Abstract
Background. The interpretation of the change scores of the Barthel Index (BI) in follow-up or outcome studies has been hampered by the fact that its minimal clinically important difference (MCID) has not been determined. Objective. This article was written to establish the MCID of the BI in stroke patients. Methods. Both anchor-based and distribution-based methods were used to establish the MCID. In the anchor-based method, 43 stroke inpatients participated in a follow-up study designed to determine the MCID of the BI using patients' global ratings of the activities of daily living function on a 15-point Likert-type scale. The mean change scores on the 20-point scale of the BI of the MCID group, based on the patients' ratings on the Likert-type scale, served as the first estimate of the MCID. In the distribution-based method, 56 chronic stroke patients participated in the test-retest reliability study to determine the MCID of the BI. One standard error of measurement (SEM) served as the second estimate for the MCID. The larger MCID value of the 2 estimates was chosen as the MCID of the BI. Results. In the anchor-based study, there were 20 patients in the MCID group, with a mean change score of 1.85 points (ie, the first MCID estimate). In the distribution-based study, the SEM based on test-retest agreement was 1.45 points (ie, the second MCID estimate). The MCID of the BI in stroke patients was estimated to be 1.85 points. Conclusion. The authors' results, within the limitations of their design, suggest that if the mean BI change score within a stroke group has reached 1.85 points in a study, the change score on the BI can be perceived by patients as important and beyond measurement error (ie, such a change score is clinically important).