Test-retest reliability and minimal detectable change of gait speed in individuals undergoing rehabilitation after stroke.

BACKGROUND AND PURPOSE: Gait speed is commonly used to assess walking ability in persons with stroke. Previous research related to the psychometric properties of gait speed has been conducted primarily with individuals who were able to walk independently and/or were in the later stages of recovery after stroke. The purpose of this research was to examine the test-retest reliability and minimal detectable change (MDC90) of gait speed in individuals with stroke who required varying levels of assistance to ambulate during rehabilitation.

METHODS: Patients who could ambulate with or without physical assistance and were undergoing inpatient rehabilitation were recruited. Gait speed was measured over the middle five meters of a nine-meter walk at a comfortable pace. Data were analyzed using the intraclass correlation coefficient (ICC2,1) and the MDC90.

RESULTS: Thirty-five patients who were a mean 34.5 (standard deviation = 17.7) days post-stroke agreed to participate. For all the subjects combined, the ICC2,1 was 0.862 and MDC90 was 0.30 m/sec. For the 13 subjects who required physical assistance to walk, the ICC2,1 = 0.971 and MDC90 = 0.07 m/sec. For the 22 subjects who could walk without physical assistance, the ICC2,1 = 0.80 and MDC90 = 0.36 m/sec.

DISCUSSION: Gait speed is a reliable measure of walking ability for a wide variety of patients undergoing rehabilitation after stroke. Gait speed is more sensitive to change in patients who require physical assistance to walk than in those who can walk without assistance. A change of more than 0.30 m/sec may be necessary in order to determine whether a change in gait speed exceeds measurement error and patient variability.