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BRI a better indicator than BMI for CVD – Chinese study

Findings from a recent study suggest that higher body roundness index (BRI) trajectories are associated with a greater likelihood of developing cardiovascular disease, and are better indicators than body mass index.

BRI measures abdominal body fat and height, while body mass index (BMI) considers the height-weight relationship as a health indicator – but the latter has often been criticised for not being a reliable measure of health.

Cardiovascular diseases (CVD) account for millions of deaths annually, and doctors can often look at factors like diet and exercise to determine a patient’s risk, and thus identify helpful action.

Medical News Today reports that a recent study, published in the Journal of the American Heart Association, explored the relationship between body roundness index trajectories and CVD.

BMI measures height and weight and helps identify if patients are overweight or obese, but it does not differentiate between fat mass and muscle, so it’s not the only component doctors use to determine health risks.

Cheng-Han Chen, MD, a board certified interventional cardiologist and medical director of the Structural Heart Programme at MemorialCare Saddleback Medical Centre in California, who was not involved in the study, said there were several limitation with BMI.

“While relatively simple to use, it has many flaws that limit its ability to assess a person’s health status. Most importantly, it does not account for body fat content and distribution, and does not account for muscle and bone mass. In addition, it does not account for racial, ethnic, and sex differences. These many limitations make it a relatively poor indicator of physical health.”

The body roundness index (BRI), on the other hand, looks at waist circumference and height and helps reflect fat proportion in the body.

Body roundness and CVD risk

The researchers involved in the latest study, and led by a team from Nanjing Medical University’s CDC in Wuxi, China, wanted to examine the relationship between BRI trajectories and CVD risk.

Their research included middle-aged and older Chinese participants in the China Health and Retirement Longitudinal Study. In total, researchers were able to analyse data from 9 935 participants. They excluded individuals who already had CVD or who had missing BRI data at baseline. The average age of participants was about 59.

The researchers had data from blood samples, blood pressure, and BRI, as well as baseline data on lifestyle risk factors, and the incidence of stroke and cardiac events.

In their analysis, they looked at BRI trajectories, or the course of BRI over time, using models that corrected for different covariates.

For example, they were able to take into account medical and medication history.

Participants were split into three BRI trajectory categories: low-stable, moderate-stable, and high-stable. The scientists noted that those in the high-stable BRI category were more likely to have certain characteristics like high blood pressure, diabetes, and increased age. They were also more likely to be male but less likely to smoke or drink.

From 2017 to 2020, there were just more than 3 000 cardiac events documented and 894 recorded deaths.

Overall, researchers found that the moderate-stable and high-stable BRI trajectory groups were at a higher risk for CVD than the low-stable BRI trajectory group.

In their crude model, the moderate-stable group had a 61% increased risk for CVD compared with the low-stable group, and the high-stable group had a 163% increased risk. After adjusting for variables, researchers still observed an increased risk for cardiovascular disease in the moderate and high BRI trajectory groups.

They found that the moderate-stable group had a 29% increased risk for stroke and a 14% increased risk for cardiac events compared with the low-stable group. The high-stable group had a 46% increased risk for stroke and a 35% increased risk for cardiac events compared with the low-stable group.

They also found that considering BRI trajectory helped with CVD risk reclassification.

The results indicate that having BRI increase for a prolonged period increases the risk for cardiovascular disease and that it may be helpful to take BRI into account to better prevent cardiovascular disease.

Study limitations

This research does have limitations. First, it focused on Chinese participants who were middle-aged and older, so studies with greater diversity may be necessary to confirm the findings. It also means the results may not be generalisable to other groups.

The researchers acknowledge that the study time frame might have been insufficient, so more long-term studies may be helpful. In addition, the high-stable BRI trajectory group accounted for just under 8% of the study population, which could have affected the results.

Some of the data were participant-reported. Particularly, the CVD diagnosis was from self-reported physician assessments. The authors acknowledge that this self-reporting could cause information bias.

The researchers were also only able to focus on CVD because they were unable to look at causes of death, which could be helpful in future studies. Finally, they acknowledge the possibility of unmeasured bias and bias from unaccounted factors. They agree that future research can help confirm their findings.

Despite these limitations, the data do present the potential benefits of using BRI as a health indicator.

“By taking into account waist circumference as well as height, this metric better reflects the distribution of fat in the body than BMI does,” said Chen. “As such, it should be better able to provide information on an individual’s health risk and indicate when intervention would be recommended to help reduce the risk. It’s a useful finding that might lead to wider adoption of BRI as a tool to help assess an individual’s heart disease risk.”

Study details

Body Roundness Index Trajectories and the Incidence of Cardiovascular Disease: Evidence From the China Health and Retirement Longitudinal Study

Man Yang, Jia Liu, Qian Shen et al.

Published in Journal of the American Heart Association on 25 September2024

Abstract

Background
Several previous cross‐sectional studies suggested that body roundness index (BRI) may be associated with cardiovascular disease (CVD). However, the association should be further validated. Our study aimed to assess the association of the BRI trajectories with CVD among middle‐aged and older Chinese people in a longitudinal cohort.

Methods and Results
A total of 9 935 participants from the CHARLS (China Health and Retirement Longitudinal Study) with repeated BRI measurements from 2011 to 2016 were included. The BRI trajectories were identified by group‐based trajectory modelling. The primary outcome was incident CVD (stroke or cardiac events), which occurred in 2017 to 2020. Cox proportional hazards regression models were used to examine the association of BRI trajectories with CVD risk. Participants were divided into 3 BRI trajectories, named the low‐stable BRI trajectory, moderate‐stable BRI trajectory and high‐stable BRI trajectory, accounting for 49.81%, 42.35%, and 7.84% of the study population, respectively. Compared with participants in the low‐stable BRI trajectory group, those in the moderate‐stable and high‐stable BRI trajectory groups had an increased risk of CVD, with multivariable adjusted hazard ratios of 1.22 (95% CI, 1.09–1.37) and 1.55 (95% CI, 1.26–1.90), respectively. Furthermore, simultaneously adding the BRI trajectory to the conventional risk model improved CVD risk reclassification (all P<0.05).

Conclusions
A higher BRI trajectory was associated with an increased risk of CVD. The BRI can be included as a predictive factor for CVD incidence.

 

AHA article – Body Roundness Index Trajectories and the Incidence of Cardiovascular Disease: Evidence from the China Health and Retirement Longitudinal Study (Open access)

 

Medical News Today article – BMI vs. BRI: Why body roundness may be a better indicator of heart disease risk (Open access)

 

See more from MedicalBrief archives:

 

Moving away from BMI as a health risk indicator

 

Fat mass index, not BMI, associated with CVD events in people with diabetes

 

BMI a weak indicator of fatty tissue content, large analysis finds

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