Reliability of the Canadian Occupational Performance Measure in patients with ankylosing spondylitis

The Canadian Occupational Performance Measure (COPM) is a client-centered measure, designed to detect changes in occupational performance over time. The main aim of our study was to examine the test-retest reliability of the Norwegian version of the COPM in patients with ankylosing spondylitis (AS) in 3 different retest modes of data collection.

A total of 119 patients with AS completed the baseline COPM interview before randomization into one of 3 modes of retest data collection performed 2 weeks later: by personal interview, telephone interview, or mailed questionnaire. Scores were computed for Performance and Satisfaction, and the 2 sets of scores were examined for reliability by intraclass correlations (ICC), and by the Bland-Altman procedure for calculation of smallest detectable difference (SDD).

The ICC coefficients for Performance and Satisfaction were as follows: 0.92 and 0.93 (rescoring by personal interview), 0.73 and 0.73 (rescoring by telephone interview), and 0.90 and 0.90 (rescoring by mail). SDD for the Performance and Satisfaction scores were 1.47 and 1.80, respectively, for rescoring by personal interview; 3.14 and 4.00 for rescoring by telephone interview; and 2.20 and 2.41 for rescoring by mailed survey.

The results confirm that the COPM is a reliable instrument for use in clinical practice in patients with AS, and may serve as an instrument to promote a patient-centered approach in the planning and evaluation of rehabilitation programs. Mailed questionnaires may replace personal interview in followup examinations, while rescoring by telephone interview is less reliable.