the 2 sets of eligibility criteria (21% to 28% versus 56% to 73%), in neither case could their exclusion be justified on statistical grounds.

CONCLUSIONS

The degree of patient selection introduced by use of additional vascular risk factors as eligibility criteria for trials can differ substantially between apparently similar sets of risk factors. Given that the potential for additional eligibility criteria to undermine generalizability and prolong recruitment outweighs any benefits in terms of statistical power, the exclusion of patients with no risk factors is difficult to justify.

Blood Pressure as a Risk Factor for Stroke and the Impact of Antihypertensive Treatment

We review hypertension and blood pressure levels as risk factors for stroke and the impact of antihypertensive treatment on the prevention of first stroke event and of recurrent stroke, not only with respect to the prevention of vascular events but also the prevention of cognitive deterioration, dementia, and physical disability. We review whether pharmacological blockage of the renin-angiotensin system has additional long-term effects over that of control of blood pressure levels alone, and the benefit of treatment with antihypertensive drugs in normotensive patients. Therapeutic objectives for blood pressure levels after stroke are defined together with recommendations of drugs and doses which have been demonstrated to have the greatest benefit in the prevention of stroke.

Population-based study of event-rate, incidence, case fatality, and mortality for all acute vascular events in all arterial territories (Oxford Vascular Study)

BACKGROUND

Acute coronary, cerebrovascular, and peripheral vascular events have common underlying arterial pathology, risk factors, and preventive treatments, but they are rarely studied concurrently. In the Oxford Vascular Study, we determined the comparative epidemiology of different acute vascular syndromes, their current burdens, and the potential effect of the ageing population on future rates.

METHODS

We prospectively assessed all individuals presenting with an acute vascular event of any type in any arterial territory irrespective of age in a population of 91 106 in Oxfordshire, UK, in 2002-05.

FINDINGS

2024 acute vascular events occurred in 1657 individuals: 918 (45%) cerebrovascular (618 stroke, 300 transient ischaemic attacks [TIA]); 856 (42%) coronary vascular (159 ST-elevation myocardial infarction, 316 non-ST-elevation myocardial infarction, 218 unstable angina, 163 sudden cardiac death); 188 (9%) peripheral vascular (43 aortic, 53 embolic visceral or limb ischaemia, 92 critical limb ischaemia); and 62 unclassifiable deaths. Relative incidence of cerebrovascular events compared with coronary events was 1.19 (95% CI 1.06-1.33) overall; 1.40 (1.23-1.59) for non-fatal events; and 1.21 (1.04-1.41) if TIA and unstable angina were further excluded. Event and incidence rates rose steeply with age in all arterial territories, with 735 (80%) cerebrovascular, 623 (73%) coronary, and 147 (78%) peripheral vascular events in 12 886 (14%) individuals aged 65 years or older; and 503 (54%), 402 (47%), and 105 (56%), respectively, in the 5919 (6%) aged 75 years or older. Although case-fatality rates increased with age, 736 (47%) of 1561 non-fatal events occurred at age 75 years or older.

INTERPRETATION

The high rates of acute vascular events outside the coronary arterial territory and the steep rise in event rates with age in all territories have implications for prevention strategies, clinical trial design, and the targeting of funds for service provision and research.

Absence of Microemboli on Transcranial Doppler Identifies Low-Risk Patients With Asymptomatic Carotid Stenosis

Background and Purpose— Carotid endarterectomy clearly benefits patients with symptomatic severe stenosis (SCS), but the risk of stroke is so low for asymptomatic patients (ACS) that the number needed to treat is very high. We studied transcranial Doppler (TCD) embolus detection as a method for identifying patients at higher risk who would have a lower number needed to treat.

Methods— Patients with carotid stenosis of ≥60% by Doppler ultrasound who had never been symptomatic (81%) or had been asymptomatic for at least 18 months (19%) were studied with TCD embolus detection for up to 1 hour on 2 occasions a week apart; patients were followed for 2 years.

Results— 319 patients were studied, age (standard deviation) 69.68 (9.12) years; 32 (10%) had microemboli at baseline (TCD+). Events were more likely to occur in the first year. Patients with microemboli were much more likely to have microemboli 1 year later (34.4 versus 1.4%; P <0.0001) and were more likely to have a stroke during the first year of follow-up (15.6%, 95% CI, 4.1 to 79; versus 1%, 95% CI, 1.01 to 1.36; P <0.0001).

Conclusions— Our findings indicate that TCD− ACS will not benefit from endarterectomy or stenting unless it can be done with a risk <1%; TCD+ may benefit as much as SCS if their surgical risk is not higher. These findings suggest that ACS should be managed medically with delay of surgery or stenting until the occurrence of symptoms or emboli.

Magnetic resonance brain imaging in patients with acute stroke: feasibility and patient related difficulties

OBJECTIVES

To assess organisational and patient specific limitations and safety of magnetic resonance imaging (MRI) as the first line investigation for hospital admitted stroke patients.

METHODS

Consecutive patients admitted with acute stroke were assessed and an attempt was made to perform MRI in all patients. Oxygen saturation and interventions required during scanning were recorded.

RESULTS

Among 136 patients recruited over 34 weeks, 85 (62%) underwent MRI. The patients' medical instability (15 of the 53 not scanned), contraindications to MRI (six of the 53 not scanned), and rapid symptom resolution (10 of the 53 not scanned) were the main reasons for not performing MRI. Of the 85 patients who underwent MRI, 26 required physical intervention, 17 did not complete scanning, and 11 of the 61 who had successful oxygen saturation monitoring were hypoxic during MRI. Organisational limitations accounted for only 13% of failures to scan.

CONCLUSIONS

Up to 85% of hospital admitted acute stroke patients could have MRI as first line imaging investigation, but medical instability is the major limitation. Hypoxia is frequent in MRI. Patients should be monitored carefully, possibly by an experienced clinician, during scanning.

Poststroke dementia

Dementia is one of the major causes of dependency after stroke. The prevalence of poststroke dementia (PSD)-defined as any dementia occurring after stroke-is likely to increase in the future. In community-based studies, the prevalence of PSD in stroke survivors is about 30% and the incidence of new onset dementia after stroke increases from 7% after 1 year 48% after 25 years. Having a stroke doubles the risk of dementia. Patient-related variables associated with an increased risk of PSD are increasing age, low education level, dependency before stroke, prestroke cognitive decline without dementia, diabetes mellitus, atrial fibrillation, myocardial infarction, epileptic seizures, sepsis, cardiac arrhythmias, congestive heart failure, silent cerebral infarcts, global and medial-temporal-lobe atrophy, and white-matter changes. Stroke-related variables associated with an increased risk of PSD are stroke severity, cause, location, and recurrence. PSD might be the result of vascular lesions, Alzheimer pathology, white-matter changes, or combinations of these. The cause of PSD differs among studies in relation to the mean age of patients, ethnicity, criteria used, and time after stroke. In developed countries, the proportion of patients with presumed Alzheimer's disease among those with PSD is between 19% and 61%. Patients with PSD have high mortality rates and are likely to be functionally impaired. These patients should be treated according to the current guidelines for stroke prevention.

Trends in Stroke Incidence in Auckland, New Zealand, During 1981 to 2003

BACKGROUND AND PURPOSE

Long-term trends in stroke incidence in different populations have not been well characterized, largely as a result of the complexities associated with population-based stroke surveillance.

METHODS

We assessed temporal trends in stroke incidence using standard diagnostic criteria and community-wide surveillance procedures in the population (approximately 1 million) of Auckland, New Zealand, over 12-month calendar periods in 1981-1982, 1991-1992, and 2002-2003. Age-adjusted first-ever (incident) and total (attack) rates, and temporal trends, were reported with 95% confidence intervals (CIs). Rates were analyzed by sex and major age groups.

RESULTS

From 1981 to 1982, stroke rates were stable in 1991-1992 and then declined in 2002-2003, to produce overall modest declines in standardized incidence (11%; 95% CI, 1 to 19%) and attack rates (9%; 95% CI, 0 to 16%) between the first and last study periods. Some favorable downward trends in vascular risk factors such as cigarette smoking were counterbalanced by increasing age and body mass index, and frequency of diabetes, in patients with stroke.

CONCLUSIONS

There has been a modest decline in stroke incidence in Auckland over the last 2 decades, mainly during 1991 to 2003, in association with divergent trends in major risk factors.

Thyroid diseases and cerebrovascular disease

BACKGROUND AND PURPOSE

Acute cerebral ischemia has been described in different diseases of the thyroid gland, and not only as a result of thyrotoxic atrial fibrillation and cardioembolic stroke. The purpose of this review is to summarize the studies on the relationship between thyroid diseases and cerebrovascular diseases, discussing the main findings for overt hyperthyroidism and hypothyroidism, as well as for subclinical thyroid dysfunction.

SUMMARY OF REVIEW

In overt hyperthyroidism, cardioembolic stroke is clearly associated to thyrotoxic atrial fibrillation, and in subclinical hyperthyroidism with serum thyroid-stimulating hormone levels <0.1 mU/L, the incidence of atrial fibrillation is increased. Although in vitro and in vivo studies indicate a hypercoagulability state in hyperthyroidism, there is insufficient evidence to prove that this state leads to an increased risk of cardiac emboli. However, the hypothesis that overt hyperthyroidism may cause acute cerebral venous thrombosis is intriguing. Possible associations between hyperthyroidism and Moyamoya or Giant cell arteritis have only been described in case reports. There is enough evidence that overt hypothyroidism is associated with several traditional and newer atherosclerotic risk factors, especially hypertension, hyperlipidemia, and hyperhomocysteinemia. For subclinical hypothyroidism, these associations are less certain. Hypothyroidism has been associated with signs of aortic or coronary atherosclerosis, but no case-control or cohort studies have ever investigated hypothyroidism as a possible risk factor for atherothrombotic stroke.

CONCLUSIONS

Hyperthyroidism is associated with atrial fibrillation and cardioembolic stroke. Hypothyroidism is associated with a worse cardiovascular risk factor profile and leads to progression of atherosclerosis. Associations between hyperthyroidism and acute cerebral venous thrombosis, Moyamoya, and Giant cell arteritis have been suggested, but sound evidence is lacking. Additional studies are needed to clarify these issues.

Trends in mortality and hospital admission rates for abdominal aortic aneurysm in England and Wales, 1979-1999

BACKGROUND

The aim of this study was to investigate trends in population-based mortality, hospital admission and case fatality rates for abdominal aortic aneurysm (AAA) from 1979 to 1999.

METHODS

This was an analysis of routine statistics from 79 495 death certificates in England and Wales and 3217 hospital inpatient admissions in the Oxford Region.

RESULTS

Mortality rates for all AAAs increased between 1979 and 1999 from 13 to 25 per million in women and from 80 to 115 per million in men. Admission rates increased in the same time interval from three to 22 admissions per million per year in women, and from 52 to 149 per million per year in men. Case fatality rates for all non-ruptured AAAs that were operated on decreased from 25.8 to 9.0 per cent and for all ruptured AAAs from 69.9 to 54.4 per cent.

CONCLUSION

Mortality rates and hospital admission rates for AAA rose in men and even more so in women between 1979 and 1999. Perioperative mortality for ruptured AAA declined a little during the study but nonetheless was still very high at the end. This reinforces the importance of detecting and treating AAA before rupture occurs.