Trajectories of Opioid Use Before and After Cancer Diagnosis: A Population-Based Cohort Study

Background: Opioid use prior to cancer diagnosis increases the likelihood of long-term use during survivorship, however, patterns of use before and after diagnosis are not understood.

Methods: We used population-based dispensing data linked with cancer and death notifications to identify two cohorts of adults residing in New South Wales initiating opioids within 24 months prior to a first cancer diagnosed between 2014 and 2016: 'survivors' (alive 24 months following diagnosis) and 'decedents' (died within 24 months). We used group-based trajectory modelling to identify trajectories of monthly opioid dispensings and dispensed oral morphine equivalent milligrams (OMEmg) during the 24 months before/after cancer diagnosis.

Results: There were 21,843 survivors with four prediagnosis opioid dispensing trajectories: infrequent (58% of the cohort), late increasing (26%), moderate (10%), and sustained dispensing (6%). We observed an overall increase in dispensed OMEmg of 83 OMEmg (95% CI: 76-91) during the month of diagnosis, with strong opioid formulations comprising most treatment postdiagnosis. Within each prediagnosis opioid trajectory group, we observed five to six postdiagnosis trajectory groups, including no opioid dispensing. Moderate and sustained prediagnosis groups had large proportions of people continuing or increasing opioid dispensing after diagnosis, while small proportions discontinued opioid treatment. We observed similar trajectories in the decedent cohort.

Conclusions: There is considerable heterogeneity in opioid use before and after cancer diagnosis. Our findings suggest noncancer factors drive a significant proportion of postdiagnosis opioid use, but use increased significantly from the month of cancer diagnosis and never returned to prediagnosis levels.