Minimum detectable change in gait velocity during acute rehabilitation following hip fracture.

PURPOSE: Early ambulation and rehabilitation are recommended for patients undergoing surgical fixation of hip fracture. Gait velocity may be used as an outcome measure for these patients during acute rehabilitation. As an outcome measure, an estimate of meaningful change (responsiveness) in gait velocity for these patients, however, has not been described. The minimum detectable change (MDC) is a value that represents true change in a measure beyond that accounted for by measurement error. The purpose of this study was to quantify MDC in gait velocity as an index of responsiveness for persons in the acute stage of rehabilitation following hip fracture. METHODS: The study design was a descriptive cohort study with one repeated measure. A volunteer sample of 16 subjects over the age of 65, at a mean of 4.7 days postsurgical fixation of unilateral hip fracture, participated in the study. The study was conducted in an acute care rehabilitation practice in a large, tertiary care hospital. We measured gait velocity with the 10-meter walk test, estimated test-retest reliability with an intraclass correlation coefficient and quantified responsiveness of gait velocity as the MDC at a 95% level of confidence. RESULTS: Mean gait velocity was 15 cm/s and the test-retest reliability coefficient was equal to 0.823. The MDC in gait velocity during acute rehabilitation following surgical repair for hip fracture was 8.2 cm/s. CONCLUSIONS: Self-selected gait velocity in patients during acute rehabilitation following surgical fixation for hip fracture must improve by 8.2 cm/s or more to designate the change as being real change beyond the bounds of measurement error.