A POPULATION-BASED STUDY OF ACCESS TO IMMUNIZATION AMONG URBAN VIRGINIA CHILDREN SERVED BY PUBLIC, PRIVATE, AND MILITARY HEALTH-CARE SYSTEMS

Background Pediatric immunization rates have increased in the United S tates since 1990. Nevertheless, national survey data indicate that up to one third of 2-year-old children in some states and urban areas lac k at least one recommended dose of diphtheria-tetanus-pertussis (DTP)- , polio-, or measles-containing vaccines. Immunization has become a ke y measure of preventive pediatric health care in the United States. To achieve and maintain the national immunization goal that 90% of child ren receive all recommended immunizations by 2 years of age, the role of the health care system in immunization delivery must be examined. U rban eastern Virginia has a diverse population that obtains immunizati on services from public, private, and military providers and insurers. At the time of this survey, immunization services in Virginia were av ailable free to all children through public health clinics and to mili tary families when using a military facility. Objective. To examine ac cess to pediatric immunization services and health system factors asso ciated with underimmunization in a representative sample of children a t 12 and 24 months of age. Methods. We conducted a household survey in urban eastern Virginia from April through September 1993. A total of 12 770 households in Norfolk and Newport News, VA, were selected for i nclusion in the study using probability-proportionate-to-size cluster sampling. Use of probability-proportionate-to-size sampling ensured th at children within each city had equal probability of being included i n the survey. Selected households were visited by trained interviewers to determine their eligibility, defined as having at least one child 12 to 30 months of age residing in the household. In eligible househol ds, parents were asked to participate in a standardized, 15-minute int erview. Survey respondents were asked about household demographics, an d for each eligible child, the immunization history, health insurance, the name and location of all immunization providers, the usual immuni zation provider, and any problems the parent had experienced accessing immunization services with that child. Up-to-date (UTD) immunization status was defined as having all recommended doses of DTP, polio, and measles-mumps-rubella at 12 months (three DTP and two polio immunizati ons) and 24 months (four DTP, three polio, and one measles-mumps-rubel la immunizations). The child's immunization history was assessed from parent and provider records only. Data analysis accounted for the surv ey's cluster sampling design tie, within-cluster correlation). Because the immunization rates of the two cities did not differ significantly , unweighted analyses were used for ease of computation. Significance was determined for contingency tables by Wald's chi(2) test. Results. A total of 749 children (91% of eligible households) participated in t he survey. Study children were born between October, 1990, and July, 1 992. Immunization records were obtained for 705 children (94%). Eighty -seven percent of respondents were mothers, 44% were African-American, 40% of children were military dependents, and 40% were enrolled in th e Women, Infants and Children (WIC) program. Sixty-five percent of chi ldren were UTD at 12 months and 53% at 24 months. Parents reported tha t their children's usual immunization providers were private doctors ( 34%); public health, hospital clinics, or community health centers (32 %); and military clinics or a military contract provider (34%). At lea st one problem accessing immunization services was reported by 35% of respondents, ranging from 29% among those who used a private doctor as their child's usual immunization provider to 46% among those using a military contract provider. Overall, the most commonly reported proble m was clinic waiting time (12%), with reports of waiting time as a pro blem occurring most often among those using the military contract prov ider (22%) and public health clinics (17%). The second most common pro blem was difficulty obtaining a timely appointment (10%), with appoint ment problems ranging from 18% to 24% among those using military facil ities compared with 4% to 6% among those using other providers. Some o f the other problems reported were taking time away from work, office hours, cost, and transportation, with the frequency varying by type of usual provider. Household risk factors for children not being UTD at 12 and 24 months included having a greater number of children, single parenthood, lack of education beyond high school, teenage mother, Afri can-American ethnicity, and not finding the child's immunization recor d at home, After adjusting for these household factors by multiple log istic regression, the system-related factors significantly associated with not being UTD at 12 months were not being in WIC (odds ratio [OR] = 2.1, 95% confidence interval [CI] 1.4-3.3), having Civilian Health and Medical Program of the Uniformed Services (OR = 5.2; CI: 2.9-9.5) or Medicaid (OR = 2.7; CI: 1.4-5.3) insurance, longer clinic waiting t ime (for each hour, OR = 1.6; CI: 1.2-2.0), and transportation problem s (OR = 2.6; CI: 1.3-5.2); and at 24 months were not being in WIC (OR = 2.0; CI: 1.1-3.7), problems obtaining an appointment (OR = 4.5; CI: 1.8-8.6), and use of a military contract clinic (OR = 5.6; CI: 2.6-11. 9). Although not all reported problems accessing services were indepen dent risk factors for underimmunization, a dose-response relationship was found between the total number of different reported problems and children not being UTD at 24 months. Conclusions This is the first pop ulation-based study of the association between immunization coverage r ates and access to public, private, and military health care systems. Overall, one third of parents perceived barriers to pediatric immuniza tion services, and parent-reported problems accessing services had a d ose-response association with underimmunization. The most commonly rep orted problems were long waiting times and difficulty obtaining appoin tments, but the pattern and magnitude of problems reported differed am ong public, private, and military services. Despite free immunizations , parents most often reported problems accessing public and military p roviders. Thus, parents did not necessarily consider cost-free and geo graphically available pediatric services to be barrier-free. Enrollmen t in WIC was associated with significantly increased immunization rate s, although this study was conducted before linkage of the W