Assessment of Mobility in Older People Hospitalized for Medical Illness Using the de Morton Mobility Index and Cumulated Ambulation Score-Validity and Minimal Clinical Important Difference

BACKGROUND AND PURPOSE: Older adults acutely hospitalized for medical illness typically have comorbidity and disability, and in-hospital physical inactivity greatly increases the likelihood of developing new disability. Thus, assessment of the patients' mobility status is crucial for planning and carrying out targeted interventions that ensure mobilization during hospital admission. The aim of this study was to determine convergent validity, known group validity, floor and ceiling effects, and anchor-based minimal clinically important difference (MCID) of the more time-consuming de Morton Mobility Index (DEMMI) and the less time-consuming Cumulated Ambulation Score (CAS) in older adults acutely hospitalized for medical illness. METHODS: In this multicenter cohort study, 235 older hospitalized adults, with a mean (standard deviation) age of 84.8 (7.1) years, were consecutively included. Assessments of mobility using the DEMMI (score range 0-100), the CAS (score range 0-6), and the Barthel Index (BI, score range 0-100) were performed by physical or occupational therapists at hospital admission and discharge. In addition, at discharge patients and therapists were independently asked to assess the patients' current mobility status compared with their mobility status at hospital admission using the Global Rating of Change scale. RESULTS AND DISCUSSION: Complete data sets were obtained for 155 patients. Baseline characteristics of those with complete data sets did not differ from those with incomplete data sets, except for the number of secondary diagnoses, which was lower in the latter. Significant and moderate relationships existed both at admission and at discharge between scores in the DEMMI and the BI (r(s) = 0.68, P < .0001, and r(s) = 0.71, P < .0001), and between scores in the CAS and the BI (r(s) = 0.60, P < .0001, and r(s) = 0.57, P < .0001). Use of a gait aid and discharge to inpatient rehabilitation or nursing home were associated with significantly lower DEMMI and CAS scores. No floor or ceiling effects were present in the DEMMI, while a ceiling effect was present in the CAS. The MCID scores based on patients' assessments were 10.7 points for the DEMMI and 0.67 for the CAS. CONCLUSIONS: These data show that the DEMMI is valid and responsive to changes in mobility and can be considered to have the required properties for measuring mobility in older adults who are hospitalized in medical and geriatric wards. In contrast, the CAS appears to be appropriate to identify whether a patient is independently mobile or needs assistance, while the measure is less suitable for measuring improvements in mobility.