Adiposity-based obesity classification and cardiometabolic and kidney outcomes: a longitudinal UK Biobank analysis.

Abstract

Obesity is commonly diagnosed using BMI, which does not capture total adiposity or fat distribution, as highlighted by the recent Lancet D&E Commission report. We assessed the prognostic value of an adiposity-based classification combining body fat percentage (BF%) and waist circumference (WC) in relation to cardiometabolic and kidney outcomes and evaluated its concordance with BMI. We classified 489,311 UK Biobank participants into five risk groups (Groups 1-5) with increasingly adverse adiposity profiles based on BF%-WC. Associations with three-point major adverse cardiovascular events (3P-MACE), type 2 diabetes (T2D), and chronic kidney disease (CKD) were estimated using cumulative incidence and Cox PH models. Comparison with BMI categories was visualised with an alluvial plot. Over a median 13.1 years (IQR 1.7), 24,778 (5.1%) participants experienced 3P-MACE, 30,376 (6.2%) had incident T2D, and 14,906 (3.0%) had incident CKD. The BF%-WC classification yielded stepwise risk stratification across endpoints. Compared to the reference Group 1, Group 5 had significantly higher risk: age- and sex-adjusted HR 9.23 (95% CI 8.70-9.83) for T2D, 2.27 (2.10-2.41) for CKD, and 1.63 (1.60-1.71) for 3P-MACE. Discordance with BMI was notable: 32.6% of individuals in the high-risk Group 5 had a BMI in the normal-to-overweight range, while the overweight category spanned all BF%-WC risk groups. An adiposity-based classification integrating BF% and WC associates significantly with cardiometabolic and kidney outcomes and reveals discordance with BMI, reinforcing the Commission's framing of obesity as a disease driven by excess adiposity. SciLifeLab & Wallenberg DDLS Program; Knut and Alice Wallenberg Foundation; Swedish Research Council (2021-02623); Vinnova (2023-04234).