Risk factors for indicators of opioid-related harms amongst people living with chronic non-cancer pain: findings from a 5-year prospective cohort study

Background: The literature suggests patient characteristics and higher opioid doses and long-term durationare associated with problematic opioid behaviours but no one study has examined the role of all these factorssimultaneously in a long-term prospective cohort study.Methods: Five-year, community-based, prospective cohort of people prescribed opioids for chronic non-cancerpain (CNCP). Logistic mixed effect models with multiple imputation were used to address missing data.Oral morphine equivalent (OME) mg per day was categorised as: 0 mg OME/day, 149 mg OME/day (reference),5089 mg OME/day, 90199 mg OME/day and 200mg+ OME/day. Patient risk factors included: age,gender, substance use, mental health history and pain-related factors. Main outcomes included: PrescribedOpioids Difficulties Scale (PODS), Opioid-Related Behaviours In Treatment (ORBIT) scale, and ICD-10 opioiddependence. Multiple confounders for problematic opioid behaviours were assessed.Findings: Of 1,514 participants 44.4% weremale (95%CI 41.946.9) and theirmean agewas 58 years (IQR 4867).Participants had a mean duration of pain of 10 years (IQR 4.520.0) and had been taking strong opioids for amedian of four years (IQR 1.010.0). At baseline, median OME/day was 73 (IQR 35148). At 5-years, 85% werestill taking strong opioids. PODS moderate-high scores reduced from 59.9% (95%CI 58.861.0) at baseline to51.5% (95%CI 50.053.0) at 5-years. Around 9% met criteria for ICD-10 opioid dependence at each wave. Inadjusted mixed effect models, the risk factors most consistently associated with problematic opioid use were:younger age, substance dependence, mental health histories and higher opioid doses.Interpretation: Both patient risk factors and opioid dose are associatedwith problematic opioid use behaviours