Epidemiological Factors Associated with Prescription of Opioids for Chronic Non-Cancer Pain in Adults: A Country-Wide, Registry-Based Study in Denmark Spans 2004–2018

PURPOSE: Denmark has a high consumption of prescribed opioids, and many citizens with chronic non-cancer pain (CNCP). Therefore, we aimed to characterize and assess epidemiological risk factors associated with long-term non-cancer opioid use among Danish citizens. PATIENTS AND METHODS: We conducted a longitudinal, retrospective, observational, register-based study using nationwide databases containing essential medical, healthcare, and socio-economic information. Statistical analysis, including backward stepwise logistic regression analysis, was used to explain long-term opioid use by individuals filling at least one prescription for an opioid product N02AA01–N02AX06 during 01/01/2004–31/12/2017, follow-up until the end of 2018. RESULTS: The analyzed cohort contained N=1,683,713 non-cancer opioid users, of which 979,666 were classified with CNCP diagnosis using ICD-10 codes. Long-term opioid use was predicted by a mean of 1,583.30 and a median of 300 oral morphine equivalent mg (OMEQ) per day during the first year, together with divorced, age group 40–53 years, retirement, receiving social welfare or unemployment ≥6 months. In addition, living in Northern Jutland, co-medications such as beta-blockers, anti-diabetics, anti-rheumatics, and minor surgery ≤90 days before inclusion. Protective variables were an education level of secondary school or higher, children living at home, household income of middle or highest tertile, opioid doses in either the 2nd or 3rd quartile OMEQ, male, the oldest age group, living in the Capital Region or Zealand, co-medication lipid-lowering, one comorbidity, heart failure, surgeries ≤90 days before the index: lips/teeth/jaw/mouth/throat, heart/vessels, elbow/forearm, hip/thigh, knee/lower leg/ankle/foot. CONCLUSION: Long-term opioid users differ epidemiologically from those using opioids for a shorter period. The study findings are essential for future recommendations revision in Denmark and comparable countries.