Clinimetric Evaluation of the English Version of the Conceptualization of Pain Questionnaire (COPAQ).

objectiveVery few validated instruments measure a child's concept of pain. The Conceptualization of Pain Questionnaire (COPAQ) is a unidimensional instrument measuring this construct, developed in Catalan and translated into English. The clinimetric properties of the English version have not been evaluated. We conducted a Rasch analysis to evaluate its structural validity and internal consistency, and a Confirmatory Factor Analysis (CFA) to evaluate its structural validity.

methodsWe analyzed an existing data set from a previous study. Item fit was evaluated using INFIT and OUTFIT statistics, item difficulty was estimated using Rasch coefficients, and internal consistency using Cronbach alpha. Structural validity was measured using item loadings from the CFA.

resultsWe included data from 497 adolescents (average age 14 y [SD 1.28], 51% male). There was a wide range of difficulty across items. One item demonstrated excessive positive outfit, and 2 items were close to the cutoff for excessive negative outfit. The COPAQ demonstrated poor overall fit to the unidimensional Rasch Model and did not demonstrate adequate internal consistency (Cronbach alpha=0.6). Results from the CFA suggest the items do not measure the single construct they intend to measure. DISCUSSION: The English version of the COPAQ did not have adequate internal consistency or structural validity. More work is required to assess the content validity of current instruments measuring a child's concept of pain. Developing validated instruments measuring a child's concept of pain aligned with the biopsychosocial model should be prioritized.