Obesity impacting stroke incidence, mortality in China
MedWire News: The rising prevalence of obesity in the Chinese population is increasing people’s risk for suffering and dying of a stroke, shows a large prospective study.
Lydia Bazzano (Tulane University School of Medicine, New Orleans, Louisiana, USA) and colleagues studied 154,736 Chinese people aged 40 years or older. During follow-up lasting an average of 8.3 years, 7489 people suffered a stroke, 3924 of which were fatal.
The researchers note in the Annals of Neurology that stroke is currently the leading cause of death in China.
In all, 12% of the cohort was underweight (body mass index [BMI] <18.5 kg/m2), 65% was of normal weight (BMI 18.5–24.9 kg/m2), 20% was overweight (BMI 25.0–29.9 kg/m2), and 3% was obese (BMI ≥30.0 kg/m2).
The age-standardized stroke rates per 100,000 person-years were 369.8, 497.0, 722.2, and 852.0 for underweight, normal weight, overweight, and obese people, respectively.
Overweight and obesity conferred respective 43% and 72% increases in ischemic stroke risk and 60% and 89% increases in hemorrhagic stroke risk, relative to normal weight, after accounting for variables including age, gender, cigarette smoking, urban residence, and physical inactivity.
Stroke mortality was 15% and 47% more likely in overweight and obese people, respectively, than in normal weight people.
Hypertension and diabetes were more common in overweight and obese individuals than normal weight people. Accounting for these conditions reduced the size of the effect of BMI on ischemic stroke incidence but did not reduce its significance. But it did reduce the effect of hemorrhagic stroke and stroke mortality to borderline or nonsignificance.
This indicates that obesity per se may influence ischemic stroke incidence, but that other factors relating to obesity have a stronger impact on hemorrhagic stroke incidence and stroke mortality.
But Bazzano et al stress: “Rather than lessening the importance of BMI as a predictor of stroke risk, the uniformity of this result across studies robustly supports the value of maintaining a BMI within the normal range as an essential tool in strategies for the prevention of stroke.”
In an accompanying editorial, Tobias Kurth (INSERM, Paris, France) and Michael Leitzmann (Regensburg University Medical Center, Germany) said: “The obesity epidemic has clearly reached China, particularly among younger individuals.”
They stressed: “Implementing effective strategies for the prevention and treatment of overweight and obesity is urgently required to decrease the clinical and public health burden of stroke in China. Only then will it be possible to prevent the sleeping giant of obesity and stroke from fully awakening in this country.”
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By Eleanor McDermid