People who have a body mass index (BMI) greater than 30 kg/m2 but do not have the metabolic complications commonly associated with obesity: metabolic syndrome, hypertension, dyslipidemia or dysglycemia have been categorized as being ‘metabolically healthy obese’ (MHO)—a term that was first described in the 1980s. Whether MHO is associated with an excess risk of cardiovascular disease (CVD) events has been a topic of debate since then. Till now, there were important limitations in the research that had been conducted on MHO including small sample size and inconsistent definitions of metabolic health.
A recent study by researchers from the University of Birmingham in the UK was undertaken to determine how—and if—BMI and metabolic dysfunction were linked. The researchers evaluated the electronic health records of 3.5 million men and women by developing body size phenotypes which were defined by four BMI categories (underweight, normal weight, overweight, and obesity) and three metabolic abnormalities (diabetes, hypertension, and hyperlipidemia). The primary endpoints of the study were the first record of 1 of 4 cardiovascular presentations (coronary heart disease [CHD], cerebrovascular disease, heart failure, and peripheral vascular disease).
Relevant findings from the five-year long follow up included:
- MHO individuals had a higher risk of CHD (HR: 1.49; 95% CI: 1.45 to 1.54), cerebrovascular disease (HR: 1.07; 95% CI: 1.04 to 1.11), and heart failure (HR: 1.96; 95% CI: 1.86 to 2.06) as compared with normal weight individuals with no metabolic abnormalities
- A significant minority of MHO individuals developed metabolic risk factors during the study (diabetes 5.6%; hypertension, 10.5%; hyperlipidemia, 11.5%)
- Risk for CHD, cerebrovascular disease and heart failure in normal weight, overweight, and obese individuals increased with increasing number of metabolic abnormalities
Why is this Clinically Relevant?
- The results from this study indicate that obesity and number of metabolic factors are tightly linked and need to be addressed to mitigate risk
- Patients diagnosed with “metabolically healthy” obesity still had significant CV risk, with an almost 50% increase in CHD—the precursor of myocardial infarcts or heart attacks– and an almost twofold increase in heart failure
- The fact that normal-weight individuals were diagnosed with metabolic risk factors was concerning and should prompt healthcare providers to screen patients more vigilantly
- Obesity combined with metabolic risk factors was found to be associated with the worst prognosis, and clinicians should continue to encourage targeted nutritional options and improved lifestyle behaviors to improve outcomes