Kurth T, Moore SC, Gaziano JM, Kase CS
Background:
Stroke remains a leading cause of morbidity and mortality worldwide. Effective therapies for the treatment of acute ischemic stroke are commonly used but often do not completely reverse the impairment in brain function. The association between many individual behavioral risk factors and stroke incidence has been studied. Although healthy lifestyle has been associated with decreased risk of coronary heart disease, the combined effects of health-related behavior on the risk of stroke and stroke subtypes have not been studied.
Objective:
To evaluate whether a composite of healthy lifestyle factors reduces the risk of stroke and stroke subtypes in apparently healthy women.
Methods:
This is a prospective cohort study among 37,636 women 45 years or older participating in the Women's Health Study. The Women's Health Study was a recently completed randomized trial of low-dose aspirin and vitamin E in the primary prevention of cardiovascular disease and cancer. A health index was calculated using the following self-reported lifestyle factors: smoking, alcohol consumption, exercise, body mass index, and diet, assigning scores of 0 to 4 to each individual variable category, for which a higher score indicated healthier behavior. The health index ranged from 0 to 20. Healthiest behavior was defined as never smoking, consumption of 4 to less than 10.5 alcoholic drinks per week, exercising 4 or more times weekly, a body mass index of less than 22, and a healthy diet (ie, high in cereal fiber, folate, and omega-3 fatty acids, with a high ratio of polyunsaturated to saturated fat and low in trans-fat and glycemic load). Stroke was self-reported and confirmed by medical records review.
Results:
After a mean of 10 years of follow-up, 450 strokes (356 ischemic, 90 hemorrhagic, and 4 undefined) were confirmed. There was a strong association between smoking and body mass index and the risk of stroke, whereas there was no apparent association between alcohol consumption and exercise and stroke risk. The diet score was inversely associated with stroke risk. The overall health index showed strong associations between total and ischemic stroke but not hemorrhagic stroke. Compared with participants with 0 to 4 health index points, women with 17 to 20 health index points had multivariable-adjusted hazard ratios of 0.45 for total stroke (95% confidence interval [CI], 0.24-0.83; P < .001 for trend), 0.29 for ischemic stroke (95% CI, 0.14-0.63; P < .001 for trend), and 1.27 for hemorrhagic stroke (95% CI, 0.36-4.29; P = .62 for trend). Additional adjustment for the potential consequences of an unhealthy lifestyle-indicators of hypertension, diabetes mellitus, and increased cholesterol-attenuated these associations, although these remained statistically significant. For a 1-unit increase in the health index, there was a 5% reduction in total stroke (95% CI, -2% to -7%), a 6% reduction in ischemic stroke (95% CI, -3% to -9%), and 0% reduction in hemorrhagic stroke (95% CI -6% to 6%). The beneficial effect of a healthy lifestyle was apparent in all age groups. There was no effect modification for randomization to aspirin or vitamin E.
Discussion:
In this large prospective cohort of apparently healthy women, a lifestyle consisting of abstinence from smoking, a low body mass index, moderate alcohol consumption, regular exercise, and healthy diet was associated with a significantly reduced risk of total and ischemic stroke but not of hemorrhagic stroke. These associations were apparent even after controlling for hypertension, diabetes mellitus, and increased cholesterol. These findings underscore the importance of healthy behavior in the prevention of stroke.
Comment:
This cohort consisted mostly of white health professional women and, hence, generalizability is limited. Nevertheless, the study confirms the common sense notion that healthy living prevents cardiovascular morbidity; it extends this concept to stroke prevention. Given the devastating sequelae of strokes and the absence of treatment that assures complete restoration of functioning, the results of this study can be used for public health campaigns advocating healthy living.
SL