DETERMINING MEANINGFUL CHANGES IN GAIT SPEED AFTER HIP FRACTURE. Kerstin M. Palombaro*; Rebecca L. Craik; Kathleen K. Mangione Physical Therapy, Arcadia University, Glenside, PA PURPOSE: The purpose of this study was to determine the minimal detectable change (MDC) and the minimal clinically important difference (MCID) for habitual and fast gait speeds in a sample of elders post hip fracture. BACKGROUNDS/SIGNIFICANCE: The majority of older adults who sustain a hip fracture do not recover pre-fracture walking ability. The speed of walking is a determinant of safe community ambulation that includes crossing streets within the time frame of a traffic light and for efficient completion of instrumental and basic activities of daily living. Interventions such as gait training and therapeutic exercise are focused on improving safety, walking speed, and independence in walking. The MDC in gait speed has not been described; determining if a particular intervention results in a meaningful change, therefore, remains subjective. SUBJECTS: The sample consisted of 92 persons (mean age of 78.7 +/- 7.50) who were 9.2 +/- 17.0 months post hip fracture. The sample was drawn from three separate hip fracture studies (2 observational studies and 1 exercise trial) all of which collected gait speed data. METHODS AND MATERIALS: GaitMAT II was used for all three studies and is a walkway that contains 9728 pressure sensitive switches. A minimum of 2 trials were obtained as participants walked in response to one of two commands, (walk at your usual or free gait speed) and (walk as fast as you possibly can). Gait speed was defined as the distance traversed between closure of the first and last switches contacted divided by the elapsed time between the switches. The exercise trial sub-sample (n =30) completed the physical function (PF) subscale of the SF-36, a quality of life measure. Five PT experts familiar with hip fracture and gait speed defined a clinically meaningful change in gait speed. ANALYSES: MDC was determined by calculating and doubling the standard error of the measure (SEM). MCID was determined from expert opinion and from self-reported improvement in the PF scale of the SF-36. A Receiver Operator Characteristic (ROC) curve was constructed for the exercise trial sample. A five point change in PF and a 2-SEM change in gait speed were used to calculate sensitivity and specificity for the ROC curve. RESULTS: MDC for free gait speed was calculated as 0.08 m/sec and for fast gait speed as 0.10 m/sec. The median value of the clinical expert opinion of clinically meaningful change in gait speed was 0.10 m/sec. The break point in the ROC curve was 0.02 m/sec and corresponded to a sensitivity of 0.9, a specificity of 0.44, and a positive likelihood ratio of 1.59. CONCLUSIONS: The calculated minimal detectable change for gait speed was supported by clinical expert opinion. The ROC curve indicated a minimal increase in the likelihood of predicting a change in gait speed based on a change in the physical function score of the SF-36. The poor combination of sensitivity and specificity was most likely due to the use of a self-report measure (SF-36) and the small sample size. Further work is needed to determine the MDC and MCID for gait speed timed with a stopwatch in more varied samples of elders. FUNDING SOURCE: None KEYWORDS: gait speed, hip fracture, minimal detectable change, minimal clinically important difference Copyright 2009 by the American Physical Therapy Association. Requests for reprints should be directed to the corresponding author of the article. Educators, students, and other academic customers may receive permission to reprint copyrighted material from Physical Therapy (ISSN 1538-6724) by contacting the Copyright Clearance Center Inc, 222 Rosewood Dr, Danvers, MA 01923. Other types of customers who want permission to reprint should contact the APTA Editorial Office, Attn: Physical Therapy.