Body mass index in mid-life is associated with a first stroke in men: a prospective population study over 28 years.

BACKGROUND AND PURPOSE Data on the association between obesity and stroke are still limited. We examined the possible association between mid-life body mass index (BMI) and risk of stroke in the prospective Multifactor Primary Prevention Study in Göteborg, Sweden. METHODS 7402 apparently healthy men aged 47 to 55 at baseline were followed-up over a 28-year period. Incidence of fatal and nonfatal stroke was recorded in a local stroke registry through the Swedish National Register on Cause of Death and the Swedish Hospital Discharge Registry. RESULTS A total of 873 first strokes were recorded, including 495 ischemic, 144 hemorrhagic, and 234 unspecified strokes. Compared with men with low normal weight (BMI, 20.0 to 22.49 kg/m2), men with BMI >30.0 kg/m2 had a multiple adjusted hazard ratio of 1.93 (95% CI, 1.44 to 2.58) for total stroke, 1.78 (95% CI, 1.22 to 2.60) for ischemic stroke, and 3.91 (95% CI, 2.10 to 7.27) for unspecified stroke. There was no significant association between BMI and hemorrhagic stroke. Adjustment for potential mediators, eg, hypertension, diabetes and serum cholesterol levels, attenuated but did not eliminate the risk. CONCLUSIONS In this prospective population-based study of men, increased BMI in mid-life was associated with an increased risk for total, ischemic, and unspecified stroke, but not with hemorrhagic stroke. The result supports the role of mid-life BMI as a risk factor for stroke later in life and suggests a differentiated effect on stroke subtypes.