Validity, responsiveness and feasibility of an Italian version of the Canadian Occupational Performance Measure for patients with ankylosing spondylitis

OBJECTIVES: The purpose of the present study was to produce an Italian version of the Canadian Occupational Performance Measure (COPM) in a group of patients with Ankylosing Spondylitis (AS) and examine the psychometric properties of this version, evaluating its internal consistency, external validity and reliability. Responsiveness and feasibility were also taken into account. METHODS: The Italian COPM, the Italian version of the COPM, was administered to 30 Caucasian patients affected by AS (24 males, 6 females, median age 48 yrs, range 32-67, median disease duration 14 yrs, range 1-30 yrs) together with the Bath Ankylosing Spondylitis Functional Index (BASFI), the Bath Ankylosing Spondylitis Disease Activity (BASDAI) and the Italian version of the Health Assessment Questionnaire (HAQ). Internal consistency was evaluated with Cronbach's alpha for reliability. Construct validity of the COPM was evaluated by a correlation between the BASFI, BASDAI and HAQ scores. Test-retest reliability was assessed by the Intraclass correlation coefficient. Responsiveness and feasibility were also considered. RESULTS: All patients completed the validation study. The questionnaire was internally consistent (alpha coefficient=0.774). A significant correlation was recorded between the COPM and the BASFI (rho=-0.566, p<0.01), BASDAI (rho=-0.491, p<0.01). Test-retest reliability showed a good correlation coefficient and it was confirmed by Bland-Altman method. CONCLUSIONS: The Italian COPM is a valid and reliable instrument focused to detect change in a client's perception of occupational performance over time, in AS patients. Our results confirm the utility of this questionnaire to measure outcome and in planning treatment intervention for patients with AS.