PERSISTENT USE OF PRESCRIPTION OPIOIDS FOLLOWING SURGERY FOR DEGENERATIVE CERVICAL MYELOPATHY: OBSERVATIONAL STUDY WITH PROSPECTIVELY COLLECTED DATA FROM LINKED NORWEGIAN NATIONWIDE REGISTRIES

Sources of Funding: This work is funded by the NIHR SPCR Post-doctoral fellowship (C111). LW has also been supported by the NIHR Exeter BRC and the Bateman Professorial Fellowship. Conflicts of Interest: No conflicts of interest Purpose Degenerative cervical myelopathy (DCM) is the most common cause of spinal cord impairment. We aimed to describe patterns of medication in the year before, and two years post-surgery, and to identify factors associated with post-surgical persistent opioid use. Methods Patients undergoing surgery for DCM in the Norwegian Registry for Spine Surgery were included, with complete 2-year medication data in the Norwegian Prescription Database (2012 to 2018). Persistent opioid use was defined as >180 Defined Daily Doses (DDDs) or >4500mg oral morphine equivalents for 365 days, dispensed across ≥ 3 / 4 of the year. Medication use (opioids, benzodiazepines, z-hypnotics) was described 1 year before and 2 years post-surgery. Patient-reported outcome measures (PROMs) included pain, function, health-related quality of life, and myelopathy severity at baseline, 3 months, and 1 year post-surgery. Descriptive statistics were used for medication use. Mixed logistic regression examined associations between prognostic factors and persistent opioid use at 2 years. Mixed linear regression explored change in PROMs over time. Results We included 831 (88%), of whom 90 (11%) were persistent opioid users 2 years postoperatively, and 52 (81%) were preoperative persistent opioid users. Preoperative persistent opioid use (adjusted odds ratio (AOR) 108.7; 95% CI 37.69 to 313.45) and smoking (AOR 2.2; 95% CI 1.07 to 4.62) increased odds, while cord signal change reduced odds (AOR 0.1; 95% CI 0.03 to 0.57). Persistent opioid users had worse PROMs. Conclusions Eleven percent of DCM surgical patients were persistent opioid users at 2 years. Preoperative use was the strongest predictor.