medwireNews: BMI does not identify all patients at risk for developing obesity-related metabolic disease, US researchers caution in a research letter to JAMA Surgery.
“Although current surgical management of obesity targets populations based on BMI thresholds, this study emphasizes the importance of a more nuanced approach than BMI to identify risk of obesity-related disease,” write Dan Eisenberg (VA Palo Alto Health Care System, California) and co-workers.
“This approach likely includes other factors to better classify obesity and alter subsequent treatment of populations at risk for metabolic disease,” they propose.
Information was collated for 66,259 veterans (93.7% men, average age 62.0 years) who received care from the Veterans Health Administration network between 2005 and 2007.
The team identified men with a lean BMI (<25 kg/m2) or obesity (>30 kg/m2) and classified them as metabolically healthy or unhealthy based on the diagnosis of one or more obesity-related comorbidities, namely type 2 diabetes, hyperlipidemia or dyslipidemia, hypertension, and nonalcoholic fatty liver disease (NAFLD).
Thus, 7661 patients were metabolically healthy and lean (MHL); 17,217 were metabolically unhealthy and lean (MUL), 6267 were metabolically healthy with obesity (MHO), and 35,114 were metabolically unhealthy with obesity.
Overall, 67.0% of the people included in the study had hypertension, 48.9% had hyperlipidemia or dyslipidemia, 27.5% had type 2 diabetes, and 1.2% had NAFLD.
As expected, the rates of these comorbidities were lowest in the MHL group and highest in the MUO group, and this pattern continued after 5 years of follow-up, Eisenberg and co-authors report.
Over 5 years of follow-up, the MHL group were significantly less likely to develop new or additional obesity-related metabolic diseases than the MUL group, but patients in both groups received diagnoses of hypertension (23.8 vs 33.7%, respectively), hyperlipidemia or dyslipidemia (22.6 vs 28.3%), and type 2 diabetes (3.3 vs 5.8%).
The MHO group participants were significantly less likely than their MUO counterparts to develop hypertension (36.1 vs 49.5%, respectively), hyperlipidemia or dyslipidemia (37.7 vs 44.4%), and type 2 diabetes (12.3 vs 19.7%). The rates of NAFLD did not significantly differ between the MHO and MUO groups.
“Transitioning to different BMI thresholds over time could modify risk for disease,” the researchers observe, adding that the study is limited by not adjusting for the significantly older median ages in the two metabolically unhealthy versus metabolically healthy groups.
Nevertheless, they conclude: “Our findings suggest that preexisting metabolic disease is a risk factor for new-onset [type 2 diabetes] or [hypertension] within 5 years” and that “[s]tandard BMI thresholds may misclassify metabolic disease risk in some individuals at risk for obesity-related metabolic disease over time despite a normal BMI.”
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