Obesity and Risk for First Ischemic Stroke Depends on Metabolic Syndrome: The HUNT Study

Background and Purpose: Obesity is one of the most prevalent modifiable risk factors of ischemic stroke. However, it is still unclear whether obesity itself or the metabolic abnormalities due to obesity increase the risk of ischemic stroke. We therefore investigated the association between metabolic health, weight, and risk of ischemic stroke in a large prospective cohort study. Methods: In the Norwegian HUNT study (Trøndelag Health Study), we included 35 105 participants with complete information on metabolic risk factors and relevant covariates. Metabolically unhealthy state was defined as sex specific increased waist circumference in addition to 2 or more of the following criteria: hypertension, increased blood pressure, decreased high-density lipoprotein, triglycerides or glucose, or self-reported diagnosis of diabetes. We then applied Cox proportional hazard models to estimate the risk for ischemic stroke among overweight and obese metabolically healthy and unhealthy participants compared with metabolically healthy, normal weight participants. Results: A total of 1161 ischemic stroke cases occurred after an average observation time of 11.9 years. In general, metabolically unhealthy participants were at increased risk of ischemic stroke (for obese participants: hazard ratio, 1.30 95% CI, 1.09–1.56 compared with metabolically healthy participants with a normal body mass index). Hypertension appeared to be the most important metabolic risk factor. Metabolically healthy participants with overweight or obesity were at similar risk of ischemic stroke compared with normal weight participants (hazard ratio, 1.02 95% CI, 0.81–1.28 for participants with obesity). Obesity and overweight even over an extended period of time seems to be benign about ischemic stroke, as long as it was not associated with metabolic abnormalities. Conclusions: Obesity was not an independent ischemic stroke risk factor in this cohort, and the risk depended more on the metabolic consequences of obesity.