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Obesity without metabolic syndrome does not indicate future risk for CVD
Patients with obesity who were metabolically healthy were not necessarily at lower risk for future CVD, according to a study published in the Journal of the American College of Cardiology.
“This study provides new evidence that [metabolically healthy obesity] alone is not a stable or reliable characterization of lower clinical risk,” Morgana L. Mongraw-Chaffin, PhD, assistant professor in the department of epidemiology and prevention at Wake Forest School of Medicine in Winston-Salem, North Carolina, and colleagues wrote. “Instead, [metabolically healthy obesity] signals an opportunity for weight reduction, and prevention and management of existing [metabolic syndrome] components should be prioritized.”
MESA trial patients
Researchers analyzed data from 6,809 participants from the MESA study who did not have a history of CVD events at baseline. Participants underwent clinical evaluation every 2 years starting in 2000, and five study visits were included in this analysis. Data such as sex, age, race/ethnicity, income, education, smoking status and physical activity were self-reported. Statin use and LDL were measured at each visit.
Patients were categorized based on their metabolic syndrome and obesity status at baseline:
- metabolically healthy normal weight (BMI < 30 kg/m2 without metabolic syndrome);
- metabolically unhealthy normal weight (BMI < 30 kg/m2 with metabolic syndrome);
- metabolically healthy obesity (BMI 30 kg/m2 without metabolic syndrome); and
- metabolically unhealthy obesity (BMI 30 kg/m2 with metabolic syndrome).
When analyzing patients who transitioned from metabolically healthy obesity to metabolically unhealthy obesity, researchers excluded patients with metabolically unhealthy normal weight at baseline (n = 968) and those who transitioned from metabolically healthy normal weight to metabolically unhealthy normal weight during follow-up (n = 836). This resulted in a final sample of 5,005 patients for this analysis.
The primary outcomes of interest were incident CHD, HF, stroke, combined CVD and all-cause mortality. Patients were followed up for a median of 12.2 years.
Metabolically healthy obesity at baseline was not significantly linked to incident CVD vs. metabolically healthy normal weight. During follow-up, nearly one-half of patients with metabolically healthy obesity at baseline developed metabolic syndrome.
Risk for CVD
Compared with patients with stable metabolically healthy obesity or healthy normal weight, those with unstable metabolically healthy obesity had increased odds of CVD (OR = 1.6; 95% CI, 1.14-2.25).
There was a significant and linear association between dose response for duration of metabolic syndrome and CVD at one visit (OR = 1.62; 95% CI, 1.27-2.07), two visits (OR = 1.92; 95% CI, 1.48-2.49) and three or more visits (OR = 2.33; 95% CI, 1.89-2.87).
At any point during follow-up, approximately 62% of the relationship between obesity and CVD was mediated by metabolic syndrome.
“These results implicate [metabolically healthy obesity] as an opportunity for primary prevention of CVD, whereas [metabolically unhealthy obesity] offers the opportunity only for secondary prevention through treatment of already existing risk factors,” Mongraw-Chaffin and colleagues wrote. “Given the strong mediation of the obesity/CVD relationship by [metabolic syndrome], prevention of incident [metabolic syndrome] and resulting CVD at the population level will necessitate the prevention of obesity.”
In a related editorial, Prakash Deedwania, MD, FACC, professor of medicine at University of California at San Francisco School of Medicine, and Carl J. Lavie, MD, FACC, FACP, FCCP, medical director of cardiac rehabilitation and prevention and director of the stress testing laboratory at Ochsner Clinical School at University of Queensland School of Medicine in New Orleans, wrote: “In a perfect world, everyone would remain lean and fit across their lifetimes, but this is hardly the case in current Westernized societies, in which typically there is both weight gain and loss of [cardiorespiratory fitness] with aging. Clearly, prevention and treatment of obesity, especially moderate and severe degrees of obesity and progressive obesity, are needed, but at least in the overweight and mildly obese patients, greater emphasis is needed to promote [physical activity] and increased levels of [cardiorespiratory fitness] for the prevention and treatment of most CVD.” – by Darlene Dobkowski
Disclosures: Mongraw-Chaffin, Deedwania and Lavie report no relevant financial disclosures. Another author reports he was once employed by Merck Research Laboratories.