How valid are IMS DA summary statistics of children's vaccination status?

Abstract

In the IMS DA data of 15 237 children born in 2008, 12 740 (83.6%) had a vaccination record of PCV7. One-hundred and eleven of the 167 questionnaires sent to the child's general practitioners were returned, giving an adjusted response rate of 111/167 (66.5%). Based on the general practitioners' responses, 71 (64%) of these children were fully vaccinated according to their general practitioner's records making the revised estimated vaccination rate for this cohort 94.1% CONCLUSION: This validation study has shown that caution is needed if using historical IMS patient-level data to analyse the effectiveness of PCV7 as there is a potential under-recording of immunization leading to under representation of vaccination rates by approximately 10%. Copyright © 2016 John Wiley & Sons, Ltd.