Cross-validation of the factor structure of the McGill Pain Questionnaire.

Low back pain patients' responses to the McGill Pain Questionnaire (MPQ) were factor analyzed using the principal factor method and direct oblique rotation procedures. Four factors were extracted that accounted for 55% of the total variance. Coefficients of congruence were computed in order to relate the current factors with those extracted in a previous factor analytic investigation. The results provided positive evidence that the sensory pressure, evaluative, and affective-sensory factors that were previously identified are stable dimensions underlying the MPQ responses of low back pain patients. However, it is necessary to conduct further cross-validation studies using patients from a wide variety of treatment settings.