Comparison of psychometric properties of three mobility measures for patients with stroke

Background and Purpose - This study compared the validity, responsiveness, and interrater reliability of 3 mobility measures in stroke patients from the acute stage up to 180 days after stroke onset. The 3 measures were the Rivermead Mobility Index (RMI), a modified RMI (MRMI), and the Mobility Subscale of the Stroke Rehabilitation Assessment of Movement ( STREAM). Methods - The validity and responsiveness of the 3 mobility measures were prospectively examined by monitoring 57 stroke patients with the measures and the Barthel Index at 14, 30, 90, and 180 days after stroke onset. Two individual raters used the 3 measures to evaluate a different sample of 40 patients on 2 separate occasions to determine the interrater reliability. Results - The Spearman rho between STREAM and MRMI was greater than or equal to0.92; the intraclass correlation coefficient ( ICC, a measure of agreement) between them was greater than or equal to0.89, indicating high concurrent validity of both measures. RMI showed a moderate to high relationship and agreement with STREAM and MRMI (rho greater than or equal to 0.78, ICC greater than or equal to 0.5). Responsiveness of the 3 measures was high before 90 days after stroke onset ( standardized response mean greater than or equal to 0.83) and low at 90 to 180 days after stroke onset ( 0.2 less than or equal to standardized response mean less than or equal to 0.4). The score changes of the 3 measures at each stage were significant ( P less than or equal to 0.05), except for RMI and MRMI at 90 to 180 days after stroke onset. The interrater agreement of the 3 measures was high ( ICC greater than or equal to 0.92). Conclusions - All 3 measures examined showed acceptable levels of reliability, validity, and responsiveness in stroke patients. The psychometric characteristics of STREAM were slightly superior to those of the other 2 measures among our patients. We prefer and recommend STREAM for measuring mobility disability in stroke patients.