Responsiveness and Minimal Clinically Important Difference of the Canadian Occupational Performance Measure Among Patients With Frozen Shoulder.

Importance: Patient-reported outcome measures provide insights into intervention effects on patients. The Canadian Occupational Performance Measure (COPM) emphasizes identifying priorities in daily activity engagement and evaluating an individual's perception of changes over time.

Objective: To assess the responsiveness of the COPM and the minimal clinically important difference (MCID) among patients with frozen shoulders.

Design: Prospective, single-blind, randomized controlled trial.

Setting: Two physical medicine and rehabilitation clinics.

Participants: Ninety-four patients with frozen shoulders enrolled in a previous study.

Outcomes and measures: Baseline and 3-mo evaluations of the COPM and other measures. Responsiveness was assessed using effect size (ES) and standardized response mean (SRM). The MCID values were determined through a distribution-based approach, which used the 0.5 standard deviation and ES methods, and an anchor-based approach, which used the receiver operating characteristic curve method.

Results: The ES and SRM results indicated that the COPM had high responsiveness. The distribution-based MCID values for COPM Performance and COPM Satisfaction were 1.17 and 1.44, respectively. The anchor-based MCID values were 2.5 (area under the curve [AUC] = 0.78, 95% confidence interval [CI] [0.64-0.91]) and 2.1 (AUC = 0.76, 95% CI [0.60-0.91]), respectively.

Conclusions and relevance: The findings suggest that the COPM is a responsive outcome measure for patients with frozen shoulder. The established MCID values for the COPM can be valuable for interpreting changes in patient performance and satisfaction, thus aiding clinical interventions and research planning. Plain-Language Summary: This is the first study to review the effectiveness of the Canadian Occupational Performance Measure (COPM) to determine the success of occupational therapy interventions for people with a frozen shoulder. The findings suggest that the COPM is an effective and valuable tool for clients with a frozen shoulder to understand their experiences and treatment priorities and to detect meaningful changes in their performance and satisfaction after an occupational therapy intervention.