Having three or more traits of the metabolic syndrome significantly increases the risk of dying from coronary heart disease, cardiovascular disease or any other cause, according to a study in Circulation: Journal of the American Heart Association.
Researchers compared the risk of death among people with a clustering of metabolic abnormalities to the risk of people with cardiovascular disease, people with diabetes and people without metabolic syndrome, cardiovascular disease or diabetes.
It is particularly interesting that patients with even one or two metabolic syndrome traits, or those with the metabolic syndrome but without diabetes were at increased risk for death from coronary heart disease and cardiovascular diseases,” said Nathan D. Wong, Ph.D., professor and director of the Heart Disease Prevention Program, division of cardiology at the University of California, Irvine.
Metabolic syndrome is characterized by a group of metabolic risk factors. They include excessive fat tissue in and around the abdomen, blood-fat disorders, insulin resistance or glucose intolerance, and high normal blood pressure or hypertension.
According to the American Heart Association, the underlying causes of this syndrome are obesity, physical inactivity and genetic factors.
Researchers reviewed data from 6,255 patients who participated in the second National Health and Nutrition Examination Survey (NHANES 2) from 1976 through 1980 and had causes of death documented over an average of 13 years. They ranged in age from 30 to 75, and 54 percent were women.
In this study, a person was diagnosed with metabolic syndrome if three or more of these characteristics were found:
- A body mass index of 30 kg/m² or greater (obesity)
- HDL cholesterol less than 1.04 mmol/L (40 mg/dL) if male or less than 1.29 mmol/L (50 mg/dL) if female
- Triglycerides greater than or equal to 1.69 mmol/L (150 mg/dL) if fasting or greater than or equal to 4.52 mmol/L (400 mg/dL) if not fasting
- Blood pressure greater than or equal to 130/85 mmHg or on anti-hypertension medication
- Glucose greater than or equal to 6.1 mmol/L (110 mg/dL) if fasting or two-hour post-load glucose greater than or equal to 7.77 mmol/L (140 mg/dL)
Overall, 26 percent of participants had metabolic syndrome and 19.8 percent had pre-existing cardiovascular disease, meaning they reported that a physician had diagnosed them with coronary heart disease, heart failure, stroke or other cardiac disease. The remaining 54 percent didn’t have metabolic syndrome, diabetes or cardiovascular disease.
Compared to people with no metabolic syndrome factors, the risk of CHD death was twice as high for those with one to two factors and three-and-a-half times higher for people with metabolic syndrome (three or more factors).
Compared to those with neither metabolic syndrome, diabetes, nor CVD, participants with the metabolic syndrome but no diabetes had a 65 percent greater risk of CHD death. Those with diabetes had a 2.9-times greater risk. Risks were greatest for those with pre-existing CVD alone (4.2-times) and for participants with combined diabetes and CVD (6.5-times).
“The study emphasizes the importance of close risk-factor monitoring and management, particularly blood pressure and dyslipidemia (abnormal levels of blood fats), which are common in those with the metabolic syndrome,” Wong said.
In addition, he said, the findings showing the highest death risk among those with both diabetes and pre-existing CVD support the recently released revision of the National Cholesterol Education Program Adult Treatment Panel III guidelines for lipid management, which have placed these people in the “very high risk” category, warranting very aggressive risk-factor intervention.
“We recommend physicians provide adequate resources for their patients with metabolic syndrome to improve compliance to diet and exercise regimens. Many physicians who may not have the time to counsel a patient for an hour on diet or exercise do not refer to a registered dietitian or exercise specialist when they should,” Wong said.
“More attention to the medical management of elevated risk factors is essential to prevent the metabolic syndrome, diabetes and their complications.”
The study’s lead author is Shaista Malik, M.D., MPH. Other co-authors are Stanley S. Franklin, M.D.; Tripthi Kamath, Ph.D.; Gilbert J. L’Italien, Ph.D.; Jose R. Pio, B.S.; and G. Rhys Williams, Sc.D.
This research was supported in part by a grant from the Bristol Myers-Squibb Pharmaceutical Research Institute.