MMPI Profile as an Outcome “Predictor” in the Treatment of Noncancer Pain Patients Utilizing Intraspinal Opioid Therapy

Abstract

Objective. To evaluate changes in Minnesota Multiphasic Personality Inventory (MMPI) profiles pre- and post-treatment involving intrathecal opioid therapy. Patients and Methods. This study reports on 30 patients that were evaluated pre- and post-intraspinal opioid therapy. Treatment duration was slightly more than four years. Each patient experienced chronic non-cancer pain deemed suitable for trialing and subsequent implantation of a drug administration system (DAS). On average the patients had experienced pain for 8.4 years and had a mean of 3.2 pain-related surgeries. Results. The patients could be divided into "positive change group" and "negative change group" based upon pre- and post-treatment MMPI profiles. Those patients in the negative change group had more "normal profiles" pretreatment. This group evidenced less reduction in pain and was found to be using slightly higher levels of intraspinal opioids. Conclusions. These results would suggest that the MMPI profile may not be a good "predictor" of long-term outcome utilizing intraspinal opioid therapy. Indeed, patients with the more normal profile pretreatment did not fare as well as those with the more elevated profile. A positive change in MMPI profile from pre- to post-treatment was associated with a higher level of pain reduction. Patient selection therefore should be based not on a single test such as the MMPI, but on consistency across multiple sources of information including physical examination, complaints of pain and disability, behavioral observations, and psychological testing.