(P-369) Patterns of Prescription and Co-prescription of Opioids and Benzodiazepines in the Period 2010 to 2018: A Real-world, Population-based Study

Background: Concomitant use of opioids and benzodiazepines has been linked to increased risk of overdose, death, and other safety adverse events. The patterns of use of both drug classes in our setting remain unknown.

Objectives: To describe the patterns of opioid-benzodiazepine prescribing and co-prescribing in a population of 5 million inhabitants over a period of 9 years, 2010 to 2018.

Methods:

Design: retrospective, population-based study.
Setting: the study was conducted in the region of Valencia, Spain, with a population of 5 million inhabitants. We included all adult patients receiving at least one prescription for opioids, including tramadol, buprenorphine, fentanyl, hydromorphone, morphine, oxycodone and tapentadol. From these, we identified patients receiving at least one benzodiazepine prescription (N05BA, N05CD and N05CF) in that same period. Data was extracted from the Valencia Health System Integrated Database (VID).
Exposures or interventions: exposure to opioids and benzodiazepines, prescribed separately or concomitantly.
Statistical analysis: first, we calculated the total number of prescriptions and patients treated. Second, we described the patterns of initiation, use and concomitant use. Initiation was defined as not being exposed to both drug classes in the previous 180 days since the index prescription. Concomitant use or overlap was defined as having at least one day covered by both medications. Third, we described the proportion of patients receiving overlapped prescription and their duration.

Results: From 2010 to 2018 a total of 1, 238, 164 patients refilled 26,506,447 opioid prescriptions. From these, 855,528 patients refilled 36,939,118 benzodiazepine prescriptions in that same period.
With regard to the patterns of prescription, we identified the following categories: initiation with opioids and no benzodiazepine prescription in the whole period (31.8%), patients starting on benzodiazepines before starting opioids (30.7%), and initiation on opioids before using benzodiazepines (18.3%). Finally, 2.6% of patients started on both groups at the same time, while 16.6% were classified as not naïve.
In total, 638,942 patients have prescriptions of both groups and 330,213 patients had at least one day of overlap. Median consecutive and median total overlap days were 15 (p25=7; p75=30) and 30 (p25=11; p75=90) respectively.

Conclusions: A significant number of patients received concomitant opioid and benzodiazepine prescription. The impact of these patterns of potential misuse on health outcomes should be urgently evaluated.