Development and validation of a video-animated tool for assessing mobility

Abstract

Background: Existing self-report measures of mobility ignore important contextual features of movement and require respondents to make complex judgments about specific tasks. Thus, we describe the development and validation of a short form (sf) video-animated tool for assessing mobility, the Mobility Assessment Tool-MAT-sf.

Methods: This study involves cross-sectional and longitudinal analyses examining the measurement properties of the MAT-sf. The MAT-sf consists of 10 animated video clips that assess respondents' level of proficiency in performing each task. The main outcome measures used for validation included the Pepper Assessment Tool for Disability (PAT-D), the Short Physical Performance Battery (SPPB), and 400-m walk test.

Results: Participants (n = 234), 166 women and 68 men, had an average age of 81.9 years and a variety of comorbidities with 65.4% having high blood pressure. An average SPPB score of 8.6 (range 2-12) suggests that the study sample had evidence of compromised physical function but was quite heterogeneous. The MAT-sf had good content validity, excellent test-retest reliability (r = .93), and criterion-related validity with the PAT-D. Moreover, the MAT-sf added considerable variance to the prediction of both SPPB scores and 400-m gait speed over and above the PAT-D mobility subscale. The MAT-sf also discriminated between older adults who completed or failed the 400-m walk test.

Conclusion: The MAT-sf is an innovative psychometrically sound measure of mobility. It has utility in epidemiological studies, translational science, and clinical practice.

Figure 1.

Snapshots of the 10 items and their response scales for the MAT-sf (instructions for downloading the computer program can be found in the research note at the end of the manuscript).

Figure 2.

The item response and information curves for each of the 10 items in the MAT-sf. For Items 5–10, the response scale was dichotomous: no or yes. Thus, there is only a single curve needed to describe the ability level for that item. For Items 1 and 2, there are four categorical responses; for Items 1 and 2, none = 0 (yellow line), 5–15 minutes = 1 (green line), 20–30 minutes = 2 (blue line), and >30 minutes = 3 (red line); and for Items 3 and 4, none = 0 (yellow line), 1 = 1 (green line), 2 = 2 (blue line), and either 3 or 4 = 3 (red line).