Further evidence challenges obesity paradox
medwireNews: UK Biobank data add to the evidence challenging the existence of the obesity paradox by showing that cardiovascular disease (CVD) risk increases linearly with increasing adiposity in middle-aged men and women.
Stamatina Iliodromiti and colleagues from the University of Glasgow, UK, did observe a J-shaped association between BMI and CVD risk, but this became more linear when the data were adjusted for smoking and comorbidity.
Therefore, “the observed detrimental ‘impact’ of low BMI on CVD outcomes is likely a result of confounding,” the authors write in the European Heart Journal.
Specifically, “the disproportionally greater number of ill people in the low categories of BMI that are at increased risk of CVD events inflate the [hazard ratio] of CVD events in this BMI category,” they add.
The study included 296,535 members (57.8% women, mean age 55 years) of the UK Biobank cohort who were of White European descent and did not have CVD at baseline.
During an average 5-year follow-up period, 3.3% of women and 5.7% of men developed a fatal or nonfatal CVD event.
The researchers found that individuals with a very low BMI (≤18.5 kg/m2) had a higher incidence of CVD than those with a BMI of 22–23 kg/m2, for whom the CVD risk was lowest, but only in the unadjusted analysis.
For those with a BMI above 22 kg/m2, CVD incidence increased linearly, with each standard deviation (SD) increase in BMI (5.2 kg/m2 in women and 4.3 kg/m2 in men) associated with a significant 13% increased risk for CVD events in both sexes.
By contrast, the team observed linear associations in both unadjusted and adjusted analyses of other measures of adiposity.
Specifically, each SD increase in waist circumference (12.6 and 11.4 cm in women and men, respectively) was associated with a significant 16% increased risk for CVD in women and a significant 10% increased risk in men when compared with women and men with waist circumferences of 74 and 83 cm, respectively.
Similar increases in CVD risk were seen with each SD increase in waist-to-hip ratio, waist-to-height ratio, and percentage body fat mass.
“Our study has extended previous work, which looked only at associations of BMI with health outcomes by demonstrating novel associations with other well validated measures of adiposity and fat distribution,” Iliodromiti et al remark.
They add that their findings “strongly reaffirm that being overweight heightens the risk of CVD and that individuals should seek to keep their weights as close to recommended levels [as possible] to lessen their risks of CVD.”
The team concludes: “The association of BMI with CVD is more susceptible to bias rather than other adiposity measures and, therefore, health care professionals should challenge any public misconception of some ‘protective’ effect of fat on CVD risk.”
By Laura Cowen
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