Association of Baseline Skeletal Muscle Mass Index With Adverse Events and Rehabilitation Outcomes in Patients Admitted for Rehabilitation

Abstract

Objective

To assess the associations of baseline skeletal muscle mass index (SMI) with adverse events and rehabilitation outcomes in patients admitted for rehabilitation.

Design

A retrospective cohort study.

Participants

The subjects were 409 patients (mean age, 79 years; men, 167 [41%]) undergoing rehabilitation because of neurologic disease, musculoskeletal disorders, or hospital-associated deconditioning. Patients were divided into 2 groups according to the definition of sarcopenia by the Asian Working Group for Sarcopenia: those with low SMI (<7.0 kg/m² in men and <5.7 kg/m² in women) and those with high SMI (≥7.0 kg/m² in men and ≥5.7 kg/m² in women).

Interventions

Not applicable.

Main Outcome Measures

The primary outcomes were adverse events including death and acute illness requiring transfer to other hospitals for specialized treatments. The secondary outcomes were rehabilitation outcomes including the efficiency scores (changes in functional independence measure [FIM] score divided by length of stay) of FIM for motor function (FIM-M) and FIM for cognitive function (FIM-C).

Results

Of the 409 patients, 299 (73%) had a low SMI. The adjusted hazard ratio (95% confidence interval) of the low SMI group relative to the high SMI group for adverse events was 2.79 (1.06-7.34). There were no significant differences between the 2 groups in FIM-M efficiency scores [mean ± SD, low SMI group: 0.4 (0.58) vs high SMI group: 0.47 (0.54), P=.3] and FIM-C efficiency scores [mean ± SD, 0.05 (0.14) vs 0.06 (0.2), P=.4]. Multiple linear regression models did not show significant associations between the low SMI group and FIM-M efficiency or FIM-C efficiency scores (β=0.064, P=.3; β=−0.05, P=.4, respectively).

Conclusion

Low baseline SMI was significantly associated with adverse events but not with rehabilitation outcomes in patients undergoing rehabilitation.