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Lifestyle habits and risk of stroke: methodological considerations and differences according to gender and stroke subtypes
- Tobias Kurth (20 February 2009)
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Combined effect of health behaviours and incidence of stroke
- Indu Elizabeth Mathew, Aju Mathew (21 February 2009)
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Life style and Risk of Stroke
- Rizaldy Pinzon (14 March 2009)
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Lifestyle factors and risk of first and subsequent stroke
- Smitha Addala, Soma Banerjee (Geriatric SpR, St. Mary's Hospital, W21NY), Diane Ames (Consultant Stroke Physician, St. Mary's Hospital, W2 1NY) (16 March 2009)
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Tobias Kurth, Senior researcher INSERM Unit 708 - Neuroepidemiology, Paris, France
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I read with great interest the study by Myint and colleagues showing that the combination of four lifestyle factors (current non-smoking, physically not inactive, moderate alcohol intake (1-14 units a week), and a plasma concentration of vitamin C >=50 micromol/l, indicating fruit and vegetable intake of at least five servings a day, led to an approximately two-fold decrease in the risk of stroke in men and women [1]. The finding is very reassuring and support previous results of large- scale, US-based cohort studies [2, 3]. A few points merit further comments. First, while the authors show several multivariable models, they report as main result relative risk estimates from a multivariable model that also controlled for body mass index, systolic blood pressure, and cholesterol concentration. These factors, however, are strongly influenced by lifestyle habits and thus can be considered potential mediators of the associating between lifestyle habits and stroke. In addition, controlling for potential direct consequences of exposure may lead to biased effect estimates [4]. Thus, lifestyle habits may have an even stronger influence on stroke occurrence. Second, the association between lifestyle habits and risk of stroke in the study is magnified in women. When compared with men who have a combination of all four lifestyle habits, women seem to achieve a similar risk reduction of stroke already after summing two. Lastly, the EPIC-Norfolk data do not allow differentiating between ischemic and hemorrhagic stroke. Data from the Women's Health Study suggest that a lifestyle considered to be healthy was associated with markedly reduced risk of ischemic but not hemorrhagic stroke [2]. In fact, the risk of hemorrhagic stroke was highest for women who were classified to live the "healthiest" lifestyle. In Summary, data from the study by Myint and colleagues are strongly supporting the influence of lifestyle habits on stroke risk and all efforts should be made to emphasise a healthy lifestyle. Future research should focus on potential gender differences of the association between overall and specific lifestyle habits and stroke as well as on potential differences of lifestyle habits on major stroke subtypes. References: 1. Myint PK, Luben RN, Wareham NJ, Bingham SA, Khaw KT. Combined effect of health behaviours and risk of first ever stroke in 20 040 men and women over 11 years' follow-up in Norfolk cohort of European prospective investigation of cancer (EPIC Norfolk): prospective population study. BMJ 2009;338:b349. 2. Kurth T, Moore SC, Gaziano JM, Kase CS, Stampfer MJ, Berger K, et al. Healthy lifestyle and the risk of stroke in women. Arch Intern Med 2006;166(13):1403-9. 3. Chiuve SE, Rexrode KM, Spiegelman D, Logroscino G, Manson JE, Rimm EB. Primary prevention of stroke by healthy lifestyle. Circulation 2008;118(9):947-54. 4. Robins JM. Data, design, and background knowledge in etiologic inference. Epidemiology 2001;12(3):313-20. Competing interests: None declared |
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Indu Elizabeth Mathew, Primary care physician Community Health Center, Elappully, Palakkad, Kerala, India, Aju Mathew
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We read the paper from the EPIC-Norfolk cohort with great interest (1). The study unequivocally reveals the importance of lifestyle modification in reducing the burden of stroke in a western population. We also commend the authors for excluding the events occuring within 2 years of follow up from the analysis to account for ‘reverse causation’, although we believe excluding the first 5 years of follow up would have been more appropriate given that the outcome of interest has a longer latency. We are also perplexed by the fact that the authors have evaluated the independent relative risk (Table 2) for a category combining ‘no alcohol consumption’ with >14 units/week of consumption (no or high alcohol consumption vs. moderate alcohol consumption). It would have been interesting if it were assessed separately since there is no physiological basis for having a composite group of the two categories of individuals. Another issue that could influence such a study is called the ‘Hawthorne effect’ in which the individuals in the cohort can undergo behavioural changes because of the study itself. However, given the large number of individuals in the cohort (more than 20 000), it is highly unlikely that it could bias the results. 1. Myint PK, Luben RN, Wareham NJ, Bingham SA, Khaw KT. Combined effect of health behaviours and risk of first ever stroke in 20 040 men and women over 11 years' follow-up in Norfolk cohort of European prospective investigation of cancer (EPIC Norfolk): prospective population study. BMJ 2009;338-349. Competing interests: None declared |
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Rizaldy Pinzon, Neurologist Bethesda hospital Yogyakarta Indonesia 55224
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This study confirm that smoking, drinking too much alcohol, and eating few vegetables and little fruit contribute to the chances of a stroke. Stroke is the most leading cause of death and disability. The incidence of stroke is rapidly increase in many developing countries. The lifestyle changes is commonly observed in developing countries. This study remind us that even small changes to our lifestyle factors, such as an improved diet, drinking alcohol in moderation, not smoking and being active, can reduce the risk of stroke. Changes in lifestyle relating to tobacco and diet might make important contributions to further reductions in the incidence of stroke. The future study should analyze subgroup without alcohol consumption. In many developing countries, alcohol consumption was not very common. This study is very helpful for the clinicians to make an advice for the high risk population for reducing the burden of stroke. Competing interests: None declared |
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Smitha Addala, Junior Doctor West Middlesex University Hospital, TW7 6AF, Soma Banerjee (Geriatric SpR, St. Mary's Hospital, W21NY), Diane Ames (Consultant Stroke Physician, St. Mary's Hospital, W2 1NY)
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We commend the authors for their study looking at the independent effect of lifestyle factors on the on risk of stroke. Myint et al, demonstrate very clearly that modifiable risk factors such as diet, alcohol, exercise and smoking are associated with a lower relative risk of stroke independent of confounding factors such blood pressure and atrial fibrillation. There is a need for such high quality evidence to back up current guidelines. They also quite rightly point out that a large percentage of all strokes occur in people who do not have known risk factors such as hypertension and atrial fibrillation. Previous stroke is a good predictor of subsequent stroke (1) and it is also important to screen and address all relevant risk factors in this high risk population. This includes addressing areas such as diet and lifestyle, obesity, sedentary lifestyle and alcohol intake. We recently conducted an audit of medical notes over a period of 6 weeks of all patients discharged from the acute stroke unit at a London teaching hospital. We found that screening for risk factors such as BMI and alcohol intake by medical staff was relatively low (17% and 50% respectively) compared to, for example, screening for hypercholesterolaemia and smoking (94% and 78%). Furthermore, lifestyle advice regarding exercise, diet and weight, salt restriction and alcohol was given only in the minority of patients (0%, 28%, 0% and 11%). On the other hand, risk factors such as hyperlipidaemia and atrial fibrillation were very actively addressed with 89% of stroke patients being prescribed a statin on discharge and 100% with atrial fibrillation either being anticoagulated or having a documented contraindication for anticoagulation. We addressed this problem promptly within our department and each patient now receives a brief session with a specialist nurse and an education pack regarding lifestyle measures to reduce risk of subsequent stroke. This is then documented in the medical notes. We would encourage others to take similar measures to prevent what we believe would be a common problem across many hospitals. Recognition of the importance of life-style factors in stroke aetiology needs to be reinforced routinely by hospital medical staff. (1) RCP London National Clinical Guidelines for Stroke, 2nd Edition, June 2004. Competing interests: None declared |
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