Immunization Coverage of Vulnerable Children: A Comparison of Health Center and National Rates Ashley Schempf, BS Robert Politzer, ScD Shannon Stokley, MPH April 30, 2002 Funded by the Bureau of Primary Health Care, HRSA/DHHS

Overview  Background and Objectives  Methods  Results  Limitations  Discussion  Follow-up Study  Conclusions

Background  Vaccines are ranked as the most valuable preventive service  Lower vaccination rates among poor, minority, and urban children  Disparities persist despite free vaccines and public assistance provided by the federal government

Immunization Trends by Race 4:3:1:3 Series Completion, Children mo. Health, US 2001, Table 73

Immunization Trends by Poverty 4:3:1:3 Series Completion, Children mo. Health, US 2001, Table 73

Community Health Centers (CHCs)  Serve a fifth of the nation’s 48 million underserved people  Have eliminated disparities for other preventive services  May ameliorate gaps in immunization coverage by  Providing high-quality coordinated primary care to reduce missed opportunities within the system  Fostering equal and regular access by providing enabling services that combat personal barriers to care

Methods User-Visit Survey, 1995  Two-stage sampling design selected 50 centers with probability proportional to size  Patients with at least one medical encounter with a clinician in the last year were randomly selected  76% response rate  n= 277 NHIS, 1995  State stratification for primary sampling units  Household interviews  Oversample of black and Hispanic persons  86.5% response rate  n= 5,901 Two-tailed t-tests were performed to detect differences both within and between weighted sample proportions

National and Health Center Poverty Distribution

National and Health Center Race/Ethnicity Distribution

Health Center and National Comparison: Overall Immunization Coverage Sources: User-Visit Survey, BPHC/HRSA, 1995; NHIS, NIP/CDC, 1995 ** ^ * ^ p<.10 * p<.05 ** p<.01 ***p<.001 *

Health Center and National Comparison: Immunization Disparities By Race/Ethnicity * *** * ** * DTP Polio MMR Sources: User-Visit Survey, BPHC/HRSA, 1995; NHIS, NIP/CDC, 1995 ^ p<.10 * p<.05 ** p<.01 ***p<.001 ^

Health Center and National Comparison: Immunization Disparities By Race/Ethnicity *** * ** ^ Hib HepB DTP, Polio, MMR Sources: User-Visit Survey, BPHC/HRSA, 1995; NHIS, NIP/CDC, 1995 ^ p<.10 * p<.05 ** p<.01 ***p<.001 ^

Discussion  Few significant disparities were observed at health centers  Registries and recall/reminder tracking systems are recommended to improve coverage  Persistent Black polio disparity may be tempered by declining clinical relevance  Higher Hib and Hepatitis B coverage at CHCs shows promise for an expanding immunization schedule

Limitations  Limited CHC sample size  Recall bias  Multivariate analysis would control for income  Prospective design to demonstrate causality

Follow-up Study  Better matched national reference  <$20,000 household income  >= 1 medical visit in past year  Additional sociodemographic and access variables  Multivariate analysis

National Low-Income and CHC Race/Ethnicity Distribution

National Low-Income and CHC Insurance Distribution

Health Center and Nation Low-Income: Overall Immunization Coverage Comparison Sources: User-Visit Survey, BPHC/HRSA, 1995; NHIS, NCHS/CDC, 1995 * ^ p<.10 * p<.05 ** p<.01 ***p<.001 *

Health Center and Nation Low-Income: Immunization Comparison By Insurance * DTP Polio MMR Sources: User-Visit Survey, BPHC/HRSA, 1995; NHIS, NIP/CDC, 1995 ^ p<.10 * p<.05 ** p<.01 ***p<.001 ^

Health Center and Nation Low-Income: Immunization Comparison By Insurance * Hib HepB DTP, Polio, MMR Sources: User-Visit Survey, BPHC/HRSA, 1995; NHIS, NIP/CDC, 1995 ^ p<.10 * p<.05 ** p<.01 ***p<.001 * ** ***

Health Center and Nation Low-Income: Immunization Comparison By Hispanic Ethnicity *** ** * p<.05 ** p<.01 ***p<.001 Sources: User-Visit Survey, BPHC/HRSA, 1995; NHIS, NIP/CDC, 1995

Multivariate Models  Comparative Models include  Personal Characteristics  Household Characteristics  Access Indicators  Full Models also include  Education in the national reference  Language, usual source of care, satisfaction with waiting times, and health beliefs in the health center

Multivariate Results: Comparative Models  Race/Ethnicity remained significant only for MMR in the nation (OR.66 for black children)  In the national sample, consistent predictors included insurance status, Hispanic ancestry, number of children, and single parenthood.  At health centers, birth order was a marginally significant predictor.

Multivariate Results: Full Models  National Full Model  Education was highly consistent  OR for parents >high school education  Health Center Full Model  Health beliefs and travel time emerged consistently predictive  Birth order became more significant  OR for first-born children

Conclusions  Serving nearly 20% of the nation’s low-income uninsured children, CHCs are uniquely positioned to address continuing disparities in the context of comprehensive primary care.  Health centers appear to be particularly effective in improving immunization for Hispanic and uninsured children.  Birth order and travel time are identifiable risk factors that could be addressed for further coverage improvement at health centers.