10 Lifestyle, Medical Interventions Can Yield 90% Stroke Risk Reduction: So Why Is Stroke Still So Common?
Abstract & Commentary
By Dara Jamieson, MD, Associate Professor of Clinical Neurology, Weill Cornell Medical College. Dr. Jamieson reports she is a retained consultant for Boehringer Ingelheim, Merck, and Ortho-McNeil, and is on the speaker's bureau for Boehringer Ingelheim and Merck.
Synopsis: Ten risk factors are associated with approximately 90% of ischemic and hemorrhagic strokes. Hypertension, smoking, abdominal obesity, physical inactivity, and diet are the most important modifiable risk factors for stroke.
Sources: O'Donnell MJ, et al, for INTERSTROKE investigators. Risk factors for ischaemic and intracerebral haemorrhagic stroke in 22 countries (the INTERSTROKE study): A case-control study. Lancet 2010;376:112-123. Tu JV. Reducing the global burden of stroke: INTERSTROKE. Lancet 2010;376:74-75. The Emerging Risk Factors Collaboration. Diabetes mellitus, fasting blood glucose concentration, and risk of vascular disease: A collaborative meta-analysis of 102 prospective studies. Lancet 2010;375:2215–2222.
The interstroke study is an international, multicenter, case-control study, designed to establish the association of traditional and emerging risk factors with stroke and its primary subtypes. The results of phase 1 with cases and controls from 22 countries of high, middle, and low income (Argentina, Australia, Brazil, Canada, Chile, China, Colombia, Croatia, Denmark, Ecuador, Germany, India, Iran, Malaysia, Mozambique, Nigeria, Peru, Philippines, Poland, South Africa, Sudan,and Uganda) between March 1, 2007, and April 23, 2010 have been reported. The ongoing Phase 2 study is expected to be completed in the next three years. Cases were patients with acute first stroke; age- and sex-matched controls had no history of stroke. All participants completed a structured questionnaire and a physical examination, and most provided blood and urine samples. The odds ratios (ORs) and population-attributable risks (PARs) for the association of all stroke, ischemic stroke, and intracerebral hemorrhage were calculated with selected risk factors. Phase 1 included 3,000 cases (n = 2337, 78%, with ischemic stroke; n = 663, 22%, with intracerebral hemorrhage) and 3,000 controls. Significant risk factors for all stroke were: history of hypertension (OR 2.64, 99% CI 2.26-3.08; PAR 34.6%, 99% CI 30.4-39.1); current smoking (2.09, 1.75-2.51; 18.9%, 15.3-23.1); increased waist-to-hip ratio (1.65, 1.36-1.99 for highest vs lowest tertile; 26.5%, 18.8-36.0); diet risk score (1.35, 1.11-1.64 for highest vs lowest tertile; 18.8%, 11.2-29.7); regular physical activity (0.69, 0.53-0.90; 28.5%, 14.5-48.5); diabetes mellitus (1.36, 1.10-1.68; 5.0%, 2.6-9.5); excess alcohol intake (1.51, 1.18-1.92 for more than 30 drinks per month or binge drinking; 3.8%, 0.9-14.4); increased psychosocial stress (1.30, 1.06-1.60; 4.6%, 2.1-9.6) and depression (1.35, 1.10-1.66; 5.2%, 2.7-9.8); cardiac causes (2.38, 1.77-3.20; 6.7%, 4.8-9.1); and ratio of apolipoproteins B to A1 (1.89, 1.49-2.40 for highest vs lowest tertile; 24.9%, 15.7-37.1). Collectively, these risk factors accounted for 88.1% (99% CI 82.3-92.2) of the PAR for all stroke. When hypertension was defined as a history of hypertension or blood pressure >160/90 mm Hg, the combined PAR was 90.3% (85.3-93.7) for all stroke. These risk factors were all significant for ischemic stroke, whereas hypertension, smoking, increased waist-to-hip ratio, high fat diet, and excess alcohol intake were significant risk factors for intracerebral hemorrhage.
Diet played a role in stroke risk: increased consumption of fruit and fish, but not vegetables, was associated with reduced stroke risk. Increased risk of stroke was associated with increased consumption of red meat, organ meats, eggs, fried foods, pizza, and salty snacks. A history of alcohol intake of one to 30 drinks per month was associated with a reduced risk of ischemic stroke, whereas consumption of more than 30 drinks per month or binge drinking was associated with increased risk of ischemic stroke, compared with never or former alcohol intake. Some risk factors differentiated between stroke types: increased concentration of total cholesterol was not associated with risk of ischemic stroke, but was associated with reduced risk of intracerebral hemorrhage.
A meta-analysis, from 102 prospective studies (with data from almost 700,000 people) in the Emerging Risk Factors Collaboration, of individual records of diabetes, fasting blood glucose concentration, and other risk factors in people without initial vascular disease was used to calculate hazard ratios (HRs) for vascular disease. Adjusted HRs with diabetes were: 2.00 (95% CI 1.83-2.19) for coronary heart disease; 2.27 (1.95-2.65) for ischemic stroke; 1.56 (1.19-2.05) for hemorrhagic stroke; 1.84 (1.59-2.13) for unclassified stroke; and 1.73 (1.51-1.98) for the aggregate of other vascular deaths. With an adult population-wide prevalence of 10%, diabetes accounts for approximately 11% of vascular deaths and confers about a two-fold excess risk of ischemic stroke.
Commentary
Five risk factors (hypertension, current smoking, abdominal obesity, high-fat diet, and physical inactivity) in the INTERSTROKE study accounted for more than 80% of the global risk of ischemic stroke and intracerebral hemorrhage. With the addition of five other risk factors, the PAR for all stroke rose to 90%. The ten risk factors noted are generally well known but their impact is sobering. Stroke risk reduction begins at a very young age with life-long adherence to a healthy life-style. Avoidance of life-style risk factors can be advised by the health care provider, but the individual must take personal responsibility for implementation of a healthy life-style. A smoke-free life-style with physical activity, a reduced-fat diet, a normal body habitus, appropriate alcohol intake, and stress reduction can substantially reduce the burden of stroke. Treatment of elevated blood pressure, by life-style choices and medical compliance, is a collaboration between an individual and his or her health care provider that can significantly decrease stroke risk. Data from the Emerging Risk Factors Collaboration indicated a greater cerebrovascular risk for diabetes, than in the INTERSTROKE study, but both studies emphasized the importance of glucose management in stroke risk reduction. Strict attention to these stroke risk factors may lead to a substantial reduction in the almost 800,000 strokes that occur each year in the United States.
Ten risk factors are associated with approximately 90% of ischemic and hemorrhagic strokes. Hypertension, smoking, abdominal obesity, physical inactivity, and diet are the most important modifiable risk factors for stroke.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
- Award-winning Medical Content
- Latest Advances & Development in Medicine
- Unbiased Content