Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 58, Num. 6, 2010, pp. 863-868

Neurology India, Vol. 58, No. 6, November-December, 2010, pp. 863-868

Original Article

Stroke risk factors and subtypes in different age groups: A hospital-based study

Chih-Ying Wu¹, Hung-Ming Wu¹, Jiann-Der Lee¹, Hsu-Huei Weng²

¹ Department of Neurology, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Chiayi, Taiwan
² Department of Radiology, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Chiayi, Taiwan
Correspondence Address: Jiann-Der Lee, 6.West Sec. Chiapu Road, Putzu City, Chiayi Hsien, Taiwan, R.O.C, Taiwan
jdlee540908@adm.cgmh.org.tw

Date of Acceptance: 31-Jul-2010

Code Number: ni10248

PMID: 21150050
DOI: 10.4103/0028-3886.73747

Abstract

Background/Aims: To compare the influence of stroke risk factors between different stroke types and age groups in Taiwan.

Materials and Methods: During the study period, March 2007 to August 2008, 1,161 patients with acute ischemic stroke were admitted to the neurological ward. All the patients had risk factors work up and stroke subtype categorization.

Results: The study cohort included 736 men and 425 women. Patients were grouped into three age groups: below 50 years (153, 13.2%); 50-75 years, (702, 60.5%) and above 75 years (306, 26.4%). Stroke subtypes included: (1) large-artery atherosclerosis (14.6%), cardioembolism (12%), small-artery occlusion (39.4%), stroke of other determined etiology (1.5%) and stroke of undetermined etiology (32.6%). Older patient group had higher frequency of hypertension and diabetes mellitus. Younger age group of patients had high frequency of obesity and elevated serum triglyceride levels. Smoking and alcohol consumption were strongly related to men, and heart disease and obesity were related to women.

Conclusions: The influence of risk factors at different ages is different. Awareness of the stroke risk factors before stroke and treatment with appropriate therapies or life modifications may have a bearing on the outcomes.

Keywords: Age stratification, stroke, stroke risk factors, stroke subtypes

Introduction

Stroke is an important health issue worldwide and the risk factor profile may vary with ethnicity, geographic region, age, gender and stroke subtype. ^{[1],[2],[3],[4],[5],[6],[7]} To reduce the stroke burden preventive strategies are important. The well established risk factors of ischemic stroke include hypertension, diabetes mellitus, heart disease, previous stroke, smoking, alcohol and hyperlipidemia and also obesity. ^{[8],[9],[10],[10],[11]} Hospital-based stroke registries help to study the relationship between stroke, risk factors and prognosis. Our on-line registration system records the patients who are admitted to all four branches of Chang Gung hospitals, distributed from the north to the south of Taiwan, due to acute stroke. Our registration items include stroke history, past history, clinical presentations, stroke risk factors, related examination reports and clinical scores of the National Institutes of Health (NIH) stroke scale, Barthel index and Modified Rankin scale of each stroke patient.

This is a prospective hospital-based study aimed at to analyze the risk factors and the stroke subtypes in different age groups in Taiwan.

Materials and Methods

The clinical data of 1,161 patients with stroke admitted to the Chang Gung Memorial Hospital, Linkuo Medical Center, between March 2007 and August 2008 were collected prospectively and the permission of the Hospital Ethical Committee was obtained to analyze the data. All patients were examined by neurologists. The investigation workup included brain computed tomography (CT) and/or magnetic resonance imaging (MRI), electrocardiography (ECG) and transcranial colored Doppler/coded common carotid Doppler (TCD/CCCD). Patients also received cerebral angiography, including CT-angiography (CTA), MR-angiography (MRA), conventional angiography, transthoracic echocardiography (TTE) or further transesophageal echocardiography (TEE) if further evaluation was needed to determine the stroke subtypes. Ischemic stroke was defined as a stroke with either a normal CT scan or evidence of a recent infarct in the clinically relevant area of the brain. Patients who suffered from acute stroke symptoms and recovered completely within 24 h were diagnosed to have transient ischemic attack (TIA) and were included in the analysis. Patients with intracranial hemorrhage or venous sinus thrombosis were excluded from the study. The data collected included: age, sex, and the stroke risk factors, hypertension, diabetes mellitus (DM), heart disease, previous stroke, smoking, alcohol consumption, obesity., serum cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL) and triglyceride (TG) serum level. Patients were considered to be hypertensive if the average systolic blood pressure (BP) or diastolic BP was 140 mmHg and 90 mmHg respectively after 7 days of acute stroke, or if the patients were taking antihypertensive medication. Diabetes mellitus was defined by either of the following criteria: (1) if the patient had the diagnosis and (2) if at least two fasting glucose readings were 126 mg/dl or higher. Heart diseases include atrial fibrillation, rheumatic heart disease, non-rheumatic valvular heart disease, patent foramen ovale, congestive heart failure, infective endocarditis, sick sinus syndrome and ischemic heart disease. Previous stroke history was defined by previous diagnosis by a neurologist. A patient was defined as a smoker if he or she had been a current smoker in the last 6 months (20 cigarettes per day in men and 15 per day in women) or a smoker for more than 6 months. Positive alcohol consumption was recorded if a patient had drunk, daily, more than 20 g of alcohol per day for more than 6 months. Cholesterol, LDL, HDL and TG were done during hospitalization after fasting for at least 8 h. Our study recorded serum lipid concentrations without defining them as normal or abnormal. A stroke patient with a history of dyslipidemia may have normal serum lipid levels if controlled with medicine before the index stroke. Obesity was defined as a body mass index (BMI) above 25, calculated by the body height and weight checked at admission. Stroke subtypes were classified according to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification system: ^[12] (1) large-artery atherosclerosis (LAD), (2) cardioembolism (CE), (3) small-artery occlusion (SAO), (4) stroke of other determined etiology (SOD) and (5) stroke of undetermined etiology (SUD). The patients with TIA were also classified by TOAST classification based the clinical and investigative evidence. The data obtained were evaluated according to age, gender, risk factors and stroke subtypes. Statistical analysis was done using the SPSS version 16 software. The X-square method, Student's t-test and one-way ANOVA with post-hoc Scheffι's method were used for the comparison of descriptive statistical methods (average, standard deviation) and qualitative data. Significance was found to be P <0.05 and the confidence range was 95%.

Results

Of the 1,161 patients, 736 were males (63.4%, mean age 64.46 years (SD: 13.75) and 425 females (36.6%, mean age 68.64 (SD: 12.86). The age distribution was: below 50 years (153, 13.2%); 50-75 years (702 patients (60.5%) and above 75 years (306, 26.4%). Stroke subtype by TOAST criteria: LAD - 169 (14.6%); CE - 139 (12%); SAO - 457 (39.4%); SOD - 17 (1.5%); and SUD - 379 (32.6%). The frequencies of the various risk factors in the different age groups are shown in [Table - 1].

The risk factors hypertension and DM were more frequent in the older group than in the younger group. Patients above the age of 75 years had lower serum concentrations of triglyceride than those of the younger group. There was no difference between the groups with age below 50 years and those aged 50-75 years. When the patients were divided by gender, heart disease, smoking, alcohol consumption and obesity showed a significant gender difference, as shown in [Table - 2].

The distribution of different stroke subtypes in the different age groups is shown in [Table - 3], [Figure - 1]. In the younger age group there was higher proportion of SAO and SOD and it was SUD in in the older group. However, only SOD showed a significant difference by the chi-square test of trend (P = 0.013). The data of gender in the different age groups is shown in [Table - 4], [Figure - 2]. An increasing number of female patients were seen in the older age group. There was no significant between the stroke subtypes by gender (Χ² = 2.34, P = 0.673).

The relationship between serum and increasing age was significant [Table - 5], but no obvious relationship between LDL, HDL and cholesterol concentration and the age. There was a significantly lower concentration of TG in the above 75-years group compared with the other two younger groups by Scheffι's method in the post hoc analysis. Seventy-two patients in our study belonged to the very old age group (aged 85 or older). There were significantly higher proportions of SUD (44.4%) and SVO (27.8%) and higher ratio of heart disease (37.5%) in the very old patients, shown in [Table - 6].

Discussion

This stroke registry-based study analysed the relation between different stroke risk factors and age, as well as stroke subtype. Hypertension and DM were frequent risk factors in the older patients. Similar were the observations with regard to hypertension in other studies, but not with regard to DM. ^{[2],[13],[14]} The increasing prevalence of DM in the older age group seen in this study may be related to the changing dietary habits in the population. In this study incidence of stroke subtypes, SAO and SOD was higher in the young group as compared to the old group, thus suggesting possible differences in the etiological factors in different age groups. Collagen vascular diseases, moyamoya disease, polycythemia vera and fibromuscular dysplasia were the risk factors in five patients with SOD stroke subtype. Small artery occlusion in younger patients has more diverse causes and requires extensive investigative workup. ^[15]

The significantly higher frequency of smoking and alcohol consumption in the males is probably related to the cultural differences, as these habits are quite common for Chinese male. Cigarettes and alcoholic beverages are popular measures to show welcome and hospitality in Chinese culture, but are inappropriate for decent women. Higher percentage of heart diseases and obesity in female patients observed in this study has not been documented in Taiwan before, however such observations have been reported from studies in Spain. ^[7]

Dyslipidemia is an important risk factor for coronary artery disease, ^{[16],[17],[18]} but its relation to stroke is still controversial. In this study significantly low levels of serum triglyceride were observed in the above 75 age group compared to the other groups. This may reflect the poor nutritional status in the elderly ^[19] or dietary habits in the young. Younger patients are more likely to be exposed to western-type diet, which contains higher total fat. ^[20] The other possible factor could be statin therapy in the older patients. Based on these observations we may not be able to conclude that hypertriglyceridemia is a risk factor for ischemic stroke in young Chinese and further prospective, community-based studies are needed. Studies have questioned the reliability of fasting serum lipid profile in the diagnosis of dyslipidemia immediate to the ictus. One prospective study suggestd that the ideal timing for lipid profile screening is 12 weeks after the acute stroke. ^[21] It is also not clear whether the fasting lipid profile represents the normal state. ^[22] Teno et al. showed that postprandial hypertriglyceridemia, despite normal fasting triglyceride levels, may be an independent risk factor for early atherosclerosis. Exposure to elevated postprandial triglyceride levels may last for many hours. Frequent checking of lipid levels at different times may improve the sensitivity of detecting the abnormalities. Earlier studies have also shown that low fasting serum triglyceride levels in acute stroke may be related to larger infarct volume and more severe stroke. ^[23],[24] In young patients lacunar strokes may be more common than the large artery stroke as shown in our study.

In the very old patient group, CE and LAA were the common stroke subtypes in a study in Spain, ^[25] while SVO was the common stroke subtype in a study in Argentina. ^[26] In our study there were significantly higher proportions of SUD (44.4%) and SVO (27.8%) and higher ratio of heart disease (37.5%) in the very old patients. Coronary heart disease is more common in patients aged 80 years or older, while hyperlipidemia and smoking are common in younger patients. ^{[2],[25],[26]}

[Table - 7] summarizes the distribution of stroke subtypes by TOAST classification in different studies. The frequency distribution of stroke subtypes varied from registry to registry. This may in part be due to differences in the study design, racial-ethnic differences and patient selection methods. With changing era, the lifespan, cardiovascular risk factors profile, there may be changes in the presentation of stroke syndromes. ^[27] Following this issue with time and changing the policies is very important. This work details the present day profile and management of ischemic stroke in Taiwan.

Acknowledgments

This work was supported by the Medical Research Project, Chang Gung Memorial Hospital (CMRPG660323).^[32]

References

Copyright 2010 - Neurology India

The following images related to this document are available:

Photo images