Obese black women had a higher cardiovascular risk, according to a new study.
But for white women, excess weight did not increase cardiovascular risk if they don’t have metabolic syndrome, prove the study in the Journal of the American Heart Association, published online May 20, 2015.The Obese black women had a 17% greater risk for the cardiovascular diseases.
Michelle D. Schmiegelow, MD, of the cardiology department at Copenhagen University Hospital Gentofte, Denmark — and a former guest researcher at Stanford University School of Medicine — characterized cardiovascular risk in postmenopausal women according to obesity level and metabolic health status across racial and ethnic subgroups making them more vaulnerable to heart diseases.
They started with 14,364 women ages 50 to 79 from the Women’s Health Initiative (WHI) who had data available on fasting serum lipids and serum glucose and no history of cardiovascular disease or diabetes at baseline.
About 47% were white, 36% black, and 18% Hispanic. Women were categorized by weight as normal, overweight, or obese. They were also categorized by metabolic health status — defined, first, as the presence of metabolic syndrome (metabolically unhealthy: ≥3 metabolic abnormalities) and, second, as the number of metabolic abnormalities.
Over 13 years of follow-up, 1,101 women had a first cardiovascular event (coronary heart disease or ischemic stroke). Among black women without metabolic syndrome, overweight women had higher adjusted cardiovascular risk than normal-weight women (hazard ratio 1.49). Among white women without metabolic syndrome, however, overweight women had a risk similar to that of normal weight women (HR 0.92, interaction P=0.05).
Similarly, obese black women without metabolic syndrome had a higher adjusted risk (HR 1.95) than obese white women (HR 1.07, interaction, P=0.02). Among participants with only two metabolic abnormalities, cardiovascular risk increased in black women who were overweight (HR 1.77) or obese (HR 2.17) but not in white women who were overweight (HR 0.98) or obese (HR 1.06).
“It appeared that the cardiovascular disease risk was elevated in black women by the presence of only two or three metabolic abnormalities to a degree that would require four or more metabolic abnormalities among white women,” said Schmiegelow in an American Heart Association media release.
Previous studies focusing primarily on white participants have also found obesity without a clustering of at least three metabolic disorders to be unrelated to increased cardiovascular disease risk. This study is unique in its inclusion of a large number of black subjects.
Overweight and obese women with ≤1 metabolic abnormality had no increased cardiovascular risk, regardless of race or ethnicity.
This study suggests that at least in a postmenopausal population, metabolic abnormalities may underestimate cardiovascular disease risk in black women and overestimate it in white women, said Schmiegelow. A better clinical approach might be an individualized one in which the type and sum of metabolic abnormalities are factored into a woman’s overall risk profile, especially in nonwhite populations.
These results should not fuel complacency. The authors noted that a recently published study found that after 5 years of follow-up, 31.8% of metabolically healthy obese individuals, mainly men, had become metabolically unhealthy, and 51.5% after 20 years. And since obesity might still be associated with increased metabolic risk among black women without metabolic syndrome, the study highlights the need for preventive lifestyle interventions as a window of opportunity. “Our findings underscore the importance of preventing the development of metabolic disorders, particularly in black overweight and obese women, in whom metabolic disorders were more strongly associated with increased cardiovascular risk than in white women,” the authors wrote.