Psychometric properties of the Cumulated Ambulation Score: a systematic review.

INTRODUCTION: In the geriatric population, independent mobility is a key factor in determining readiness for discharge following acute hospitalization. The Cumulated Ambulation Score (CAS) is a potentially valuable score that allows day-to-day measurements of basic mobility. The CAS was developed and validated in older patients with hip fracture as an early postoperative predictor of short-term outcome, but it is also used to assess geriatric in-patients with acute medical illness. Despite the fast-accumulating literature on the CAS, to date no systematic review synthesizing its psychometric properties has been published. Therefore, we aimed to provide a comprehensive review of the psychometric properties of the CAS, summarizing the present evidence on this measure as a basis for further research to investigate its applicability across a wider range of functional abilities and care settings.

EVIDENCE ACQUISITION: A literature search was conducted on research articles published between 2006 and June 2016 in journals indexed by MEDLINE and Scopus databases using as a search item "Cumulated Ambulation Score"[All Fields], and selecting studies that presented a psychometric analysis of the scale. Of 49 studies identified, 17 examined the psychometric properties of the CAS.

EVIDENCE SYNTHESIS: Most papers dealt with patients after hip fracture surgery, and only 4 studies assessed the CAS psychometric characteristics also in geriatric in-patients with acute medical illness. Two versions of CAS (CAS1 and the more detailed CAS2 version) and two different methods to calculate the total score (1-day and 3-day CAS) were used in the selected papers. Most of the papers assessed reliability and validity, using different statistics, and only one showed evidence of sensitivity to change of the score.

CONCLUSIONS: This systematic review shows international interest of researchers in the CAS, despite the short time frame since its first publication in 2006. The results support the reliability, validity, and sensitivity to change of the tool. Since different versions of CAS are available and two scores are commonly used, we suggest that clinicians and researchers in the future choose the more detailed CAS2 version, already used by the large majority of studies, and report whether they used the 1- or 3-day score.