Patterns of opioid use in older people diagnosed with cancer in New South Wales, Australia.

Purpose: Opioids provide effective analgesia for most cancer patients, but little is known about individual-level opioid use after cancer diagnosis. We examined the patterns of and factors associated with opioid use in older people diagnosed with cancer.

Methods: We used the Department of Veterans' Affairs (DVA) client data linked with the New South Wales (NSW) Cancer Registry and the Repatriation Pharmaceutical Benefits Scheme data. We included people aged ≥65 years diagnosed with cancer in NSW, Australia in 2005 to 2015. We examined patterns of opioid use in the 12 months after cancer diagnosis and used cause-specific hazards models to examine factors associated with opioid use.

Results: Of 13 527 people diagnosed with cancer, 51% were dispensed opioids after their diagnosis. We observed the highest proportions of use in people diagnosed with pancreas, liver, or lung cancers. Opioid use was associated with female sex, younger age, more advanced degree of cancer spread, opioid use before cancer diagnosis, and multimorbidity. Forty-four percentages of all people dispensed opioids had a history of opioid use in the 12 months before their cancer diagnosis; these people had higher median number of different opioids and opioid dispensings, and a shorter time to first opioid dispensing than opioid-naive people.

Conclusion: Our study suggests that many older cancer patients were dispensed opioids before their cancer diagnosis. Previously opioid-treated people had more intense opioid use patterns after diagnosis than opioid-naïve people. Acknowledging the history of opioid use is important as it may complicate pain treatment in clinical practice.