sábado, 30 de maio de 2015

Physical Activity and Risk of Stroke in Women FREE

Frank B. Hu, MD, PhD; Meir J. Stampfer, MD, DrPH; Graham A. Colditz, MD, DrPH; Alberto Ascherio, MD, DrPH; Kathryn M. Rexrode, MD; Walter C. Willett, MD, DrPH; JoAnn E. Manson, MD, DrPH







Results During 8 years (560,087 person-years) of follow-up, we documented 407 incident cases of stroke (258 ischemic strokes, 67 subarachnoid hemorrhages, 42 intracerebral hemorrhages, and 40 strokes of unknown type). In multivariate analyses controlling for age, body mass index, history of hypertension, and other covariates, increasing physical activity was strongly inversely associated with risk of total stroke. Relative risks (RRs) in the lowest to highest MET quintiles were 1.00, 0.98, 0.82, 0.74, and 0.66 (P for trend=.005). The inverse gradient was seen primarily for ischemic stroke (RRs across increasing MET quintiles, 1.00, 0.87, 0.83, 0.76, and 0.52; P for trend=.003). Physical activity was not significantly associated with subarachnoid hemorrhage or intracerebral hemorrhage. After multivariate adjustment, walking was associated with reduced risk of total stroke (RRs across increasing walking MET quintiles, 1.00, 0.76, 0.78, 0.70, and 0.66; P for trend=.01) and ischemic stroke (RRs across increasing walking MET quintiles, 1.00, 0.77, 0.75, 0.69, and 0.60; P for trend=.02). Brisk or striding walking pace was associated with lower risk of total and ischemic stroke compared with average or casual pace.
Conclusion These data indicate that physical activity, including moderate-intensity exercise such as walking, is associated with substantial reduction in risk of total and ischemic stroke in a dose-response manner.

METHODS


During 8 years (560,087 person-years) of follow-up, we documented 407 incident cases of stroke (258 ischemic strokes, 67 subarachnoid hemorrhages, 42 intracerebral hemorrhages, and 40 strokes of unknown type). As described elsewhere,27 women who were more physically active tended to be leaner and were less likely to be current smokers. Increasing total physical activity level was strongly associated with progressively lower risk of total stroke (Table 1). Age-adjusted RRs of total stroke across increasing MET quintiles for total physical activity were 1.00, 0.87, 0.68, 0.57, and 0.49 (P for trend <.001). Further adjustment for smoking, body mass index, and other covariates only somewhat attenuated the association for total stroke (RRs across increasing MET quintiles, 1.0, 0.98, 0.82, 0.74, and 0.66; P for trend=.005). Additional adjustment for intake of fruits and vegetables did not materially alter the results (corresponding RRs, 1.0, 0.97, 0.80, 0.71, and 0.63; P for trend=.003). Further adjustment for antihypertensive, cholesterol-lowering, or hypoglycemic medications did not change the results. The inverse association was primarily observed for ischemic stroke (multivariate RRs across increasing MET quintiles, 1.0, 0.87, 0.83, 0.76, and 0.52; P for trend=.003). Significant trends indicate an overall linear relationship between physical activity level and risk of total and ischemic stroke. Spline regression analysis demonstrated a dose-response relationship between physical activity level and incidence of ischemic stroke (Figure 1). Physical activity level had no significant relationship with either subarachnoid hemorrhage (RR for lowest vs highest MET quintile, 0.77; 95% confidence interval [CI], 0.36-1.66; P for trend=.64) or intracerebral hemorrhage (RR for lowest vs highest MET quintile, 1.20; 95% CI, 0.45-3.19; P for trend=.34). The wide CIs of these estimates are in part due to the small number of cases. Thus, we combined intracerebral hemorrhage and subarachnoid hemorrhage in subsequent analyses (Table 1).






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