Validity, Responsiveness, and Predictive Ability of the Japanese Version of the Cumulated Ambulation Score in Patients with Hip Fracture

OBJECTIVES: The aim of the current study was to investigate the validity, the responsiveness, and the predictive ability for discharge to own home of the Japanese version of the Cumulated Ambulation Score (CAS-JP). This was achieved by analyzing the CAS-JP after hip fracture surgery at multiple time points until patient discharge. METHODS: Patients who underwent hip fracture surgery were evaluated using CAS-JP, the Barthel Index, and walking ability on postoperative day (POD) 1, 7, and 14 and at discharge. Floor and ceiling effects, responsiveness, and correlations between CAS-JP and other functional outcomes were assessed at each time point. The predictive ability of CAS-JP for discharge to own home was also analyzed using the area under the curve (AUC) of the receiver operating characteristic. RESULTS: A total of 121 patients were included in this study. On POD7, POD14, and at discharge, strong correlations were observed between CAS-JP and the Barthel Index (r=0.81, 0.82, and 0.87, respectively), and between CAS-JP and walking status (r=0.82, 0.81, and 0.76, respectively). CAS-JP had a large effect size (1.64–2.25) and standardized response mean (1.49–1.81). The predictive ability of CAS-JP for discharge to own home, as indicated by the AUCs, were 0.73 (95% CI: 0.62–0.83) on POD7 and 0.74 (95% CI: 0.62–0.86) on POD14. CONCLUSIONS: CAS-JP has sufficient validity and responsiveness as a mobility assessment tool in postoperative hip fracture patients. Furthermore, this study showed that early postoperative mobility status evaluation using CAS-JP can sufficiently predict discharge to own home.