Marked increase of stroke incidence in men between 1972 and 1990 in Frederiksberg, Denmark

Diverging Temporal Trends in Stroke Incidence in Younger vs Older People: A Systematic Review and Meta-analysis

IMPORTANCE

Overall stroke incidence is falling in high-income countries, but data on time trends in incidence of young stroke (ie, stroke in individuals younger than 55 years) are conflicting. An age-specific divergence in incidence, with less favorable trends at younger vs older ages, might be a more consistent underlying finding across studies.

OBJECTIVE

To compare temporal trends in incidence of stroke at younger vs older ages in high-income countries.

DATA SOURCES

PubMed and EMBASE were searched from inception to February 2022. One additional population-based study (Oxford Vascular Study) was also included.

STUDY SELECTION

Studies reporting age-specific stroke incidence in high-income countries at more than 1 time point.

DATA EXTRACTION AND SYNTHESIS

For all retrieved studies, 2 authors independently reviewed the full text against the inclusion criteria to establish their eligibility. Meta-analysis was performed with the inverse variance-weighted random-effects model. Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline was followed.

MAIN OUTCOMES AND MEASURES

The main outcome was age-specific divergence (<55 vs ≥55 years) in temporal trends in stroke incidence (relative temporal rate ratio [RTTR]) in studies extending to at least 2000. RTTRs were calculated for each study and pooled by random-effects meta-analysis, with stratification by administrative vs prospective population-based methodology, sex, stroke subtype (ischemic vs intracerebral hemorrhage vs subarachnoid hemorrhage) and geographical region.

RESULTS

Among 50 studies in 20 countries, 26 (13 prospective population-based and 13 administrative studies) reported data allowing calculation of the RTTR for stroke incidence at younger vs older ages across 2 or more periods, the latest extending beyond 2000. Reported trends in absolute incidence of young individuals with stroke were heterogeneous, but all studies showed a less favorable trend in incidence at younger vs older ages (pooled RTTR = 1.57 [95% CI, 1.42-1.74]). The overall RTTR was consistent by stroke subtype (ischemic, 1.62 [95% CI, 1.44-1.83]; intracerebral hemorrhage, 1.32 [95% CI, 0.91-1.92]; subarachnoid hemorrhage, 1.54 [95% CI, 1.00-2.35]); and by sex (men, 1.46 [95% CI, 1.34-1.60]; women, 1.41 [95% CI, 1.28-1.55]) but was greater in studies reporting trends solely after 2000 (1.51 [95% CI, 1.30-1.70]) vs solely before (1.18 [95% CI, 1.12-1.24]) and was highest in population-based studies in which the most recent reported period of ascertainment started after 2010 (1.87 [95% CI, 1.55-2.27]).

CONCLUSIONS AND RELEVANCE

Temporal trends in stroke incidence are diverging by age in high-income countries, with less favorable trends at younger vs older ages, highlighting the urgent need to better understand etiology and prevention of stroke at younger ages.

Epidemiology of intracerebral hemorrhage: A systematic review and meta-analysis

Background

Intracerebral hemorrhage (ICH) is associated with high mortality and disability rates. This study aimed to investigate the relationship between sex, age, study year, risk factors, bleeding site, median year of study, and the incidence of ICH.

Method

Literature on the incidence of ICH published on 1 January 1980 and 1 January 2020, was systematically retrieved from PubMed and Embase databases. The random-effects model and subgroup analysis were used to explore the relationship between the incidence of ICH and different ages, sex, bleeding sites, and risk factors.

Results

We summarized the epidemiological changes in ICH in the past 40 years according to 52 studies and found that the total incidence of ICH is 29.9 per 100,000 person-years (95% CI: 26.5–33.3), which has not decreased worldwide. The incidence of ICH in the Asian population is much higher than in other continents. In addition, the incidence of ICH increases with age and differs at the 85-year-old boundary. Men are more likely to develop ICH than women, and the basal ganglia region is the most common area for ICH. Of the 10 risk factors examined in this study, those with hypertension had the highest incidence of ICH, followed by those with excessive alcohol consumption and heart disease.

Conclusion

The prevention and treatment of ICH still need to be improved continuously according to age, sex, risk factors, and other factors, and targeted and normative strategies should be gradually developed in the future.

Worldwide Incidence of Aneurysmal Subarachnoid Hemorrhage According to Region, Time Period, Blood Pressure, and Smoking Prevalence in the Population: A Systematic Review and Meta-analysis

Importance

Subarachnoid hemorrhage (SAH) from ruptured intracranial aneurysms is a subset of stroke with high fatality and morbidity. Better understanding of a change in incidence over time and of factors associated with this change could facilitate primary prevention.

Objective

To assess worldwide SAH incidence according to region, age, sex, time period, blood pressure, and smoking prevalence.

Data Sources

We searched PubMed, Web of Science, and Embase for studies on SAH incidence published between January 1960 and March 2017. Worldwide blood pressure and smoking prevalence data were extracted from the Noncommunicable Disease Risk Factor and Global Burden of Disease data sets.

Study Selection

Population-based studies with prospective designs representative of the entire study population according to predefined criteria.

Data Extraction and Synthesis

Two reviewers independently extracted data according to PRISMA guidelines. Incidence of SAH was calculated per 100 000 person-years, and risk ratios (RRs) including 95% CIs were calculated with multivariable random-effects binomial regression. The association of SAH incidence with blood pressure and smoking prevalence was assessed with linear regression.

Main Outcomes and Measures

Incidence of SAH.

Results

A total of 75 studies from 32 countries were included. These studies comprised 8176 patients with SAH were studied over 67 746 051 person-years. Overall crude SAH incidence across all midyears was 7.9 (95% CI, 6.9-9.0) per 100 000 person-years; the RR for women was 1.3 (95% CI, 0.98-1.7). Compared with men aged 45 to 54 years, the RR in Japanese women older than 75 years was 2.5 (95% CI, 1.8-3.4) and in European women older than 75 years was 1.5 (95% CI, 0.9-2.5). Global SAH incidence declined from 10.2 (95% CI, 8.4-12.5) per 100 000 person-years in 1980 to 6.1 (95% CI, 4.9-7.5) in 2010 or by 1.7% (95% CI, 0.6-2.8) annually between 1955 and 2014. Incidence of SAH declined between 1980 and 2010 by 40.6% in Europe, 46.2% in Asia, and 14.0% in North America and increased by 59.1% in Japan. The global SAH incidence declined with every millimeter of mercury decrease in systolic blood pressure by 7.1% (95% CI, 5.8-8.4) and with every percentage decrease in smoking prevalence by 2.4% (95% CI, 1.6-3.3).

Conclusions and Relevance

Worldwide SAH incidence and its decline show large regional differences and parallel the decrease in blood pressure and smoking prevalence. Understanding determinants for regional differences and further reducing blood pressure and smoking prevalence may yield a diminished SAH burden.

Diagnostic accuracy of flair in detection of acute subarachnoid hemorrhage in patients presenting with severe headache

BACKGROUND

Fluid attenuation inversion recovery (FLAIR) magnetic resonance imaging (MRI) sequences are previously described for the evaluation of acute subarachnoid hemorrhage (SAH) and demonstrated good sensitivity. This study was designed to find the diagnostic accuracy of FLAIR in detection of acute SAH in patients presenting with severe headache considering the fact that controversy has been observed in previous studies.

OBJECTIVE

To determine diagnostic accuracy of FLAIR in detection of acute subarachnoid hemorrhage in patients presenting with severe headache using lumber puncture as gold standard.

METHODOLOGY

A total of 245 patients fulfilling selection criteria were enrolled in the study through the emergency department of Combined Military Hospital, Lahore. MRI was performed by Philips Intera Achieva 1.5T super conducting MR unit (Philips Medical Systems, the Netherlands), with the use of a head coil. FLAIR examination was performed at 6700/150 (TR/TE) with an inversion time (TI) of 2200ms, a field of view 230mm, matrix 189×256, scan time of 3min 50s and section thickness 5mm in axial plane. Following MRI, patients underwent lumbar puncture for cerebrospinal fluid (CSF) examination after 8-12h from the onset of event. MRI and CSF analysis results were then compared.

RESULTS

Out of 245 cases, 49.39% (n=121) were between 20-55 years of age while 50.61% (n=124) were between 56-70 years of age, mean±sd was calculated as 52.13±10.45 years, 53.88% (n=132) were male while 46.12% (n=113) were females, frequency of acute subarachnoid hemorrhage in patients presenting with severe headache was recorded as 5.71%(n=14), diagnostic accuracy of FLAIR in detection of acute subarachnoid hemorrhage in patients presenting with severe headache taking lumbar puncture as gold standard as 78.57% sensitivity, 96.53% specificity, 57.89% positive predictive value, 98.67% negative predictive value and accuracy rate was calculated as 95.29%.

CONCLUSION

Diagnostic accuracy of FLAIR in detection of acute subarachnoid hemorrhage in patients presenting with severe headache taking lumbar puncture as gold standard is higher and reliable.

Incidence of Hospitalized Stroke in the Czech Republic: The National Registry of Hospitalized Patients

BACKGROUND

Contemporary stroke incidence data are not available in some countries and regions, including in Eastern Europe. Based on previous validation of the accuracy of the National Registry of Hospitalized Patients (NRHOSP), we report the incidence of hospitalized stroke in the Czech Republic (CR) using the NRHOSP.

METHODS

The results of the prior validation study assessing the accuracy of coding of stroke diagnoses in the NRHOSP were applied, and we calculated (1) the overall incidence of hospitalized stroke and (2) the incidence rates of hospitalized stroke for the three main stroke types: cerebral infarction (International Classification of Diseases Tenth Revision, CI I63), subarachnoid hemorrhage (SAH I60), and intracerebral hemorrhage (ICH I61). We calculated the average annual age- and sex-standardized incidence.

RESULTS

The overall incidence of hospitalized stroke was 241 out of 100,000 individuals. The incidence of hospitalized stroke for the main stroke types was 8.2 cases in SAH, 29.5 in ICH, and 211 in CI per 100,000 individuals. The standardized annual stroke incidence adjusted to the 2000 World Health Organization population for overall stroke incidence of hospitalized stroke was 131 per 100,000 individuals. Standardized stroke incidence for stroke subtypes was 5.7 cases in SAH, 16.7 in ICH, and 113 in CI per 100,000 individuals.

CONCLUSIONS

These studies provide an initial assessment of the burden of stroke in this part of the world. The estimates of hospitalized stroke in the CR and Eastern Europe suggest that ICH is about three times more common than SAH, and hemorrhagic stroke makes up about 18% of strokes.

First-ever stroke following hip replacement surgeries: a large population-based survey

OBJECTIVE

This study was designed to determine the prevalence, subtypes and risk factors of first-ever stroke following hip replacement (HR) in a large population of Taiwan.

METHODS

Using the National Health Insurance system of Taiwan, we identified patients undergoing HR from 2000 to 2011 and randomly selected 4 : 1 age- and sex-matched controls for each HR patients. The index date for HR patients was defined the date for HR. All study subjects were followed from the index date until stroke occurred at admission. T-test and chi-square test were used for continuous and categorical variables, respectively. The hazard ratios of risk factors were determined with Cox proportional hazard regression model.

RESULTS

A total of 3604 HR patients and 14 394 controls were enrolled. In comparison with controls, patients undergoing HR had a significantly higher incidence of comorbidities (i.e. atrial fibrillation, hypertension, diabetes) and consumed more medications (i.e. antihypertension, antidiabetes, nonsteroid anti-inflammatory drugs and anticoagulants) before surgery. The HR patients had a significant higher incidence of first-ever stroke, especially for those aged over 65. (Hazard ratio: 1·33, 95% confidence interval: 1·12-1·58) The significantly higher risk for first-ever stroke occurred within 3 months and ≥ 1 year after HR. The incidence rate of ischaemic stroke is about five times than that of haemorrhagic stroke.

CONCLUSION

Our study identifies multiple risk factors that cause cerebrovascular complications after HR, which is vital in creating treatment plans to prevent for said problems.

Increased incidence of subarachnoid hemorrhage during cold temperatures and influenza epidemics

OBJECTIVE

This study investigated whether the increased incidence of aneurysmal subarachnoid hemorrhage (SAH) in winter is related to temperature or increased incidence of influenza. Such relationships may elucidate the pathogenesis of intracranial aneurysm rupture.

METHODS

A nationwide sample of 18,714 patients with SAH was linked with weekly temperature and influenza-like illness consultation data. Poisson regression analyses were used to calculate incidence density ratios (IDRs) with corresponding 95% CIs for the association of SAH incidence with temperature and influenza epidemics; IDRs were adjusted for study year (aIDR). In addition, SAH incidence data from 30 European population-based studies were linked with daily temperature data from the European Climate Assessment.

RESULTS

The aIDR for SAH during influenza epidemics was 1.061 (95% CI 1.022–1.101) in the univariable and 1.030 (95% CI 0.989–1.074) in the multivariable analysis. This association declined gradually during the weeks after epidemics. Per 1°C temperature drop, the aIDR was 1.005 (95% CI 1.003–1.008) in the univariable and 1.004 (95% CI 1.002–1.007) in the multivariable analysis. In the European population-based studies, the IDR was 1.143 (95% CI 1.129–1.157) per 1°C temperature drop.

CONCLUSIONS

The incidence of SAH is increased during cold temperatures and epidemic influenza. Future studies with individual patient data are needed to investigate causality between temperature or influenza and SAH.

Risk of Stroke in Migraineurs Using Triptans. Associations with Age, Sex, Stroke Severity and Subtype

BACKGROUND

Identifying migraineurs by triptan utilization we studied risk for stroke in migraineurs compared to the general population.

METHODS

A cohort study including all citizens 25-80years of age in Denmark 2003-2011 was conducted. All persons prescribed triptans, and all those hospitalized for a first stroke were identified in the Danish Registries. Information on stroke severity/subtype and cardiovascular risk factors was available for stroke patients.

FINDINGS

Of the 49,711 patients hospitalized for a first stroke, 1084 were migraineurs using triptans. Adjusting for age, sex, income, and educational level, risk for stroke was higher among migraineurs in respect to all strokes (RR 1.07; CI 1.01-1.14) and ischemic strokes (RR 1.07; CI 1.00-1.14). Risk for hemorrhagic stroke was increased but only in women (RR 1.41; CI 1.11-1.79). Risk was for mild strokes (RR 1.31; CI 1.16-1.48) while risk for severe strokes was lower among migraineurs (RR 0.77; CI 0.65-0.91). Risk was age-related; highest among women 25-45years (RR≈1.7). Risk was unrelated to numbers of dispensations.

INTERPRETATION

Migraineurs identified by triptan utilization had higher risk for stroke. Strokes were minor and cardiovascular risk factors were less prevalent pointing to a migraine-specific etiology of stroke different from that of thromboembolism.

The obesity paradox in stroke: lower mortality and lower risk of readmission for recurrent stroke in obese stroke patients

BACKGROUND

Although associated with excess mortality and morbidity, obesity is associated with lower mortality after stroke. The association between obesity and risk of recurrent stroke is unclear.

AIMS

The study aims to investigate the association in stroke patients between body mass index and risk of death and readmission for recurrent stroke.

METHODS

An administrative Danish quality-control registry designed to collect a predefined dataset on all hospitalized stroke patients in Denmark 2000–2010 includes 45 615 acute first-ever stroke patients with information on body mass index in 29 326. Data include age, gender, civil status, stroke severity, computed tomography, and cardiovascular risk factors. Patients were followed up to 9·8 years (median 2·6 years). We used Cox regression models to compare risk of death and readmission for recurrent stroke in the four body mass index groups: underweight (body mass index < 18·5), normal weight (body mass index 18·5–24·9), overweight (body mass index 25·0–29·9), obese (body mass index ≥ 30·0).

RESULTS

Mean age 72·3 years, 48% women. Mean body mass index 23·0. Within follow-up, 7902 (26·9%) patients had died; 2437 (8·3%) were readmitted because of recurrent stroke. Mortality was significantly lower in overweight (hazard ratio 0·72; confidence interval 0·68–0·78) and obese (hazard ratio 0·80; confidence interval 0·73–0·88) patients while significantly higher in underweight patients (hazard ratio 1·66; confidence interval 1·49–1·84) compared with normal weight patients. Risk of readmission for recurrent stroke was significantly lower in obese than in normal weight patients (hazard ratio 0·84; confidence interval 0·72–0·92).

CONCLUSIONS

Obesity was not only associated with reduced mortality relative to normal weight patients. Compared with normal weight, risk of readmission for recurrent stroke was also lower in obese stroke patients.

Risk factors of stroke in Western and Asian countries: a systematic review and meta-analysis of prospective cohort studies

Background

There has been an increasing trend in the incidence of stroke worldwide in recent years, and the number of studies focusing on the risk factors for stroke has also increased every year. To comprehensively evaluate the risk factors of stroke identified in prospective Western and Asian cohort studies.

Methods

Population-based cohort studies on stroke were searched in databases (PubMed, EMBASE, Web of Science, Google Scholar, etc.), and the library of the Third Military Medical University was manually searched for relevant information. A meta-analysis of Western and Asian studies on risk factors was performed. The pooled hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated to assess the final group of cohort studies.

Results

After screening, 22 prospective cohort studies were included in the analyses of this investigation. Two factors, smoking and alcohol consumption, showed statistically significant differences between Western and Asian populations, and the results were as follows (W/A): 2.05 (95% CI, 1.68 ~ 2.49)/1.27 (95% CI, 1.04 ~ 1.55) and 0.89 (95% CI, 0.76 ~ 1.04)/1.28 (95% CI, 1.07 ~ 1.53). The factor BMI = 18.5-21.9 kg/m² showed statistically significant differences only in Western populations, 0.96 (95% CI, 0.93 ~ 0.99); the factor SBP = 120-139 mm Hg showed statistically significant differences only in Asian populations, 2.29 (95% CI, 1.04 ~ 5.09).

Conclusions

The prevalences of risk factors affect the stroke morbidity in Western and Asian populations, which may be biased by race. The meta-analysis of population-based studies suggests that different preventive measures should be adopted for Western and Asian population groups that are at high risk for stroke.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2458-14-776) contains supplementary material, which is available to authorized users.

Socioeconomic position and incidence of ischemic stroke in Denmark 2003-2012. A nationwide hospital-based study

BACKGROUND

A greater burden of stroke risk factors in general is associated with a higher risk for stroke among people of lower than those of higher socioeconomic position. The relative impact of individual stroke risk factors is still unclear.

METHODS AND RESULTS

We studied the relations between socioeconomic position, measured as household income and length of education, and all hospital admissions for a first ischemic stroke among 54 048 people over the age of 40 years in Denmark in 2003-2012 in comparison with the general Danish population (23.5 million person-years). We also studied the cardiovascular risk factor profile associated with socioeconomic position in stroke patients. Relative risks for stroke were estimated in log-linear Poisson regression models. The risk for hospitalization for a first ischemic stroke was almost doubled for people in the lowest income group, and the risk of those of working age (<65 years) was increased by 36% among people with the shortest education. Diabetes, obesity, smoking, and high alcohol consumption in particular and, to a lesser extent, previous myocardial infarction or intermittent arterial claudication were significantly overrepresented among stroke patients with lower socioeconomic position. Atrial fibrillation and hypertension were not.

CONCLUSIONS

In Denmark, there is a strong relation between low socioeconomic position and risk for hospitalization for stroke. Lifestyle, as indicated by smoking, obesity, and alcohol consumption, and diabetes appears to increase the risk for stroke in people with lower socioeconomic position.

Use of oral anticoagulation therapy in atrial fibrillation after stroke: results from a nationwide registry

Background. The knowledge is still sparse about patient related factors, influencing oral anticoagulation therapy (OAC) rates, in stroke patients with atrial fibrillation (AF). Aims. To assess the use of OAC in ischemic stroke patients diagnosed with AF and to identify patient related factors influencing the initiation of OAC. Methods. In the nationwide Danish Stroke Registry we identified 55,551 patients admitted with acute ischemic stroke from 2003 to 2011. Frequency analysis was used to assess the use of OAC in patients with AF, and logistic regression was used to determine independent predictors of OAC. Results. 17.1% (n = 9,482) of ischemic stroke patients had AF. OAC prescription rates were increasing, and in 2011 46.6% were prescribed OAC, 42.5% had a contraindication, and 3.7% were not prescribed OAC without a stated contraindication. Younger age, less severe stroke, and male gender were positive predictors of OAC, while excessive alcohol consumption, smoking, and institutionalization were negative predictors of OAC (P values < 0.05). Conclusions. Advanced age, severe stroke, female gender, institutionalization, smoking, and excessive alcohol consumption were associated with lower OAC rates. Contraindications were generally present in patients not in therapy, and the assumed underuse of OAC may be overestimated.

Temporal trends in stroke admissions in Denmark 1997-2009

Background

The Stroke burden is increasing in many populations where health institutions may experience more patients. We wanted to examine whether incidence rates and absolute number of hospitalized stroke patients remained stable in Denmark during a 13 years period where exposure to major stroke risk factors decreased, changes in stroke treatment was implemented, and the age of the population increased.

Methods

The Danish National Patient Register was used to identify all subjects 25 years of age or above admitted with a first time stroke in Denmark from 1997–2009. Incidence rates (IRs) and age-adjusted Poisson regression analyses were used to examine trends in age-, gender- and stroke subtype (ischaemic or unspecified).

Results

During the 13-year observation period there were 53.5 million person-years at risk (PY) and a total of 84,626 male and 84,705 female stroke patients were admitted to Danish hospitals. The IRs of hospitalized strokes per 1000 PY was 3.21 (95% confidence interval [CI] 3.16-3.27) in 1997, 3.85 (95% CI 3.79-3.91) in 2003 and 3.22 (95% CI 3.16-3.28) in 2009, respectively.

Incidence rate ratios of hospitalized stroke events adjusted for age in the period 2007–2009 compared to 1997–2000 were 0.89 (95% CI 0.87- 0.91) for men and 0.92 (95% CI 0.90-0.94) for women.

The incidence of hospitalized unspecified strokes decreased from 1997 to 2009 whereas there was a steep rise in incidence for hospitalization with specified ischemic stroke during this period.

Conclusion

This study found a constant rate of stroke hospitalization in Denmark from 1997–2009. The overall rate of hospitalized strokes adjusted for age decreased during this period.

Trends in stroke survival incidence rates in older Australians in the new millennium and forecasts into the future

AIMS

The objective of this study is (i) to evaluate trends in the incidence rates of stroke survivors aged 60 years and older over a 11-year period in the Australian Capital Territory (ACT) and (ii) to forecast future trends in Australia until 2051.

METHODS

Analysis of age- and sex-specific standardized incidence rates of older first-ever stroke survivors in ACT from 1999-2000 to 2009-2010 and projections of number of stroke survivors (NSS) in 2021 and 2051 using 2 models based only on (i) demographic changes and (ii) assuming changing of both incidence rates and demography.

RESULTS

In the ACT in the first decade of the 21st century, the absolute numbers and age-adjusted standardized incidence rates of stroke survivors (measured as a function of age and period) increased among both men and women aged 60 years or older. The trend toward increased survival rates in both sexes was driven mainly by population aging, whereas the effect of stroke year was more pronounced in men compared with women. The absolute NSS (and the financial burden to the society) in Australia is predicted to increase by 35.5%-59.3% in 2021 compared with 2011 and by 1.6- to 4.6-fold in 2051 if current only demographic (first number) or both demographic and incidence trends (second number) continue.

CONCLUSIONS

Our study demonstrates favorable trends in stroke survivor rates in Australia in the first decade of the new millennium and projects in the foreseeable future significant increases in the absolute numbers of older stroke survivors, especially among those aged 70 years or older and men.

Body mass index and stroke: overweight and obesity less often associated with stroke recurrence

BACKGROUND

Although obesity is associated with excess mortality and morbidity, mortality is lower in obese than in normal weight stroke patients (the obesity paradox). Studies now indicate that obesity is not associated with increased risk of recurrent stroke in the years after first stroke. We studied the association between body mass index (BMI) and stroke patient's risk of having a history of previous stroke (recurrent stroke).

METHODS

A registry designed to collect data on all hospitalized stroke patients in Denmark 2000-2010 includes 61,872 acute stroke patients with information on BMI in 38,506. Data include age, sex, civil status, stroke severity (Scandinavian Stroke Scale), computed tomography, and cardiovascular risk factors. There were 28,382 patients with complete covariate information. We used multiple logistic regression models on this data set to compare the risk of stroke being recurrent in the 4 BMI groups: underweight (BMI<18.5), normal weight (BMI 18.5-24.9), overweight (BMI 25.0-29.9), and obese (BMI≥30.0).

RESULTS

Of the patients with complete covariate information, 22,811 (80.1%) had first-ever stroke; in 5571 patients (19.6%), stroke was recurrent. Multiple logistic regression analysis adjusting for age, stroke severity, sex, BMI, civil status, and cardiovascular risk factors showed that being obese and overweight in comparison with normal weight was associated with a significantly lower risk of stroke being recurrent (obese: odds ratio [OR]=.90, confidence interval [CI] .82-.98; overweight: OR=.89, CI .83-.96). Being underweight was associated with a significantly higher risk of stroke being recurrent (OR=1.23; CI 1.06-1.43).

CONCLUSIONS

The obesity paradox in stroke can be extended to include also stroke recurrence. Obese and overweight stroke patients had experienced less previous strokes than normal weight stroke patients.

Cause-specific mortality after stroke: relation to age, sex, stroke severity, and risk factors in a 10-year follow-up study

We investigated cause-specific mortality in relation to age, sex, stroke severity, and cardiovascular risk factor profile in the Copenhagen Stroke Study cohort with 10 years of follow-up. In a Copenhagen community, all patients admitted to the hospital with stroke during 1992-1993 (n = 988) were registered on admission. Evaluation included stroke severity, computed tomography scan, and a cardiovascular risk profile. Cause of death within 10 years according to death certificate information was classified as stroke, heart/arterial disease, or nonvascular disease. Competing-risks analyses were performed by cause-specific Cox regression after multiple imputation of missing data, assuming that values were missing at random. Death was due to stroke in 310 patients (31%), to heart/arterial disease in 209 patients (21%), and to nonvascular diseases in 289 patients (29%); 180 patients were still alive after 10 years (18%). Stroke was the dominant cause of death during first year, with an absolute risk of 20.2% versus 5.2% for heart/arterial disease and 6.5% for nonvascular disease. The subsequent absolute risk of death per year was 2.8% for stroke, 4.5% for heart/arterial disease, and 5.2% for nonvascular disease. Death after stroke was associated with older age, male sex, greater stroke severity, and diabetes regardless of the cause of death. Previous stroke and hemorrhagic stroke were associated with death by stroke, ischemic heart disease was associated with death by heart/arterial disease and atrial fibrillation was associated with death by cardiovascular disease (stroke or heart/arterial disease). Hypertension, smoking, and alcohol consumption were not associated with cause-specific death.

Explaining poorer stroke outcomes in women: women surviving 3 months have more severe strokes than men despite a lower 3-month case fatality

BACKGROUND

Women who survive stroke are more disabled and more often institutionalized than men.

OBJECTIVE

We explore this phenomenon by studying case fatality and stroke severity in stroke survivors separately for men and women.

METHODS

A Danish stroke registry (2000-2007) contains information about 26,818 patients with first-ever ischemic stroke, including stroke severity (Scandinavian Stroke Scale, 0 worst to 58 best), computed tomography scan, cardiovascular risk factors, and death 3 months after stroke. We modeled stroke severity by generalized additive linear model and 3-month case fatality with logistic model adjusting for age and cardiovascular risk factors.

RESULTS

Male to female ratio was 51.5% to 48.5%. Mean age was 68.8 (SD 12.6) years in men; 73.7 (13.8) years in women. Stroke was more severe in women (mean [SD] Scandinavian Stroke Scale, 42.2 [16.0]) than in men (mean [SD] Scandinavian Stroke Scale, 45.6 [14.2]) also after adjustment for age and cardiovascular risk factors; significant in patients older than 75 years. In survivors at 3 months, stroke was more severe in women than men, given same age and cardiovascular risk factor profile; significant in patients older than 75 years. More women (11.9%) had died within 3 months than men (8.6%). However, adjusting for age, stroke severity, and risk factor profile, 3-month case fatality was lower in women than men; significant in patients older than 78 years.

CONCLUSIONS

Although 3-month case fatality was lower in women than men, strokes were more severe among survivors at 3 months in women than in men. In addition, strokes were more severe in women. Our data help elucidate why women survive stroke better but have poorer functional outcomes that require more care than men.

Seasonality, incidence and prognosis in atrial fibrillation and stroke in Denmark and New Zealand

OBJECTIVES

There are relatively few large studies of seasonal variation in the occurrence of stroke in patients with atrial fibrillation (AF). We investigated the seasonal variation in incidence rates of hospitalisation with stroke in patients from Denmark and New Zealand.

DESIGN

Cohort study.

SETTING

Nationwide hospital discharge data from Denmark and New Zealand.

PARTICIPANTS

243 381 (median age 75) subjects having a first-time hospitalisation with AF in Denmark and 51 480 (median age 76) subjects in New Zealand constituted the study population. Subjects with previous hospitalisation with stroke were excluded. PRIMARY AND SECONDARY EFFECT MEASURES: Peak-to-trough ratio of the seasonal variation in incidence rates of stroke in AF patients adjusted for an overall trend was primary effect measure and was assessed using a log-linear Poisson regression model. Secondary effect measures were incidence rate ratios of AF and 30-day case fatality for stroke patients.

RESULTS

Incidence rates of AF per 1000 person-years in Denmark increased by 5.4% (95% CI 5.3% to 5.7%) for patients aged <65 and 5% (95% CI 4.9% to 5.1%) for patients aged ≥65, whereas the increase was 0.2% (95% CI -0.2% to 0.6%) for patients aged <65 and 2.6% (95% CI 2.4% to 2.8%) for patients aged ≥65 in New Zealand. In Denmark 36 088 subjects were hospitalised with stroke, and 7518 subjects in New Zealand, both showing peaks during winter with peak-to-trough ratios of 1.22 and 1.27, respectively and a decreasing trend. The 30-day case fatality risk for stroke patients having AF is now (2000-2008) about 20% in both countries.

CONCLUSIONS

Although incidence rates of hospitalisation with stroke in patients with AF have decreased in recent years, stroke remains a common AF complication with a high case fatality risk. The marked winter peak in incidence rates of hospitalisation with stroke in AF patients suggests that there are opportunities to reduce this complication. Further studies are necessary to identify how to optimise treatment of AF and prevention of stroke.

Age trajectories of stroke case fatality: leveling off at the highest ages

BACKGROUND

Mortality rates level off at older ages. Age trajectories of stroke case-fatality rates were studied with the aim of investigating prevalence of this phenomenon, specifically in case-fatality rates at older ages.

METHODS

A registry of all hospitalized stroke patients in Denmark included 40,155 patients with evaluations of stroke severity, computed tomography, and cardiovascular risk factors. Data on mortality were used to construct age trajectories of 3-day, 1-week, 1-month, and 1-year case-fatality rates in men and women.

RESULTS

Of the 40,155 patients, 19,301 (48%) were women (mean age, 74.5 years) and 20,854 (52%) were men (mean age, 69.7 years). In both women and men, 3-day case-fatality rates leveled off, beginning in the patients' mid-70s. In women, 1-week case-fatality rates leveled off further in their early 80s, whereas in men, 1-week case-fatality rates accelerated with age. One-month and 1-year case-fatality rates accelerated with age for both sexes.

CONCLUSIONS

It is an apparent paradox that case-fatality rates in the acute state of stroke level off at the highest ages. Heterogeneity, innate or acquired, in regard to survival capacity may explain the phenomenon.

Stroke in the very old: a systematic review of studies on incidence, outcome, and resource use

Background and Purpose. Stroke incidence increases with age and is likely to increase in the aging populations. We investigated incidence, outcome, and resource use in very old subjects with stroke. Methods. We performed a systematic review of available data through electronic search of the literature databases and manual search of reference lists. Data were extracted for the age groups of over 80, 80 to 84 years old, and over 85. Overall incidence rates, expressed as the number of first strokes per 1000 person-years, were estimated using Poisson regression analysis. Odds ratios for the comparisons between subjects over and under 80 were calculated with the Mantel-Haenszel method. Results. We found a high incidence of stroke in the very old. The estimated incidence rates were 20.78 (95% CI 19.69 to 21.87) in subjects over 80, 17.23 (95% CI 15.97 to 18.49) for those 80 to 85 years old, and 20.78 (95% CI 16.74 to 23.78) for those over 85. Subjects over 80 contributed 29.95% of strokes; rates were similar among genders. Thirty-day case fatality rate and occurrence of dependency were higher in subjects over 80, although associated with less frequent hospital and stroke unit admission and less diagnostic resource use. Conclusions. The contribution of very old subjects to the global burden of stroke is relevant and may require efficient dedicated stroke services.

Predictors of early and late case-fatality in a nationwide Danish study of 26,818 patients with first-ever ischemic stroke

BACKGROUND AND PURPOSE

Predictors of early case-fatality (3-day, 7-day, and 30-day) in first-ever ischemic stroke were identified and compared with predictors of late case-fatality (90-day and 1-year).

METHODS

A registry designed to register hospitalized patients with stroke in Denmark 2000 to 2007 holds 26,818 patients with first-ever ischemic stroke with information on stroke severity (Scandinavian Stroke Scale), CT scan, cardiovascular risk factors, marital status, and fatality within 1 year. Multiple logistic regression was used in identifying predictors.

RESULTS

Mean age was 71.2 years; 48.5% were women; mean Scandinavian Stroke Scale score was 43.9. Early case-fatality showed stroke severity and age were significant predictors of 3-day, 7-day, and 30-day case-fatality (nonlinear effect). In addition, atrial fibrillation (OR, 1.56) predicted 30-day case-fatality. For late case-fatality, significant predictors of 90-day and 1-year case-fatality were age, stroke severity (nonlinear effect), atrial fibrillation (OR, 1.37 and 1.57), and diabetes (OR, 1.35 and 1.33), respectively. Male gender (OR, 1.28), previous myocardial infarction (OR, 1.40), and smoking (OR, 1.21) were also associated with 1-year case-fatality. Alcohol consumption, hypertension, intermittent arterial claudication, and marital state had no influence. All case-fatality rates accelerated with increasing age, but 3-day and 7-day case-fatality rates tended to level off or decline at the highest ages.

CONCLUSIONS

Age and stroke severity were the only significant predictors of fatality within the first poststroke week; they were associated with late case-fatality as well. Cardiovascular risk factors were associated with late case-fatality; with the exception of atrial fibrillation, they were not significantly associated with early case-fatality rates.

The effect of survival bias on case-control genetic association studies of highly lethal diseases

BACKGROUND

Survival bias is the phenomenon by which individuals are excluded from analysis of a trait because of mortality related to the expression of that trait. In genetic association studies, variants increasing risk for disease onset as well as risk of disease-related mortality (lethality) could be difficult to detect in genetic association case-control designs, possibly leading to underestimation of a variant's effect on disease risk.

METHODS AND RESULTS

We modeled cohorts for 3 diseases of high lethality (intracerebral hemorrhage, ischemic stroke, and myocardial infarction) using existing longitudinal data. Based on these models, we simulated case-control genetic association studies for genetic risk factors of varying effect sizes, lethality, and minor allele frequencies. For each disease, erosion of detected effect size was larger for case-control studies of individuals of advanced age (age >75 years) and/or variants with very high event-associated lethality (genotype relative risk for event-related death >2.0). We found that survival bias results in no more than 20% effect size erosion for cohorts with mean age <75 years, even for variants that double lethality risk. Furthermore, we found that increasing effect size erosion was accompanied by depletion of minor allele frequencies in the case population, yielding a "signature" of the presence of survival bias.

CONCLUSIONS

Our simulation provides formulas to allow estimation of effect size erosion given a variant's odds ratio of disease, odds ratio of lethality, and minor allele frequencies. These formulas will add precision to power calculation and replication efforts for case-control genetic studies. Our approach requires validation using prospective data.

Female survival advantage relates to male inferiority rather than female superiority: A hypothesis based on the impact of age and stroke severity on 1-week to 1-year case fatality in 40,155 men and women

BACKGROUND

It is generally believed that differences in age, stroke characteristics, and cardiovascular risk factors account for observed sex-specific differences in stroke survival.

OBJECTIVES

We aimed to study female stroke survival advantage before and after the average age of menopause, and whether female survival advantage applies only to patients for whom stroke is the most likely cause of death.

METHODS

The Danish National Indicator Project, a registry designed to list all hospitalized stroke patients in Denmark beginning in March 2001, had 40,155 registered patients as of February 2007. All registered patients had undergone evaluation including stroke severity (as measured by the Scandinavian Stroke Scale [SSS], using a total score of 0-58, in which lower scores indicate more severe strokes), computed tomography, and cardiovascular risk factors. Patients were followed from admission until death or censoring. Case fatality (stratified by 1 week, 1 month, 3 months, and 1 year) in men and women was correlated with age and stroke severity. Adjustment for cardiovascular risk factors was performed by means of multivariate regression analysis.

RESULTS

A total of 20,854 (51.9%) men and 19,301 (48.1%) women were registered. Women were significantly older than men at the time of stroke (74.5 vs 69.7 years, respectively; P < 0.001) and had signficantly more severe strokes, as expressed by the mean SSS score (39.6 vs 43.3; P < 0.001). Stratification of 1-week to 1-year case fatality according to age and stroke severity indicated that women survived significantly better than men from the mid-fifties onward, when controlling for age, stroke severity, and cardiovascular risk factor profile. The observed female survival advantage increased with age. The female survival advantage was seen in patients with severe as well as mild strokes, but not in those younger than age 50 years.

CONCLUSIONS

Our findings dispute the effects of female sex hormones as the underlying cause of female survival superiority over men. Instead, we propose the hypothesis that the progressive deficiency of male sex hormones (testosterone), beginning in men in middle age, is the underlying cause of the gap in survival rates between men and women. Accordingly, the female survival advantage is rooted in male inferiority rather than innate female superiority.

The Tayside Stroke Cohort: exploiting advanced regional medical informatics to create a region-wide database for studying the pharmacoepidemiology of stroke

PURPOSE

Observational studies can provide valuable information where data from randomised controlled trials is lacking. We aimed to generate a region-wide longitudinal register of stroke patients using record-linkage of existing clinical and research datasets.

METHODS

The population were residents of Tayside, Scotland from 1994-2005. Stroke cases were identified from hospital inpatient admission records, death certificates and prescribing data. These were augmented with data derived from free-text CT-brain scan reports. Strokes were classified as intracerebral haemorrhage (ICH), subarachnoid haemorrhage (SAH) or ischaemic stroke (IS). The methodology was validated by audit of patient case-records. The incidence was calculated using direct standardisation to the standard European population for ages 45-84. Twenty-eight day case-fatality rates were calculated as percentages.

RESULTS

There were 12 620 all-cause incident strokes (ICH 1057; SAH 511; IS 6257; undetermined 4795). Standardised incidences per 100 000 by subtypes of stroke were: ICH 35 (95%CI 33-38), SAH 19 (17-22) and IS 210 (205-217). The 28-day case-fatality rates were: ICH 49% (95%CI 46-52), SAH 38% (34-43) and IS 19% (18-20). Comparisons with previous studies were favourable for ICH and SAH. For IS the incidence was lower and fatality rate higher than elsewhere. Three hundred and three sets of patient case records were audited. The positive predictive value (PPV) for identifying cases of stroke was 94.7% (95%CI 91.6-96.7).

CONCLUSIONS

The case ascertainment in the TSC compares favourably to established stroke cohorts. This cost effective resource can now be linked with multiple other clinical and research datasets in Tayside to further understanding of stroke and its treatment.

One-month to 10-year survival in the Copenhagen stroke study: interactions between stroke severity and other prognostic indicators

We studied the association of stroke severity with survival from 1 month to 10 years after stroke and explored how stroke severity interacts with other prognostic indicators with time. The study is based on 999 stroke patients from the community-based Copenhagen Stroke Study (mean age, 74.3±11.0 years; 56% women; mean Scandinavian Stroke Scale [SSS], 38.0±17.4). Evaluation included stroke severity (based on the SSS), computed tomography scan, and a cardiovascular risk profile. Using logistic regression models, we examined the relevance of the SSS on mortality at 1 month and 1, 5, and 10 years. We analyzed the proportion of the variation explained by the models and bias of risk factors estimates with and without the SSS in the model. Mortality rate was 16.6% at 1 month, 31.5% at 1 year, 60.2% at 5 years, and 81.3% at 10 years. In models including the SSS, 22.4%, 20.9%, 32.8%, and 39.5% of the variance was explained for the endpoints of 1 month, 1 year, 5 years, and 10 years, respectively. When SSS was left out of the model, the corresponding values were 6.9%, 13.3%, 29.0%, and 35.1%. Factors significantly associated with survival were SSS at 1 month; SSS, age, diabetes, and stroke type at 1 year; SSS, age, sex, previous stroke, other complicating diseases, diabetes, smoking, and atrial fibrillation at 5 years; and SSS, age, sex, other complicating diseases, and diabetes at 10 years. Our data suggest that stroke severity is significantly associated with short-term and long-term survival. It is the all-important predictor of short-term survival, whereas it is of less importance in predicting long-term survival.

The incidence of major stroke subtypes in southern Italy: a population-based study

BACKGROUND AND PURPOSE

Stroke is characterized by well-defined clinical major subtypes, but there are few studies on incidence rates, aetiologies and outcomes in population-based setting. We assessed the age/sex incidence of the major stroke subtypes in a region of Southern Italy.

METHODS

We established a multisource, prospective population-based register in Puglia, Southern Italy to identify all residents with a first-ever stroke between 1 January 2001 and 31 December 2002.

RESULTS

One hundred and twenty-seven first-ever strokes were diagnosed, and stroke subtype was defined in 119 cases. The incidence rates per 100 000 adjusted to the European population (AEP) were 112 for cerebral infarction (CI), 30 for intracerebral haemorrhage (IH), four for subarachnoid haemorrhage (SH) and nine for undetermined stroke (US). The incidence rates for CI, IH and US approximately doubled with each decade of life and were higher in men. AEP incidence rates for CI in the age groups 45-84 were lower compared to other studies, whilst the corresponding rates for IH were higher.

CONCLUSIONS

This population had a lower incidence of CI compared to other population-based studies from Northern Europe and the United States. Furthermore, with the projected increase in the segment of the very old in the general population, our data indicate that both CI and IH will dramatically increase in the near future.

Incidence, case fatality, and functional outcome of intracerebral haemorrhage over time, according to age, sex, and ethnic origin: a systematic review and meta-analysis

BACKGROUND

Since the early 1980s, imaging techniques have enabled population-based studies of intracerebral haemorrhage. We aimed to assess the incidence, case fatality, and functional outcome of intracerebral haemorrhage in relation to age, sex, ethnic origin, and time period in studies published since 1980.

METHODS

From PubMed and Embase searches with predefined inclusion criteria, we identified population-based studies published between January, 1980, and November, 2008. We calculated incidence and case fatality. Incidences for multiple studies were pooled in a random-effects binomial meta-analysis. Time trends of case fatality were assessed with weighted linear-regression analysis.

FINDINGS

36 eligible studies described 44 time periods (mid-year range 1983-2006). These studies included 8145 patients with intracerebral haemorrhage. Incidence did not decrease between 1980 and 2008. Overall incidence was 24.6 per 100 000 person-years (95% CI 19.7-30.7). Incidence was not significantly lower in women than in men (overall incidence ratio 0.85, 95% CI 0.61-1.18). Using the age group 45-54 years as reference, incidence ratios increased from 0.10 (95% CI 0.06-0.14) for people aged less than 45 years to 9.6 (6.6-13.9) for people older than 85 years. Median case fatality at 1 month was 40.4% (range 13.1-61.0) and did not decrease over time, and was lower in Japan (16.7%, 95% CI 15.0-18.5) than elsewhere (42.3%, 40.9-43.6). Six studies reported functional outcome, with independency rates of between 12% and 39%. Incidence of intracerebral haemorrhage per 100 000 person-years was 24.2 (95% CI 20.9-28.0) in white people, 22.9 (14.8-35.6) in black people, 19.6 (15.7-24.5) in Hispanic people, and 51.8 (38.8-69.3) in Asian people.

INTERPRETATION

Incidence of intracerebral haemorrhage increases with age and has not decreased between 1980 and 2006. Case fatality is lower in Japan than elsewhere, increases with age, and has not decreased over time. More data on functional outcome are needed.

FUNDING

Netherlands Heart Foundation.

Incidence and Case Fatality of Subarachnoid Haemorrhage in Northern Greece: The Evros Registry of Subarachnoid Haemorrhage

Background

Epidemiological data on subarachnoid haemorrhage incidence and case-fatality rates are scarce in the southeastern Mediterranean region. We conducted a population-based study in Evros Province, located in north-eastern Greece, to determine subarachnoid haemorrhage incidence over a 5-year period (2001–2005).

Methods

Evros Province has a well-defined, largely homogeneous population with healthcare organised around a single tertiary-care University Hospital. We organised a prospective computerised registry of permanent Evros residents admitted or transferred to our hospital with a diagnosis of subarachnoid haemorrhage. Standard World Health Organization definitions and overlapping case-finding methods were used to identify all cases of first ever in a lifetime subarachnoid haemorrhage in all age groups, occurring during the study period. The diagnosis was confirmed by computed tomography scan in all hospitalised cases. Sudden deaths attributable to subarachnoid haemorrhage were systematically recorded province-wide by our forensic department and are included in the study.

Results

During the 5-year period, 51 cases of subarachnoid haemorrhage were recorded (28 men, 23 women; mean age 59 ± 17 years). The crude annual incidence rates were 8·3/100000 persons (95% confidence interval: 5·5–12·0) for men, 7·5/100000 (4·8–11·3) for women and 7·9/100000 (5§9–10§4) for all subjects. The standardised incidence rates for groups aged 45–84 years in the European population were 9·3/100000 (5·8–12·8) for men, 6·5/100000 (3·7–9·4) for women and 7·9/100000 (5·7–10·2). The 28-day case-fatality rates for men, women and all subjects were 36% (21–54%), 35% (19–55%) and 35% (24–49%), respectively.

Conclusions

The incidence and case-fatality rate of subarachnoid haemorrhage haemorrhage in Greece appear to be similar to other developed countries. No gender differences in subarachnoid haemorrhage incidence and case-fatality rate were documented.

Worldwide stroke incidence and early case fatality reported in 56 population-based studies: a systematic review

This systematic review of population-based studies of the incidence and early (21 days to 1 month) case fatality of stroke is based on studies published from 1970 to 2008. Stroke incidence (incident strokes only) and case fatality from 21 days to 1 month post-stroke were analysed by four decades of study, two country income groups (high-income countries and low to middle income countries, in accordance with the World Bank's country classification) and, when possible, by stroke pathological type: ischaemic stroke, primary intracerebral haemorrhage, and subarachnoid haemorrhage. This Review shows a divergent, statistically significant trend in stroke incidence rates over the past four decades, with a 42% decrease in stroke incidence in high-income countries and a greater than 100% increase in stroke incidence in low to middle income countries. In 2000-08, the overall stroke incidence rates in low to middle income countries have, for the first time, exceeded the level of stroke incidence seen in high-income countries, by 20%. The time to decide whether or not stroke is an issue that should be on the governmental agenda in low to middle income countries has now passed. Now is the time for action.

Sex-related time-dependent variations in post-stroke survival--evidence of a female stroke survival advantage

BACKGROUND

Women live longer than men, yet most studies show that gender has no influence on survival after stroke.

METHODS

A registry was started in 2001, with the aim of registering all hospitalized stroke patients in Denmark, and it now holds 39,484 patients of which 48% are female. We studied the influence of gender on post-stroke mortality, from the time of admission through the subsequent years until death or censoring (mean follow-up time: 538 days). All patients underwent an evaluation including stroke severity, computed tomography and cardiovascular risk factors. Independent predictors of death were identified by means of a survival model based on 22,222 individuals with a complete data set.

RESULTS

Females were older and had severer stroke. Interestingly, the risk of death between genders was time dependent. The female/male stroke mortality rate favoured women from the first day of stroke and remained so during the first month suggesting a female survival advantage. Throughout the second month the rate reversed in favour of men suggesting that women in that period are paying a 'toll' for their initial survival advantage. Hereafter, the rate steadily decreased, and after 4 months women continued to have the same low risk as in the first week.

CONCLUSIONS

Our study suggests a female superiority in stroke survival competence.

Incidence of subarachnoid haemorrhage: a systematic review with emphasis on region, age, gender and time trends

BACKGROUND AND AIM

To update our 1996 review on the incidence of subarachnoid haemorrhage (SAH) and assess the relation of incidence with region, age, gender and time period.

METHODS

We searched for studies on the incidence of SAH published until October 2005. The overall incidences with corresponding 95% confidence intervals were calculated. We determined the relationship between the incidence of SAH and determinants by means of univariate Poisson regression.

RESULTS

We included 51 studies (33 new), describing 58 study populations in 21 countries, observing 45,821,896 person-years. Incidences per 100,000 person-years were 22.7 (95% CI 21.9 to 23.5) in Japan, 19.7 (18.1 to 21.3) in Finland, 4.2 (3.1 to 5.7) in South and Central America, and 9.1 (8.8 to 9.5) in the other regions. With age category 45-55 years as the reference, incidence ratios increased from 0.10 (0.08 to 0.14) for age groups younger than 25 years to 1.61 (1.24 to 2.07) for age groups older than 85 years. The incidence in women was 1.24 (1.09 to 1.42) times higher than in men; this gender difference started at age 55 years and increased thereafter. Between 1950 and 2005, the incidence decreased by 0.6% (1.3% decrease to 0.1% increase) per year.

CONCLUSIONS

The overall incidence of SAH is approximately 9 per 100,000 person-years. Rates are higher in Japan and Finland and increase with age. The preponderance of women starts only in the sixth decade. The decline in incidence of SAH over the past 45 years is relatively moderate compared with that for stroke in general.

Epidemiology of stroke in Europe: Geographic and environmental differences

The development of stroke registries has allowed the accumulation of a wealth of data on the descriptive epidemiology of stroke and its evolution in space and in time. For instance, there has been an observed decrease of stroke incidence and mortality in Western Countries during the past 20 years. The use of brain imaging technologies including CT scan and MRI, along with improved cardiac and vascular imaging, has allowed better identification of risk factors for stroke. Hypertension remains the main risk factor for both ischemic and hemorrhagic strokes, and its treatment is effective in reducing first-ever and recurrent stroke incidence. Major medical progress has been achieved in the development of effective medications for hypertension control in the last 2 decades. Despite these advances, we observe large differences in the incidence and mortality rates of stroke throughout the European community. In this review we pose some questions regarding the possible reasons for these differences and we analyze the issue of environmental factors such as meteorological factors and pollution as stroke risk factors.

Higher total serum cholesterol levels are associated with less severe strokes and lower all-cause mortality: ten-year follow-up of ischemic strokes in the Copenhagen Stroke Study

BACKGROUND AND PURPOSE

Evidence of a causal relation between serum cholesterol and stroke is inconsistent. We investigated the relation between total serum cholesterol and both stroke severity and poststroke mortality to test the hypothesis that hypercholesterolemia is primarily associated with minor stroke.

METHODS

In the study, 652 unselected patients with ischemic stroke arrived at the hospital within 24 hours of stroke onset. A measure of total serum cholesterol was obtained in 513 (79%) within the 24-hour time window. Stroke severity was measured with the Scandinavian Stroke Scale (0=worst, 58=best); a full cardiovascular risk profile was established for all. Death within 10 years after stroke onset was obtained from the Danish Registry of Persons.

RESULTS

Mean+/-SD age of the 513 patients was 75+/-10 years, 54% were women, and the mean+/-SD Scandinavian Stroke Scale score was 39+/-17. Serum cholesterol was inversely and almost linearly related to stroke severity: an increase of 1 mmol/L in total serum cholesterol resulted in an increase in the Scandinavian Stroke Scale score of 1.32 (95% CI, 0.28 to 2.36, P=0.013), meaning that higher cholesterol levels are associated with less severe strokes. A survival analysis revealed an inverse linear relation between serum cholesterol and mortality, meaning that an increase of 1 mmol/L in cholesterol results in a hazard ratio of 0.89 (95% CI, 0.82 to 0.97, P=0.01).

CONCLUSIONS

The results of our study support the hypothesis that a higher cholesterol level favors development of minor strokes. Because of selection, therefore, major strokes are more often seen in patients with lower cholesterol levels. Poststroke mortality, therefore, is inversely related to cholesterol.

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.

Cardiovascular Risk Factors and 5-Year Mortality in the Copenhagen Stroke Study

BACKGROUND

The treatment of cardiovascular risk factors has improved over the recent years and may have improved survival. The aim of this study was to investigate the up-to-date prognostic significance of cardiovascular risk factors for 5-year survival in a large unselected ischemic stroke population.

METHODS

We studied 905 ischemic stroke patients from the community-based Copenhagen Stroke Study. Patients had a CT scan and stroke severity was measured by the Scandinavian Stroke Scale on admission. A comprehensive evaluation was performed by a standardized medical examination and questionnaire for cardiovascular risk factors, age, and sex. Follow-up was performed 5 years after stroke, and data on mortality were obtained for all, except 6, who had left the country. Five-year mortality was calculated by the Kaplan-Meier procedure and the influence of multiple predictors was analyzed by Cox proportional hazards analyses adjusted for age, gender, stroke severity, and risk factor profile.

RESULTS

In Kaplan-Meier analyses atrial fibrillation (AF), ischemic heart disease, diabetes, and previous stroke were associated with increased mortality, while smoking and alcohol intake were associated with decreased mortality. No association was found for hypertension or intermittent claudication. In the final Cox proportional hazard model predictors of 5-year mortality were AF (hazard ratio, HR 1.4; 95% CI 1.1-1.7), diabetes (HR 1.3; 95% CI 1.0-1.6), smoking (HR 1.2; 95% CI 1.0-1.4), and previous stroke (HR 1.4; 95% CI 1.1-1.7), after adjustment for age, gender, and stroke severity.

CONCLUSIONS

AF, diabetes, smoking, and previous stroke significantly affect long-term survival. Although smoking and daily alcohol consumption appeared to be associated with improved survival in the univariate analyses, adjustment for other factors and especially age revealed the lethal effect of smoking, while the positive effect of alcohol disappeared. More focus on secondary preventive measures, such as anticoagulation for AF, smoking cessation, and proper treatment of diabetes may significantly improve long-term survival.

Sex Differences in Stroke Survival: 10-Year Follow-up of the Copenhagen Stroke Study Cohort

BACKGROUND

Although diverging, most studies show that sex has no significant influence on stroke survival.

METHODS

In a Copenhagen, Denmark, community all patients with stroke during March 1992 to November 1993 were registered on hospital admission. Stroke severity was measured using the Scandinavian Stroke Scale (0-58); computed tomography determined stroke type. A risk factor profile was obtained for all including ischemic heart disease, hypertension, diabetes mellitus, atrial fibrillation, previous stroke, smoking, and alcohol consumption. Date of death was obtained within a 10-year follow-up period. Predictors of death were identified using a Cox proportional hazards model.

RESULTS

Of 999 patients, 559 (56%) were women and 440 (44%) were men. Women were older (77.0 v 70.9 years; P < .001) and had more severe strokes (Scandinavian Stroke Scale: 36.1 v 40.5; P < .001). Age-adjusted risk factors showed no difference between sexes for ischemic heart disease, hypertension, atrial fibrillation, diabetes mellitus, and previous stroke. Men more often were smokers and alcohol consumers. Unadjusted survival in men and women did not differ: 70.3% versus 66.7% (1-year), 40.0% versus 38.9% (5-year), and 17.4% versus 18.7% (10-year), respectively. Adjusting for age, stroke severity, stroke type, and risk factors, women had a higher probability of survival at 1 year (hazard ratio 1.47, 95% confidence interval 1.10-2.00); 5 years (hazard ratio 1.47, 95% confidence interval 1.23-1.76); and 10 years (hazard ratio 1.49, 95% confidence interval 1.28-1.76). Before 9 months poststroke, no difference in survival was seen. Severity of stroke had the same effect on sex.

CONCLUSION

Stroke is equally severe in men and women. Short-term survival is the same. Having survived stroke, women, however, live longer.

Strokes attributable to underuse of warfarin and antiplatelets

Despite their proven efficacy in stroke prevention, warfarin and antiplatelets remain underused. We determined the frequency of ischemic strokes attributable to underuse of warfarin and antiplatelets for stroke prevention in a Danish community. We included all patients with ischemic stroke in a Copenhagen community with 302,000 inhabitants admitted to the hospital between September 1999 and May 2000 (n = 426). Patients who did not receive warfarin or antiplatelet medication even though they were at known risk for cardiovascular disease before the incident stroke were identified; they had known atrial fibrillation, prior myocardial infarction, angina, or prior stroke transient ischemic attack (TIA). Sufficient information on cardiovascular risk factors before stroke was available in 404 patients. A total of 54 patients had atrial fibrillation known before the stroke. Of these, 16 had not received warfarin or antiplatelets on admission, 27 had not received warfarin but had received antiplatelets, and 11 had received warfarin. Assuming that warfarin and antiplatelets reduces the risk of stroke by 66% and 25%, respectively, it was calculated that between 6 and 12 of these strokes with atrial fibrillation could have been prevented if warfarin or antiplatelets had been given before stroke. A total of 147 patients had known stroke/TIA and/or myocardial infarction/angina before stroke (41 patients had not received antiplatelets on admission). If antiplatelet therapy had been given before stroke, 10 of these strokes could have been prevented. Our findings indicate that underuse of warfarin and antiplatelets is still of considerable magnitude and attributable to 4% to 5% (16 to 22 out of 404) of the ischemic strokes in a Danish urban community.