title: Hospital-Diagnosed Pertussis Infection in Children and Long-term Risk of Epilepsy.
abstract: OBJECTIVE
  Pertussis is associated with encephalopathy and seizures in infants. However, the risk of childhood epilepsy following pertussis is unknown.
  
  
  OBJECTIVE
  To examine whether pertussis is associated with the long-term risk of epilepsy.
  
  
  METHODS
  We used individually linked data from population-based medical registries covering all Danish hospitals to identify a cohort of all patients with pertussis born between 1978 and 2011, followed up through 2011. We used the Civil Registration System to identify 10 individuals from the general population for each patient with pertussis, matched on sex and year of birth.
  
  
  METHODS
  Inpatient or hospital-based outpatient diagnosis of pertussis.
  
  
  METHODS
  Cumulative incidence and hazard ratio of time to hospital-based epilepsy diagnosis (pertussis cohort vs general population cohort), adjusted for birth year, sex, maternal history of epilepsy, presence of congenital malformations, and gestational age. Unique personal identifiers permitted unambiguous data linkage and complete follow-up for death, emigration, and hospital contacts.
  
  
  RESULTS
  We identified 4700 patients with pertussis (48% male), of whom 90 developed epilepsy during the follow-up. The cumulative incidence of epilepsy at age 10 years was 1.7% (95% CI, 1.4%-2.1%) for patients with pertussis and 0.9% (95% CI, 0.8%-1.0%) for the matched comparison cohort. The corresponding adjusted overall hazard ratio was 1.7 (95% CI, 1.3-2.1).
  
  
  CONCLUSIONS
  In Denmark, risk of epilepsy was increased in children with hospital-diagnosed pertussis infections compared with the general population; however, the absolute risk was low.
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus N, Denmark.
authors.forename: Morten
authors.initials: M
authors.lastname: Olsen
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus N, Denmark.
authors.forename: Sandra K
authors.initials: SK
authors.lastname: Thygesen
authors.affiliation: Department of Pediatrics, Aarhus University Hospital, Aarhus N, Denmark.
authors.forename: John R
authors.initials: JR
authors.lastname: Østergaard
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus N, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Nielsen
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus N, Denmark3Department of Health Research and Policy (Epidemiology), Stanford University, Stanford, California4Department of Neurology and Neurological Sciences, Stanford University, S.
authors.forename: Victor W
authors.initials: VW
authors.lastname: Henderson
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus N, Denmark.
authors.forename: Vera
authors.initials: V
authors.lastname: Ehrenstein
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus N, Denmark.
authors.forename: Mette
authors.initials: M
authors.lastname: Nørgaard
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus N, Denmark.
authors.forename: Henrik Toft
authors.initials: HT
authors.lastname: Sørensen
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D004827:Epilepsy / Q000453:epidemiology*; D005260:Female; D006760:Hospitalization; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D012042:Registries; D012306:Risk; D014917:Whooping Cough / Q000453:epidemiology*; D055815:Young Adult