Preliminary psychometric evaluation of a measure of adherence to clinic-based sport injury rehabilitation

Objectives: to examine the psychometric properties of the Sport Injury Rehabilitation Adherence Scale (SIRAS), an instrument designed to assess adherence during clinic-based sport injury rehabilitation sessions. Design: rehabilitation professionals completed the SIRAS for their patients on one occasion in Study 1, two occasions one week apart in Study 2, and multiple (range=6–48) occasions in Study 3. Setting: an orthopedic physical therapy clinic specializing in sports medicine. Participants: one hundred and forty-five general physical therapy patients in Study 1, 31 patients undergoing rehabilitation following knee surgery in Study 2, and 43 patients undergoing rehabilitation following anterior cruciate ligament reconstruction in Study 3. Main outcome measure: the SIRAS. Results: In Study 1, a Cronbach's alpha coefficient of .82 was obtained for the SIRAS, scores on the SIRAS were weakly correlated (r=.21) with attendance at rehabilitation sessions, and the SIRAS items loaded on a single factor in a principal components analysis. In Study 2, a test–retest intraclass correlation coefficient of .77 was obtained for the SIRAS and, in Study 3, a modified interrater intraclass correlation coefficient of .57 was obtained for repeated administrations of the SIRAS across rehabilitation professionals. Conclusions: the results of this study provide preliminary evidence in support of the internal consistency, unidimensionality, discriminant validity, test–retest reliability, and interrater reliability of the SIRAS.