Ab0141 Neuropathic and Nociplastic Pain Are Common in Adult Chronic Nonbacterial Osteitis (Cno)

Background: Chronic nonbacterial osteitis (CNO) is a rare bone disease that has historically been labelled as synovitis, acne, pustulosis, hyperostosis, osteitis (SAPHO)-syndrome due to its wider spectrum of inflammatory features. CNO is characterized by sterile bone inflammation causing bone pain. However, other mechanisms beyond nociceptive inflammatory pain may be involved in patients' pain experience. Objectives: We investigate the prevalence of neuropathic and nociplastic pain profiles in adult CNO and assess their association with clinical characteristics and treatment outcomes. Methods: Survey study among the Dutch adult CNO cohort. Patients were invited to participate in surveys about pain profiles, including PAIN-detect for neuropathic pain, Central Sensitization Inventory (CSI), Fibromyalgia Rapid Screening Tool (FiRST), and ACTTION-APS Pain Taxonomy (AAPT) scoring for nociplastic pain and symptoms consistent with fibromyalgia. Clinical characteristics and CNO-related pain scores assessed by Brief Pain Inventory were compared between patients with nociceptive pain exclusively and those with nociceptive pain plus neuropathic and/or nociplastic pain (mixed pain profile). Results: 80 patients participated in the surveys (response rate 44%). 31% (95% CI 21-41) of patients classified as "likely (>90% probability)" having neuropathic pain according to PAIN-detect. 53% (95% CI 41-64) of patients displayed degrees of sensitization consistent with a nociplastic pain profile. 61% (50-72) screened positive for fibromyalgia on FiRST and 14% (7-23) of patients fulfilled the AAPT criteria for fibromyalgia. The presence of neuropathic and/or nociplastic pain (mixed pain profile) was associated with longer diagnostic delay (mean difference 2.8 years, 95% CI 0.4-5.2, p=0.023), lower educational level (72% versus 20%, p<0.001), and opioid use for CNO-related symptoms (37% versus 13%, p=0.036). Despite comparable disease duration and extent, patients with a mixed pain profile reported significantly higher CNO-related bone pain scores. Conclusion: This study demonstrates the frequent coexistence of neuropathic and nociplastic pain alongside nociceptive inflammatory bone pain in adult CNO patients. Disease burden in CNO may extend beyond just inflammatory activity, highlighting the need for a multifaceted management approach. REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests: None declared.