Impact of multiple injections on immunization rates among vulnerable children.

BACKGROUND: In 1997, the Advisory Committee on Immunization Practices (ACIP) recommended a switch from oral polio vaccine (OPV) to inactivated polio vaccine (IPV) for the first two infant doses. The ACIP also recommended use of diphtheria, tetanus, and acellular pertussis vaccine (DTaP) for infants. These recommendations resulted in two additional injections at the 2- and 4-month immunization visits. This study evaluates the implementation of new IPV and DTaP immunization recommendations and their impact on immunization coverage levels. METHODS: Immunization coverage was assessed in public clinics in three urban areas before and after the recommendations. One pre- and three post-recommendation cohorts were followed to 12 months of age. RESULTS: Almost all (> or = 88%) infants in the pre-recommendation cohort received OPV, DTP, and only one or two injections. Almost all (> or = 78%) infants in the post-recommendation cohorts received IPV, DTaP, and three or four injections. The percentage of infants in the post-recommendation cohorts up-to-date for immunizations at 12 months of age was slightly higher than those in the pre-recommendation cohort. CONCLUSIONS: Providers rapidly switched from OPV and DTP to IPV and DTaP. Coverage at 12 months of age was higher among IPV/DTaP recipients than among OPV/DTP recipients. Provider and parent acceptance of four injections at a visit was high. The recent pneumococcal conjugate vaccine recommendations potentially add a fifth injection at 2 and 4 months of age. Acceptance or rejection of five injections by providers and parents needs early assessment.

Impact of the change in polio vaccination schedule on immunization coverage rates: a study in two large health maintenance organizations.

OBJECTIVE: In January 1997, one of the most significant changes to United States vaccine policy occurred when polio immunization guidelines changed to recommend a schedule containing inactivated polio vaccine (IPV). There were concerns that parent or physician reluctance to accept IPV into the routine childhood immunization schedule would lead to lowered coverage. We determined whether adoption of an IPV schedule had a negative impact on immunization coverage. DESIGN: A cohort study of 2 large health maintenance organizations (HMOs), Group Health Cooperative and Kaiser Permanente Northern California, was conducted. For analysis at 12 months of age, children who were born between October 1, 1996, and December 31, 1997, and were commercially insured and covered by Medicaid were continuously enrolled; for analysis at 24 months of age, children who were born between October 1, 1996, and June 30, 1997, and were commercially insured and covered by Medicaid were continuously enrolled. The 3 measures of immunization status at 12 and 24 months of age were up-to-date status, cumulative time spent up-to-date, and the number of missed opportunity visits. RESULTS: At both HMOs, children who received IPV were as likely to be up to date at 12 months as were children who received oral poliovirus vaccine (OPV), whereas at Group Health, children who received IPV were slightly more likely to be up to date at 24 months (relative risk: 1.12; 95% confidence interval [CI]: 1.05, 1.19). These findings were consistent for children who were covered by Medicaid. At Kaiser Permanente, children who received IPV spent ~3 fewer days up to date in the first year of life, but this difference did not persist at 2 years of age. At Group Health, children who received IPV were no different from those who received OPV in terms of days spent up to date by 1 or 2 years of age. At Group Health, children who received IPV were less likely to have a missed opportunity by 12 months old (odds ratio [OR] 0.46; 95% CI: 0.31, 0.70), but this finding did not persist at 24 months of age. At Kaiser Permanente, children who received IPV were more likely to have a missed opportunity by 12 months (OR 2.06; 95% CI: 1.84, 2.30), and 24 months of age (OR 1.50; 95% CI: 1.36, 1.67). CONCLUSIONS: The changeover from an all-OPV schedule to one containing IPV had little if any negative impact on vaccine coverage. Use of IPV was associated with a small increase in the likelihood of being up to date at 2 years of age at one of the HMOs and conversely was associated with a small increase in the likelihood of having a missed-opportunity visit in the other HMO.polio, poliomyelitis, vaccination, immunization coverage.

Variation in clinician recommendations for multiple injections during adoption of inactivated polio vaccine.

OBJECTIVES: To describe variation in clinician recommendations for multiple injections during the adoption of inactivated poliovirus vaccine (IPV) in 2 large health maintenance organizations (HMOs), and to test the hypothesis that variation in recommendations would be associated with variation in immunization coverage rates. DESIGN: Cross-sectional study based on a survey of clinician practices 1 year after IPV was recommended and computerized immunization data from these clinicians' patients. STUDY SETTINGS: Two large West Coast HMOs: Kaiser Permanente in Northern California and Group Health Cooperative of Puget Sound. OUTCOME MEASURES: Immunization status of 8-month-olds and 24-month-olds cared for by the clinicians during the study. RESULTS: More clinicians at Group Health (82%), where a central guideline was issued, had adopted the IPV/oral poliovirus vaccine (OPV) sequential schedule than at Kaiser (65%), where no central guideline was issued. Clinicians at both HMOs said that if multiple injections fell due at a visit and they elected to defer some vaccines, they would be most likely to defer the hepatitis B vaccine (HBV) for infants (40%). At Kaiser, IPV users were more likely than OPV users to recommend the first HBV at birth (64% vs 28%) or if they did not, to defer the third HBV to 8 months or later (62% vs 39%). In multivariate analyses, patients whose clinicians used IPV were as likely to be fully immunized at 8 months old as those whose clinicians used all OPV. At Kaiser, where there was variability in the maximum number of injections clinicians recommended at infant visits, providers who routinely recommended 3 or 4 injections at a visit had similar immunization coverage rates as those who recommended 1 or 2. At both HMOs, clinicians who strongly recommended all possible injections at a visit had higher immunization coverage rates at 8 months than those who offered parents the choice of deferring some vaccines to a subsequent visit (at Kaiser, odds ratio [OR]: 1.2; 95% confidence interval [CI]: 1.0-1.5; at Group Health, OR: 1.8; 95% CI: 1.1-2.8). CONCLUSIONS: Neither IPV adoption nor the use of multiple injections at infant visits were associated with reductions in immunization coverage. However, at the HMO without centralized immunization guidelines, IPV adoption was associated with changes in the timing of the first and third HBV. Clinical policymakers should continue to monitor practice variation as future vaccines are added to the infant immunization schedule.

Health department clinics as pediatric immunization providers: a national survey.

OBJECTIVE: To describe a national sample of health department immunization clinics in terms of populations served, patient volume trends, services offered, and immunization practices. METHODS: Telephone survey conducted with health departments sampled from a national database, using probability proportional to population size. RESULTS: All (100%) 166 sampled and eligible clinics completed the survey. The majority of pediatric patients were uninsured (42%) or enrolled in Medicaid (34%). Most children (69%) and adolescents (70%) were referred to the health department, with only 12% using these clinics as a medical home. A number of clinics (72%) reported recent increases in adolescents served. Less than 25% of clinics offered comprehensive care, 47% conducted semiannual coverage assessments, and 76% and 38% operated recall systems for children and adolescents. Storage of records in an electronic database was common (83%). CONCLUSIONS: Although the majority of these clinics do not provide comprehensive care, they continue to serve vulnerable children, including adolescents, Medicaid enrollees, and the uninsured, and may represent the main contact with the healthcare system for such patients. Because assuring the immunization of these children is essential to their health and the health of our nation as a whole, this immunization safety net must be preserved. Experience implementing key recommendations such as coverage assessment and feedback as well as reminder or recall may enable health department staff to assist private provider colleagues. Further research is needed to investigate how patient populations, services offered, and immunization practices vary by different clinic characteristics.

Vaccination status of children in the Women, Infants, and Children (WIC) Program: are we doing enough to improve coverage?

BACKGROUND: Vaccination-promoting strategies in the Supplemental Nutrition Program for Women, Infants, and Children (WIC) have been shown to produce dramatic improvements in coverage and other health outcomes. OBJECTIVES: To determine national and state-specific population-based vaccine coverage rates among preschool children who participate in the WIC program, and to describe the strategies for promoting vaccination in WIC. DESIGN/METHODS: Demographic data, WIC participation, and vaccination histories for children aged 24 to 35 months in 1999 were collected from parents through the National Immunization Survey. The healthcare providers for the children in the survey were contacted to verify and complete vaccination information. We defined children as up-to-date (UTD) if they had received four doses of diphtheria and tetanus toxoids and pertussis vaccine (DPT), three doses of poliovirus vaccine, one dose of measles-mumps-rubella vaccine (MMR), and three doses of Haemophilus influenzae type b vaccine (Hib) by 24 months. Description of state-level vaccination-promoting activities in WIC was collected through an annual survey completed by the state WIC and immunization program directors. RESULTS: Complete data were collected on 15,766 children, of whom 7783 (49%) participated in WIC sometime in their lives. Nationally, children who had ever participated in WIC were less well-immunized at 24 months compared to children who had not: 72.9% UTD (95% CI, 71.3-74.5) versus 80.8% UTD (95% CI, 79.5-82.1), respectively. In 42 states, 24-month coverage among WIC participants was less than among non-WIC participants, including 13 states where the difference was > or = 10%. Vaccination activities linked with WIC were reported from 76% of 8287 WIC sites nationwide. States conducting more-frequent interventions and reaching a higher proportion of WIC participants had 40% higher vaccination coverage levels for the WIC participants in that state (p<0.05). CONCLUSIONS: Children served by WIC remain less well-immunized than the nation's more-affluent children who do not participate in WIC. Thus, WIC remains a good place to target these children. This study provides evidence that fully implemented WIC linkage works to improve vaccination rates. Strategies that have been shown to improve the vaccination coverage levels of WIC participants should be expanded and adequately funded to protect these children.

Processes for obtaining nonmedical exemptions to state immunization laws.

OBJECTIVES: This study sought to determine the specific processes required for obtaining religious and philosophical exemptions to school immunization laws. METHODS: State health department immunization program managers in the 48 states that offer nonmedical exemptions were surveyed. Categories were assigned to reflect the complexity of the procedure within a state for obtaining an exemption. RESULTS: Sixteen of the states delegated sole authority for processing exemptions to school officials. Nine states had written policies informing parents who seek an exemption of the risks of not immunizing. The complexity of the exemption process, in terms of paperwork or effort required, was inversely associated with the proportion of exemptions field. CONCLUSIONS: In many states, the process of claiming a nonmedical exemption requires less effort than fulfilling immunization requirements.

The impact of record scattering on the measurement of immunization coverage.

BACKGROUND: Lack of a consolidated immunization record may lead to problems with determining individual immunization needs at office visits as well as measuring vaccination coverage levels of a clinician's practice or a community's population. OBJECTIVES: For children with multiple immunization providers, evaluate the difference in coverage levels using data from all responding immunization providers compared with: 1) the most recent immunization provider's records, 2) the first immunization provider's records, and 3) a randomly selected immunization provider's records. Identify characteristics of the most recent provider that may be associated with reporting incomplete immunization histories. METHODS: Data from the 1995 National Immunization Provider Record Check Study (NIPRCS) were used for analysis. The NIPRCS is a provider validation study of the household reported immunization histories of all children 19 to 35 months of age included in the National Health Interview Survey (NHIS). Providers identified by the child's parent during the NHIS interview are mailed a 2-page survey to report all immunizations (type and date) the child received, regardless of the provider who administered the shots, and child's first and most recent visit dates to the practice. RESULTS: Of the 1352 children with provider data, 304 (22%) had received immunizations from more than one provider. Compared with information from all providers and depending on the vaccine, the most recent provider records underestimated coverage by 9.6 to 13.4 percentage points; the initial provider records underestimated coverage by 15.6 to 34.6 percentage points; and the randomly selected provider records underestimated coverage by 10.0 to 20.7 percentage points. Public facilities and having an immunization summary sheet in the patient's chart were associated with having complete records. CONCLUSION: Scattered immunization records significantly compromise the ability of clinicians to determine the immunization status of their patients who received immunizations at other sites of health care. Routinely assessing immunization coverage levels at the practice level, implementing a recall system, and developing community-wide immunization registries are some strategies to reduce the problem of scattered immunization records.immunization, assessment, provider validation, record scattering.

National, state and urban-area vaccination-coverage levels among children aged 19-35 months, United States, 1999.

BACKGROUND: Assessment of vaccination coverage is an important component of the U.S. vaccination program and is primarily measured by the National Immunization Survey (NIS). METHODS: The 1999 NIS is a nationally representative sample of children aged 19 to 35 months, verified by provider records, that is conducted to obtain estimates of vaccination coverage rates. Coverage estimates are calculated for the nation, states, and selected urban areas for recommended vaccines and selected vaccine series. RESULTS: Coverage estimates are presented by a variety of demographic and healthcare-related factors: overall, by poverty status, race/ethnicity, selected milestone ages, participation in WIC, level of urbanicity, provider participation in VFC, and by provider facility type. In 1999, national coverage estimates were high for most vaccines and among most demographic groups. State and urban-area level estimates varied.

Immunization pockets of need: science and practice.

Despite high overall immunization coverage levels among U.S. preschool children, areas of underimmunization, called pockets of need, remain. These areas, which pose both a personal health and a public health risk, are typically poor, crowded, urban areas in which barriers to immunization are difficult to overcome and health care resources are limited. The purpose of this report is to review barriers to immunization of preschool children living in pockets of need and to discuss current issues in the identification of and implementation of interventions within these areas. The Centers for Disease Control and Prevention administers a federal grants program that funds state and metropolitan immunization programs. This program promotes a three-pronged approach for addressing pockets of need: (1) identification of target areas, (2) selection and implementation of programmatic strategies to improve immunization coverage, and (3) evaluation of progress or impact. At each step, scientific evidence can guide programmatic efforts. While there is evidence that state and metropolitan immunization programs are currently making efforts to address pockets of need, much work remains to be done to improve immunization coverage levels in pockets of need. Public health agencies must take on a broadened role of accountability, new partnerships must be forged, and it may be necessary to strengthen the oversight authority of public health. These tasks will require a concentration and redirection of resources to support the development of an immunization delivery infrastructure capable of ensuring the timely delivery of immunizations to the most vulnerable of America's children.

Effect of patient reminder/recall interventions on immunization rates: A review.

CONTEXT: Immunization rates for children and adults remain below national goals. While experts recommend that health care professionals remind patients of needed immunizations, few practitioners actually use reminders. Little is known about the effectiveness of reminders in different settings or patient populations. OBJECTIVES: To assess the effectiveness of patient reminder systems in improving immunization rates, and to compare the effectiveness of different types of reminders for a variety of patient populations. DATA SOURCES: A search was performed using MEDLINE, EMBASE, PsychINFO, Sociological Abstracts, and CAB Health Abstracts. Relevant articles, as well as published abstracts, conference proceedings, and files of study collaborators, were searched for relevant references. STUDY SELECTION AND DATA EXTRACTION: English-language studies involving patient reminder/recall interventions (using criteria established by the Cochrane Collaboration) were eligible for review if they involved randomized controlled trials, controlled before-after studies, or interrupted time series, and measured immunization rates. Of 109 studies identified, 41 met eligibility criteria. Studies were reviewed independently by 2 reviewers using a standardized checklist. Results of studies are expressed as absolute percentage-point changes in immunization rates and as odds ratios (ORs). Studies with similar characteristics of patients or interventions were pooled (random effects model). DATA SYNTHESIS: Patient reminder systems were effective in improving immunization rates in 33 (80%) of the 41 studies, irrespective of baseline immunization rates, patient age, setting, or vaccination type. Increases in immunization rates due to reminders ranged from 5 to 20 percentage points. Reminders were effective for childhood vaccinations (OR, 2.02; 95% confidence interval [CI], 1.49-2.72), childhood influenza vaccinations (OR, 4. 25; 95% CI, 2.10-8.60), adult pneumococcus or tetanus vaccinations (OR, 5.14; 95% CI, 1.21-21.78), and adult influenza vaccinations (OR, 2.29; 95% CI, 1.69-3.10). While reminders were most effective in academic settings (OR, 3.33; 95% CI, 1.98-5.58), they were also highly effective in private practice settings (OR, 1.79; 95% CI, 1. 45-2.22) and public health clinics (OR, 2.09; 95% CI, 1.42-3.07). All types of reminders were effective (postcards, letters, and telephone or autodialer calls), with telephone reminders being most effective but costliest. CONCLUSIONS: Patient reminder systems in primary care settings are effective in improving immunization rates. Primary care physicians should use patient reminders to improve immunization delivery. JAMA. 2000;284:1820-1827.

Decline in physician referrals to health department clinics for immunizations: the role of vaccine financing.

BACKGROUND: Physicians frequently refer children to health department clinics (HDCs) for immunizations because of high out-of-pocket costs to parents and poor reimbursement for providers. Referrals for immunizations can lead to scattered care. In 1994, two vaccine financing reforms began in New York State that reduced patient costs and improved provider reimbursement: the Vaccines for Children Program (VFC, mostly for those on Medicaid and uninsured) and a law requiring indemnity insurers to cover childhood immunizations and preventive services. OBJECTIVE: To measure reported changes in physician referrals to HDCs for immunizations before and after the vaccine financing reforms. DESIGN: In 1993, a self-administered survey measured immunization referral practices of primary care physicians. In 1997, we resurveyed respondents of the 1993 survey to evaluate changes in referrals. SETTING/ PARTICIPANTS: Three hundred twenty-eight eligible New York State primary care physicians (65% pediatricians and 35% family physicians) who responded to the 1997 follow-up immunization survey (response rate of 82%). RESULTS: The proportion of physicians reporting that they referred some or all children out for immunizations decreased from 51% in 1993 to 18% in 1997 (p<0.001). In 1997, physicians were more likely to refer if they were family physicians (28% vs. 13%,p<0.01), or did not obtain VFC vaccines (29% vs. 13%,p<0.001). According to physicians who referred in 1993, decreased referrals in 1997 were due to the new insurance laws (noted by 61%), VFC (60%), Child Health Plus (a statewide insurance program for poor children, 28%), growth in commercial managed care (23%), Medicaid managed care (19%), and higher Medicaid reimbursement for immunizations that is due to VFC (18%). For physicians noting a decline in referrals, the magnitude of the decline was substantial-60% fewer referrals for VFC-eligible patients and 50% fewer for patients eligible under the new insurance law. CONCLUSIONS: Vaccine financing reforms decreased the proportion of physicians who referred children to HDCs for immunizations, and may have reduced scattering of pediatric care.

Impact of vaccine financing on vaccinations delivered by health department clinics.

OBJECTIVES: This study measured the number of childhood vaccinations delivered at health department clinics (HDCs) before and after changes in vaccine financing in 1994, and it assessed the impact of changes in financing on HDC operations. METHODS: We measured the number of vaccination doses administered annually at all 57 HDCs in New York State between 1991 and 1996, before and after the financing changes. Interviews of HDC personnel assessed the impact of financing changes. A secondary study measured trends in Pennsylvania and California. RESULTS: HDC vaccinations for preschool children in New York State declined slightly prior to the financing changes (6%-8% between 1991 and 1993) but declined markedly thereafter (53%-56% between 1993 and 1996). According to nearly two thirds of New York State's HDCs, the primary cause for this decline was the vaccine-financing changes. HDC vaccinations for preschool children in Pennsylvania declined by 12% between 1991 and 1993 and by 56% between 1993 and 1997. HDC vaccinations for polio-containing vaccines in California declined by 31% between 1993 and 1997. CONCLUSIONS: Substantially fewer vaccinations have been administered at HDCs since changes in vaccine financing, thereby keeping preschool children in their primary care medical homes.

Reviews of evidence regarding interventions to improve vaccination coverage in children, adolescents, and adults. The Task Force on Community Preventive Services.

This paper presents the results of systematic reviews of the effectiveness, applicability, other effects, economic impact, and barriers to use of selected population-based interventions intended to improve vaccination coverage. The related systematic reviews are linked by a common conceptual approach. These reviews form the basis for recommendations by the Task Force on Community Preventive Services (the Task Force) regarding the use of these selected interventions. The Task Force recommendations are presented on pp. 92-96 of this issue.

Evaluation of children's health insurance: from New York State's CHild Health Plus to SCHIP.

BACKGROUND: The legislation and funding of the State Children's Health Insurance Program (SCHIP) in 1997 resulted in the largest public investment in child health care in 30 years. The program was designed to provide health insurance for the estimated 11 million uninsured children in the United States. In 1991 New York State implemented a state-funded program-Child Health Plus (CHPlus)-intended to provide health insurance for uninsured children who were ineligible for Medicaid. The program became one of the prototypes for SCHIP: This study was designed to measure the association between CHPlus and access to care, utilization of care, quality of care, and health care costs to understand the potential impact of one type of prototype SCHIP program. METHODS: The study took place in the 6-county region of upstate New York around and including the city of Rochester. A before-and-during design was used to compare children's health care for the year before they enrolled in CHPlus versus the first year during enrollment in CHPlus. The study included 1828 children (ages 0-6.99 years at enrollment) who enrolled between November 1, 1991 and August 1, 1993. A substudy involved 187 children 2 to 12.99 years old who had asthma. Data collection involved: 1) interviews of parents to obtain information about demographics, sources of health care, experience and satisfaction with CHPlus, and perceived impact of CHPlus; 2) medical chart reviews at all primary care offices, emergency departments, and health department clinics in the 6-county region to measure utilization of health services; 3) claims analysis to assess costs of care during CHPlus and to impute costs before CHPlus; and 4) analyses of existing datasets including the Current Population Survey, National Health Interview Survey, and statewide hospitalization datasets to anchor the study in relation to the statewide CHPlus population and to assess secular trends in child health care. Logistic regression and Poisson regression were used to compare the means of dependent measures with and without CHPlus coverage, while controlling for age, prior insurance type, and gap in insurance coverage before CHPlus. ENROLLMENT: Only one third of CHPlus-eligible children throughout New York State had enrolled in the program by 1993. Lower enrollment rates occurred among Hispanic and black children than among white children, and among children from lowest income levels. PROFILE OF CHPlus ENROLLEES: Most enrollees were either previously uninsured, had Medicaid but were no longer eligible, or had parents who either lost a job and related private insurance coverage or could no longer afford commercial or private insurance. Most families heard about CHPlus from a friend, physician, or insurer. Television, radio, and newspaper advertisements were not major sources of information. Nearly all families had at least 1 employed parent. Two thirds of the children resided in 2-parent households. Parents reported that most children were in excellent or good health and only a few were in poor health. The enrolled population was thus a relatively low-risk, generally healthy group of children in low-income, working families. ACCESS AND UTILIZATION OF HEALTH CARE: Utilization of primary care increased dramatically after enrollment in CHPlus, compared with before CHPlus. Visits to primary care medical homes for preventive, acute, and chronic care increased markedly. Visits to medical homes also increased for children with asthma. There was, however, no significant association between enrollment in CHPlus and changes in utilization of emergency departments, specialty services, or inpatient care. QUALITY OF CARE: CHPlus was associated with improvements in many measures involving quality of primary care, including preventive visits, immunization rates, use of the medical home for health care, compliance with preventive guidelines, and parent-reported health status of the child. (ABSTRACT TRUNCATED)

Evolution of a children's health insurance program: lessons from New York State's Child Health Plus.

The State Children's Health Insurance Program (SCHIP) was passed by Congress in 1997. It provides almost $40 billion in federal block grant funding through the year 2007 for states to expand health insurance for children. States have the option of expanding their Medicaid programs, creating separate insurance programs, or developing combination plans using both Medicaid and the private insurance option. New York State's child health insurance plan, known by its marketing name Child Health Plus, was created by the New York Legislature in 1990. New York's program, along with similar ones from several other states, served as models for the federal legislation, especially for state health insurance plans offered through private insurers. New York's program provides useful data for successful implementation of SCHIP.

Evaluation of New York State's Child Health Plus: methods.

BACKGROUND: The State Children's Health Insurance Program (SCHIP) is the largest public investment in child health care in 30 years, targeting 11 million uninsured children, yet little is known about the impact of health insurance on uninsured children. In 1991 New York State implemented Child Health Plus (CHPlus), a health insurance program that was a prototype for SCHIP. A study was designed to measure the association between CHPlus and access to care, utilization of services, and quality of care. METHODS: The setting was a 6-county region in upstate New York (population 1 million) around and including the city of Rochester. A before-and-during design was used to compare children's health care for the year before they enrolled in CHPlus versus the first year during CHPlus, for 1828 children (ages 0-6.99 years at enrollment) who enrolled between November 1, 1991 and August 1, 1993. An additional study involved 187 children 2 to 12.99 years old who had asthma. Parents were interviewed to assess demographic characteristics, sources of health care, experience with CHPlus, and impact of CHPlus on their children's quality of care and health status. Medical charts were reviewed to measure utilization and quality of care, for 1730 children 0 to 6.99 years and 169 children who had asthma. Charts were reviewed at all primary care offices and at the 12 emergency departments and 6 public health department clinics in the region. CHPlus claims files were analyzed to determine costs during CHPlus and to impute costs before CHPlus from utilization data. ANALYSES: Logistic regression and Poisson regression were used to compare the means of dependent measures with and without CHPlus coverage, while controlling for age, prior insurance type, and gap in insurance coverage before CHPlus. CONCLUSIONS: This study developed and implemented methods to evaluate the association between enrollment in a health insurance program and children's health care. These methods may also be useful for evaluations of SCHIP.