National Study of Discontinuation of Long-Term Opioid Therapy Among Veterans

Thesis (Master's)--University of Washington, 2014Introduction: Veterans have high rates of chronic pain and long-term opioid therapy (LTOT). Understanding predictors of discontinuation from LTOT will clarify the risks for opioid abuse and dependence among veterans, and inform Veterans Healthcare Administration (VHA) policy. Methods: All veterans with at least 90 days of opioid use within a 180 day period were identified using national VHA data between 2009 and 2011. Discontinuation was defined as 6 months with no opioid prescriptions. We utilized Cox proportional hazards analysis to determine clinical and demographic correlates for discontinuation. Results: A total of 542,843 patients met criteria for LTOT. The sample was primarily male (93%), and white (74%), with a mean age of 57.8 years. The median daily morphine equivalent dose was 26 mg and 7% received high-dose therapy (i.e. greater than 100 mg/day morphine-equivalent). At one year after initiation, 7.5% of the LTOT sample had discontinued opioids. Of those who discontinued (20%, N=110,460), the mean time to discontinuation was 530 days. Factors significantly associated with discontinuation included both younger and older age, lower average dosage, shorter acting opioid formulations and receiving less than 90 days of opioids in the previous year. While tobacco use disorders decreased the likelihood of discontinuation, co-morbid mental illness and substance use disorders increased the likelihood of discontinuation. Conclusions: LTOT in the VHA system is marked by extended duration of use at relatively low daily doses with few discontinuation events. Opioid discontinuation is more likely in veterans with mental health and substance use disorders and less likely among smokers. Further research is needed to delineate causes and consequences of opioid discontinuation