Is the Obesity Paradox a Valid Concept for Stroke?

Seemant Chaturvedi, MD

New evidence sheds light on this mysterious concept.

For some chronic diseases, including stroke, studies have suggested that overweight or obese patients have a survival advantage over normal weight or underweight patients. This concept is referred to as the obesity paradox because it is at odds with conventional thinking, since obesity is strongly associated with multiple deleterious health conditions, such as diabetes mellitus, hypertension, and sleep apnea. To test whether the obesity paradox in stroke is caused by patient selection bias, investigators assessed stroke patient data entered in the Danish Stroke Register, covering the years 2003 through 2011, and identified those with an index stroke followed by death within 1 month (identified through the Danish Registry of Causes of Death). The authors assessed the rates of death according to category of body-mass index (BMI), classified as underweight (<18.5), normal (18.5–25), overweight (>25–30), and obese (>30).

Of the 71,617 patients available for analysis, 11% died within the first month, 70% of these due to stroke. BMI was inversely related to age at stroke onset (P<0.001). After adjustment for major predictors of stroke outcomes such as age and stroke severity, obese and overweight patients had no significantly increased likelihood of death compared with normal-weight patients, within either 1 week or 1 month after stroke onset.

Citation(s):

Dehlendorff C et al. Body mass index and death by stroke: No obesity paradox. JAMA Neurol 2014 Jun 2; [e-pub ahead of print].