title: Association of opioid agonist therapy with lower incidence of hepatitis C virus infection in young adult injection drug users.
abstract: OBJECTIVE
  Injection drug use is the primary mode of transmission for hepatitis C virus (HCV) infection. Prior studies suggest opioid agonist therapy may reduce the incidence of HCV infection among injection drug users; however, little is known about the effects of this therapy in younger users.
  
  
  OBJECTIVE
  To evaluate whether opioid agonist therapy was associated with a lower incidence of HCV infection in a cohort of young adult injection drug users.
  
  
  METHODS
  Observational cohort study conducted from January 3, 2000, through August 21, 2013, with quarterly interviews and blood sampling. We recruited young adult (younger than 30 years) injection drug users who were negative for anti-HCV antibody and/or HCV RNA.
  
  
  METHODS
  Substance use treatment within the past 3 months, including non-opioid agonist forms of treatment, opioid agonist (methadone hydrochloride or buprenorphine hydrochloride) detoxification or maintenance therapy, or no treatment.
  
  
  METHODS
  Incident HCV infection documented with a new positive result for HCV RNA and/or HCV antibodies. Cumulative incidence rates (95% CI) of HCV infection were calculated assuming a Poisson distribution. Cox proportional hazards regression models were fit adjusting for age, sex, race, years of injection drug use, homelessness, and incarceration.
  
  
  RESULTS
  Baseline characteristics of the sample (n = 552) included median age of 23 (interquartile range, 20-26) years; 31.9% female; 73.1% white; 39.7% who did not graduate from high school; and 69.2% who were homeless. During the observation period of 680 person-years, 171 incident cases of HCV infection occurred (incidence rate, 25.1 [95% CI, 21.6-29.2] per 100 person-years). The rate ratio was significantly lower for participants who reported recent maintenance opioid agonist therapy (0.31 [95% CI, 0.14-0.65]; P = .001) but not for those who reported recent non-opioid agonist forms of treatment (0.63 [95% CI, 0.37-1.08]; P = .09) or opioid agonist detoxification (1.45 [95% CI, 0.80-2.69]; P = .23). After adjustment for other covariates, maintenance opioid agonist therapy was associated with lower relative hazards for acquiring HCV infection over time (adjusted hazard ratio, 0.39 [95% CI, 0.18-0.87]; P = .02).
  
  
  CONCLUSIONS
  In this cohort of young adult injection drug users, recent maintenance opioid agonist therapy was associated with a lower incidence of HCV infection. Maintenance treatment with methadone or buprenorphine for opioid use disorders may be an important strategy to prevent the spread of HCV infection among young injection drug users.
authors.affiliation: Clinical Addiction Research and Education Unit, Section of General Internal Medicine, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts2Department of Medicine, Boston Medical Center, Boston, Massachusetts.
authors.forename: Judith I
authors.initials: JI
authors.lastname: Tsui
authors.affiliation: Department of Epidemiology and Biostatistics, University of California, San Francisco.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Evans
authors.affiliation: Department of Medicine, University of California, San Francisco.
authors.forename: Paula J
authors.initials: PJ
authors.lastname: Lum
authors.affiliation: Department of Epidemiology and Biostatistics, University of California, San Francisco4Department of Medicine, University of California, San Francisco.
authors.forename: Judith A
authors.initials: JA
authors.lastname: Hahn
authors.affiliation: Division of Epidemiology, Biostatistics and Preventive Medicine, Department of Internal Medicine, University of New Mexico Health Sciences Center, Albuquerque.
authors.forename: Kimberly
authors.initials: K
authors.lastname: Page
mesh_terms: D000293:Adolescent; D000328:Adult; D002047:Buprenorphine / Q000008:administration & dosage; D015331:Cohort Studies; D018562:Disease Transmission, Infectious / Q000517:prevention & control; D055030:Drug Users / Q000706:statistics & numerical data*; D005260:Female; D006526:Hepatitis C / Q000453:epidemiology* / Q000517:prevention & control* / Q000635:transmission; D006801:Humans; D015994:Incidence; D007275:Injections, Intravenous / Q000009:adverse effects; D008297:Male; D008691:Methadone / Q000008:administration & dosage; D009294:Narcotics / Q000008:administration & dosage*; D058850:Opiate Substitution Treatment / Q000379:methods*; D009293:Opioid-Related Disorders / Q000150:complications / Q000188:drug therapy* / Q000453:epidemiology; D016012:Poisson Distribution; D016016:Proportional Hazards Models; D015819:Substance Abuse, Intravenous / Q000150:complications / Q000188:drug therapy* / Q000453:epidemiology; D055815:Young Adult
chemical_list: D009294:Narcotics; D002047:Buprenorphine; D008691:Methadone