SAN DIEGO—The metabolic syndrome, already identified by the National Cholesterol Education Program Adult Treatment Panel III as a significant independent risk factor for cardiovascular disease, doubles the risk of stroke. Although it is a less potent stroke risk factor than diabetes, metabolic syndrome occurs more often than diabetes and thus constitutes a clinically relevant precursor of cerebrovascular events, said researchers at the 29th International Stroke Conference.
Boston researchers evaluated 1,881 participants of the Framingham Offspring Study to compare the impact of the metabolic syndrome and diabetes on the 10-year risk of stroke and transient ischemic attack. All of the study subjects were free of diabetes and cerebrovascular disease at the start of the study. Some 27.6% of the men and 21.5% of the women met the study criteria for metabolic syndrome, excluding diabetes.
During a maximum follow-up of 14 years, 5.6% of men and 4.3% of women had a stroke or transient ischemic attack. Compared with participants without the metabolic syndrome, men with the condition had a 78% increased risk of stroke and women had more than double the stroke risk compared with women without the syndrome.
“The risk of stroke doubled with diabetes mellitus or metabolic syndrome,” said lead investigator Robert Najarian, medical student III, Boston University. But because metabolic syndrome is more prevalent than diabetes, the population-attributable risk of metabolic syndrome is actually greater than that of diabetes.
“About 20% of strokes could be prevented if criteria for the met-abolic syndrome could be prevented,” he said. Even after controlling for the level of systolic blood pressure, stroke risk increased 2-fold with the metabolic syndrome, indicating that an elevated systolic blood pressure does not fully explain the increased stroke risk present with this condition.
According to researchers from the Northern Manhattan Study, the metabolic syndrome may be a more potent risk factor for ischemic stroke among Hispanics than among whites or blacks. In this study, 3,298 community residents were enrolled (53% were Hispanic) to investigate the effect of the metabolic syndrome on stroke risk by race and ethnicity. More than 42% of the total cohort met the diagnostic criteria for this syndrome. With a mean follow-up of 4.9 years, 132 total strokes were detected in the entire cohort. The metabolic syndrome was found to increase the risk of stroke by 50% after adjusting for other risk factors. For Hispanics, the metabolic syndrome was associated with a more than 2-fold increase in the risk of stroke, while it increased the risk of stroke by 10% to 20% in blacks and whites, reported Bernadette Boden-Albala, DrPH, lead investigator of the study and assistant professor of sociomedical sciences in neurology, Columbia University, New York City. “The portion of stroke attributed to metabolic syndrome was 38% in Hispanics but only 4% in whites and 8% in blacks,” she said.
Increased arterial stiffness may explain the excess stroke risk with metabolic syndrome, said Tanja Rundek, MD, PhD, assistant professor of neurology, Columbia University. Carotid artery stiffness was assessed in 857 participants of the Northern Manhattan Study. Those with metabolic syndrome had a greater degree of arterial stiffness in all sex, race, and ethnic groups. The mean arterial stiffness was 2.10 among those with the metabolic syndrome compared with 1.97 among those without metabolic syndrome.