Could BRI Replace BMI?
Opinions differ on whether the BRI should replace the BMI. Zhang’s team concluded that the BRI needs to be validated in additional independent cohorts. If it does, it could become a practical screening tool in patient care.
Yang’s research group is optimistic about the BRI’s future: “The longitudinal trajectory of the BRI could be used as a novel indicator of cardiovascular disease risk, which provides a new possibility for cardiovascular disease prevention,” they wrote.
However, even BRI Co-creator Thomas has concerns. “Our entire medical system has been built around the BMI,” she told JAMA, referring to factors such as children’s growth charts and dosage recommendations for medications. That cannot be changed overnight.
Any anthropometric measure intended to replace BMI would need to be rigorously validated across all age groups, genders, and ethnicities. The impact of interventions such as bariatric surgery, diet, and exercise on the new measure would also need to be demonstrated.
Anthropometric Measures Only for Clinical Use
Even if BRI proves to be a “better” metric than BMI for patient care, Müller believes it would be no more suitable for research than BMI. “Regardless of the anthropometric measure, these are practical tools for everyday use,” he stressed.
“A high BRI, like a high BMI, is a risk factor — similar to high blood pressure, high cholesterol levels, or smoking — but it is not a disease,” he added. “In practice, as a physician, I know that a patient with a high BMI or BRI has an increased risk. I need to pay attention to that patient.”
Problems arise when indices like BMI or BRI are used in research. “These ‘invented’ anthropometric measures have no biological basis, which can harm obesity research,” Müller emphasized.
He cited the example of genetic research into obesity, which seeks to identify associations between specific genetic patterns and BMI values. “Why should weight in kilograms divided by height in meters squared be genetically determined?” he asked. “These measures are human-made constructs that have nothing to do with biology.”
Müller believes that the use of BMI has created a “gray area in obesity research” that may account for many of the “unexplained” phenomena in this field.
The BMI Might Be Responsible for the ‘Healthy Obese’
One such phenomenon is the much-discussed “healthy obese,” referring to individuals with a BMI over 30 who do not have high blood sugar, high blood pressure, metabolic disorders, or elevated uric acid levels. “It’s speculated that it must be due to genetic factors, but in reality, the classification is simply wrong,” Müller said.
According to Müller, research should rely on other methods to determine obesity or relevant fat. For example, to assess diabetes risk, liver fat needs to be measured through enzyme tests, ultrasonography, CT, or MRI.
Visceral fat is also important in assessing cardiometabolic risk. “In the doctor’s office, it’s acceptable to estimate this by looking at waist circumference or even BRI. But for research, that’s inadequate,” noted Müller. Direct measurement of trunk fat with dual-energy x-ray absorptiometry or visceral fat with CT or MRI is needed.
“You always have to distinguish between research and patient care. In daily practice, measures like BRI or BMI are sufficient for assessing cardiometabolic risk. But in research, they are not,” Müller explained. To accurately study the disease risks associated with obesity, one must be aware that “with BMI, you cannot create scientifically valid patient or population groups because this value is far too imprecise.”
This story was translated from Medscape’s German edition using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication. A version of this article appeared on Medscape.com.