Extra-immunization as a clinical indicator for fragmentation of care

Objectives. We assessed whether extra-immunization can serve as a clinical indicator for fragmentation of care. Methods. Using public-use files of the 1999-2003 National Immunization Survey, we classified children 19-35 months of age by their vaccination providers for the degree of fragmentation of care as ordered from lowest with one vaccine provider, to increasing fragmentation with multiple providers in one facility type, to multiple providers in more than one facility type. Extra-immunization was defined conservatively based on the year-specific recommendations of the Advisory Committee on Immunization Practices (ACIP) for immunizations due before 18 months of age. Of note, 1999-2003 transitioned from oral to inactivated poliovirus vaccines. Results. The rate for extra-immunization was 9.4% (95% confidence interval [CI] 9.2, 9.7). Of single vaccines, the rate for polio vaccine was highest (5.7%, 95% CI 5.5, 6.0). Extra-immunization was lowest for the 69% of children with only one vaccination provider (6.4%, 95% CI 6.1, 6.7), was higher in children who had more than one vaccination provider with one vaccination facility type (13.9%, 95% CI 13.2, 14.6), and highest with more than one facility type (24.1%, 95% CI 22.5, 25.6). Logistic regression (including race/ethnicity, language, provider type, survey year, and a parent-held immunization record) confirmed that multiple providers (adjusted odds ratio [AOR] = 2.30), multiple facility types (AOR=4.67), Spanish language (AOR=1.29), and race/ethnicity (black AOR=1.16, Hispanic AOR=1.31) were each associated with extraimmunization. Excluding poliovirus vaccine from the analysis, AORs for multiple providers and multiple facility types increased to 3.64 and 8.95, respectively. Conclusions. Extra-immunization is associated with receiving immunizations from multiple providers and multiple facility types.