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Obesity is a risk factor of heart disease regardless of MetS
Being overweight or obese are risk factors for myocardial infarction and ischemic heart disease, regardless of whether individuals also metabolic syndrome, according to a study published by JAMA Internal Medicine.
Drs Børge Nordestgaard and Mette Thomsen from Herlev Hospital, Copenhagen University Hospital, Denmark, investigated whether overweight and obesity with and without metabolic syndrome are associated with increased risk of myocardial infarction and ischemic heart disease.
They examined 71,527 individuals from the Copenhagen General Population Study and categorised them according to BMI as; normal weight, overweight, or obese, and according to absence or presence of metabolic syndrome.
During a median of 3.6 years’ follow-up, they recorded 634 incidences of myocardial infarctions and 1,781 incidences of ischemic heart disease. For myocardial infarctions, multivariable adjusted hazard ratios vs, normal weight individuals without metabolic syndrome were 1.26 (95% CI, 1.00-1.61) in overweight and 1.88 (95% CI, 1.34-2.63) in obese individuals without metabolic syndrome and 1.39 (95% CI, 0.96-2.02) in normal weight, 1.70 (95% CI, 1.35-2.15) in overweight, and 2.33 (95% CI, 1.81-3.00) in obese individuals with metabolic syndrome.
For ischemic heart disease, they authors write that the “results were similar but attenuated”. Normal weight vs. overweight vs. obesity and presence vs. absence of metabolic syndrome did not interact on risk of myocardial infarction or ischemic heart disease (p=0.90 and p=0.44).
Among individuals both with and without metabolic syndrome there were increasing cumulative incidences of myocardial infarction and ischemic heart disease from normal weight through overweight to obese individuals (log-rank trend p=0.006 to p<0.001).
Although the multivariable adjusted hazard ratio for myocardial infarction in individuals with vs without metabolic syndrome was 1.54 (95% CI, 1.32-1.81) across all BMI categories, addition of metabolic syndrome to a multivariable model including BMI and other clinical characteristics improved the Harell C-statistic only slightly for risk of myocardial infarction (comparison p=0.03) but not for ischemic heart disease (p=0.41).
"These findings suggest that overweight and obesity are risk factors for myocardial infarction and ischemic heart disease regardless of the presence or absence of metabolic syndrome and that metabolic syndrome is no more valuable than BMI in identifying individuals at risk," the study concludes.
In a related commentary, Drs Chandra L Jackson and Meir J Stampfer, from the Harvard School of Public Health, Boston, write: "Besides questions related to how much added value there is to assessing MetS [metabolic syndrome] (beyond its component elements), the findings from this study have important implications and clearly corroborate the clinical and public health message that adiposity is not benign and that achieving and maintaining a healthy body weight is of paramount importance.
"The findings of Thomsen and Nordestgaard add important new evidence to counter the common belief in the scientific and lay communities that the adverse health effects of overweight are generally inconsequential as long as the individual is metabolically healthy," they continue.
"In contrast, this study adds further evidence for the increased risks associated with overweight, even among those who might be considered metabolically healthy. These results also underscore the importance of focusing on weight gain prevention due to the difficulty in achieving and maintaining weight loss to reverse being overweight or obese," they conclude.