Divergent trajectories in fatal drug harms across high-income settings: a comparative synthesis of public surveillance indicators, 2015-23.

backgroundFatal drug-related harms have risen across high-income countries over the past decade, yet national surveillance systems differ substantially in case definitions, reporting timeliness, and indicator coverage. These differences make it difficult to determine whether observed cross-national differences reflect epidemiological divergence or heterogeneous measurement.

methodsTo address this, we compared public surveillance indicators of fatal drug-related harm across the USA, Canada, England and Wales, and European countries reporting to the European Union Drugs Agency (2015-23), using three domains: drug-supply toxicity, surveillance latency, and treatment-system integration.

resultsFatal drug-harm indicators suggested divergent trajectories: the USA experienced rapid mortality escalation through 2022 followed by a modest decline, while England and Wales reported continued increases in registration-based deaths. In Canada, deaths involving three or more substances increased from 20% in 2018 to 42% in 2023, with opioid-stimulant combinations accounting for ~60% of deaths by 2023. European estimates remained provisional due to incomplete national reporting. Differences between occurrence-based and registration-based surveillance influenced the apparent timing of trends. Continuity of opioid agonist treatment across incarceration transitions emerged as a measurable treatment-integration signal.

conclusionsHigh-income settings appear to follow distinct fatal drug-harm trajectories shaped by drug-supply toxicity, surveillance architecture, and treatment-system integration. A structured multi-domain framework can help distinguish epidemiological divergence from variation caused by measurement and reporting. It can also guide improvements in timely surveillance, treatment-continuity monitoring, and cross-jurisdictional learning.