Does the European Association for the Study of obesity new definition better capture the risk of functional limitation?

Background : The European Association for the Study of Obesity (EASO) proposed a diagnostic framework incorporating waist-to-height ratio (WHtR) and obesity-related complications. Existing evidence has largely focused on the association between newly defined obesity and all-cause mortality, without addressing its impact on functional limitations, which are indicative of health span. Methods : This study utilized data from community-dwelling adults aged 50 years or older, who were recruited from the English Longitudinal Study of Ageing (ELSA). Participants were classified into four categories: normal weight, EASO overweight, EASO new obesity, and BMI obesity. Functional limitation was assessed using activities of daily living (ADL) and instrumental activities of daily living (IADL), from which a summed ADL/IADL score was derived and a binary indicator of functional limitation was defined. Generalized estimating equations (GEE) were used to model the association between newly defined obesity and longitudinal changes in ADL/IADL scores. After excluding participants with baseline functional limitation, Cox proportional hazards models were applied to estimate the effect of newly defined obesity on incident functional limitation. Results : Among the 7,161 participants, 29.3% originally classified as BMI overweight were reclassified as EASO new obesity. In GEE analyses, compared with normal weight, EASO new obesity and BMI obesity were associated with a faster increase in ADL/IADL scores over time ( β = −0.030, P = 0.011; β = −0.065, P < 0.001). At baseline, 5,221 participants were free of functional limitation. In Cox proportional hazards models, EASO new obesity and BMI obesity were associated with higher risk of incident functional limitation (EASO new obesity: HR = 1.37, 95% CI : 1.20-1.56; BMI obesity: HR = 1.52, 95% CI : 1.33-1.74) while EASO overweight was associated with lower risk ( HR = 0.83, 95% CI : 0.70-0.98). Conclusions : The EASO framework may help differentiate risk heterogeneity within the BMI overweight range and suggests potential value for functional limitation stratification in ageing populations.