Risk Factors for Stroke: A Hospital-Based Study

Background

The stroke is third leading cause of death in world and most patients die with an acute event in stroke. Various clinical variable have been investigated as risks factors of stroke. The study was aimed to identify these risks factors for stroke.

Material and Methods

This prospective study included 205 consecutive patients of stroke. The risk factors of stroke were investigated .Examination included clinical, neurological evaluation, laboratory tests, and brain CT. The follow-up at 14 days were done for all patients. Patients included were with acute first ever stroke onset of 48 hours of hospital admission. All patients completed a structured questionnaire and a physical examination and most provided blood for relevant investigations.

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Results

205 cases stroke subtypes were (n=156, 76%, with ischaemic stroke (CI); n=49, 24%, with intracerebral hemorrhagic stroke (ICH) .The significant risk factors for all stroke were: Hypertension (p=0.003), diabetes (p=<0.001), Hypercholesterolemia (p=0.686); atrial fibrillation (p=0.445),cardiac diseases (p=0.938), smoking (p=0.926) for brain infarction and hypertension (p = 0.002), diabetes (p=< 0. 001), Hypercholesterolemia (p=0.018); atrial fibrillation (p =0. 449), cardiac diseases (p=0. 749),smoking (p=0. 829) for hemorrhagic stroke .Age significance (CI; p=<0.247 vs. ICH ;p=0.013) and age category significance were (CI; p=<0.001vs.ICH;p=0.871) for subtype of stroke . The high mRS (p<0.001 low GCS score (p<0.001) on admission were associated with worst outcome for both stroke subtype. These risk factors were all significant for CI as well as ICH.

Conclusions

This study signifies the association of risks factors with acute stroke. Targeted interventions that reduce these risk factors could substantially reduce the burden of stroke.

Keywords: acute stroke; Risk factors, outcome

INTRODUCTION

The stroke is third leading cause of death worldwide and 10% of patients with an acute ischemic stroke die as acute event.^1-5 Stroke has major impact on mortality, morbidity and economic burden. Various clinical risk factors have been associated with stroke. The identification of these risk factors is of prime importance for specific therapies.^6-8 and underdeveloped countries have largest burden of stroke estimated for more than 85% of stroke mortality worldwide.^4-5 A few studies show data to identify risk factors for stroke specifically for hemorrhagic stroke.^4-8The international multi centre case-control study designed to establish the association of risks factors of stroke has been reported previously.⁹

MATERIAL AND METHODS

The patients who presented within 24 hours after symptom onset to our Hospital with a first-ever acute stroke were prospectively included from January 1^st 2011 to June 2012.The WHO definition of stroke was used to define stroke.¹⁰ The ethics committee approved this study. The stroke was diagnosed when neurological deficits were confirmed on CT scan brain in every patient. Patients with transient ischemic attack (TIAs) and subarachnoid hemorrhage (SAH) were excluded. A 12-lead ECG and echocardiography were done. Stroke severity on admission was assessed with mRS ¹¹ and GCS. The history of preexisting stroke risk factors was assessed. The hypertension was defined as history of hypertension or antihypertensive treatment or had two measurement of blood pressure BP >160/95 mm Hg or single measurement of BP>180/110 Hg during admission^12,13, diabetes mellitus was defined as by preadmission history of diabetes mellitus and its drugs or venous plasma glucose concentration of 7.0mmol/l after an overnight fast on at least two separate measurement and or 11.1 mmol/l two hour post prandially¹⁴, current cigarette smoking was defined as who smoked at least one cigarette/tobacco per day for preceding three months or more^7,15, Hypercholesterolemia defined as by preadmission history with cholesterol >5 mmol/l, and LDL-cholesterol >3 mmol/l¹⁴ and history of coronary artery disease. The cause of death due to stroke declared unless another cause of death was found. Our approach to assessment of all key vascular risk factors, history of hypertension and diabetes mellitus, smoking and ischemic heart disease was consistent with international studies.^16-19

Structured questionnaires were prepared and physical examinations were performed . Patients with stroke measurements were completed in the supine position wherever appropriate. Blood pressure and heart rate were recorded on admission and after hospitalization. Hypertension was defined with self-reported history of hypertension with blood pressure of higher than 160/90 mmHg (mean of two measurements). The data entry and analyses were done on software statistical package SPSS 20. Chi square test both parametric and nonparametric done where appropriate for those in proportion. Quantitative data was expressed as mean and standard deviation. Stroke subtype both CI and ICH were cross tabulated as dependent variable to risk factors of stroke as independent variables to get p value which show association as such to each other. Data was reported in frequency tables. Differences between groups and the effect of patient characteristics on clinical outcome was also assessed

RESULTS

During the January 1^st 2011 to June 31^st 2012, 205patients (mean age +/- SD, 63.78+/-10.03) range 45 to 85 years were admitted to our hospital with a first-ever acute stroke. There were 111 males and 94 women (54.1% vs. 45.9%). The maximum frequency of stroke was seen between ages 55-74 (table). Mean systolic blood pressure was 162+/- 29.14.and mean diastolic blood pressure 102+/- 19.46. Glasgow coma scale (GCS) and mRS were shown in table. Out of 205 stroke patients 156(76%) had brain infarctions and 49(24%) were having hemorrhagic stroke.

Table shows the characteristics of the 205 patients with acute stroke. Hypertension was the most common risk factor 156 (76%) followed by hypercholesterolemia 145 (70.7 %) smoking 123 (60.0%) coronary artery disease 49(24%) diabetes mellitus 34 (16.6%)) and atrial fibrillation 23 (11.2%).

The mean fasting blood sugar was 6.50 +/-2.42mmol/l and mean random blood sugar was 6.36+/-3.8 mmol/l. Mean cholesterol was 6.50+/- 1.16 mmol/l.

Out of 205 patients with acute stroke 33(16%) died. Mortality was common between ages 55-74 years. Significant association of stroke observed between age (p=0.013) and age category (p<0.001) as compared to gender .GCS score <1-8 revealed more mortality as compared to patient having GCS >9. Hemorrhagic stroke showed high mortality 17(8.2%) as compared to ischemic stroke 16(7.8%). Both have significant association with mortality .Clustering of risk factors along with comorbidities influenced the hospitals mortality. The mRS score depicting functional disability as well mortality prognosticator was associated with worst outcome with high as compared to lowest score (mRS 6 vs. mRS1-5) shown (Table). In our analysis high mRS score (p<0.001), low GCS score (p<0.001) on admission were associated with high mortality.

DISCUSSION

Out of 205 patients the stroke subtype were brain infarction 156(76%) and intracerebral heamorrhage 49(24%) and in this study of risk factors for stroke all cases completed routine neuroimaging. Our results showed that many risk factors accounted for more than 80% of all stroke, both in ischaemic and intracerebral haemorrhagic stroke. The significant association of risk factors for stroke subtype were: Hypertension (CI ;p = 0.002 vs.ICH; p = 0.002) , diabetes (CI ;p = 0.002 vs.ICH; p = 0.030), Hypercholesterolemia (CI ;p = 0.686 vs.ICH; p = 0.002) as compared to atrial fibrillation (CI; p =0. 445 ICH; p =0. 449), cardiac diseases (CI; p=0. 938vs.ICH;p=0. 749 ),smoking (CI; p=0. .926 ICH; p=0. 829) .Age significance (p=0.013) for ICH as compared to CI (p=.237 whereas age category significance (p= <0.001) for ICH as compared to CI (p=.871).The high mRS (p<0.001 low GCS score (p<0.001) on admission were associated with worst outcome .Hypertension , IHD, smoking, diabetes mellitus, are common modifiable vascular risk factors for stroke as shown in previous epidemiological studies^.4,5,20-24 For both subtype of stroke we observed significant association with these risk factors which are modifiable save age .Our study help us to guide optimum selection of risk-factor target population to prevent CVA.^21,22.

Our study showed that hypertension and its level was the most important potential risk factor for both stroke subtype, particularly for intracerebral haemorrhagic stroke as observed previously²³ The hypertension underestimates the association as we used high cut point for blood pressure of 160/90 mm Hg. Estimated actual blood pressure is also problematic as it might be raised in acute stroke phase. Subsequently blood pressure might be lower than usual because of use of antihypertensive drugs and poor food intake. We used two mean reading in order to avoid these biases to minimum levels. The blood pressure is readily reduced by inexpensive drugs and salt reduction.²⁴

Studies have shown stronger association of stroke risk with waist to hip ratio than with body-mass index as well as lack of physical activity¹⁹

We found cigarettes smoking were associated with stroke. Smoking was a strong risk factor for all subtype of stroke. Few studies showed smoking has no hazard.²⁵ The alcohol intake has relation with stroke.²⁶ Our study showed cholesterol have association with stroke as have been shown in other studies.²⁷

An obvious limitations of our studies are apolipoproteins.^28, waist to hips ratio, body mass index, diet physical activity and abdominal obesity have not been investigated as risk factors and their clustering in stroke as have been observed in previous studies. Diet has association with stroke.²⁹ However for almost all risk factors that relied on past medical history were substantiated on examination and investigations to establish their relationship to stroke .In our study 16% died of stroke which is consistent with previous studies in Pakistan,^30-31 and developed countries.^32-33 The largest scale national level case-control studies will be required to assess the importance of risk factors for stroke, but our present sample size might be inadequate to provide reliable information about the importance of each risk factor.

CONCLUSION

Stroke causes great morbidity and mortality. We reports 16 % mortality rate at 14 days after acute stroke. Our findings suggest that risk factors are significantly associated of the risk of ischaemic and intracerebral haemorrhagic stroke .Hypertension, smoking, diabetes, hypercholesterolemia and ischemic heart disease are common risk factors for stroke Others risk factors such as abdominal obesity, alcohol ingestion, abdominal central obesity, diet, lack of physical activity and apolipoproteins are common potentially modifiable vascular risk factors needs to look for in order to prevent stroke .We need a large national epidemiological studies of stroke that requires routine neuroimaging and vascular access should be feasible to effected people of low and middle income. Targeted interventions that reduce blood pressure, hypercholesterolemia diabetes mellitus and smoking, promote physical activity and a healthy diet, could reduce the national burden and costs of stroke.

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Table-1: Characteristics of stroke subtype according to risk factors, gender, GCS and mRS score

*P-value asym. 2-sided

**P-value Univariate analysis