Differential Impacts of Methadone and Buprenorphine/Naloxone on Pain‐Related Outcomes Among People With Non‐Heroin Opioid Use Disorder: Secondary Analyses From a Pragmatic Canadian Multisite Trial

ABSTRACT Introduction In addition to their use as opioid agonist therapy (OAT), methadone and buprenorphine/naloxone also have analgesic properties. However, there is limited information on the relative effectiveness of these medications for analgesia in the context of treatment for non‐heroin opioid use disorder (OUD). This study estimated the impact of type of OAT on pain among individuals with non‐heroin OUD. Methods Using data from OPTIMA, a Canadian, randomised, 24‐week clinical trial comparing buprenorphine/naloxone (via take‐home doses) to methadone (via daily witnessed ingestion) for the treatment of non‐heroin OUD, we evaluated the impact of type of OAT on pain outcomes (measured by the Brief Pain Inventory) among participants with major pain at baseline. Results Mean pain severity scores significantly decreased in both arms over 24 weeks (methadone 4.89–2.16, buprenorphine/naloxone 4.94–1.08). There was a time by arm interaction, suggesting better performance of buprenorphine/naloxone up to week 9, and methadone afterwards. Mean pain‐related function scores also significantly decreased over time (methadone 5.31–2.70, buprenorphine/naloxone 5.56–3.37), with no significant differences in overall scores between arms ( p = 0.675). Methadone was associated with higher odds of achieving both pain severity and pain‐related function response at week 24 (30% reduction in pain scores from baseline). Discussion and Conclusions Among people with non‐heroin OUD initiating OAT, both methadone and buprenorphine/naloxone were associated with improvements in pain outcomes. However, methadone was associated with a higher likelihood of achieving pain severity and functional treatment response at week 24. These findings suggest the need to consider the type of OAT in the shared‐decision making process for people with non‐heroin OUD and comorbid pain.