The Canine Orthopedic Index. Step 2: Psychometric Testing

Abstract

ObjectiveTo perform psychometric testing an owner self‐administered questionnaire, the Canine Orthopedic Index (COI), designed to assess outcome in dogs with orthopedic disease.Study DesignOriginal study.Sample PopulationOwners (n = 20) of dogs with osteoarthritis (OA) for item (question) pretesting, and 80 owners of dogs with OA for reliability and validity testing.MethodsStandard methodology for the stepwise development and testing of instruments designed to assess subjective states was followed. Items generated in previous studies were pretested for readability, ambiguity, and inter‐item correlations; poorly performing items were removed; and the reduced set of items subjected to factor analysis, reliability, and validity testing.ResultsFour factors were identified and named on the basis of the items contained in them: “Stiffness,” “Gait,” “Function,” and “Quality of Life.” Cronbach's α ranged from 0.76 to 0.86, suggesting the items in each factor could be assessed as a group to compute factor scores (i.e., stiffness, gait, function, and quality of life scores). The test–retest analysis revealed κ values from 0.68 to 0.80. Overall, the scores amongst the 4 factors correlated moderately well (r = 0.52–0.58), with a mild correlation (r = 0.35) between gait and function scores.ConclusionsThe COI is a psychometrically sound owner completed instrument that can assess 4 domains in dogs with OA: Stiffness, Gait, Function, and Quality of Life.