Mumps, measles, and rubella vaccine and the incidence of autism recorded by general practitioners: a time trend analysis.
OBJECTIVE
To estimate changes in the risk of autism and assess the relation of autism to the mumps, measles, and rubella (MMR) vaccine.


METHODS
Time trend analysis of data from the UK general practice research database (GPRD).


METHODS
General practices in the United Kingdom.


METHODS
Children aged 12 years or younger diagnosed with autism 1988-99, with further analysis of boys aged 2 to 5 years born 1988-93.


METHODS
Annual and age specific incidence for first recorded diagnoses of autism (that is, when the diagnosis of autism was first recorded) in the children aged 12 years or younger; annual, birth cohort specific risk of autism diagnosed in the 2 to 5 year old boys; coverage (prevalence) of MMR vaccination in the same birth cohorts.


RESULTS
The incidence of newly diagnosed autism increased sevenfold, from 0.3 per 10 000 person years in 1988 to 2.1 per 10 000 person years in 1999. The peak incidence was among 3 and 4 year olds, and 83% (254/305) of cases were boys. In an annual birth cohort analysis of 114 boys born in 1988-93, the risk of autism in 2 to 5 year old boys increased nearly fourfold over time, from 8 (95% confidence interval 4 to 14) per 10 000 for boys born in 1988 to 29 (20 to 43) per 10 000 for boys born in 1993. For the same annual birth cohorts the prevalence of MMR vaccination was over 95%.


CONCLUSIONS
Because the incidence of autism among 2 to 5 year olds increased markedly among boys born in each year separately from 1988 to 1993 while MMR vaccine coverage was over 95% for successive annual birth cohorts, the data provide evidence that no correlation exists between the prevalence of MMR vaccination and the rapid increase in the risk of autism over time. The explanation for the marked increase in risk of the diagnosis of autism in the past decade remains uncertain.
Boston Collaborative Drug Surveillance Program, Boston University School of Medicine, 11 Muzzey Street, Lexington, MA 02421, USA. jkaye@narsil.com
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Kaye
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del Mar Melero-Montes
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Jick
D017677:Age Distribution; D001321:Autistic Disorder / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D002648:Child; D002675:Child, Preschool; D005194:Family Practice; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D022542:Measles-Mumps-Rubella Vaccine / Q000009:adverse effects*; D018570:Risk Assessment; D006113:United Kingdom / Q000453:epidemiology
D022542:Measles-Mumps-Rubella Vaccine