Comparing a computer-based childhood vaccination registry with parental vaccination cards: a population-based study of Delaware children.

We conducted a population-based study in Delaware to examine the reliability of childhood vaccination data in a comprehensive computer-based record system versus parental vaccination cards. We sampled 1-005 children born between January- 1991- and September- 1993. We oversampled for children whose mothers received Medicaid or were uninsured at the time of delivery. Of the survey responders- 276 (56%) had access to written records- and 409 (83%) records were located in the Delaware immunization computer database. The kappa coefficient was 0.18. The observed agreement was 59.8%. When the two databases were combined- the up-to-date rate for 2-year-olds was 58.4%- an increase of 12.7% and 24.2% from the computer database and the parental records- respectively. The computer database was 78.1% sensitive and the parental records were 54.9% sensitive. These results indicate that a comprehensive computer-based record system- with adequate provider participation and proper data management- can be more reliable than parental vaccination cards.