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
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.
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
d. A new variant form of ASD may be associated with the MMR vaccine.
studies were used to address the four hypotheses and showed no association
between MMR vaccination and the development of ASD.
study satisfied the validity criteria for both a systematic review and
a harm study.
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.
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