Comparative Associations of Traditional and New Obesity Framework With Cardio‐Kidney‐Metabolic Syndrome and All‐Cause Mortality: A Prospective Cohort Study

BACKGROUND: The Lancet Commission redefined obesity by integrating body mass index (BMI) and anthropometric measures, but it remains unclear if they better identify risk for cardiovascular-kidney-metabolic (CKM) syndrome. We aim to compare the CKM risk and all-cause mortality predicted by these new criteria against traditional BMI-based criteria. METHODS: Using Cox models to investigate the associations between different obesity phenotypes, which were normal weight, Anthropometric excess adiposity & Traditionally-defined non-obesity, Traditionally-defined obesity & Non-anthropometric excess adiposity, and excess adiposity by both criteria, with Anthropometric excess adiposity by the anthropometric criteria alone, Traditionally-defined obesity by BMI alone, and CKM syndrome and mortality in the UK Biobank. We further compared whether the anthropometric diagnostic sub-categories were associated with different levels of risk. RESULTS: Among 352 740 participants (mean age 56.8 years; 56% female) with a median follow-up of 13.2 years, compared to normal weight, the "Anthropometric excess adiposity & Traditionally-defined non-obesity" (HR 1.55, 95% CI 1.52-1.59) and "Traditionally-defined obesity & Non-anthropometric excess adiposity" (HR 1.61, 95% CI 1.29-2.02) exhibited similarly elevated risks for CKM syndrome. Those meeting both criteria had the highest risk (HR 2.61, 95% CI 2.56-2.66) for CKM syndrome. Anthropometric excess adiposity had an increased CKM risk (HR 2.00, 95% CI 1.96-2.04), which was lower than that for Traditionally-defined obesity (HR 2.45, 95% CI 2.41-2.49). Among the anthropometric sub-categories, the three BMI-inclusive definitions yielded similar HRs for CKM risk, which were higher than those of Traditionally-defined obesity and the non-BMI sub-categories. CONCLUSION: By incorporating central adiposity, the anthropometric criteria improve CKM risk stratification by identifying high-risk individuals overlooked by traditional standards, especially those with adverse body composition despite lower BMI.