The relative risk of fatal poisoning by methadone or buprenorphine within the wider population of England & Wales

Objective: To examine the population-wide overdose risk emerging from the prescription of methadone and buprenorphine for opioid substitution treatment in England and Wales. Design: Retrospective administrative data study. Setting: National databases for England and Wales. Participants/cases: Drug-related mortality data were drawn from the Office for National Statistics, and prescription data for methadone and buprenorphine were obtained from the National Health Service for the years 2007–2012. During this 6-year period, a total of 2366 methadone-related deaths and 52 buprenorphine-related deaths were registered, corresponding to 17 333 163 methadone and 2 602 374 buprenorphine prescriptions issued. The analysis encompassed poisoning deaths among members of the wider population of England and Wales who consumed, but were not prescribed these medications, in addition to patients prescribed methadone or buprenorphine. Main outcome measures :Mortality risk: substance-specific overdose rate...