The test-retest reliability of 2 mobility performance tests in patients with chronic stroke

Objective. This study examined test-retest agreement and measurement errors for the Rivermead Mobility Index (RMI) and the Mobility subscale of the Stroke Rehabilitation Assessment of Movement (M-STREAM) in patients with chronic stroke and mild to moderate disability. The authors aimed to determine the level of agreement between test and retest as well as the extent to which a mobility score varies on test-retest measurements. Methods. Both mobility measures were tested on 50 chronic stroke patients twice, 7 days apart. Intraclass correlation coefficient (ICC2,1), a relative reliability index, was used to examine the level of agreement between test and retest. Absolute reliability indices, including the standard error of measurement and the smallest real differences, were used to determine the extent to which the mobility scores varied due to chance variation in measurement. Results. Test-retest agreements were excellent for both mobility measures. The standard errors of measurement of the RMI and the M-STREAM, representing the smallest change threshold that indicates a real improvement (beyond measurement error) for a group of individuals, were 0.8 and 1.5, respectively. The smallest real differences of the RMI and the M-STREAM, exhibiting the smallest change threshold that indicates a real improvement for a single individual, were 2.2 and 4.2, respectively. Conclusion. The RMI and the M-STREAM have high agreement between the test-retest measurements with acceptable measurement errors due to variation in measurement. The 2 measures can be used by clinicians and researchers to assess the mobility performance and monitor changes over time in stroke patients.