title: Factors associated with spontaneous clearance of chronic hepatitis C virus infection.
abstract: Spontaneous clearance of chronic hepatitis C virus (HCV) infection (CHC) is rare. We conducted a retrospective case-control study to identify rates and factors associated with spontaneous clearance of CHC.
  
  
  
  We defined cases as individuals who spontaneously resolved CHC, and controls as individuals who remained chronically infected. We used data obtained on HCV testing between 1994 and 2013 in the West of Scotland to infer case/control status. Specifically, untreated patients with ⩾2 sequential samples positive for HCV RNA ⩾6months apart followed by ⩾1 negative test, and those with ⩾2 positive samples ⩾6months apart with no subsequent negative samples were identified. Control patients were randomly selected from the second group (4/patient of interest). Case notes were reviewed and patient characteristics obtained.
  
  
  
  25,113 samples were positive for HCV RNA, relating to 10,318 patients. 50 cases of late spontaneous clearance were identified, contributing 241 person-years follow-up. 2,518 untreated, chronically infected controls were identified, contributing 13,766 person-years follow-up, from whom 200 controls were randomly selected. The incidence rate of spontaneous clearance was 0.36/100 person-years follow-up, occurring after a median 50months' infection. Spontaneous clearance was positively associated with female gender, younger age at infection, lower HCV RNA load and co-infection with hepatitis B virus. It was negatively associated with current intravenous drug use.
  
  
  
  Spontaneous clearance of CHC occurs infrequently but is associated with identifiable host and viral factors. More frequent HCV RNA monitoring may be appropriate in selected patient groups.
  
  
  
  Clearance of hepatitis C virus infection without treatment occurs rarely once chronic infection has been established. We interrogated a large Scottish patient cohort and found that it was more common in females, patients infected at a younger age or with lower levels of HCV in the blood, and patients co-infected with hepatitis B virus. Patients who injected drugs were less likely to spontaneously clear chronic infection.
authors.affiliation: MRC, University of Glasgow Centre for Virus Research, Glasgow, UK. Electronic address: naomi.bulteel@nhs.net.
authors.forename: Naomi
authors.initials: N
authors.lastname: Bulteel
authors.affiliation: University of Glasgow Medical School, Glasgow, UK.
authors.forename: Prasanna
authors.initials: P
authors.lastname: Partha Sarathy
authors.affiliation: The Walton Liver Clinic, Glasgow Royal Infirmary, Glasgow, UK.
authors.forename: Ewan
authors.initials: E
authors.lastname: Forrest
authors.affiliation: The Walton Liver Clinic, Glasgow Royal Infirmary, Glasgow, UK.
authors.forename: Adrian J
authors.initials: AJ
authors.lastname: Stanley
authors.affiliation: School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, UK.
authors.forename: Hamish
authors.initials: H
authors.lastname: Innes
authors.affiliation: Glasgow, UK.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Mills
authors.affiliation: School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, UK; Blood-borne Viruses and Sexually Transmitted Infections Section, Health Protection Scotland, Glasgow, UK.
authors.forename: Heather
authors.initials: H
authors.lastname: Valerio
authors.affiliation: West of Scotland Specialist Virology Centre, Glasgow Royal Infirmary, Glasgow, UK.
authors.forename: Rory N
authors.initials: RN
authors.lastname: Gunson
authors.affiliation: West of Scotland Specialist Virology Centre, Glasgow Royal Infirmary, Glasgow, UK.
authors.forename: Celia
authors.initials: C
authors.lastname: Aitken
authors.affiliation: Department of Gastroenterology, Southern General Hospital, Glasgow, UK.
authors.forename: Jude
authors.initials: J
authors.lastname: Morris
authors.affiliation: Gartnavel General Hospital, Glasgow, UK.
authors.forename: Ray
authors.initials: R
authors.lastname: Fox
authors.affiliation: The Walton Liver Clinic, Glasgow Royal Infirmary, Glasgow, UK.
authors.forename: Stephen T
authors.initials: ST
authors.lastname: Barclay
mesh_terms: D016022:Case-Control Studies; D005260:Female; D016174:Hepacivirus; D019698:Hepatitis C, Chronic; D006801:Humans; D008297:Male; D012367:RNA, Viral; D012189:Retrospective Studies; D012606:Scotland
chemical_list: D012367:RNA, Viral
keywords: Gender; HBV/HCV co-infection; HCV; Spontaneous clearance