title: The impact of benzodiazepine use in patients enrolled in opioid agonist therapy in Northern and rural Ontario.
abstract: Benzodiazepine use is common among patients in opioid agonist therapy; this puts patients at an increased risk of overdose and death. In this study, we examine the impact of baseline and ongoing benzodiazepine use, and whether patients are more likely to terminate treatment with increasing proportion of benzodiazepine positive urine samples. We also study whether benzodiazepine use differs by geographic location.
  
  
  
  We conducted a retrospective cohort study using anonymized electronic medical records from 58 clinics offering opioid agonist therapy in Ontario. One-year treatment retention was the primary outcome of interest and was measured for patients who did and did not have a benzodiazepine positive urine sample in their first month of treatment, and as a function of the proportion of benzodiazepine-positive urine samples throughout treatment. Cox proportional hazard model was used to characterize one-year retention.
  
  
  
  Our cohort consisted of 3850 patients, with the average retention rate of 43.4%. Baseline benzodiazepine users had a retention rate of 39.9% and non-users had a retention rate of 44%. Patients who were benzodiazepine negative on admission benefited from an increased median days retained of 265 vs. 215 days. Patients with more than 75% of urines positive for benzodiazepines were 175% more likely to drop out of treatment than those patients with little or no benzodiazepine use.
  
  
  
  Baseline benzodiazepine use is predictive of decreased retention. Patients who have a higher proportion of benzodiazepine-positive urine samples are more likely to drop out of treatment compared to those who have little or no benzodiazepine detection in their urine.
authors.affiliation: Northern Ontario School of Medicine, Sudbury, ON, P3E 2C6, Canada.|School of Rural and Northern Health, Laurentian University, 935 Ramsey Lake Rd., Sudbury, ON, P3E 2C6, Canada.
authors.forename: Alexandra M
authors.initials: AM
authors.lastname: Franklyn
authors.affiliation: Northern Ontario School of Medicine, Sudbury, ON, P3E 2C6, Canada.|School of Rural and Northern Health, Laurentian University, 935 Ramsey Lake Rd., Sudbury, ON, P3E 2C6, Canada.
authors.forename: Joseph K
authors.initials: JK
authors.lastname: Eibl
authors.affiliation: Northern Ontario School of Medicine, Sudbury, ON, P3E 2C6, Canada.
authors.forename: Graham
authors.initials: G
authors.lastname: Gauthier
authors.affiliation: Northern Ontario School of Medicine, Sudbury, ON, P3E 2C6, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Pellegrini
authors.affiliation: School of Rural and Northern Health, Laurentian University, 935 Ramsey Lake Rd., Sudbury, ON, P3E 2C6, Canada.
authors.forename: Nancy E
authors.initials: NE
authors.lastname: Lightfoot
authors.affiliation: Northern Ontario School of Medicine, Sudbury, ON, P3E 2C6, Canada. dmarsh@nosm.ca.|School of Rural and Northern Health, Laurentian University, 935 Ramsey Lake Rd., Sudbury, ON, P3E 2C6, Canada. dmarsh@nosm.ca.|Canadian Addiction Treatment Centers, 13291 Yonge St., Ste. 403, Richmond Hill, Ontario, L4E 4L6, Canada. dmarsh@nosm.ca.
authors.forename: David C
authors.initials: DC
authors.lastname: Marsh
mesh_terms: D000328:Adult; D001569:Benzodiazepines / Q000009:adverse effects* / Q000652:urine; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D008691:Methadone; D009864:Ontario; D058850:Opiate Substitution Treatment; D009293:Opioid-Related Disorders / Q000534:rehabilitation*; D010352:Patient Dropouts / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012424:Rural Population / Q000706:statistics & numerical data*; D016896:Treatment Outcome
chemical_list: D001569:Benzodiazepines; D008691:Methadone
keywords: Benzodiazepines; Concurrent drug use; Northern Ontario; Opioid agonist therapy; Treatment retention