Sarcopenic obesity in nursing home residents: a multi-center study on diagnostic methods and their association with instrumental activities of daily living.

Background: Sarcopenic obesity (SO) in nursing home residents is rarely studied. We aimed to evaluate and compare the prevalence and consistency of different SO diagnostic methods and to investigate which criterion demonstrated a stronger association with instrumental activities of daily living (IADL) disability.

Methods: We consecutively recruited older adults aged ≥ 60 years, residing in 15 nursing homes in Zigong City, China. Sarcopenia obesity was defined according to the European Society for Clinical Nutrition and Metabolism (ESPEN) and the European Association for the Study of Obesity criteria (SO), recommending skeletal muscle mass (SMM) adjusted by body weight (SMM/W) to identify low muscle mass. Further, we adapted ESPEN criteria (SO) by employing SMM adjusted by body mass index (SMM/BMI).

Results: We included 832 participants (median age 73.0 years, 296 women). The prevalence of SO and SO was 43.5% and 45.3%, respectively. SO showed good consistency with SO (Cohen's kappa = 0.759). More than one-third of participants in the normal weight group were diagnosed with SO or SO. Even within the underweight group, the prevalence of SO and SO was 8.9% and 22.2%, respectively. Participants with IADL disability had significantly lower SMM/W and SMM/BMI, but higher fat mass percentage of body weight (FM%) than participants without IADL disability. After full adjustment for potential confounders, SO (OR 1.68, 95% CI 1.21 to 2.32), but not SO (OR 1.28, 95% CI 0.93 to 1.75), remained significantly associated with IADL disability.

Conclusions: Both SO and SO showed a high prevalence among nursing home residents, even among individuals with underweight or normal weight. While SO had a good consistency with SO, only SO was independently associated with IADL disability. Screening and diagnosis of SO should be conducted in nursing home residents irrespective of BMI.