TUESDAY, Dec. 16, 2003 (HealthDayNews) -- Four different conditions associated with metabolic syndrome -- high blood pressure, high blood triglycerides, low "good" cholesterol and insulin resistance -- are linked to a higher risk of heart attack and stroke.
A new study finds, however, that a fifth player in metabolic syndrome -- obesity -- is not independently as big a factor in creating cardiovascular problems. But it is associated with the other conditions, and having any combination of those conditions raises the risk even higher.
"Each of them is bad, and taken together, they are really bad," says study author John Ninomiya, a doctoral candidate in epidemiology at the University of California at San Diego.
"Metabolic syndrome contributes to the risk of both myocardial infarction and stroke in both men and women," says Dr. Michael Criqui, a professor and vice chairman of the department of family and preventive medicine at the University of California, San Diego, School of Medicine. "It's highly significant. There are no exceptions to the rule, if you will."
Criqui is a co-author of the study, which appears in the Dec. 16 issue of Circulation.
"The implications are huge, in the sense that it is estimated that conservatively that approximately 25 percent of the U.S. adult population has metabolic syndrome and it increases with age. When you have people over 40, it's as many as 40 percent," adds Dr. Prakash Deedwania, author of an accompanying editorial and chief of cardiology at VA Central California Health Care System in Fresno. "With the aging of America, a lot of people are going to be in that age group and you can expect that this will lead to a new epidemic."
Metabolic syndrome is diagnosed when a person has at least three of these five conditions: insulin resistance, abdominal obesity based on waist circumference, high blood pressure, low "good" cholesterol and hypertension.
"This labels a particular type of patient, a profile," says Dr. Keith A. Siller, director of New York University's Comprehensive Stroke Care Center in New York City.
Unlike other studies on metabolic syndrome, this one looked at a broad-based sample of the population. "The strength of the study is that it's in a population that attempted to be representative sample of the United States," Criqui says. "The results then are sort of generalizable to very broad area."
The study authors used data on 10,357 U.S. adults collected between 1988 and 1994 as part of the Third National Health and Nutrition Examination Survey (NHANES III) to analyze the relationship of metabolic syndrome to heart attack and stroke.
Almost one-quarter of the respondents (24 percent) had metabolic syndrome as defined by the National Cholesterol Education Program Adult Treatment Panel (NCEP-ATP III).
Having this syndrome doubled the risk of heart attack and stroke. High triglycerides increased the odds of having a heart attack or stroke by 66 percent, while high blood pressure raised the odds by 44 percent. Insulin resistance elevated the risk by 30 percent and low HDL ("good") cholesterol by 35 percent.
Surprisingly, having a wide girth was not independently associated with heart attack or stroke, as had been shown in previous studies. "They're all bad guys, except for the waist circumference," Criqui says.
The findings have implications for prevention of vascular disease. "This is new information to alert physicians to identify patients who have this profile," Siller says. "Now it is crystal clear that these are the people at the highest risk of vascular disease."
There are also likely to be implications for treatment, as the findings suggest that the different hallmarks of metabolic syndrome may have a common genesis. "We are going to try to treat the underlying mechanisms because the combination of them raises the stakes so high. They're even more dangerous when combined," Siller says.