Idiopathic thrombocytopenic rpura and the second dose of MR

摘要

An increase in idiopathic thrombocytopenic purpura (ITP) cases in the 6 weeks following the first dose of the measles, mumps and rubella (MMR) vaccine has been established, with absolute risks estimated as 1 in 22 300 and 1 in 21 000 vaccine doses,2 with two in every three cases attributable to the vaccine. However, the risk after a second dose of MMR vaccine has not been investigated. Hospital admissions for children aged from 3 to <6 years with a discharge diagnosis of ITP (ICD-code D693 in any diagnosis field) were identified from computerised hospital episode data from North, East and South London, Essex, East Anglia, Sussex and Kent for the period from 1 April 1997 to 31 December 2005. These admissions were then linked to second MMR dose records held on population-based child-health database systems.