Metabolic syndrome is a cluster of risk factors such as abdominal obesity and high blood pressure that can increase the risk of other conditions such as stroke and diabetes.
"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," says Dr. Michelle Schmiegelow, author of the Journal of the American Heart Association study and research fellow at University Hospital Gentofte, Denmark.
Metabolic syndrome is a cluster of risk factors that occur together and increase the risk of stroke and diabetes. The risk factors are increased blood pressure, high triglyceride levels, low levels of "good" cholesterol, impaired glucose metabolism and abdominal obesity.
Previous studies have indicated that obesity without metabolic syndrome (defined here as having at least three of the risk factors) is not associated with an increase in cardiovascular disease risk. However, these studies focused predominantly on white participants.
Researchers analyzed a multiethnic group of postmenopausal women aged 50-79 recruited by the Women's Health Initiative, assessing cardiovascular disease risk according to weight and metabolic health status.
Of the 14,364 participants, around 47% were white, 36% were black and 18% were Hispanic. Participants were classified as "overweight" if approximately 10% over their ideal body weight for size and "obese" if around 30 pounds over their ideal weight.
Participants were followed up for 13 years. During this time, 1,101 women had either developed coronary heart disease or had an ischemic stroke for the first time.
The researchers found that, among black women with 2-3 metabolic risk factors, the relative risk of cardiovascular disease increased by 117% in those that were obese and increased by 77% in women who were overweight.
In comparison, white women with 2-3 metabolic risk factors who were obese or overweight experienced cardiovascular events as often as white women with normal weight and without any metabolic disorders.
In the absence of metabolic syndrome, black women who were obese or overweight had a higher risk of cardiovascular disease compared with normal weight black women. In contrast, white women without metabolic syndrome had a similar risk of cardiovascular disease regardless of weight classification.
Dr. Schmiegelow suggests the findings imply that metabolic syndrome may underestimate cardiovascular disease risk in black women and overestimate it in white women, at least in postmenopausal women.
Diabetes and high blood pressure 'elevate the risk of death'
For the other study, published in the Journal of Clinical Endocrinology & Metabolism, researchers assessed the findings of a health screening program at Kangbuk Samsung Hospital in South Korea, in which 155,971 people participated between 2002 and 2009.
Data were collected by conducting questionnaires and measuring the body weight, body mass index, blood pressure, cholesterol and blood sugar of each participant. Death records from the Korea National Statistical Office were also obtained to measure the mortality of the participants.
"Our research found people who had metabolic syndrome had a 1.6-fold-increase in cardiovascular mortality compared to those who did not have the condition," says Prof. Ki-Chul Sung. "Women who have metabolic syndrome faced a greater risk of death from any cause than their counterparts who did not."
A total of 12.6% of the participants had metabolic syndrome when first screened. While the findings indicate that people with metabolic syndrome face a greater risk of death from cardiovascular disease than those with the condition, this difference disappeared when participants with diabetes or high blood pressure were removed from the analysis.
"The analysis tells us diabetes and high blood pressure are significant factors that elevate the risk of death from cardiovascular disease among people with metabolic syndrome," states study author Prof. Eun-Jung Rhee, of Sungkyunkwan University School of Medicine.
"Younger people who have metabolic syndrome should be aware of the risk, particularly those who have diabetes and high blood pressure."
In the US, metabolic syndrome is commonplace. Medical News Today recently reported on a study published in JAMA that found more than a third of adults in the US have metabolic syndrome, with almost half of adults aged 60 and above affected by the condition.