Cohort profile: POPPY II - A population-based cohort examining the patterns and outcomes of prescription opioid use in New South Wales, Australia

Purpose The POPPY II cohort is an Australian state-based cohort linking data for a population of individuals prescribed opioid medicines, constructed to allow a robust examination of the long-term patterns and outcomes of prescription opioid use. Participants The cohort includes 3 569 433 adult New South Wales residents who initiated a subsidised prescription opioid medicine between 2003 and 2018, identified through pharmacy dispensing data (Australian Pharmaceutical Benefits Scheme) and linked to 10 national and state datasets and registries including rich sociodemographic and medical services data. Findings to date Of the 3.57 million individuals included in the cohort, 52.7% were female and 1 in 4 people were aged ≥65 years at the time of cohort entry. Approximately 6% had evidence of cancer in the year prior to cohort entry. In the 3 months prior to cohort entry, 26.9% used a non-opioid analgesic and 20.5% used a psychotropic medicine. Overall, 1 in 5 individuals were initiated on a strong opioid (20.9%). The most commonly initiated opioid was paracetamol/codeine (61.3%), followed by oxycodone (16.3%). Future plans The POPPY II cohort will be updated periodically, both extending the follow-up duration of the existing cohort, and including new individuals initiating opioids. The POPPY II cohort will allow a range of aspects of opioid utilisation to be studied, including long-term trajectories of opioid use, development of a data-informed method to assess time-varying opioid exposure, and a range of outcomes including mortality, transition to opioid dependence, suicide and falls. The duration of the study period will allow examination of population-level impacts of changes to opioid monitoring and access, while the size of the cohort will also allow examination of important subpopulations such as people with cancer, musculoskeletal conditions or opioid use disorder