Principal dimensions of the pain experience and psychological disturbance in chronic low back pain patients.

The principal dimensions of the pain experience of 102 patients with chronic low back pain were studied and components of the pain experience were compared to pre-treatment measures of emotional disturbance. Responses on the McGill Pain Questionnaire (MPQ) were factor analyzed revealing dimensions of the pain experience that seemed to represent sensory, affective, and evaluative aspects. Patients with high scores on the MMPI hypochondriasis scale portrayed their pain as more intense and as high in terms of affective and evaluative descriptors on the MPQ. Other MMPI scales reflecting emotional disturbance (depression, hysteria) were also associated with a more intense description of pain and higher scores on an affective descriptor dimension. The evaluation descriptive dimension was highly related to the overall intensity of the pain experience. Only the affective dimension was related to emotional disturbance separately from the effects of intensity alone.