A synthesis of oral morphine equivalents (OME) for opioid utilisation studies

Purpose: Oral Morphine Equivalent (OME) doses are increasingly being used as a metric to represent opioid use. Driven by a growing need from pharmacoepidemiological studies, the objective of this study was to develop a comprehensive OME conversion table that can be used by researchers to calculate OMEs in a consistent and systematic way.

Methods: Clinical guidelines and literature sources were collated and synthesised to develop recommended OME conversion factors that can be used for research studies on opioids (including different formulations and routes of administration) currently available internationally including Australia, the United Kingdom, Europe, the United States and Canada.

Results: No single resource includes all opioids that are currently available. Although there was some variation in conversion factors reported in different sources, overall, suggested conversion factors were mostly consistent across national and international sources.

Conclusions: The use of the OME metric appears optimal for opioid utilisation studies as it facilities both interpretation and comparison between opioids and geographical locations. We have presented a synthesis of published OME conversion factors that can be applied to pharmacoepidemiological studies of opioids, in addition to a discussion of the considerations and caveats in using OME as a metric for opioid use. Copyright © 2015 John Wiley & Sons, Ltd.