title: Factors associated with spontaneous clearance of hepatitis C virus among illicit drug users.
abstract: BACKGROUND
  Spontaneous clearance of hepatitis C virus (HCV) occurs in approximately 25% of individuals.
  
  
  METHODS
  To better understand the characteristics associated with clearance, the present study evaluated HCV clearance in a community-based cohort study. The Community Health and Safety Evaluation project recruited 3553 individuals via community organizations and door-to-door canvassing of a random sample of single occupancy hotels in the community to monitor uptake of health services and to estimate the incidence of communicable infections. Cohort data were linked with longitudinal laboratory databases, including HCV antibody and polymerase chain reaction assay results.
  
  
  RESULTS
  Overall, 762 individuals had HCV antibody and RNA testing performed between 1999 and 2005. Spontaneous HCV clearance was observed in 179 individuals (23.5%), while HCV persistence was observed in 583 individuals (76.5%). The ability to develop protective immunity against HCV, as demonstrated by viral clearance, occurred more often in individuals of Aboriginal ethnicity (adjusted OR [AOR] 2.9, 95% CI 2.0 to 4.3; P<0.001) and female individuals (AOR 1.6, 95% CI 1.1 to 2.4; P=0.01). The rate of spontaneous HCV clearance was reduced in individuals using any type of illicit drugs (AOR 0.54, 95% CI 0.29 to 1.00; P=0.05) and those with HIV coinfection (AOR 0.58, 95% CI 0.38 to 0.88; P=0.01). Of 218 HIV-infected subjects, 48 of 51 (94%) in whom the order of HCV and HIV infection was established were infected with HCV a median of 2.4 years (range 0.2 to 10 years) before becoming infected with HIV.
  
  
  CONCLUSIONS
  Aboriginal ethnicity and female sex were associated with increased rates of HCV clearance, while HIV coinfection and illicit drug use were associated with increased HCV persistence.
authors.affiliation: Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada. jgrebely@interchange.ubc.ca
authors.forename: Jason
authors.initials: J
authors.lastname: Grebely
authors.forename: Jesse D
authors.initials: JD
authors.lastname: Raffa
authors.forename: Calvin
authors.initials: C
authors.lastname: Lai
authors.forename: Mel
authors.initials: M
authors.lastname: Krajden
authors.forename: Brian
authors.initials: B
authors.lastname: Conway
authors.forename: Mark W
authors.initials: MW
authors.lastname: Tyndall
mesh_terms: D001955:British Columbia / Q000453:epidemiology; D016208:Databases, Factual; D005260:Female; D015658:HIV Infections / Q000150:complications / Q000453:epidemiology / Q000208:ethnology / Q000821:virology; D016174:Hepacivirus / Q000235:genetics / Q000276:immunology*; D006526:Hepatitis C / Q000150:complications / Q000453:epidemiology* / Q000208:ethnology / Q000821:virology*; D018937:Hepatitis C Antibodies / Q000097:blood; D006801:Humans; D007113:Immunity, Innate; D015994:Incidence; D004930:Inuit / Q000706:statistics & numerical data; D008137:Longitudinal Studies; D008297:Male; D016133:Polymerase Chain Reaction; D012367:RNA, Viral / Q000032:analysis; D012075:Remission, Spontaneous; D012737:Sex Factors; D015819:Substance Abuse, Intravenous
chemical_list: D018937:Hepatitis C Antibodies; D012367:RNA, Viral