Development and initial psychometric evaluation of the Mobility Activities Measure for Inpatient Rehabilitation Settings (Mobam-in).

OBJECTIVE

To describe the development and the initial psychometric evaluation of a mobility measure for inpatient postacute rehabilitation settings—the Mobility Activities Measure for Inpatient Rehabilitation Settings (Mobam-in).

DESIGN

Self-report-based psychometric study.

SETTING

Postacute rehabilitation unit of a public hospital.

PARTICIPANTS

A consecutive sample of inpatients (N=239) receiving postacute rehabilitation care.

INTERVENTIONS: Not applicable.

MAIN OUTCOME MEASURES: We developed a 30-item mobility measure, using the Mobility Activities Measure (Mobam) framework, to assess functioning across 5 mobility activity domains classified within the International Classification of Functioning, Disability and Health. These were (1) changing and maintaining body position involving only sitting and/or lying (4 items); (2) changing and maintaining body position involving standing up (6 items); (3) carrying and moving objects using the hand and shoulder (6 items); (4) handling objects using only the hand and/or forearm (7 items); and (5) walking and moving (7 items). Psychometric analyses were conducted to test assumptions underlying the scaling and scoring of Mobam-in scales, and to test both the reliability and validity.

RESULTS

Multitrait scaling and confirmatory factor analyses (with Tucker-Lewis Index median, .99; root mean square error of approximation median, .025) supported the assumption of unidimensionality concerning each domain. Five dimensions appeared to be stable across diverse diagnostic groups (the percentage of items with discriminant validity ranged from 93% to 100%, Cronbach coefficient ranged from .859 to .966). Rasch model (Masters' partial credit) showed that all items could be located along a continuum in each dimension, with goodness-of-fit criteria of infit and outfit mean-square values between 0.6 and 1.4. Test-retest reliability was excellent (intraclass correlation coefficients median, .98). Groups with more severe conditions and lower functional independence scored lower on Mobam-in scales, as hypothesized.

CONCLUSIONS

Mobam-in covers 5 dimensions of mobility activities. The Mobam framework is an effective reference for building outcome instruments.