The responsiveness and minimal important change of the Danish version of the Canadian Occupational Performance Measure.

Introduction: The Canadian Occupational Performance Measure (COPM) is a well-known measurement used in occupational therapy. Only few studies have examined the responsiveness, i.e. the ability to reveal a real change in clients’ status, or the minimal important change (MIC), i.e. the smallest measured change in a score, perceived as being relevant by patients.

Objective: To establish the responsiveness, and the MIC of the Danish version of the COPM.

Methods: A cross-sectional study was performed in three Danish settings, including 88 clients (45% men), aged 16-90 years with different diagnoses. To determine construct responsiveness, the mean changes of the COPM performance and satisfaction score (COPM-P/S), were compared and correlated with the mean changes in WHO-5 and EQ-5D-5L. To determine criterion responsiveness, data were analysed with ROC curves to motivate the cut-point values for the MIC of the COPM-DK scores. The MIC cut-points were interpret based on an assessment of anchor-based questions.

Results: The mean change for COPM-P/S was 3.1 and 3.0. Small positive correlations were found between the COPM-DK scores and the WHO-5 and EQ-5D-5L scores. In relation to anchor-based questions, the area under the ROC curve (AUC), were 0.76 and 0.75. The optimal cut-point values for the COPM-P/S-scores based on either all positive answers or the two highest, were 1.2 or 4.20 (COPM-P) and 1.67 or 5.80 (COPM-S).

Conclusion: The capability of the COPM-DK to detect changes in perceived occupational performance issues was supported. We recommend a MIC on 3.5 points on both scales.