The Danish Pain Research Biobank (DANPAIN-Biobank): a collection of blood, cerebrospinal fluid, and clinical data for the study of neuroimmune and glia-related biomarkers of chronic pain.

Background: Chronic pain is a major health problem worldwide but the limited knowledge of its underlying pathophysiology impairs the opportunities for diagnostics and treatment. Biomarkers of chronic pain are greatly needed to understand the disease and develop new targets for interventions and drug treatments, and potentially introduce more precise diagnostic procedures. Much evidence points to a neuroimmune pathology for many chronic pain conditions and that important neuroimmune biomarkers exist in the cerebrospinal fluid (CSF) of patients with chronic pain. Systematic collection of CSF in large cohorts of chronic pain patients and healthy volunteers has proven difficult, however. We established the Danish Pain Research Biobank (DANPAIN-Biobank) with the aim of studying potential neuroimmune and glia-related biomarkers of chronic pain. In this paper, we describe the methods and the study population of the DANPAIN-Biobank. Methods: In this cross-sectional study, we included (I) participants with high-impact (HI) chronic pain from a tertiary, interdisciplinary pain center; (II) participants with osteoarthritic pain scheduled for arthroplasty surgery of the hip or knee at a regional hospital; and (III) pain-free volunteers. All participants completed a questionnaire assessing pain, functional impairment, anxiety, depression, and insomnia before samples of blood and CSF were extracted. Quantitative sensory tests were performed on participants with HI chronic pain and pain-free volunteers, and postoperative outcome scores were available on participants with osteoarthritic pain. Results: Of the 352 participants included, 201 had HI chronic pain (of which 71% had chronic widespread pain), 81 had chronic osteoarthritic pain, and 70 were pain-free volunteers. Samples were handled uniformly, and CSF samples were frozen within 30 minutes. Conclusions: We describe the content of the DANPAIN-Biobank, which is unique in terms of the number of participants (including pain-free volunteers), extensive clinical data, and uniformity in sample handling. We believe it presents a promising new platform for the study of neuroimmune and glia-related biomarkers of chronic pain.