BackgroundOver the past 20 years prescription of opioid medicines has markedly increased in the UK, despite a lack of supporting evidence for use in commonly occurring, painful conditions. Prescribing is often monitored by counting numbers of prescriptions dispensed, but this may not provide an accurate picture of clinical practice.AimTo use an estimated oral morphine equivalent (OMEQ_e) dose to describe trends in opioid prescribing in non-cancer pain, and explore if opioid burden differed by deprivation status.Design & settingA retrospective cohort study using cross-sectional and longitudinal trend analyses of opioid prescribing data from Welsh Primary Care General Practices (PCGP) took place. Data were used from the Secure Anonymised Information Linkage (SAIL) databank.MethodAn OMEQ_e measure was developed and used to describe trends in opioid burden over the study period. OMEQ_e burden was stratified by eight drug groups, which was based on usage and deprivation.ResultsAn estimated 643 436 843 milligrams (mg) OMEQ_e was issued during the study. Annual number of prescriptions increased 44% between 2005 and 2015, while total daily OMEQ_e per 1000 population increased by 95%. The most deprived areas of Wales had 100 711 696 mg more OMEQ_e prescribed than the least deprived over the study period.ConclusionOver the study period, OMEQ_e burden nearly doubled, with disproportionate OMEQ_e prescribed in the most deprived communities. Using OMEQ_e provides an alternative measure of prescribing and allows easier comparison of the contribution different drugs make to the overall opioid burden.