Safer opioid supply and health outcomes – Authors' reply

We thank Robert Tanguay and Nickie Mathew for their comments and welcome the opportunity to clarify key aspects of our study.¹ The authors raise concerns about higher opioid toxicity rates among safer opioid supply (SOS) recipients compared with those initiating methadone. We believe it is important to emphasise our finding that opioid toxicity events declined markedly following both SOS and methadone initiation.¹ The smaller decline among SOS recipients might reflect higher baseline risk and greater ongoing exposure to the unregulated drug supply early in treatment. Importantly, opioid-related and all-cause mortality was exceedingly low in both groups throughout follow-up, highlighting the protective effect of treatment engagement. The authors contrast our findings with those of Hai Nguyen and colleagues, who evaluated population-level trends following policy changes. However, these studies did not examine outcomes among SOS recipients, did not compare SOS with methadone, and were prone to ecological fallacy due to design.2, 3 Thus, these studies are more likely to be biased than our individual-level, matched cohort analysis.