Assessing misclassification of vaccination status: Implications for studies of the safety of the childhood immunization schedule

Details

• Alternative Title:
  Vaccine
• Personal Author:
  Daley, Matthew F. ; Glanz, Jason M. ; Newcomer, Sophia R. ; Jackson, Michael L. ; Groom, Holly C. ; Lugg, Marlene M. ; McLean, Huong Q. ; Klein, Nicola P. ; Weintraub, Eric S. ; McNeil, Michael M.
• Description:
  Background:
  
  To address public concern about the safety of the childhood immunization schedule, the Institute of Medicine recommended observational studies comparing adverse health outcomes of fully vaccinated children to children under-vaccinated due to parental choice. Misclassification of vaccination status could bias such studies.
  
  Objective:
  
  To assess risk of misclassification of vaccination status within the Vaccine Safety Datalink (VSD).
  
  Design/methods:
  
  A retrospective cohort study was conducted in three phases. In phase 1, electronic health record (EHR) data were used to identify patterns of under-vaccination during the first 24 months of life potentially due to parental choice. In phase 2, a random sample of records of under-vaccinated children was manually reviewed. In phase 3, a separate sample of parents were surveyed to assess whether EHR data accurately reflected their child’s vaccination status. Phases 1 and 2 were conducted at 6 VSD sites, phase 3 at 1 site.
  
  Results:
  
  The study cohort included 361,901 children born 2004 through 2012. By 24 months of age, 198,249 (54.8%) were fully vaccinated with no delays, 84,698 (23.4%) experienced delays but were fully vaccinated by 24 months of age, 4865 (1.3%) received no vaccines, 3789 (1.0%) delayed starting vaccination until ≤4 months of age, 4781 (1.3%) had consistent vaccine-limiting (≤2 vaccines per visit), and the remaining 65,519 (18.1%) were missing vaccine series or doses. When a diagnosis code for vaccine refusal was present in EHR data, encounter notes confirmed vaccine refusal as the reason for under-vaccination for nearly 100% of sampled records. Parent surveys confirmed these findings. Parents of under-vaccinated children were more likely to report visiting an alternative medical provider than parents of fully vaccinated children.
  
  Conclusions:
  
  Specific groups of children, under-vaccinated due to parental choice, can be identified with relatively low likelihood of misclassification of vaccination status using EHR-based vaccine data and diagnosis codes.
  
  
• Subjects:
  Child, Preschool Female Humans Immunization Schedule Infant Infant, Newborn Male Retrospective Studies Surveys And Questionnaires Vaccination Vaccination Coverage Vaccines

  More +
• Keywords:
  Child Immunization Under-vaccination Vaccine Vaccine Safety Vaccine Schedule
• Source:
  Vaccine. 35(15):1873-1878
• Pubmed ID:
  28285983
• Pubmed Central ID:
  PMC6445250
• Document Type:
  Journal Article
• Funding:
  CC999999/Intramural CDC HHSUnited States/
• Volume:
  35
• Issue:
  15
• Collection(s):
  CDC Public Access
• Main Document Checksum:
  urn:sha256:ba26046ed920203ab91a9a91d3924fe5f596e8927b05d9bf834ccf5f147fea7d
• Download URL:
  https://stacks.cdc.gov/view/cdc/77178/cdc_77178_DS1.pdf
• File Type:
  [PDF - 81.32 KB ]