IS UNDERIMMUNIZATION A MARKER FOR INSUFFICIENT UTILIZATION OF PREVENTIVE AND PRIMARY-CARE

Objective: To test the hypothesis that the underimmunization of young children is a marker for the lack of preventive and acute primary care. Setting: Primary care center serving an impoverished population (90% Medicaid). Design: Historical cohort study (N=1178) of children aged 12 to 30 months that determined each child's immunization status; anemia, tuberculosis, and lead screening status; and office utilization history. Screening delay was defined as missing a recommended screening by more than 3 months past the standard screening age. Results: Thirty-four percent of the population were underimmunized at 12 months of age. Compared with fully immunized children, these children were at greater risk for screening delay: anemia, 38% vs 5% (risk ratio [RR], 7.5; 95% confidence interval [CI], 5.4 to 10.4); tuberculosis, 76% vs 44% (RR, 1.7; CI, 1.6 to 1.9); and lead, 69% vs 33% (RR, 2.1; CI, 1.9 to 2.4). These RRs increased with greater immunization delay. Compared with fully immunized children, the underimmunized group made 47% fewer preventive health visits (2.5 vs 4.7 visits per infant per year, P<.001) and 43% fewer illness Visits (2.5 vs 4.4, P<.001) and had 50% more missed appointments (2.1 vs 1.4, P<.001). Logistic regression, predicting anemia screening delay at 12 months of age, showed that underimmunization had an effect independent of utilization, with an odds ratio of 7.7 (CI, 5.2 to 12.0). Conclusion: Underimmunization was a powerful, independent marker for inadequate health supervision in this population. Implications: The current emphasis on immunizations has the benefit of targeting children at risk of lack of preventive and acute care. Improving immunization rates may have the potential to improve other aspects of primary care if immunization provision is not uncoupled from primary care.