Associations of length of stay with sarcopenia parameters in geriatric patients: age and sex differences in the oldest old

BACKGROUND: Hospital-associated deconditioning is a contributor to secondary sarcopenia, which may be driven by prolonged hospital length of stay (LoS). This study investigated the bidirectional association of LoS and sarcopenia indices (lean soft tissue, muscle strength, physical function) in older inpatients, with a focus on age- and sex-specific differences. METHODS: Using cross-sectional data from the Copenhagen PROTECT study, 1071 older inpatients (aged ≥ 65 years) were included. Appendicular lean soft tissue index (ALSTI), handgrip strength (HGS), gait speed, and 30-second chair stand test (30CST) were assessed within 24 h of admission and sarcopenia was defined per the EWGSOP2 criteria. Linear and logistic regressions examined associations between LoS and sarcopenia indices, stratified by age and sex. RESULTS: In patients ≥ 80 years, longer LoS (based on the cohort's median) was associated with lower gait speed and 30CST in both sexes (p < 0.01), and lower HGS in women (p = 0.03). In men < 80 years, longer LoS correlated with lower HGS and 30CST (p < 0.01), with higher odds of sarcopenia (Low ALSTI and low 30CST; OR = 3.14, p = 0.03). Higher 30CST and HGS were consistently associated with shorter LoS, particularly in men ≥ 80 years and women across both age groups. CONCLUSIONS: HGS and 30CST are strongly associated with LoS in older inpatients, with more pronounced effects in those ≥ 80 years. Future longitudinal studies and trials are warranted to confirm causality, that may guide rehabilitation strategies to reduce LoS through targeted interventions.