Duration of use of extended-release oxycodone and morphine among adults with cancer and non-cancer pain

Duration of use of extended-release (ER) opioids in US clinical practice has not been extensively published in the literature. The objective of this study was to assess duration of ER oxycodone and ER morphine use, two commonly used ER opioids, among cancer and non-cancer pain patients. Using data from a national commercial insurance database (MarketScan; January 2008 through September 2011), patients ≥18 years old with a new ER oxycodone or ER morphine prescription and 24 months insurance enrollment (6 months before and 18 months after index prescription) were identified. Existing patients (those with prior prescriptions in the 6 month baseline period) were excluded. The primary measure was duration of continuous use (no gaps in supply ≥15 days; sensitivity analysis ≥30 days). Survival analysis was used to compare time to discontinuation of continuous use. There were 43,519 new ER oxycodone users and 22,414 new ER morphine users. Cancer diagnoses were identified for 9% of ER oxycodone and 10% of ER morphine patients. Most patients discontinued use by 3 or 6 months (ER oxycodone: 80% and 86%, respectively; ER morphine: 72% and 81%, respectively). Time-to-event analysis indicates a rapid drop in continuous use in the first month (>50% decline), a less rapid decline between months 1 and 6 (ER oxycodone: approximately 30% to 15%; ER morphine: approximately 45% to 20%), and appear relatively stable (approximately 10-20%) thereafter, indicating that patients treated for 6 months will likely continue for up to 18 months. ER oxycodone results were similar regardless of cancer diagnosis; ER morphine patients without a cancer diagnosis were slightly more likely to continue longer term treatment than those with a cancer diagnosis. Overall, most patients dispensed a new ER oxycodone or ER morphine prescription had a non-malignant pain condition and less than one in five received continuous treatment for >6 months.