Examining minimal important change of the Canadian Occupational Performance Measure for subacute rehabilitation hospital inpatients

BACKGROUND: The Canadian Occupational Performance Measure (COPM) is an individualized patient-reported outcome designed to evaluate the self-perceptions of a patient’s occupational performance. Our study aimed to examine the minimal important change (MIC) in inpatients undergoing subacute rehabilitation. The MIC values were calculated using the three different anchor-based analyses with the transition index as an external criterion; the mean change method (MIC(MeanChange)), the receiver operating characteristic (MIC(ROC)) analysis, and the predictive modeling method adjusted for the proportion of improved patients (MIC(adjust)). In this study, the MIC(adjust) value was considered as the most valid statistical method. We recruited 100 inpatients with various health conditions from subacute rehabilitation hospitals. Data were collected twice: an initial assessment and a reassessment one month later. The systematic interview format (Five Ws and How) was used for both the initial and second assessments to prevent information bias (response shift). RESULTS: Three patients who indicated deterioration on the transition index were excluded from all analyses, and 97 patients were analyzed in this study. The MIC(adjust) values were 2.20 points (95% confidence interval 1.80–2.59) for the COPM performance score and 2.06 points (95% confidence interval 1.73–2.39) for the COPM satisfaction score. The MIC(MeanChange) and MIC(ROC) values were considered less reasonable to interpret because the proportions of the improved patients subgroup were more than 50% (82.5%). CONCLUSIONS: The MIC(adjust) value estimates from this study can help detect whether the patients’ perceived occupational performance improved or did not change. The results support the multidisciplinary use of COPM in clinical practice and research on subacute rehabilitation inpatients.