Measuring stroke survivors' functional status independence: five perspectives.

An understandable measure to describe disabilities after stroke is important for clinical practice; practitioners often use multiple measures that contain different scoring systems and scales to rate activities of daily living (ADL) independence. We compared the construct of independence in five measures used with stroke survivors. The measures evaluated independence of the stroke survivors somewhat differently. The Rasch analysis Partial Credit Model converted items from these measures to a single metric, yielding an item difficulty hierarchy of all items from the measures. Data from the measures should be interpreted carefully because other concepts or constructs in addition to ADL independence are included in some of the measures. Rasch diagnostics regarding construct validity and reliability of the combined measures also indicated that these measures are not interchangeable. Although the items of the combined ADL measures were unidimensional, they measured independence from multiple perspectives, and the scale of the combined measures was not linear.