University of Michigan
Department of Pediatrics
Evidence-Based Pediatrics Web Site

Question

• Multiple parents seek reassurance when the MMR vaccine is offered to their infants. Among pediatric patients, does the administration of the MMR vaccine cause the development of autismter?

Clinical Bottom Lines

1. There has been no emergence of an autism spectrum disorder (ASD) epidemic related to the MMR vaccine.¹
2. There is no evidence of an association between a variant form of autism and the MMR vaccine.
3. The consequences of not vaccinating are REAL, while the risk of developing ASD after MMR vaccination remains THEORETICAL
   

Summary of Key Evidence

1. This article presents a systematic review of 12 studies from five different countries, including data from 9 different data sources and patients born as early as1954. The study designs were varied and included cohort studies, case-control studies, and time-series analyses.¹
2. Studies were included in the review if they reported original epidemiological studies, described systematic methods of identifying a sample, described methods of establishing ASD diagnosis and attempted to determine if an association between MMR vaccine and ASD exists.
3. Four hypotheses were posed:
   a. Rates of ASD are higher in individuals who have received the MMR vaccine than in those who have not.
   b. An increase in ASD may be occurring as a consequence of the MMR vaccine.
   c. The development of ASD is temporally associated with receiving the MMR vaccine.
   d. A new variant form of ASD may be associated with the MMR vaccine.
4. Multiple studies were used to address the four hypotheses and showed no association between MMR vaccination and the development of ASD.
5. This study satisfied the validity criteria for both a systematic review and a harm study.
6. Article strengths include: evidence of a systematic method for reducing bias in the literature review, more than one reviewer, and correspondence with authors of other studies.
7. Article limitations center on the bias introduced at the various levels of the studies including the actual type of population likely to be not-immunized, varying secular trends in ASD diagnosis and the bias inherent to observational studies.
   

Additional Comments

• AAP policy statement from May 2001, encouraged pediatricians to continue to promote immunization of children and indicates that there is no scientific evidence supporting the association.²

Citation

1. Wilson K. Mills E. Ross C. McGowan J. Jadad A. Association of autistic spectrum disorder and the measles, mumps, and rubella vaccine: a systematic review of current epidemiological evidence. Archives of Pediatrics & Adolescent Medicine 2003;157(7):628-34.
2. AAP Policy Statement. The Pediatrician's Role in the Diagnosis and Management of Autistic Spectrum Disorder in Children. AAP Press, 2001.
3. See other CATs on the same topic: MMR Vaccination Does Not Cause Autism, Still No Association Between MMR Vaccination and Neurologic Disorders, and MMR and Autism: Another Study Fails to Find A Link.
   

CAT Author: Ranya N Sweis, MD

CAT Appraisers: John G Frohna, MD, MPH

Date appraised: September 24, 2003