Factors associated with opioid use in long term cancer survivors
Barbera L, Sutradhar R, Howell D, Corn E, O’Brien MA, Seow H, Dudgeon D, Atzema C, Earle C, DeAngelis C, Sussman J. J Pain Symptom Manage. 2019; 58(1):100-7.e2. Epub 2019 Mar 2. DOI: 10.1016/j.jpainsymman.2019.02.024.
Purpose — To evaluate factors associated with opioid use in cancer patients surviving more than 5 years without recurrence. We evaluated exposures of opioid use before cancer diagnosis, opioid use between cancer diagnosis and 5 year anniversary, surgeries and chemotherapy.
Methods — We conducted a retrospective cohort study using linked provincial administrative data. Patients were aged 24-70 and eligible for government funded pharmacare. The index date was the 5 year anniversary from diagnosis. Patients were accrued between 2010 and 2015. The main outcome was opioid prescription rate after index date. The main exposures were opioid use before diagnosis, opioid use between diagnosis and index, surgeries and chemotherapy. A negative binomial regression model was used to estimate relative rates of opioid use after index date.
Results — Our cohort included 7,431 individuals. The overall crude prescription rate after the index date was 2 per person-year. The factor most strongly associated with a higher rate of opioid use after index was continuous opioid use between diagnosis and index (RR 46.1 (95% CI 34.8-61.2)). Opioid use prior to diagnosis was also a factor (RR=1.8, 95% CI 1.44-2.19). A history of depression, comorbidity and more than 2 years of diabetes were also associated with higher risk of post-index date opioid use. Significant interactions were identified between prior opioid use and opioid use between diagnosis and index. The majority of prescriptions are from family physicians.
Conclusion — Patients who use opioids continuously between diagnosis and index date are at increased risk of continued use after 5 years of survival. Safe and appropriate pain management is an important survivorship issue.