Abstract
BACKGROUND: Based on a tripartite theoretical model of pain, the Pain Rating Index (PRI) of the McGill Pain Questionnaire (MPQ) continues to be one of the most frequently used instruments to measure clinical pain. However, language and cultural barriers have hindered its wide use and standardization in Japan. Although a number of exploratory factor analysis studies have failed to support consistently the theoretical structure of the MPQ, a few previous confirmatory factor analysis studies did statistically support the a priori model.OBJECTIVE: To test, through confirmatory factor analysis (CFA), the theoretical structure of a Japanese version of the MPQ (JMPQ), which followed a format similar to that of the original MPQ.DESIGN: This study used CFA on prospectively collected data from 199 consecutive outpatients with chronic pain at a university hospital to test the theoretical structure of the JMPQ.RESULTS AND CONCLUSIONS: CFA was completed on the first 16 PRI subclass scores; this process yielded a well fitting final model that explained 92% of the covariance in the observed data. The results supported the hypothesis that the sensory, affective and evaluative subscales of the PRI are representative of the multidimensionality of the pain experience, with minimal overlap. It is suggested that the theoretical structure of the MPQ is maintained in the JMPQ used in this study. Therefore, this study is the first step toward standardization of the JMPQ, serving as a cultural bridge in the field of pain medicine between Japan and English-speaking nations such as Canada.