Associations of sarcopenic obesity versus sarcopenia alone with functionality

Abstract

Background & aims: There have been several attempts to come up with a global operational definition of sarcopenia (S), and consequently, a definition of S has been established, to some extent. That said, the definition of sarcopenic obesity (SO), which is defined as the presence of obesity + sarcopenia, remains obscure, hindering evaluations of the prevalence and relevance of SO. It has yet to be elucidated whether SO is associated with worse functionality when compared to S alone (S without obesity). In the present study, we compare SO and S alone in terms of their associations with functional measures through the application of alternative definitions of SO. As a secondary output, we document the prevalence of SO based on alternative definitions.

Methods: This retrospective cross-sectional study included community-dwelling adults over 60 years of age who presented as outpatients to a university hospital between 2012 and 2020. All were evaluated for body composition (bioimpedance analysis), handgrip strength (Jamar hand dynamometer) and functional health status [activities of daily living (ADL), instrumental activities of daily living (IADL)]. The fat percentile method was used to define the obesity component of SO. Low muscle mass (LMM) was defined using two different adjustment methods of skeletal muscle mass (LMM adjusted by height² or LMM adjusted by BMI). S was defined based on the EWGSOP2 definition, as probable S (low muscle strength) or confirmed S (low muscle strength + LMM). Accordingly, three alternative definitions of SO were applied based on three alternative definitions of S, i.e., "obesity + sarcopenia (probable)", "obesity + sarcopenia (confirmed, LMM adjusted by height²)" and "obesity + sarcopenia (confirmed, LMM adjusted by BMI)". The associations of SO and S alone with functional measures were examined with univariate analyses and adjusted multivariate analyses.

Results: Included in the study were 1468 older adults (median age 75; 68.8% female). The prevalence of SO was very low (0.2%) based on the SO definition "obesity + sarcopenia (confirmed, LMM adjusted by height²), but it was present at a considerable and comparable rate based on SO definition "obesity + sarcopenia (probable)" and SO definition "obesity + sarcopenia (confirmed, LMM adjusted by BMI)" (4.1%, 4.0%; respectively). As SO by "obesity + sarcopenia (confirmed, LMM adjusted by height²)" had an ignorable prevalence, this definition of SO was excluded from further analyses. Multivariate analyses revealed that, when compared to the Non-S Non-Obese group, S alone definitions had odds ratio (OR) of 5.4 and 3.4 while SO definitions had an OR of 3.2 and 2.7 for impaired ADL, and an OR of 7.9 and 6.4, while SO definitions had an OR of 3.0 and 2.7 for impaired IADL. SO was thus found to be associated with a lower prevalence of impaired functional measures than that of S alone.

Conclusions: Our results suggest that the SO definition confirmed, LMM adjusted by height² has an ignorable prevalence in populations in which underweight or malnutrition is uncommon. Among sarcopenic older individuals, obesity may have a protective effect against the limitations of some functional measures, providing evidence of the possible protective effect of obesity in sarcopenic individuals.

Keywords: Definition; EWGSOP2; Fat percentile; Functionality; Sarcopenia; Sarcopenic obesity.