title: MMR vaccination and pervasive developmental disorders: a case-control study.
abstract: BACKGROUND
  Concern that measles-mumps-rubella (MMR) vaccination might cause autism has led to a fall in vaccine coverage. We investigated whether MMR vaccination is associated with an increased risk of autism or other pervasive developmental disorders.
  
  
  METHODS
  We did a matched case-control study using the UK General Practice Research Database. Cases were people born in 1973 or later who had first recorded diagnosis of pervasive developmental disorder while registered with a contributing general practice between 1987 and 2001. Controls were matched on age, sex, and general practice.
  
  
  RESULTS
  1294 cases and 4469 controls were included. 1010 cases (78.1%) had MMR vaccination recorded before diagnosis, compared with 3671 controls (82.1%) before the age at which their matched case was diagnosed. After adjustment for age at joining the database, the odds ratio for association between MMR and pervasive developmental disorder was 0.86 (95% CI 0.68-1.09). Findings were similar when restricted to children with a diagnosis of autism, to those vaccinated with MMR before the third birthday, or to the period before media coverage of the hypothesis linking MMR with autism.
  
  
  CONCLUSIONS
  Our findings suggest that MMR vaccination is not associated with an increased risk of pervasive developmental disorders.
authors.affiliation: Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK. autism@lshtm.ac.uk
authors.forename: Liam
authors.initials: L
authors.lastname: Smeeth
authors.forename: Claire
authors.initials: C
authors.lastname: Cook
authors.forename: Eric
authors.initials: E
authors.lastname: Fombonne
authors.forename: Lisa
authors.initials: L
authors.lastname: Heavey
authors.forename: Laura C
authors.initials: LC
authors.lastname: Rodrigues
authors.forename: Peter G
authors.initials: PG
authors.lastname: Smith
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Hall
mesh_terms: D020817:Asperger Syndrome / Q000209:etiology; D001321:Autistic Disorder / Q000209:etiology; D016022:Case-Control Studies; D002648:Child; D002659:Child Development Disorders, Pervasive / Q000209:etiology*; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D022542:Measles-Mumps-Rubella Vaccine / Q000009:adverse effects*; D016017:Odds Ratio
chemical_list: D022542:Measles-Mumps-Rubella Vaccine