Analgesic Equivalent Days: A Novel Approach to Assess Chronic Analgesic Use in the Population

Michael S. Ortiz1, *
1 St Vincent’s Clinical School, University of New South Wales, Sydney, NSW, Australia

© 2020 Michael S Ortiz

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: ( This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the St Vincent’s Clinical School, University of New South Wales, Sydney, NSW, Australia; E-mail:



There is no simple method to compare the use of multiple analgesic products in mild to moderate pain. The aim of this study is to validate a new tool to assess analgesic use.


A measure of Analgesic Equivalent Days (AEDs) was developed using Defined Daily Doses (DDD) and the total mg of each analgesic over a 12 month period. Comparisons were made using analgesic class and all analgesics combined.


In a group of newly initiated patients with Osteoarthritis, AEDs values indicated that patients received around 70% of AEDs from paracetamol, 20% from NSAIDs and 10% from opioids. AEDs were similar between the two paracetamol formulations. However, one group took 8 more AEDs of NSAIDs, while the other group took 7 more AEDs of opioids.


Even though the total AED scores, there was no significant difference in total analgesic use between the two formulations, differences were found among the analgesic classes. The AED methodology was sufficiently sensitive to demonstrate that one group of patients climbed higher up the analgesic ladder than the other group. AEDs are easy to calculate and seem to produce valid outcomes from both a statistical and a clinically meaningful perspective.

Keywords: Analgesic use, Osteoarthritis, Methodology, Analgesic equivalent doses, Defined daily doses, Paracetamol.