Epidemiological study of incidence and risk factors of Ischemic stroke subtypes according to Trial of ORG 10172 in acute stroke treatment criteria : A 3 years , hospital-based study

Background and Purpose: The purpose of this study was to determine the incidence and risk factor of ischemic stroke subtypes by a mechanismbased classifi cation scheme (Trial of ORG 10172 in Acute Stroke Treatment [TOAST]). Materials and Methods: This study was conducted in Indraprastha Apollo Hospital, New Delhi, between 01/01/2004 and 31/12/2006. Out of 361 admitted stroke patients, 244 (67.59%) ischemic stroke patients were analyzed retrospectively for incidence and modifi able risk factors for stroke in our region. The cause of ischemic stroke was classifi ed according to the TOAST criteria. Results: Out of 244 patients 165 (67.6%) were male and 79 (32.4%) were female, the mean age at the time of stroke was 57.1 years, the incidence of different risk factors were as follows: 139 (56.9%, odds ratio 2.71) hypertensive, 85 (34.8%, odds ratio 2.4) diabetics, 95 (38.9%, odds ratio 3.12) smokers, 58 (23.7%, odds ratio 5.34) dyslipidemics, 44 (18.0%, odds ratio 1.43) coronary artery disease (CAD) patients, 14 (5.7%, odds ratio 1.22) patients have the transient ischemic stroke in the past, 13 (5.3%, odds ratio 1.43) were given the history of atrial fi brillation. The incidence rates of ischemic stroke subtypes were as follows: Determined causes; large artery atherosclerosis 141 (57.7%), lacunes 18 (7.7%), cardio-embolism 11 (4.5%), hypercoagulable state 8 (3.2%), un-determined causes; atherosclerosis and/or lacunes 25 (10.2%), embolism and/or two more (hypercoagulable state/CAD) possible causes 7 (2.8%), negative evaluation in 34 (13.9%) patients. Ischemic stroke subtype according to the TOAST criteria was a signifi cant predictor for long-term survival. Conclusions: Our data indicate that large vessel disease is a major cause, and the hypertension, diabetes, smoking, hyperlipidemia are the most common risk factors for Ischemic stroke.


Study area and population
The present epidemiological study is a retrospective 3 years, hospital-based study done in the Department of Neurosciences at Indraprastha Apollo Hospital, New Delhi, India, a total record of 244 patients admitted in the hospital during the period 01.01.2004-31.12.2006 were evaluated for incidence, risk factors (i.e., family history, history of smoking and coexisting diseases such as HTN, diabetes mellitus (DM), dyslipidemia, thromboembolic disorders and cardiac diseases) of ischemic stroke subtypes by a mechanism-based classifi cation scheme (Trial of ORG 10172 in Acute Stroke Treatment [TOAST]) after the approval of institutional ethics committee. [10]

Subtypes of ischemic stroke
For the determination of the subtype of ischemic stroke, the original TOAST criteria were used.The 5 major categories of the TOAST classifi cation are as follows: Large-artery atherosclerosis (LAA), including large-artery thrombosis and artery-to-artery embolism; cardio-embolism; small artery occlusion; stroke of other determined cause; and stroke of un-determined cause (UND).For strokes of un-determined origin, 1 of 2 explanations was needed: a.No cause was found despite an extensive evaluation or b. a most likely cause could not be determined because >1 possible cause was found.
The subtype defi nitions were based on risk factor profi les, clinical features, and results of diagnostic tests.The latter included computed tomography scan, magnetic resonance imaging, vascular imaging (carotid duplex, transcranial Doppler), electrocardiogram, echocardiography, assessment of prothrombotic syndromes, etc.

Data and statistical analysis
Variables were analyzed by fi nding their frequencies, percentages or odds ratio.

RESULTS
A total of 91,500 patient was admitted at the Indraprastha Apollo Hospital, New Delhi, India, during the period of 3 years, between 01.01.2004 and 31.12.2006,out of which 361 had stroke (394.54/100,000),244 (0.26%, 266/100,000) were of ischemic stroke, evaluated for risk factors and stroke subtype.

Ischemic stroke subtype
The

DISCUSSION
This is a retrospective epidemiological 3 years, hospital-based study on incidence and risk factor of ischemic stroke subtypes classifi ed according to the TOAST criteria.The present hospital-based study used widely accepted standardized methods of case ascertainment and provided epidemiological data on causes of ischemic stroke in a section of Indian population.
Stroke is the main cause of adult disability and the second most leading cause of death worldwide. [3]It is known that stroke incidence, prevalence and mortality vary widely in different populations.
Studies such as the World Health Organization's Monitoring of trends and determinants of cardiovascular disease project have shown that relative to Caucasians, Asians have a higher prevalence of stroke. [11]Stroke prevalence rate in our study is comparable to most of the earlier studies done in India 394.54/100,000 versus 136-350/100,000, [12][13][14][15][16] except two studies which shows higher prevalence rate than the present study, Das et al., 2007 (545.10/100,000) and Bharucha et al., 1988 (842.3/100,000), the standardized rate in US is 424/100,000. [16]Over the past few decades, the stroke prevalence rate has shown increasing trend in India 13 in 1970-350/100,000 in 2004. [14,15,17]It may be attributed to the increasing incidence of HTN, DM, dyslipidemia, sedentary lifestyle, and change in dietary habits and lack of awareness regarding stroke risk factors.Study by Truelsen et al., in 2001 showed that the average age of stroke in developing countries is 15 years earlier than the developed world. [18]The mean age of stroke in present study was 57.1 ± 1.7 years which is comparable to study done by Biswas et al., in 2009 (Indians) 64 ± 10 years versus (Americans) 71 ± 13 years. [19]troke at earlier age has been shown by various studies conducted in India. [16,18,20]Lipska et al., in 2007 showed that key components of metabolic syndrome and smoking are associated with ischemic stroke in South Indians. [21]Many previous studies showed that the risk of stroke doubles for each successive decade after age 55 years. [22,23] 3 and 4, Figures 3 and 4].Hypertension affects millions of people worldwide and is a major risk factor for both cerebral infarction and intracerebral hemorrhage, Wolf 1999; Fields et al., 2004. [24,25]The higher the blood pressure, greater will be a stroke risk, Lewington et al., 2002. [26]hobanian et al., 2003 reported that control of high blood pressure contributes to the prevention of stroke as well as to the prevention or reduction of other target organ damage, including congestive heart failure and renal failure. [27]Risk of stroke can be reduced by at least 38% by control of HTN MacMahon and Rodgers 1996. [28]TN as a risk factor was present in 56.9% of our patients which was almost similar to 62% by Wu et al., 2010 [29] but <72% and 85% reported in United States Sacco et al., 1998 and Russia Feigin et al.,  1998 respectively. [30,31]e role of dyslipidemia in the pathogenesis of cerebrovascular disease in less certain than for CAD; more consistent association has been noted with low high-density lipoprotein (HDL) cholesterol and high total cholesterol to HDL cholesterol ratio than with total cholesterol, low-density lipoprotein cholesterol and triglycerides. [32][14][15][16] Higher prevalence of dyslipidemia in our stroke population could be attributed to the increasing trends of diabetes, HTN, sedentary lifestyle, excessive alcohol use and smoking.
Diabetes was a risk factor in 34.8% of cases in present study which is comparable to the studies done by Wu et al., 2010 (32.2%), and by Lai et al., 2008 (36.9%). [29,33]Cigarette smoking is a potent risk factor for ischemic stroke. [34]Present study recorded 38.9% male patients with smoking which is lower than 53% reported by Wu et al., 2010, [29] but higher than 31.3% reported by Lai et al., 2008. [33]moking increases stroke risk by producing acute effects on the risk of thrombus generation in narrowed arteries and chronic effects related to an increased burden of atherosclerosis. [35]r study showed that large vessel occlusive disease was the most common cause of ischemic stroke (57.7%), which is very high as compared to the available data from the developing countries indicate small vessel occlusion, is the most common cause of stroke, [36] but similar with developed countries where the large artery disease is the most frequent reason for stroke. [29,37]The relative proportion of large artery disease in different western stroke registries varies from 14% to 66%. [37]Variations in study designs, methods of patient selection and defi nitions of stroke subtypes may partially account for the wide variations in the reported frequency of large artery disease.
Present study has shown 27% stroke of un-determined etiology, which is less than the previous studies done by Kolominsky  [10,29] There are certain limitations, our study was conducted in a tertiary care referral center for neurological diseases and therefore be biased toward the more disabling and complicated disease processes, it was a retrospective collection of data from medical records, use of single occasion risk factors analysis and modest sample size.
To conclude, tobacco smoking and diabetes are growing problems in the developing countries. [38,39]Our fi ndings suggest that smoking, HTN, dyslipidemia and diabetes are the preventable stroke risk factors.Smoking cessation, prevention, identifi cation and treatment of above-mentioned risk factors are crucial for preventing stroke.Further studies involving the multiple centers and more number of patients are required to substantiate our results.
International Journal of Medicine and Public Health | Jan-Mar 2015 | Vol 5 | Issue 1

Table 1 : Demographic profi le
SE = Standard error, SES = Socioeconomic status