Waist Size Predicts Heart Disease Risk Better Than BMI, JACC Study Finds

Waist circumference and waist-to-hip ratio predict cardiovascular disease risk better than body mass index (BMI) alone, according to a study published in JACC, the flagship journal of the American College of Cardiology. In a press release on August 11, the college said that not accounting for these two measures can lead to misclassification of cardiovascular risk, including among people of clinically normal weight.

How the study was done

The work was carried out by the Cross Cohort Collaboration and covers more than 260,000 people followed for an average of 20 years. Participants had either waist circumference (WC) or waist-to-hip ratio (WHR) data and were assessed against nine outcomes: time to first fatal and non-fatal myocardial infarction, fatal and non-fatal stroke, heart failure, atrial fibrillation, total coronary heart disease, total cardiovascular disease, and coronary, cardiovascular and all-cause mortality.

What the numbers show

Among individuals of normal weight by BMI, 5% had high WC and 18% had high WHR. In the overweight group the shares were 39% and 40% respectively; among those with obesity, 9% had low WC and 45% had low WHR. Normal-weight or overweight participants with clinically high WC or WHR faced a 15%–50% greater risk for most of the nine outcomes. By contrast, people with obesity and low WC did not show a significantly different risk compared with normal-weight, low-WC participants — except for all-cause mortality, where risk was significantly lower.

What the authors say

“Indeed, it appears that WC and WHR reclassify risk defined by traditional BMI thresholds,” said Michael J. Blaha, MD, MPH, senior author and director of clinical research at the Johns Hopkins Ciccarone Center for the Prevention of Cardiovascular Disease. Lead author Zeina A. Dardari, PhD, MS, said relying solely on BMI may result in misclassification of cardiovascular risk and encouraged clinicians to consider central adiposity across the entire BMI spectrum in primary prevention.

Limitations and reaction

Harlan M. Krumholz, MD, SM, MACC, FAHA, Editor-in-Chief of JACC and a professor at Yale School of Medicine, said it is time to abandon a sole focus on body mass index: “Where fat is distributed matters, and these simple measures should be part of routine cardiovascular risk assessment.” The authors note that the study lacked data on physical activity, diet and genetic obesity risk, and included only one assessment of WC and WHR, limiting what can be said about how changes in central fat over time affect risk.