Empirical test of the factor structure of the West Haven Yale Multidimensional Pain Inventory

Objective: Although the West Haven-Yale Multidimensional Pain inventory (MP I) is frequently used in clinical evaluation and research with chronic pain patients, few studies have reported item-level factor analyses. After perf orming such an analysis, Bernstein et al. (Spine 1995;20;956-63) reported L ock of independence between the solicitous and distracting response scales in section II as well as the activities away from home and social activitie s scales in section III. They suggested that the combination of these scale s would improve the internal structure of the MPI. The purpose of this stud y was to perform a confirmatory factor analysis testing whether the MPI wou ld he improved by the consolidation of these scales. In addition, a third, empirical model was generated for comparison with the West Haven-Yale and B ernstein models. Design: This study used exploratory and confirmatory factor analysis on two independent samples of chronic pain patients (n = 472 and n = 346) to test hypotheses regarding the factor structure of the MPI. Results and Conclusion: Principal axis factor analysis resulted in an empir ical modal that suggested that the primary psychometric problem of the MPI was lack of item-factor discrimination for several items. When the three mo dels were tested using confirmatory factor analysis, improvement in model f it occurred when cross loading items were excluded. Nevertheless, the goodn ess of fit of original factor structure wets adequate, suggesting it would be premature to suggest changes in this instrument.