|Stephen F. Butler, PhD, Theresa A. Cassidy, MPH, Taryn Dailey, BA1, & Paul M. Coplan, ScD2,|
Presented at CPDD 2014
“Comparing abuse of extended-release versus immediate-release opioid analgesics adjusted for number of prescriptions and morphine-equivalent dose”
Aims: It has been suggested that abuse risk of extended-release (ER) opioids is greater than immediate-release (IR) opioids, but risk rates vary depending on the denominator. For example, widely prescribed IR opioids have high abuse rates, but dividing by their large Rx volume yields low per-Rx rates. Such estimates do not account for longer duration of ER Rxs and higher daily dose than IR Rxs, and may be a biased measure of relative risk. We compared abuse rates adjusted for various denominators.
Methods: The ASI-MVⓇ, a computerized, clinical interview for adults in substance abuse treatment, collected self-report of past 30-day abuse of IR and ER opioids in 2011-2012. Abuse risk was adjusted for all ASI-MV assessments, and for number of Rxs, days per Rx, daily dose prescribed, and morphine-equivalent conversion.
Results: In the sample of 144,736 ASI-MV assessments, abuse per 100 assessments ranged from highest to lowest: IR hydrocodone (9.3), IR oxycodone combo (7.0), ER oxycodone (5.1), IR oxycodone single-entity (3.4); IR hydromorphone (1.7), ER morphine (1.4), ER oxymorphone (1.3) and ER hydromorphone (0.02). Abuse per 10,000 prescriptions dispensed yielded: ER oxymorphone (70.7), ER oxycodone (52.2), IR hydormorphone (35.6), ER morphine (12.7), IR oxycodone combo (12.0), IR oxycodone SE (11.8), ER hydromorphone (7.8), and hydrocodone (4.1). By per-1-million morphine equivalent mg dose, the order was IR hydromorphone (2.1), IR oxycodone combo (1.6), ER oxymorphone (1.3), ER oxycodone (1.2), hydrocodone (0.9), ER morphine (0.4), IR oxycodone SE (0.4), and ER hydromorphone (0.3).
Conclusions: Abuse of certain IR opioids is higher than ER opioids using population-adjusted rates and dispensed-dose adjustment. The order is reversed by prescription adjustment. The assumptions behind using prescription adjustment to measure abuse risk in the community need to be considered.