Clinical screening and identification of sarcopenic obesity in adults with advanced knee osteoarthritis

Background and aims: Sarcopenic obesity (defined as low muscle mass and strength with high adiposity) requires attention in adults with advanced knee osteoarthritis (OA) due to implications on treatment outcomes. This study aimed to identify muscle function measures and patient characteristics associated with the presence of low muscle mass that could be used to screen and detect sarcopenic obesity in patients with knee OA in the clinical setting.

Methods: Cross-sectional study of patients with knee OA and a body mass index (BMI) ≥30 kg/m². Body composition was measured in n = 151 patients (59% female, mean age 65.1 ± 7.9 years) using dual-energy x-ray absorptiometry. Appendicular skeletal muscle mass (ASM) adjusted by BMI and below established sex-specific cut-points was used to differentiate low muscle mass. Muscle function was assessed by 4-m gait speed, 6 min walk test, and maximal grip strength (absolute, and relative, adjusted by BMI). Logistic regression was used to assess the relationship between muscle function measures, patient characteristics, and low muscle mass. Receiver operating characteristic curves and area under the curve (AUC) were used to examine the final model and identify potential clinical cut-points.

Results: Sex and relative grip strength were associated with low muscle mass (AUC 0.774, p < 0.001). Cut-points for low relative grip strength (<0.65 kg/m² in females and <1.1 kg/m² in males) were distinguished and used in combination with low muscle mass to screen and identify sarcopenic obesity. Patients with both low relative grip strength and low muscle mass (sarcopenic obesity) had impaired mobility and quality of life.

Conclusion: Relative grip strength shows promise as a clinical screening measure for sarcopenic obesity in patients with knee OA.