title: Previously diagnosed influenza infections and the risk of developing epilepsy.
abstract: Several epidemiological studies suggest a possible involvement of viral infection in the development of epilepsy. While recent research from in vitro studies increasingly supports the role of herpes simplex virus type 1 (HSV-1) in the pathogenesis of epilepsy, little is known about the role of other viral infections such as influenza. Using data from the Clinical Practice Research Datalink (CPRD), we conducted a matched case-control analysis to assess the association between GP-diagnosed influenza infections and the risk of developing an incident diagnosis of epilepsy. During the study period 11 244 incident epilepsy cases and 44 976 matched control patients were identified. Prior exposure to influenza was reported in 7·5% of epilepsy cases and 6·7% of controls [adjusted odds ratio (aOR) 1·12, 95% confidence interval (CI) 1·03-1·22]. Prior history of 'complicated influenza', i.e. influenza associated with a possible super-infection, was associated with a slightly increased epilepsy risk (aOR 1·64, 95% CI 1·10-2·46), particularly if recorded within the 2 months preceding the epilepsy diagnosis (aOR 6·03, 95% CI 1·10-33·2). Our findings suggest that prior influenza exposure does not appear to materially alter the risk of developing epilepsy. By contrast, influenza episodes accompanied by complications were associated with a slightly increased epilepsy risk.
authors.affiliation: Basel Pharmacoepidemiology Unit (BPU),Division of Clinical Pharmacy and Epidemiology,Department of Pharmaceutical Sciences,University of Basel,Switzerland.
authors.forename: J C
authors.initials: JC
authors.lastname: Wilson
authors.affiliation: Division of Infection and Immunity,Royal Free and University College Medical School,Academic Centre for Travel Medicine and Vaccines,London,UK.
authors.forename: S
authors.initials: S
authors.lastname: Toovey
authors.affiliation: Boston Collaborative Drug Surveillance Program,Boston University School of Public Health,Lexington,MA,USA.
authors.forename: S S
authors.initials: SS
authors.lastname: Jick
authors.affiliation: Basel Pharmacoepidemiology Unit (BPU),Division of Clinical Pharmacy and Epidemiology,Department of Pharmaceutical Sciences,University of Basel,Switzerland.
authors.forename: C R
authors.initials: CR
authors.lastname: Meier
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004827:Epilepsy / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D007251:Influenza, Human / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012307:Risk Factors; D015163:Superinfection / Q000453:epidemiology*; D055815:Young Adult
keywords: Case-control; epilepsy; influenza