A systematic review of the outcomes reported in multimodal pain therapy for chronic pain

Background and objectiveThere are no recommendations provided for the outcome domains of chronic pain that should be explicitly considered in each clinical trial to describe the efficacy and effectiveness of multimodal pain therapy (MPT). Our aims were to summarize all reported outcome domains in studies assessing the effects of MPT for chronic pain, and to subsequently inform a consensus-based development of a core outcome set of domains in this field. Database and data treatmentMedline, Embase and AMED were searched for studies reporting on chronic pain for at least 3months that applied MPT and investigated outcome domains. All reported outcome domains were extracted from eligible articles. The patient-reported outcome measurement information system (PROMIS) was applied for conceptual classification. ResultsFrom 3626 potentially relevant titles, 70 studies were included. The median and maximal numbers of outcome domains were 8 and 34, respectively. Although most studies (n=45/70) assessed a combination of all three core health areas, i.e. physical, mental and social health, there was great variation in the specific domains chosen to address these core health areas. No outcome domain was measured consistently in all studies. After selection of all outcome domains which were reported in at least 10% of all studies included, we identified 14 different outcome domains, mostly operationalized through the domains pain intensity (n=56/70) and depressive symptoms (n=42/70). ConclusionsThe current lack of standardization of outcome domains in MPT studies hinders to readily compare interventions from different trials and is a barrier towards evidence-based decision making. Based on these results, the development of a core outcome set of domains for MPT has been initiated.