title: Transmission of Neurodegenerative Disorders Through Blood Transfusion: A Cohort Study.
abstract: BACKGROUND
  The aggregation of misfolded proteins in the brain occurs in several neurodegenerative disorders. Aberrant protein aggregation is inducible in rodents and primates by intracerebral inoculation. Possible transfusion transmission of neurodegenerative diseases has important public health implications.
  
  
  OBJECTIVE
  To investigate possible transfusion transmission of neurodegenerative disorders.
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  Nationwide registers of transfusions in Sweden and Denmark.
  
  
  METHODS
  1 465 845 patients who received transfusions between 1968 and 2012.
  
  
  METHODS
  Multivariable Cox regression models were used to estimate hazard ratios for dementia of any type, Alzheimer disease, and Parkinson disease in patients receiving blood transfusions from donors who were later diagnosed with any of these diseases versus patients who received blood from healthy donors. Whether excess occurrence of neurodegenerative disease occurred among recipients of blood from a subset of donors was also investigated. As a positive control, transmission of chronic hepatitis before and after implementation of hepatitis C virus screening was assessed.
  
  
  RESULTS
  Among included patients, 2.9% received a transfusion from a donor diagnosed with one of the studied neurodegenerative diseases. No evidence of transmission of any of these diseases was found, regardless of approach. The hazard ratio for dementia in recipients of blood from donors with dementia versus recipients of blood from healthy donors was 1.04 (95% CI, 0.99 to 1.09). Corresponding estimates for Alzheimer disease and Parkinson disease were 0.99 (CI, 0.85 to 1.15) and 0.94 (CI, 0.78 to 1.14), respectively. Hepatitis transmission was detected before but not after implementation of hepatitis C virus screening.
  
  
  CONCLUSIONS
  Observational study design, underascertainment of the outcome, and possible insufficient statistical power.
  
  
  CONCLUSIONS
  The data provide no evidence for the transmission of neurodegenerative diseases and suggest that if transmission does occur, it is rare.
  
  
  BACKGROUND
  Swedish Research Council, Swedish Heart-Lung Foundation, Swedish Society for Medical Research, and Danish Council for Independent Research.
authors.forename: Gustaf
authors.initials: G
authors.lastname: Edgren
authors.forename: Henrik
authors.initials: H
authors.lastname: Hjalgrim
authors.forename: Klaus
authors.initials: K
authors.lastname: Rostgaard
authors.forename: Paul
authors.initials: P
authors.lastname: Lambert
authors.forename: Agneta
authors.initials: A
authors.lastname: Wikman
authors.forename: Rut
authors.initials: R
authors.lastname: Norda
authors.forename: Kjell-Einar
authors.initials: KE
authors.lastname: Titlestad
authors.forename: Christian
authors.initials: C
authors.lastname: Erikstrup
authors.forename: Henrik
authors.initials: H
authors.lastname: Ullum
authors.forename: Mads
authors.initials: M
authors.lastname: Melbye
authors.forename: Michael P
authors.initials: MP
authors.lastname: Busch
authors.forename: Olof
authors.initials: O
authors.lastname: Nyrén
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000453:epidemiology; D000690:Amyotrophic Lateral Sclerosis / Q000453:epidemiology; D003704:Dementia / Q000453:epidemiology; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006525:Hepatitis, Viral, Human / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D019636:Neurodegenerative Diseases / Q000453:epidemiology*; D010300:Parkinson Disease / Q000453:epidemiology; D012189:Retrospective Studies; D012306:Risk; D013548:Sweden / Q000453:epidemiology; D065227:Transfusion Reaction