Evidence-based measurement - Which disability scale for neurologic rehabilitation?

Objective: To compare the 10-item Barthel Index (BI), 18-item Functional In dependence Measure (FIM), and 30-item Functional Independence Measure + Fun ctional Assessment Measure (FIM+FAM) as measures of disability outcomes for neurologic rehabilitation. Methods: A total of 149 inpatients from two reh abilitation units in South England specializing in neurologic disorders wer e studied. Traditional psychometric methods were used to evaluate and compa re acceptability (score distributions), reliability (internal consistency, intrarater reproducibility), validity (concurrent, convergent and discrimin ant construct), and responsiveness (standardized response mean). Results: A ll three rating scales satisfied recommended criteria for reliable and vali d measurement of disability, and are acceptable and responsive in this stud y sample. The FIM and FIM+FAM total scales are psychometrically similar mea sures of global disability. The BI, FIM, and FIM+FAM motor scales are psych ometrically similar measures of physical disability. The FIM and FIM+FAM co gnitive scales are psychometrically similar measures of physical disability . Conclusions: In the sample studied, the BI, FIM, FIM+FAM have similar mea surement properties, when examined using traditional psychometric analyses. Although instruments with more items and item response categories generate more qualitative information about an outcome, they may not improve its me asurement. Results highlight the importance of using recognized techniques of scale construction to develop health outcome measures.