P-49 Cancer induced bone pain – the use of edmonton classification system for cancer pain and management of refractory pain

<h3>Purpose</h3> Cancer-induced bone pain (CIBP) affects a patient’s functional capacity and quality of life, but there is limited evidence to guide opioid choice. We described the prevalence of the Edmonton Classification System for Cancer Pain (ECSCP) features in patients with bone metastases and assessed the possible efficacy of methadone rotation (MR) compared to other opioid rotations (OOR) in the cohort with refractory pain. <h3>Methods</h3> Adults with bone metastases were assessed against ECS-CP features and those with worst pain intensity ≥4/10 and/or opioid toxicity graded ≥2 on the Common Terminology Criteria for Adverse Events (CTCAE) were randomised 1:1 to methadone or another opioid rotation. Standardised assessment tools were used at pre-defined study time points up to fourteen days. <h3>Results</h3> From 147 eligible participants, 92.5% completed assessment. Mean participant age was 73.2 years. One or more ECS-CP features were present in 96.4% and CIBP in 75.7% of patients. Neuropathic pain was the most prevalent pain mechanism (45%) and was associated with breakthrough pain frequency, higher pain scores and background oral morphine equivalent daily dose (OMEDD). Of those with refractory CIBP, 38 (74.5%) consented, and 29 (76.3%, MR: 14, OOR: 15) completed the study. Both groups displayed significant reduction in pain intensities and total pain interference score. OMEDD reduced significantly in MR compared to OOR group (d= -0.8, p=0.05). There was no within group or between group differences in satisfaction with analgesia at the end of the study. <h3>Conclusion</h3> Standardised assessment and classification of pain syndromes can assist in developing personalized pain interventions. This pilot study demonstrated that MR and OOR in patients with refractory CIBP are feasible, safe, and acceptable to patients. Appropriately powered multi-centre randomised controlled studies are needed to confirm the efficacy of MR and OOR in this cohort.