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No ‘obesity paradox’ in patients with high BMI, stroke
Despite some studies suggesting that patients who are obese or overweight could have lower mortality rates when strokes occur than those with average or below average BMI, no evidence of this paradox was found, according to data published in JAMA Neurology.
“Obesity was not associated with a lower risk for death after a stroke,” Christian Dehlendorff, MS, PhD, of the Danish Cancer Society Research Center in Copenhagen, Denmark, and colleagues wrote. “The obesity paradox reported in previous studies appears to be the result of selection bias due to lack of control for the severity of the diseases leading to death after a stroke.”
The researchers found that patients with higher BMI have strokes significantly earlier in life and should continue efforts toward their goals of normal weight should an incident occur.
Christian Dehlendorff
The investigators evaluated survival after stroke in relation to BMI by using data on hospital admissions for stroke from the Danish Stroke Register, from 2003 to 2012, and the Danish Registry Causes of Death. The study included all registered Danes (n=71,617) with information available on BMI (n=53,812), age, sex, civil status, stroke severity, stroke subtype, a predefined cardiovascular profile and socioeconomic status.
To overcome selection bias, the researchers only considered deaths caused by index stroke on the notion that death by stroke reported on a death certificate was due to the incident if it occurred within 1 month.
Of all study participants, results showed 7,878 (11%) died within the first month, with stroke the cause of death in 5,512 (70%). Of those with BMI information, 9.7% were categorized as underweight, 39% normal weight, 34.5% overweight and 16.8% obese.
An inverse association existed between BMI and average age at stroke onset (P<.001). No difference was observed in the risk for death by stroke in the first month among patients who were normal weight (reference), overweight (HR=0.96; 95% CI, 0.88-1.04) and obese (HR=1; 95% CI, 0.88-1.13). The researchers found similar results analyzing deaths within 1 week.
“The risk of obese patients with stroke for death did not differ from that of normal-weight patients with stroke,” the researchers wrote, “nor was there evidence of a survival advantage associated with being overweight.”
Disclosure: Jascha Fonden provided funding for this study.