title: Viral hepatitis and Parkinson disease: A national record-linkage study.
abstract: OBJECTIVE
  To study associations between viral hepatitis and Parkinson disease (PD).
  
  
  METHODS
  A retrospective cohort study was done by analyzing linked English National Hospital Episode Statistics and mortality data (1999-2011). Cohorts of individuals with hepatitis B, hepatitis C, autoimmune hepatitis, chronic active hepatitis, and HIV were constructed, and compared to a reference cohort for subsequent rates of PD.
  
  
  RESULTS
  The standardized rate ratio (RR) of PD following hepatitis B was 1.76 (95% confidence interval [CI] 1.28-2.37) (p< 0.001), based on 44 observed compared with 25 expected cases. The RR of PD following hepatitis C was 1.51 (95% CI, 1.18-1.9) (p< 0.001), based on 48.5 expected and 73 observed cases. There was no significant association between autoimmune hepatitis, chronic active hepatitis or HIV, and subsequent PD. When including only those episodes of care for PD that occurred first at least 1 year following each exposure condition, the RR for hepatitis B and hepatitis C were 1.82 (1.29-2.5) and 1.43 (1.09-1.84), respectively.
  
  
  CONCLUSIONS
  We report strong evidence in favor of an elevation of rates of subsequent PD in patients with hepatitis B and hepatitis C. These findings may be explained by factors peculiar to viral hepatitis, but whether it reflects consequences of infection, shared disease mechanisms, or the result of antiviral treatment remains to be elucidated. Further work is needed to confirm this association and to investigate pathophysiologic pathways, potentially advancing etiologic understanding of PD more broadly.
authors.affiliation: From the Unit of Health-Care Epidemiology (J.P., R.G., M.G.), Nuffield Department of Population Health, University of Oxford; and UCL Institute of Neurology (A.N., M.S., S.M., A.S., A.L.), Queen Square, London, UK.
authors.forename: Julia
authors.initials: J
authors.lastname: Pakpoor
authors.affiliation: From the Unit of Health-Care Epidemiology (J.P., R.G., M.G.), Nuffield Department of Population Health, University of Oxford; and UCL Institute of Neurology (A.N., M.S., S.M., A.S., A.L.), Queen Square, London, UK.
authors.forename: Alastair
authors.initials: A
authors.lastname: Noyce
authors.affiliation: From the Unit of Health-Care Epidemiology (J.P., R.G., M.G.), Nuffield Department of Population Health, University of Oxford; and UCL Institute of Neurology (A.N., M.S., S.M., A.S., A.L.), Queen Square, London, UK.
authors.forename: Raph
authors.initials: R
authors.lastname: Goldacre
authors.affiliation: From the Unit of Health-Care Epidemiology (J.P., R.G., M.G.), Nuffield Department of Population Health, University of Oxford; and UCL Institute of Neurology (A.N., M.S., S.M., A.S., A.L.), Queen Square, London, UK.
authors.forename: Marianna
authors.initials: M
authors.lastname: Selkihova
authors.affiliation: From the Unit of Health-Care Epidemiology (J.P., R.G., M.G.), Nuffield Department of Population Health, University of Oxford; and UCL Institute of Neurology (A.N., M.S., S.M., A.S., A.L.), Queen Square, London, UK.
authors.forename: Stephen
authors.initials: S
authors.lastname: Mullin
authors.affiliation: From the Unit of Health-Care Epidemiology (J.P., R.G., M.G.), Nuffield Department of Population Health, University of Oxford; and UCL Institute of Neurology (A.N., M.S., S.M., A.S., A.L.), Queen Square, London, UK.
authors.forename: Anette
authors.initials: A
authors.lastname: Schrag
authors.affiliation: From the Unit of Health-Care Epidemiology (J.P., R.G., M.G.), Nuffield Department of Population Health, University of Oxford; and UCL Institute of Neurology (A.N., M.S., S.M., A.S., A.L.), Queen Square, London, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Lees
authors.affiliation: From the Unit of Health-Care Epidemiology (J.P., R.G., M.G.), Nuffield Department of Population Health, University of Oxford; and UCL Institute of Neurology (A.N., M.S., S.M., A.S., A.L.), Queen Square, London, UK. michael.goldacre@dph.ox.ac.uk.
authors.forename: Michael
authors.initials: M
authors.lastname: Goldacre
mesh_terms: D004739:England / Q000453:epidemiology; D015658:HIV Infections / Q000453:epidemiology; D006525:Hepatitis, Viral, Human / Q000150:complications / Q000453:epidemiology*; D006801:Humans; D007297:Inpatients; D008499:Medical Records; D010300:Parkinson Disease / Q000453:epidemiology* / Q000209:etiology; D012189:Retrospective Studies; D013222:State Medicine; D013997:Time Factors