Corri Black, James A.
Kaye, Hershel Jick. MMR vaccine and idiopathic
British Journal of Clinical Pharmacology.
Volume 55 Issue 1 Page 107 - January 2003
Aims To estimate the relationship between idiopathic
thrombocytopaenic purpura (ITP) and the measles, mumps
and rubella (MMR) vaccination in children; calculating
the relative risk estimate for ITP with in 6 weeks
after MMR vaccination and the attributable risk of ITP
within 6 weeks after MMR vaccination.
Methods Using the General Practice Research Database
we identified children with a first- time diagnosis of
ITP from a base population of children aged less than
6 years between January 1988 and December 1999. After
describing the characteristics of all the children
identified with ITP, we focused on cases aged 13-24
months to perform a population-based, case-control
analysis to estimate the relative risk of developing
ITP within 6 weeks after MMR vaccination. We also
calculated the risk of ITP attributable to the MMR
Results Sixty-three children with a first time
diagnosis of ITP were identified; 23 cases were
between 13 and 24 months old. The relative risk
estimate for ITP within 6 weeks after MMR vaccination,
compared to the combined group of unvaccinated
children and children vaccinated with MMR more than 26
weeks previously was 6.3 (95% CI 1.3-30.1). The
attributable risk of developing ITP within 6 weeks
after MMR vaccination was estimated to be 1 in 25 000
vaccinations (95% confidence interval 21 300, 89 400).
Conclusion This study confirms the increased risk of
ITP within 6 weeks after MMR vaccination. However, the
attributable risk of ITP within 6 weeks after MMR
vaccination is low.