Barriers to Immunization in a Relatively Affluent Community

October 29, 2000

hi--sorry, i forgot to add my password--i don't think you can access medscape

unless you are a member without a password--so you wouldn't be able to read

articles. they are lengthy...here it is

From Journal of the American Board of Family Practice

Barriers to Immunization in a Relatively Affluent Community

Barbara P. Yawn, MD, MSc, Olmsted Medical Center, Department of Research,

Rochester; Zhisen Xia, PhD, Section of Clinical Epidemiology, Department of

Health Sciences Research, Mayo Clinic, Rochester; Larry Edmonson, MPH,

Olmsted County Public Health Services, Division of Disease Prevention and

Control, Rochester; M. son, MD, Department of Pediatric and

Adolescent Medicine, Mayo Clinic, Rochester, Minn; J. sen, MD,

PhD, Section of Clinical Epidemiology, Department of Health Sciences

Research, Mayo Clinic, Rochester

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Abstract

Background: Although Healthy People 2000 calls for the complete immunization

of at least 90% of children by age 20 months, few communities can claim such

success. We wanted to determine the parent-reported barriers associated with

underimmunization of infants in a relatively affluent midwestern population.

Methods: We undertook a case-control study of a population-based sample of

parents and guardians of children who were either fully immunized or

underimmunized at 20 months of age in Olmsted County, Minn.

Results: In this study, 596 of 1,216 parents (46%) of both immunized and

underimmunized children participated. Of these participants, 281 (47%)

reported barriers to immunizations, but only 15 (3%) reported major barriers.

Whereas the most commonly reported barriers were barriers of inconvenience

(waiting too long, inconvenient office hours), only delays caused by a sick

child, fear of reactions, trouble remembering an appointment, not knowing

when the next shot was due, and transportation problems were significantly

associated with underimmunization when controlling for demographic factors.

Fear of reactions, sick child delays, and not knowing when the next shot was

due had the highest attributable risk for underimmunization. Taken together,

parent-reported barriers and demographic factors explained less than 30% of

the underimmunization status of children. Parents' most common

recommendations for improving immunization status were the use of a recall or

reminder system and a single unified schedule for immunizations.

Conclusions: In this relatively affluent community, barriers to immunization

were commonly reported but few (fear of reactions, sick child delays, and not

knowing when the next shot was due) were associated with underimmunization.

The types of barriers reported were similar to those reported in other

communities, but unlike many populations studied, cost was not reported as an

Board of Family Practice]

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Introduction

Healthy People 2000 calls for the complete immunization of at least 90% of

children by age 20 months.[1] Although some managed care populations have

attained this goal,[2] few communities can claim such success.[3-5]

The reasons for this shortfall in infant immunizations have been studied,

evaluated, and discussed for decades.[6-13] In 1991 the common community

barriers to immunization of infants were listed as missed opportunities,

organizational failures in the health care delivery system, inadequate access

to care, and incomplete public awareness of the importance of immunizations

and the morbidity of vaccine preventable diseases.[14] The following family

characteristics are associated with lower likelihood of completed

immunizations by the age of 2 years: completing less formal education, large

family size, lower socioeconomic status, being nonwhite, receiving services

through a public health department, living in a single-parent family, getting

a late start on immunizations, and inadequate insurance.[15,16] Practice

barriers have been reported by private and public health clinicians as high

cost of vaccine to providers,[10,11,17-20] inadequate insurance coverage of

families,[6,10-12,21-24] inadequate use of immunization

opportunities,[10,25-29] and lack of community-based registries or tracking

systems across communities.[30]

Parent-perceived barriers have also been studied, primarily in inner-city

parents, parents receiving medical assistance, and rural

parents.[7,11,25-27,31-36] Most studies have focused on the delivery of

immunizations by the public health system. The most common parent-reported

barriers were cost, safety concerns, lack of health care access, and

inconvenience.[31-35] Four published studies included parents that were not

economically stressed[25,37-39] but only one[37] examined the association

between parent-reported barriers and the actual immunization status of the

child. A second compared the health beliefs of parents in an affluent

community with their child's immunization status.[38] Although all barriers

deserve attention, the most important barriers to recognize and address are

those associated with incomplete immunizations by age 2 years.

Previous reports of parent-perceived barriers have encouraged the development

of immunization registries and recall and reminder systems that have been

shown to be associated with increased immunization in a clinic

population.[40,41]

Middle-class communities, as well as economically stressed communities, also

fall short of the Healthy People 2000 goal of 90% immunization by age 24

months.[25,29,38] Barriers reported in the studies of more distressed

communities and public health systems might not predict barriers experienced

by parents in more affluent or less underserved areas. We report and compare

the parent-perceived barriers for fully immunized and underimmunized children

found in a population-based birth cohort of children in a relatively affluent

community. We also report the solutions suggested by parents.

Methods

Sample

Children eligible for this study were 2 and 3 years old from a birth cohort

of children born in Olmsted County, Minn, between 1 July 1992 and 30 June

1993 and still residing in Olmsted County on 1 March 1996. Olmsted County is

a metropolitan statistical area located 90 miles southeast of Minneapolis.

According to 1990 census data, 96% of its residents were white and mostly

middle class, with approximately 82% of adults having completed a high-school

education.[42] In 1994, the rate of completed immunization for 20-month-old

children in Olmsted County was 69% and for 2-year-old children, 74%.[30] At

the time of the survey, only 8% of the population was uninsured, 18% had

Medicaid insurance, 20% was covered by managed care contracts, and the rest

had fee-for-service private insurance (personal communication, Troy Stafford,

CFO, Olmsted Medical Center).

Using a population-based case-control design, a sample of parents and

guardians was selected for this study. Cases were defined as underimmunized

children who received two or fewer polio vaccines (oral polio vaccine [OPV]

or injectable polio vaccine [iPV]) or three or fewer diphtheria, pertussis,

tetanus (DPT) immunizations or no measles, mumps, and rubella (MMR)

immunizations by the age of 20 months. Hepatitis B immunizations were not

included in the definition, because not all community providers were

routinely recommending them for children during the study period. Controls

were children who were fully immunized (4 DPT, 3 OPV or IPV, and 1 MMR) by

age 20 months. The children for the cases (n = 332) and controls (n = 1,053)

were selected from a previously reported study[27] that assessed immunization

status of each child in the birth cohort based on data from the medical

records of all three Olmsted County private and the one public health

providers. Survey questionnaires were sent to parents or guardians of all

case children as well as to a 50% random sample of all eligible control

children.

The survey questionnaire was mailed to the last known address of each parent

or guardian. A second questionnaire was mailed to those with a forwarding

address and those not returning the initial questionnaire within 3 weeks. If

no response was received in an additional 3 weeks, the family was telephoned

(if a telephone number could be found) and asked to return the questionnaire.

For each case and control child, the survey requested information on such

family demographics as family structure, household income, maternal and

paternal education, and source of insurance. A checklist of potential

barriers was developed using information from the published literature and

from a similar study completed by the Anoka County, Minn, Department of

Health.[38] Parents were asked to check all barriers they experienced as well

as the two biggest barriers. For each barrier checked, parents were asked to

indicate whether it was a major or minor barrier. Several blank lines were

provided to list additional barriers. The survey instrument also provided

several blank lines for the parents to suggest what they thought would

facilitate children receiving all immunizations. The survey was to be

completed by the adult designated as most responsible for the child's care.

Data Analysis

Categorical demographic and family characteristic variables were compared for

case and control children using the chi-square statistic. Because previous

studies suggested immunization status is associated with demographic factors,

multivariable logistic regression models were used to examine the association

between parent-perceived barriers and case-control status, with and without

adjustment for demographic factors. Case status was the dependent variable.

The main effects examined were the most commonly reported barriers to

immunization. The model selection was based on the hierarchical principle.

Odds ratio and attributable risk estimates[43,44] were calculated for the

variables in the final logistic regression model.

Results

Of the 1,216 survey questionnaires that were distributed, 1,089 could be

delivered. A total of 596 questionnaires were returned completed,

representing a response rate of 49% of all questionnaires. The response rate

was 57% and 26% of mailed (66% and 48% of deliverable) questionnaires for the

mothers of the control children and case children, respectively. Family

characteristics for the case and control children were similar with respect

to maternal age, race, birth order, the number of adults and children in the

house, and number of infant health care encounters (Table 1). There were,

however, differences in maternal education and household income (Table 1).

Underimmunized (case) children were more likely than immunized (control)

children to have mothers with lower education (54.9% vs 67.6% of college or

higher, P = .034) and lower household income (19.4% vs 7.9% of less than

$20,000, P = .002).

Underimmunized children were more likely than immunized children to receive

social or public health services, such as Women, Infants and Children (WIC)

and Public Health services, for both the first and the second year of their

life. Case children also were more likely than control children to have

medical assistance or Children's Health Plan insurance in the second year of

their life (odds ratio [OR], 3.0, 95% confidence interval [CI], 1.5-5.8).

This association was not as strong in the first year (OR, 1.7, 95% CI, 0.8 to

3.3). During both the first and second year of life, using WIC was the family

characteristic with the highest attributable risk for underimmunization (data

not shown).

Barriers to immunizations were reported by the parents of completely

immunized and the parents of underimmunized infants. Overall, 281 of 596

parents (47%) reported they experienced one or more barriers. Most barriers

(more than 94%) were considered minor barriers by the parents. Table 2 lists

all the barriers reported by parents as major and minor barriers as well as

the two biggest problems reported by the parents. Waiting too long in the

waiting room and fear of a reaction to the shot were each listed as either

major or minor barriers by more than 15% of respondents (n = 98 and n = 91,

respectively). Not knowing when the next shot was needed, time concerns,

worrying about pain from the shot, and inconvenient clinic hours were listed

by about 50 (8%) respondents each. Cost was infrequently reported as a major

barrier (2% of all parents).

Although each of these stated barriers deserves attention, the barriers

reported by families with underimmunized children might be the most important

to address. Five barriers were significantly more likely to be reported by

parents of underimmunized children than parents of fully immunized children

(Table 3). Transportation had the highest odds ratio but was listed by only 8

parents as a major or minor barrier. Conversely, not knowing or having

trouble remembering the timing for the next shot had a lower odds ratio but

was reported by 63 parents overall as a major or minor barrier. Delaying

shots because of illness and fear of reaction were the other barriers

associated with underimmunization and were reported by 45 and 91 respondents,

respectively. Fear of reactions to the shots was most commonly listed as the

biggest problem by all parents.

The barriers reported and those associated with underimmunization did vary by

some maternal characteristics. Trouble remembering appointments was most

highly associated with underimmunization in mothers 33 years of age or older

(OR, 7.1; 95% CI, 1.8-27.6), whereas transportation problems were most likely

to be associated with underimmunization in women with multiple children. Fear

of reactions was associated with underimmunization in children of those

mothers who had a college education and in those who had multiple children.

Interestingly, only first-time mothers did not delay immunizations because of

the child's illness.

In multivariable analysis, there were only two significant family

demographics associated with underimmunization by age 20 months: household

income and self-payment. After adjusting for household income and

self-payment, the odds ratios for parent-perceived barriers associated with

underimmunization changed only slightly from the bivariate analyses (Table

3). The largest change in odds ratio in the multivariable analysis occurred

with transportation problems. In bivariate and multivariable analyses

controlling for income and self-payment, fear of a reaction to the

immunization had the highest attributable risk 14.4% (95% CI, 2.5, 26.4)

followed closely by not knowing when the next shot was needed 13.6% (95% CI,

2.9, 24.2) and delaying immunizations because of a sick child 12.5% (95% CI,

3.4, 21.4) (Table 3). In combination, all the reported barriers account for

only 29.2% of the underimmunization of these children.

The solutions proposed by parents to increase immunization rates did not

differ based on the child's immunization status. By far, the most commonly

suggested solution was a system of reminders (96/596, 16%). Parents suggested

that reminders be mailed or parents telephoned before an immunization was due

as well as when a child missed an immunization. The second most common

suggestion (58/596, 10%) was having a single immunization schedule for all

clinics and all clinicians. Thirty-two parents specifically commented that

they did not like schedules with broad ranges of possible immunization age

(ie, the second DPT should be administered between 2 and 4 months of age).

More convenient hours was next (32/596, 5%) with lower cost the fourth most

common suggestion (18/596, 3%). Twelve parents were concerned that

immunization status was not checked at each appointment. Fewer than 10

parents each suggested immunization clinics with or without appointment,

childcare for siblings, and better awareness of immunization safety and

benefits. Free or low-cost immunization clinics were suggested by only 3% of

the parents and were reported to be used by only 20% of those reporting cost

as a barrier.