A Composite Physical Performance Score for Predicting Discharge Functional Independence Measure motor score in Subacute Orthopedic Rehabilitation: A Retrospective Study

OBJECTIVE: To examine whether admission comfortable walking speed, Timed Up and Go test, and Berg Balance Scale add predictive value for discharge Functional Independence Measure motor score, and whether a composite score outperforms individual measures in older adults undergoing subacute orthopedic rehabilitation. DESIGN: Single-center retrospective cohort study of 158 patients aged ≥65 years admitted to a Japanese subacute rehabilitation ward. Linear regression compared a base model including common clinical factors with models adding walking speed, Timed Up and Go test, Berg Balance Scale, or an equal-weight composite score. Internal predictive performance was assessed using repeated 10-fold cross-validation. RESULTS: All three performance measures improved prediction beyond the base model. The composite score showed the best overall performance and the best cross-validated performance. The composite score remained independently associated with discharge Functional Independence Measure motor score (β=4.48, 95% confidence interval: 2.35-6.61), and adjusted mean score increased progressively across low, mid, and high score groups. CONCLUSIONS: Admission mobility and balance measures provide incremental value for predicting discharge Functional Independence Measure motor score, and a simple composite score integrating single indicators may offer a practical, clinically interpretable approach for early prediction of discharge Functional Independence Measure motor score.