Sarcopenia, obesity, or both: what is the dominant variable of the associated risks of sarcopenic obesity?

Background and objective: Sarcopenic obesity (SO), obesity, and sarcopenia have been related to adverse events in older adults, raising the question about the role of each component in the risk associated with SO. The objective of this manuscript is to evaluate the role of sarcopenia, obesity, and its interaction in the risks (frailty, disability, mortality) associated with sarcopenic obesity. Research Design and Methods: Data from the Toledo Study of Healthy Aging (TSHA) were used. This is a cohort-based study composed of community-dwelling adults ≥65 years. Obesity (Body Mass Index-BMI ≥30) and sarcopenia (the Foundation for the National Institutes of Health-FNIH criteria, standardized to our population) were assessed at baseline. Frailty, through the Frailty Phenotype (FP) and the Frailty Trait scale-5 (FTS5), and disability (Katz Index) were evaluated at baseline. Mortality, frailty, and disability were assessed at follow-up. Logistic (odds ratio, OR) and Cox (hazard ratio, HR) regression models were computed to assess the associations. Results: A total of 1 538 (74.73 years, 45.51% men) individuals were included. Cross-sectionally, SO, sarcopenia, and obesity were significantly associated with the risk of frailty and disability. Longitudinally, Sarcopenia was associated with all the adverse events (ORs/HRs ranged from 1.41 to 4.14, p-value < .05); whereas SO [FP, OR (95% confidence interval—CI): 4.27 (2.05, 8.93); FTS5, OR (95% CI): 6.14 (3.58, 10.51), p-value < .001] and obesity [FP, OR (95% CI): 3.10 (1.95, 4.94), p-value < 0.001; FTS5, OR (95% CI): 2.26 (1.17, 4.35), p-value 0.015] was only associated with incident frailty. Sarcopenia added risk to obesity for frailty (FP and FTS5) whereas obesity only did for frailty (FTS5) in sarcopenic individuals. The interaction between sarcopenia and obesity was not associated with any outcome.