The prediction of chronic pain outcome by psychological variables

Followup telephone interviews were conducted with fifty-four former patients of a multidisciplinary clinic for the evaluation of chronic pain. Interviews were conducted between thirteen and fifty-five months following initial evaluation at the pain clinic. Followup levels of pain and physical disability were compared with the following measures obtained at initial evaluation: levels of pain and physical disability and scores on the Minnesota Multiphasic Personality Inventory (MMPI), McGill Pain Questionnaire (MPQ), and Zung Depression Inventory (ZDI). In general, both physical disability measures and psychological test scores obtained at initial interview were related to followup measures. However, when the predictive value of initial pain and physical disability was accounted for, psychological test scores tended not to produce further significant increment in predictability. These findings are interpreted to mean that the predictive value of these psychological tests stems less from their reflection of a psychological state or attitude with respect to pain, and more from their tendency to reflect ongoing level of pain, disability, and other pain sequelae. The results support the hypothesis that scores on these psychological tests are, at least in part, a reflection of the actual pain and disability and may not be subject to the same clinical interpretations that scores obtained from a psychiatric sample would be.