Canadian Occupational Performance Measure: Impact of Blinded Parent-Proxy Ratings on Outcome

Background. There is potential for unintended effects on intervention outcome when using the Canadian Occupational Performance Measure (COPM) in intervention studies. Purpose. To determine the effect of blinded parent-proxy ratings of the COPM on outcomes at later endpoints. Methods. Data were drawn from a randomized trial of 50 children with hemiplegic cerebral palsy aged 19 months to seven years. Outcomes were measured at baseline, post-intervention, and six months. Parents of 36 children were randomly allocated to complete six-month COPM proxy ratings blinded or unblinded to previous ratings. A group of 32 parents rated the six-month COPM blinded and then re-rated it after access to previous ratings. Findings. There was no statistically significant difference in ratings between those completing the COPM blinded compared to unblinded. Implications. The COPM should continue to be rated blinded at post-intervention endpoints in the absence of further research to the contrary.