Multivariate cluster analysis of the MMPI-2-RF in pain patients with financial compensation: characterization of subgroups based on demographics, medico-legal and predictive outcome variables

Psychosocial factors influence the experience of, and adaptation to, pain. Previous cluster analytic studies on pain patients with financial incentives using the Minnesota Multiphasic Personality Inventory-2 (MMPI-2) have described three psychologically relevant pain subgroups that may influence symptoms and recovery. The Minnesota Multiphasic Personality Inventory-2-Restructured Form (MMPI-2-RF; Tellegen & Ben-Porath, 2008) is now offered as alternative to the MMPI-2. The MMPI-2-RF was developed to be a less time-consuming update of the MMPI-2.The purpose of the current study was to investigate whether the MMPI-2 subgroup solutions are replicated when using the newly developed MMPI-2-RF scales using an exploratory two-step cluster analysis. Similar to the MMPI-2, results demonstrated a three-cluster solution for the MMPI-2-RF, which described a Somatic, Depressed, and Pathological profiles. These subgroups were described based on their RC elevations. The Somatic profile was defined based on elevations on scales that resemble somatization (RC1); the Depressed profile was defined based on elevations on scales that resembles demoralization, negative mood and somatization (RCd, RC1 and RC2); and the Pathological profile was defined based on its multiple clinical elevations. Subgroup membership in pain patients with financial incentive was not conditioned to spine-related organic factors. Malingering, education, ethnic background, and legal status differentiated the pain subgroups. Moreover, similar to the MMPI-2, a dose-response relationship between perceived outcome and subgroup profile elevation was demonstrated. The results of the current study suggest that the MMPI-2-RF is equivalent to the MMPI-2 in determining pain subgroup membership and guiding decisions regarding interventions.