Outcomes of Interdisciplinary Pain Rehabilitation Across Subgroups of the Multidimensional Pain Inventory - A Study from the Swedish Quality Registry for Pain Rehabilitation (SQRP).

INTRODUCTION The Multidimensional Pain Inventory (MPI) is frequently used in the assessment of chronic pain. Three subgroups have been derived from MPI: Adaptive Coper (AC), Dysfunctional (DYS) and Interpersonally Distressed (ID). The primary aim of was to examine whether outcome of Interdisciplinary Multimodal Pain Rehabilitation Programs (IMMRPs) differed across the MPI subgroups. METHODS Chronic pain patients (N=34 513), included in the Swedish Quality Registry for Pain Rehabilitation, were classified into MPI subgroups and a subset that participated in IMMRPs (N=13 419) was used to examine overall treatment outcomes using a previously established Multivariate Improvement Score (MIS) and two retrospective patient-evaluated benefits from treatment. RESULTS The subgroups differed on sociodemographic characteristics, pain duration and spatial spreading of pain. DYS and ID had the best overall outcomes to MIS. AC had the best outcomes according to the two retrospective items. Transition into other subgroups following IMMRP was common and most prominent in DYS and least prominent in AC. CONCLUSION The validity of the MPI subgroups were partially confirmed. DYS and ID had the most severe clinical presentations at baseline and showed most improvement following IMMRP, but overall severity in DYS and ID at posttreatment was still higher than in the AC group. Future studies should examine how processes captured by MPI interact with neurobiological, medical, sociodemographic and adaptation/coping factors and how these interactions impact severity of chronic pain and treatment outcome.