Methadone Maintenance Treatment and Mortality in People With Criminal Convictions: A Population-Based Retrospective Cohort Study From Canada

PLoS Med. 2018 Jul 31;15(7):e1002625. doi: 10.1371/journal.pmed.1002625. eCollection 2018 Jul.


Background: Individuals with criminal histories have high rates of opioid dependence and mortality. Excess mortality is largely attributable to overdose deaths. Methadone maintenance treatment (MMT) is one of the best evidence-based opioid substitution treatments (OSTs), but there is uncertainty about whether methadone treatment reduces the risk of mortality among convicted offenders over extended follow-up periods. The objective of this study was to investigate the association between adherence to MMT and overdose fatality as well as other causes of mortality.

Methods and findings: We conducted a retrospective cohort study involving linked population-level administrative data among individuals in British Columbia (BC), Canada with a history of conviction and who filled a methadone prescription between January 1, 1998 and March 31, 2015. Participants were followed from the date of first-dispensed methadone prescription until censoring (date of death or March 31, 2015). Methadone was divided into medicated (methadone was dispensed) and nonmedicated (methadone was not dispensed) periods and analysed as a time-varying exposure. Hazard ratios (HRs) with 95% CIs were estimated using multivariable Cox regression to examine mortality during the study period. All-cause and cause-specific mortality rates were compared during medicated and nonmedicated methadone periods. Participants (n = 14,530) had a mean age of 34.5 years, were 71.4% male, and had a median follow-up of 6.9 years. A total of 1,275 participants died during the observation period. The overall all-cause mortality rate was 11.2 per 1,000 person-years (PYs). Participants were significantly less likely to die from both nonexternal (adjusted HR [AHR] 0.27 [95% CI 0.23-0.33]) and external (AHR 0.41 [95% CI 0.33-0.51]) causes during medicated periods, independent of sociodemographic, criminological, and health-related factors. Death due to infectious diseases was 5 times lower (AHR 0.20 [95% CI 0.13-0.30]), and accidental poisoning (overdose) deaths were nearly 3 times lower (AHR 0.39 [95% CI 0.30-0.50]) during medicated periods. A competing risk regression demonstrated a similar pattern of results. The use of a Canadian offender population may limit generalizability of results. Furthermore, our observation period represents community-based methadone prescribing and may omit prescriptions administered during hospital separations. Therefore, the magnitude of the protective effects of methadone from nonexternal causes of death should be interpreted with caution.

Conclusions: Adherence to methadone was associated with significantly lower rates of death in a population-level cohort of Canadian convicted offenders. Achieving higher rates of adherence may reduce overdose deaths and other causes of mortality among offenders and similarly marginalized populations. Our findings warrant examination in other study centres in response to the crisis of opiate-involved deaths.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Analgesics, Opioid / administration & dosage*
  • Analgesics, Opioid / adverse effects
  • British Columbia / epidemiology
  • Cause of Death
  • Criminals*
  • Female
  • Humans
  • Male
  • Medication Adherence
  • Methadone / administration & dosage*
  • Methadone / adverse effects
  • Middle Aged
  • Opiate Substitution Treatment* / adverse effects
  • Opiate Substitution Treatment* / mortality
  • Opioid-Related Disorders / diagnosis
  • Opioid-Related Disorders / mortality*
  • Opioid-Related Disorders / rehabilitation*
  • Protective Factors
  • Retrospective Studies
  • Risk Assessment
  • Risk Factors
  • Time Factors
  • Treatment Outcome
  • Young Adult


  • Analgesics, Opioid
  • Methadone

Grant support

This research was supported by funds provided by the Canadian Institutes of Health Research (AR: GSD-14620; JMS: 2009 s0231), the British Columbia Ministry of Justice (JMS: 2014 s0040), and Health Canada (JMS:2009s0231). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.