Background and purpose: Robust measures of functional outcome are required to determine treatment effects in stroke trials. Of the various measures available, the Barthel index (BI) is one of the more prevalent. We aimed to describe validity, reliability, and responsiveness (clinimetric properties) of the BI in stroke trials.
Methods: Narrative review of published articles describing clinimetric properties or use of the BI as a stroke trial end point.
Results: Definitive statements on properties of BI are limited by heterogeneity in methodology of assessment and in the content of "BI" scales. Accepting these caveats, evidence suggests that BI is a valid measure of activities of daily living; sensitivity to change is limited at extremes of disability (floor and ceiling effects), and reliability of standard BI assessment is acceptable. However, these data may not be applicable to contemporary multicenter stroke trials.
Conclusions: Substantial literature describing BI clinimetrics in stroke is available; however, questions remain regarding certain properties. The "BI" label is used for a number of instruments and we urge greater consistency in methods, content, and scoring. A 10-item scale, scoring 0 to 100 with 5-point increments, has been used in several multicenter stroke trials and it seems reasonable that this should become the uniform stroke trial BI.