title: Risk of mortality on and off methadone substitution treatment in primary care: a national cohort study.
abstract: OBJECTIVE
  To assess whether risk of death increases during periods of treatment transition, and investigate the impact of supervised methadone consumption on drug-related and all-cause mortality.
  
  
  METHODS
  National Irish cohort study.
  
  
  METHODS
  Primary care.
  
  
  METHODS
  A total of 6983 patients on a national methadone treatment register aged 16-65 years between 2004 and 2010.
  
  
  METHODS
  Drug-related (primary outcome) and all-cause (secondary outcome) mortality rates and rate ratios for periods on and off treatment; and the impact of regular supervised methadone consumption.
  
  
  RESULTS
  Crude drug-related mortality rates were 0.24 per 100 person-years on treatment and 0.39 off treatment, adjusted mortality rate ratio 1.63 [95% confidence interval (CI) = 0.66-4.00]. Crude all-cause mortality rate per 100 person-years was 0.51 on treatment versus 1.57 off treatment, adjusted mortality rate ratio 3.64 (95% CI = 2.11-6.30). All-cause mortality off treatment was 6.36 (95% CI = 2.84-14.22) times higher in the first 2 weeks, 9.12 (95% CI = 3.17-26.28) times higher in weeks 3-4, compared with being 5 weeks or more in treatment. All-cause mortality was lower in those with regular supervision (crude mortality rate 0.60 versus 0.81 per 100 person-years) although, after adjustment, insufficient evidence exists to suggest that regular supervision is protective (mortality rate ratio = 1.23, 95% CI = 0.67-2.27).
  
  
  CONCLUSIONS
  Among primary care patients undergoing methadone treatment, continuing in methadone treatment is associated with a reduced risk of death. Patients' risk of all-cause mortality increases following treatment cessation, and is highest in the initial 4-week period.
authors.affiliation: School of Pharmacy, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Gráinne
authors.initials: G
authors.lastname: Cousins
authors.affiliation: Health Research Board Centre for Primary Care Research, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Fiona
authors.initials: F
authors.lastname: Boland
authors.affiliation: Health Research Board Centre for Primary Care Research, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Brenda
authors.initials: B
authors.lastname: Courtney
authors.affiliation: Trinity College Centre for Health Sciences, Tallaght Hospital, Dublin, Ireland.
authors.forename: Joseph
authors.initials: J
authors.lastname: Barry
authors.affiliation: Health Research Board, Dublin, Ireland.
authors.forename: Suzi
authors.initials: S
authors.lastname: Lyons
authors.affiliation: Health Research Board Centre for Primary Care Research, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Tom
authors.initials: T
authors.lastname: Fahey
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007494:Ireland / Q000453:epidemiology; D008297:Male; D008691:Methadone / Q000627:therapeutic use*; D008875:Middle Aged; D058850:Opiate Substitution Treatment / Q000379:methods / Q000401:mortality*; D009293:Opioid-Related Disorders / Q000188:drug therapy* / Q000401:mortality*; D011320:Primary Health Care / Q000379:methods*; D018570:Risk Assessment / Q000706:statistics & numerical data; D055815:Young Adult
chemical_list: D008691:Methadone
keywords: All-cause mortality; cohort study; drug-related deaths; maintenance treatment; methadone; mortality; opioid; supervised consumption