Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 59, Num. 2, 2011, pp. 174-179

Neurology India, Vol. 59, No. 2, March-April, 2011, pp. 174-179

Original Article

Gender differences in acute stroke: Istanbul medical school stroke registry

Nilüfer Yesilot, Bahar Aksay Koyuncu, Oguzhan Çoban, Rezzan Tuncay, Sara Zarko Bahar

Department of Neurology, Istanbul University, Istanbul Medical School, Edip Aktin Stroke Unit, Capa, Istanbul, Turkey

Correspondence Address: Nilüfer Yesilot, Istanbul Tip Fakültesi, Noroloji Anabilim Dali,34293, Çapa, Istanbul, Turkey, niluferyes@yahoo.com

Date of Submission: 05-Nov-2010
Date of Decision: 30-Nov-2010
Date of Acceptance: 01-Feb-2011

Code Number: ni11053

PMID: 21483112

DOI: 10.4103/0028-3886.79130

Abstract

Keywords: Acute stroke, hospital registry, women

Introduction

Ischemic stroke (IS) is the third most common cause of death and the most common cause of disability in adults aged over 40 years. ^[1],[2] Stroke is estimated to be responsible for 14.5% of deaths in men and 15.7% of deaths in women in Turkey. ^[3] More women than men die from stroke each year and women have a higher lifetime stroke risk because they live longer. ^[4] Differences between men and women with IS regarding risk factors, clinical features, diagnostic evaluation, treatments, and response to treatment have been reported ^{[5],[6],[7],[8]} and reviewed. ^[9],[10] In order to find out if gender differences existed in Turkish stroke patients, we evaluated patients registered in the Istanbul Medical School Stroke Registry (IMSSR).

Material and Methods

The Neurology Department of Istanbul Medical School is one of the three state university neurology clinics in Istanbul, serving a population of approximately 12.5 million people. Most stroke patients come directly from their homes; only a small number of patients are referred by primary care physicians or other hospitals. The admission of patients depends on the availability of beds; minor strokes may be managed on an ambulatory basis due to the shortage of beds. Computed tomography is available for 24 hours a day and 7 days a week in the Neurology Department, whereas magnetic resonance imaging (MRI) is available in the Radiology Department and is selectively ordered. Approximately 90% of the patients admitted consist of people registered in the state health insurance system, constituting a low-intermediate income group having the characteristics of the urban population in Turkey. ^[11] IMSSR is a hospital-based registry including all stroke patients hospitalized in the Neurology Department of Istanbul Medical School. Between 1 ^st March, 1994 and 31 ^st March, 1999, patients were admitted to the general neurology ward; after 1 April, 1999, all stroke patients were admitted to a 12-bed stroke unit separated from the rest of the neurology ward. All hospitalized patients were screened for suspected stroke and all stroke patients were recorded in a logbook for the IMSSR. Patients with IS, cerebral venous thrombosis (CVT), intracerebral hemorrhage (ICH), and transient ischemic attack (TIA) were all included. Patients with subarachnoid hemorrhages were excluded. Prospectively recorded variables included age, gender, previous stroke, prestroke modified Rankin Scale (mRS), risk factors, time-to-admission, level of consciousness, severity of the neurologic deficit (inability to raise the symptomatic arm, inability to walk without assistance, or need for a gastric tube or urinary catheter), early deterioration (progression of stroke symptoms in the first 48 hours), blood pressure and mRS at the time of admission, clinical subtypes according to the Oxfordshire Community Stroke Project classification, ^[12] etiological subtypes in patients with IS according to the Trial of Org 10172 in Acute Stroke Treatment classification, ^[13] etiology of ICH, topography of infarcts and hemorrhages on imaging studies, in-hospital recurrent stroke, neurologic and systemic complications, length of hospital stay, death, mRS at the time of discharge, and anti-platelet and anti-coagulant treatment use for secondary prevention. A group of four senior neurologists, who were not blinded to patient status, evaluated the whole baseline and outcome data recorded in the IMSSR during a weekly meeting and reached a consensus.

In the present study, all IS and ICH patients who were registered between 31 ^st March, 1994 and 1 ^st April, 2004 were evaluated. Demographics, risk factors, clinical features, topography of infarcts and hemorrhages, diagnostic studies, clinical and etiologic classifications, in-hospital events, and discharge status were compared according to gender in IS and ICH patients. Categorical variables were compared using the chi-square test and parametric variables were compared using the t-test. For parametric variables, normal distributions were tested with the Kolmogorov-Smirnov test. ^[14] For patients with IS, variables with significant differences according to gender were also evaluated in the following age groups: <55, 55-64, 65-74, and ≥75 years of age. Logistic regression analysis was used to evaluate the independent effect of gender on poor outcome, which was defined as death or disability (mRS 3-6) at the time of discharge for patients with IS. In the multivariate analysis, variables that were significantly different (P<0.05) between genders and thought to be effective on outcome were selected. Age, pre-stroke disability (mRS 3-5), atrial fibrillation (AF), total anterior circulation syndrome (TACS), inability to lift the symptomatic arm, inability to walk without assistance, and the need for a gastric tube or urinary catheter were included. A forward stepwise method with SPSS version 11.0 was used.

Results

During the evaluation period, 2 014 patients were registered. Of these, 1 522 patients had IS, 320 patients had ICH, 147 patients had TIAs, and 25 patients had CVT. In the present study, only IS and ICH patients were evaluated. Of the patients with IS, 751 were females (49%). Mean age was 63.6 ± 14.6 years; females (mean age, 65.1 ± 15.3 years) were significantly older than males (mean age, 62.2 ± 13.6 years) (P<0.0001). In the age groups older than 70 years of age, 58% were females.

Prestroke disability was more common in females and this difference persisted in patients with first-ever stroke (data not shown). Females had higher frequency of AF and hypertension. Clinical features reflecting severe stroke such as inability to raise the symptomatic arm and to walk, the need for a gastric tube or urinary catheter, and mRS 3-5 at admission were also more common in females [Table - 1].

TACS was observed significantly more frequently and posterior circulation syndrome (POCS) significantly less frequently in female patients [Table - 2]. Middle cerebral artery territory infarcts were more common in females (55.5% vs 45.4%, P<0.0001), and posterior circulation infarcts in males (33.1% vs 25%, P = 0.0007). The most common etiologic subtypes of stroke were cardioembolism in females and large-artery atherosclerosis in males [Table - 2]. Severe disability (mRS 3-5) at the time of discharge was significantly more frequent in females [Table - 2]. Logistic regression analysis revealed that female gender was an independent predictor of poor outcome [Table - 3].

In all age groups, AF was more frequent in females and the difference was almost two-fold in the 65 to 74 years of age group. In females younger than 55 years of age, large-artery atherosclerosis was rarely encountered. In females, cardioembolic stroke was significantly more frequent in the 65 to 74 years of age group; the difference was less pronounced in the ≥75 years of age group [Table - 4]. Clinical features reflecting severe stroke were significantly more frequent in females over 65 years of age. History of TIA in males and prestroke disability in females were significantly higher in patients ≥75 years of age only.

Of the 320 patients with ICH (mean age, 61.2 ± 13.3 years), 150 (47%) were females. Age was not significantly different between females (62.0 ± 13.6 years) and males (mean age, 60.5 ± 13.0 years). All variables including risk factors, clinical features at admission, diagnostic studies, and outcome were analyzed in the patients with ICH, and there were no significant differences between genders in any of the variables including risk factors and outcome except for the higher frequency of smoking in males (P<0.0001, data not shown).

Discussion

This is an observational study from one large university neurology clinic in Istanbul, Turkey. Women with IS were on average 2.9 years older than men and this difference was lower than those reported. ^{[5],[6],[15],[16]} Our patients were approximately 10 years younger than those reported in most Western stroke series. ^{[15],[16],[17],[18],[19]} This difference can be explained by the 8 to 10 years lower life expectancy at birth in Turkey. ^[3] Women outnumbered men among patients older than 70 years, consistent with the disproportionate representation of older women in the Turkish population. ^[20]

Similar to our study, most ^{[5],[6],[8],[15],[21]} studies reported higher frequency of hypertension and AF in female stroke patients which may be attributable to the increasing frequency of AF and hypertension with age ^[4] and higher stroke risk of women with nonvalvular AF. ^{[22],[23],[24]} Smoking, ^{[6],[8],[15],[17],[22]} coronary artery disease (CAD), ^{[5],[8],[15],[22]} and peripheral artery disease (PAD) ^[6] were found to be more common in males, similar to our cohort.

TACS and middle cerebral artery infarctions were more common in females, while POCS and vertebrobasilar territory infarctions were more common in males. Differences in clinical syndromes have been reported, ^[21] but this difference in infarction topography has not been emphasized before.

Large-artery atherosclerosis was found to be more frequent in males and cardioembolism was found to be more frequent in females, ^[19] similar to our study. In a recent systematic review on gender differences in stroke, a higher incidence of cardioembolism in females was reported as the most consistent difference. ^[23] Roquer et al. ^[6] suggested that the higher incidence of atherothrombotic stroke is associated with the greater frequency of atherosclerotic risk factors (smoking and PAD) in males; and the higher frequency of AF is responsible for the higher frequency of cardioembolic strokes in females.

In the present cohort, severe strokes were more frequent in females similar to other registries. ^{[6],[8],[11],[24]} The higher incidence of prestroke disability ^{[8],[10],[18],[25]} and cardioembolic stroke ^[25] might account for this difference.

Some studies have reported that women with stroke living alone had a disadvantage in reaching hospitals early. ^[7],[26] We did not find any difference between genders in terms of time to admission. Widowed spouses usually live with their children and this living style of Turkish families may explain this feature of our cohort.

Women were found to be less likely to undergo echocardiography and carotid evaluation ^[20] and brain imaging ^[8] , even after adjustment for baseline differences in some studies, whereas others ^[15] did not find such a difference. In our study, higher incidence of severe hemispheric strokes and AF with lower incidence of posterior circulation symptoms in females may have resulted in the lower rate of performing MRI, magnetic resonance angiography, and angiography in them.

In this study, case fatality rate was similar for both genders but women were more disabled at discharge. A higher frequency of prestroke disability and presentation with more severe strokes may have accounted for this difference. Poor outcome defined as discharge mRS 3-6 was predicted by female gender and remained significant even after adjustment for age, prestroke disability, TACS, inability to raise arm and walk, need for gastric tube or urinary catheter, and AF. Higher proportions of females with severe disability at discharge ^[6],[15] and at follow-up were reported. ^{[6],[8],[15],[17],[27]}

When the IS data were analyzed according to age groups, large-artery atherosclerosis was more frequent in males <55 years of age. The most pronounced gender differences were in the 65 to 74 years age group. In the Austrian Stroke Registry, women had more severe neurologic deficit at admission and at discharge and this difference was significant only in patient groups >70 years of age. ^[28]

Similar to others, we did not find a significant difference between genders in terms of ICH and IS ratios. ^{[6],[27],[29]} Male preponderance of smoking was the only gender difference in patients with ICH reflecting the smoking habits of the Turkish population. ^[30] Studies evaluating gender differences analyzed patients with IS only ^[25] or all stroke patients. ^{[5],[6],[7],[8],[15],[17],[22],[24],[27]} In this cohort, IS and ICH patients were analyzed separately and gender differences were observed only in the patients with IS.

The present study has certain limitations resulting from drawbacks inherent to hospital-based registries. More severe stroke patients are usually admitted due to bed availability which might cause the data to be less applicable to the entire stroke population. Socioeconomic data, which are considered to be important in explaining outcome differences, were lacking. ^[17],[27] National Institutes of Health Stroke Scale was not routinely used during the collection of data. Therefore, outcome analyses could not be adjusted for stroke severity with this standard measure, instead, predefined clinical parameters reflecting stroke severity recorded in the database were used. The registry contained patients treated in the general neurology ward and stroke unit, but the effect of this difference was not analyzed. This issue was evaluated in a former study from our center. ^[31] Since treatment with thrombolysis was not registered for use in acute stroke treatment at the time in Turkey, it was used only in 15 patients in this registry; the lack of data on thrombolytic treatment might be another limitation of this study. Analysis of differences in age groups has some disadvantages related to subgroup analyses. ^[32] Variables classically related to prognosis in hemorrhagic strokes such as hematoma volume, presence of intraventricular blood, and rates of rebleeding were not available in our study. Finally, our outcome data are limited to in-hospital events.

In conclusion, the present study separately analyzed stroke characteristics of patients with IS and ICH according to gender differences and found that gender differences were especially present in the patients with IS. In comparison to the results of similar studies from Western countries, the present study cohort was younger, although differences in risk factors, stroke presentation, and outcomes were similar. Gender differences were most pronounced in the 65 to 74 years age group.

References

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