Establishing the reliability of mobility milestones as an outcome measure for stroke

Objective: To establish intrarater, interrater, and test-retest reliability of a standardized measure of mobility, "mobility milestones," incorporating sitting balance, standing balance, and walking ability. Design: Repeated-measures reliability study by using video data of patients with stroke. Setting: Physiotherapy and rehabilitation departments in Scotland. Participants: Forty physiotherapists recruited from within the Lothian region: 20 senior physiotherapists with at least 3 years of experience working with neurologic patients and 20 staff grade physiotherapists with less than 12 months of experience working with neurologic patients. Intervention: Videotape comprising 40 clips (36 original clips. 4 repeated clips) of stroke patients of differing levels of ability attempting the mobility milestones was produced. After a short training session in the interpretation and application of the mobility milestones, each physiotherapist viewed the tape separately and scored whether the milestone had been achieved or not. This was repeated at a separate test session 2 weeks later. Main Outcome Measure: Score for each mobility milestone. Results: Kappa statistics were used to determine interrater reliability and showed good (.61-80) to very good (.81-1.0) reliability for 3 of 4 milestones. Intraclass correlation coefficients (ICCs) were used to determine intrarater reliability of the 4 repeated clips and showed 75% of all subjects had high (ICC2.1=.91-1.0) reliability. The ICC2.1 for test-retest reliability showed a similar pattern, with 76% of subjects showing good (.81-90) or high (.91-1.0) reliability. Conclusions: The mobility milestones showed favorable levels of reliability when used by experienced or novice physiotherapists. The milestones can be adopted as a simple clinical outcome measure for use with stroke. Further research is required to establish reliability levels when the measure is used by different rehabilitation professionals.