The dynamics of health care delivery for children and adolescents have greatly evolved over the last 5 years. The growth of managed care has been especially rapid, and has coincided with other fundamental changes—declines in private coverage, growth of Medicaid, welfare reform, and the creation of the state Child Health Insurance Program (CHIP).1 Over the past 10 years, the number of children covered through employer-sponsored plans and other private plans has dropped.2 During this same period, changes to Medicaid have begun to de-couple eligibility from welfare eligibility, theoretically enabling states to expand coverage. For children, this movement from private to public coverage has accelerated the movement to managed care systems. Between 1991 and 1997, Medicaid enrollment in managed care plans increased from 9.5% to 47.8% of total Medicaid enrollment.3 Recent estimates suggest that over half of these Medicaid managed care enrollees are children.4 However, little is known about the impact of these trends on children's access to and use of services, let alone the quality and outcomes of that care.This report is the first in what is anticipated to be an annual series of reports on access to and use of health care services by America's children and youth. The report capitalizes on the existence of 2 national datasets, the Medical Expenditure Panel Survey (MEPS) and the Healthcare Cost and Utilization Project (HCUP), which have not been widely used by the child health services research community. As background to these new sources of data, we have provided a detailed description of the datasets, and review some of the fundamental tabulations. In future years, as more data are accumulated, these reports will focus on delineation of key trends and analyses addressing policy issues.The MEPS is conducted to provide nationally representative estimates of health care use, expenditures, sources of payment, and insurance coverage for the US civilian noninstitutionalized population, cosponsored by the Agency for Health Care Policy and Research (AHCPR) and the National Center of Health Statistics. This survey contains a level of detail and breadth that is far greater than other surveys of health insurance in the United States. Through the surveys detailed below, MEPS provides the linked information that is needed to examine important relationships between insurance, access, use of health care services, and costs of care for children and adolescents.MEPS comprises 4 component surveys: the Household Component (HC), the Medical Provider Component (MPC), the Insurance Component (IC), and the Nursing Home Component. The latter is not further discussed in this report. The HC is the core survey, and it forms the basis for the MPC sample and part of the IC sample. The sampling frame for the MEPS HC is drawn from respondents to the National Health Interview Survey and includes an oversampling of Hispanics and blacks.The HC collects detailed data on demographic characteristics, health conditions, health status, use of medical care services, charges and payments, access to care, satisfaction with care, health insurance coverage, income, and employment. Data are collected using an overlapping panel design over a 2.5-year period in a series of 5 rounds of interviews (Fig 1). Using computer-assisted personal interviewing technology, data on medical expenditures and health care services use for 2 calendar years are collected from each household. The overlapping panel design allows data from 2 panels to be combined to provide continuous and current estimates of based on a larger sample size. The base sample size in any given year is approximately 23 000 individuals, increasing every 5 years to a peak of 33 000. In 1996, there were 10 500 families and 6286 children <18 years. The HC is designed to provide national estimates and does not have a large enough sample to provide reliable state-based estimates.The MPC supplements and validates information on medical care events that were reported by respondents in the HC. All hospitals and pharmacies, and a sample of medical providers identified by household respondents are contacted through telephone interviews and mailed survey materials. The information provided during the HC is then verified and missing information is supplemented. Data collected in the MPC includes the following: diagnoses coded according to theInternational Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) and the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition ; physician procedure codes classified by Current Procedural Terminology, Version 4; inpatient stay codes classified by diagnosis-related group; prescription codes by national drug code, medication names, strength, and quantity dispensed; and charges, payments, and the reasons for any difference between charges and payments.While insurance information is collected from household respondents, MEPS also includes a separately constructed sample of establishments, which offer health insurance. The MEPS IC collects data on health insurance plans obtained through employers, unions, and other sources of private health insurance. Data obtained in the IC include the number and types of private insurance plans offered, benefits associated with these plans, premiums, contributions by employers and employees, and employer characteristics. Establishments participating in the MEPS IC are selected through employers and insurance providers identified by MEPS HC respondents, the Bureau of the Census, and an Internal Revenue Service list of the self-employed. Data are collected from the selected organizations through a prescreening telephone interview, a mailed questionnaire, and a telephone follow-up for nonrespondents. The IC is large enough to provide state-based estimates of health insurance for 40 states, a listing of which is available from AHCPR.MEPS is the third in a series of national probability surveys conducted by AHCPR on the financing and use of medical care in the United States. The National Medical Care Expenditure Survey was conducted in 1977 and the National Medical Expenditure Survey was conducted in 1987. These three surveys allow for analysis of trends over time in medical care, and public use files are available at the AHCPR web site (www.ahcpr.gov).This study uses data from the HCUP. HCUP is a federal-state-private sector collaboration, sponsored by AHCPR, to collect hospital discharge abstract data for purposes of research. (Information on obtaining HCUP datasets from 1988 to 1996 is also available on the AHCPR website.) For the 1996 data year, 19 statesa contributed their hospital data to HCUP, encompassing over half of all hospital discharge abstracts in the United States. The state data are translated into a uniform format to facilitate multistate comparisons and research, and together comprise the HCUP State Inpatient Databases (SID). The SID contain the universe of all inpatient discharge abstracts in participating states and contain a core set of clinical and nonclinical information found in a typical discharge abstract.The Nationwide Inpatient Sample (NIS) is drawn from the SID and approximates a 20% sample of US community hospitals, as defined by the American Hospital Association (AHA) annual survey.5 The AHA defines community hospitals as all non-federal short-term (average length of stay <30 days) general and specialty hospitals whose facilities are open to the general public. Specialty hospitals include obstetrics-gynecology, pediatric, short-term rehabilitation, orthopedic, and oncology hospitals, among others. Excluded are long-term hospitals, psychiatric hospitals, and alcohol/chemical dependency treatment facilities. The NIS collects all inpatient stays from sampled institutions and includes >900 hospitals and 6.5 million discharges for 1996, of which 1.2 million are for children <18 years old.The NIS sample is a stratified probability sample of hospitals in the frame, with sampling probabilities proportional to the number of US community hospitals in each stratum. The hospital universe is defined using the AHA annual survey of hospitals.5 This universe of hospitals is divided into strata using 5 hospital characteristics: ownership/control, bed size, teaching status, rural/urban location, and geographic region. Hospitals from HCUP participating states (the sampling frame) are selected to represent these strata, and all discharges from sampled hospitals are included in the database. Weights indicate the number of discharges that the sample discharge represents in the universe of discharges from US hospitals for that year in that stratum. The total number of discharges in the universe from that stratum is also taken from the AHA annual survey of hospitals.5The entire sample of NIS discharges for 1996 was used for this study (N = 6 542 000) from 906 hospitals. These discharges were weighted to obtain estimates that are representative of hospital inpatient discharges in the United States. The estimated total number of discharges represented in these analyses is 34 874 000. This estimate is comparable to the estimate of 34.4 million discharges (30.5 million non-newborn discharges plus 3.9 million newborns) based on the National Hospital Discharge Survey.6 The unit of analysis is the discharge, or hospital stay, rather than the patient. Because the NIS is limited to inpatient hospital data, conditions treated on an ambulatory basis are not represented here.The diagnoses recorded on hospital discharge abstracts are coded using the ICD-9-CM.7 The ICD-9-CM consists of >12 000 diagnosis codes. Although it is possible to present descriptive statistics for individual ICD-9-CM codes, it is often helpful to aggregate codes into clinically meaningful categories that group similar conditions.For this study, diagnoses and procedures were initially categorized using the Clinical Classification Software, which was developed to provide a convenient way to report hospital statistics by diagnosis or procedure.8 The Clinical Classification Software aggregates illnesses and conditions into 259 mutually exclusive categories, most of which are clinically homogeneous. Some heterogeneous categories combine several less common individual conditions. For this report, these categories were further aggregated for ease of presentation.The number of cases in the NIS was multiplied by hospital-specific discharge weights to derive national estimates of the number of discharges. Results are not presented when the unweighted number of discharges is <70. Using a generalized variance technique for proportions, it was determined that a sample of at least 70 discharges is required to ensure, with 95% confidence, that the reported proportions had a relative error of <30% (ie, if the reported value is P, the error is <.3P). All results reported are significant at P < .05; most results are significant at P < .001.All charge data are charges for the hospitalization, excluding professional (primarily physician) fees. Charges do not necessarily reflect costs nor are they synonymous with reimbursements. In the NIS, charge data are present for 98% of all discharges.These 2 databases provide critical insight into the factors driving health care for children and youth. Results are reported for each sequentially. MEPS is used as the source of information for all data on insurance coverage and utilization of ambulatory care services. HCUP is the source of all data on patterns of hospitalization.In general, children are more likely than adults to have health insurance.9 Nearly 90% of children had either private or public health insurance for some period of time during 1996 (Table 1). However, a comparison of full year MEPS data with insurance estimates from the first round of data collection reveals that there is substantial movement of children on and off insurance. When measured at a single in the of children are to year of were more likely than children in other to private health insurance or to have public insurance. insurance to in to children and of children <18 years had public insurance, with of between and years these data do not is that a substantial number of children for public insurance are not and estimated that in 1996, million children were not in children were more likely than children from other to have private health insurance and were the least likely to have public insurance (Table children were the group most likely to be When with a greater of and children were covered public health insurance. 4 as children were covered by public health insurance as children are the source of health insurance for the of children covered by the private sector data not in families with single were not were the least likely to have private health insurance in families were were the group most likely to be when with children of families or families was coverage was far less common when of the in a was in families with single were not were the most likely to be In a child was most likely to be when was 1996 MEPS data and surveys in and and the between income, and children's health insurance and found that the in the of children were during this period was a and that the of children in families from to In and found that the of coverage increased over the last the of families of coverage as a to the in in the level was more than were the most likely to be with at least with a were more likely to have private health insurance than children whose had less than a or with less than a was associated with public health insurance and whose had less than a were the most likely group to be of children were reported in or in or health were more likely than children in or health to have private health insurance. children with or health were more likely to have public insurance when with children in or health in the and were more likely than children in the or to have private health insurance. in the were more likely than children in the to have public health insurance. of children in the and were when with children in the and in were more likely to have private health insurance than children not in a source of care is associated with a greater of a of children had a source of care in 1996 (Table of health insurance status, adolescents were more likely to a source of adolescents to years were the most likely to a source of care and children years were the least likely to a source of care children, to years were more than as likely as years to a source of and trends in source of care over the last years and found that had for all In they found important difference by with Hispanics the most in a source of care in 1996, with in most their analysis that 20% of this be to increasing of of a source of care has also been associated with the costs and quality of that children years were the most likely to have an source of care to years with either public or insurance were the least likely to on and estimates based on 1996 data that of children <18 years at least ambulatory medical care in 1996 with a number of for children with at least not a source of care was associated with a in the of some ambulatory medical care services by children with data not The patterns of ambulatory health care services by site of care and include to physician and providers as as providers of of children had an based in 1996 (Table children were more likely than adolescents to have had an with the among children to 4 years children were more likely than children in other to have had an larger of children in a were also more likely to have had an when with not in a with private insurance were most likely to have had at least and children were were the least likely include ambulatory to physician and providers as as providers of in hospital and of children <18 years used ambulatory services in a hospital in to children to 4 years were more likely than children in other to have had at least The same for children when with children of other more likely to have had a were children were in or health with children in or health children were the least likely when with children with private or public health insurance to have a include all to the and include physician and of children had an in year were the least likely and children to 4 years were the most likely to have had an when with children of other of children had an when with or children and children of other in a was associated with a of children with at least with children not in a in or health were as likely as in or health to have had at least children were more likely than children, and 20% more likely than children, to have had at least in care included to general and than half of all children and adolescents had a care in 1996 and of children with at least 5 years and over were more likely than children years to have had at least care and children were less likely than children or children of other to have a care include or any of children <18 years at least prescription during to 4 years were more likely than any other group to have had at least prescription children were also more likely than or children or children of other group to have obtained a prescription in or health or private health insurance were associated with a larger of children a prescription were were the least likely to have a prescription 1996, children and <18 years for of in the United the of which were among year (Table were as likely or less likely to be adults The charge for each hospital for children and was about half that for adults with substantial the of care to charges for their on less than for the of about of children and were through the The of coded that are to a of medical care, a was in children and than adults and also significant by not As among children was than for adults with children and had a discharge and were to data not Medicaid was the for more for children and than for adults The of was for adolescents to years in to large and in private institutions in and were more likely than adults to be to a teaching and this was most among children 5 to years with for The of by of the the the of hospital were by of the (Table The length of stay was in the days) and in the However, charges were in the and in the The of from the was in the with other to children and were more likely to have private insurance in the and than in the and to half the were covered by In the a of were to hospitals, in the and proportions of were to and public hospitals. to teaching hospitals for of in the little more than a in the were in of or discharge not of hospital discharges for children and were also by (Table length of stay and charges were for the and for on The were also more likely to be through the on Medicaid and were more likely to be to public diagnoses at discharge by and from diagnoses (Table and in and to a in the Over and health in the 10 most conditions in the In the to hospital use also and In the most among adults from and difference between children and adults is that the 10 diagnoses for a far greater of for children, to for the to than for adults the 10 diagnoses for of all This the of children and youth. Although children do not have the of common conditions that adults they do have conditions. However, a number of conditions for a larger of among children and For among the 10 conditions, and to over half of all in the to group and a third of all in the to and for to group of conditions has comparable for the of the 10 diagnoses were by (Table were for the 6 conditions, for were more likely to be covered by Medicaid, and for health were more likely to be covered by private insurance. health were among insurance or covered by results provide for in the on health care access and use in children and is important is that they provide a for changes in this of health care the has been by information on the that is to the of Child health and have had a more of data and of it is The results reported to suggest the that will be in more detail in future they provide to to these new datasets to important in child health future years, data collected in the expenditures and of coverage, will be The survey has also been in to on the state Child Health Insurance Program as a source of coverage and will national of the of this new in in future years will be in insurance coverage estimates from will be a new HCUP is developed and will in the This will be constructed to examine children's use of hospital services and is designed to and of children's conditions, conditions as of care is a critical of health care for children that is not included in this report. Recent have the in children's health quality and that in care as they do in with significant for we any national to health care be it for children or This is to a of and of quality of care for children and the of a national for the collection of number of are that will future on quality for children and youth. the of Health reports of their and satisfaction with the care their children In information from of Health Survey will be available to million and analyses of these data are significant in the of care quality for important to information on quality include The HCUP were developed to in quality of care using 2 of these 33 children's health and of quality for children are of ambulatory care quality are developed by the Child and Health among MEPS and HCUP datasets have significant their use some information on their Discharge abstract data on presented this year for the first are data collected as a in the discharge of from hospitals, for The of discharge abstract data in the detailed information provided on diagnoses and procedures and the large number of data be used to into patterns of hospitalization, of conditions, and use of hospital However, data on inpatient stays were not for research there be with the and of data Although error have been the and of conditions as and drug and to what this estimates for children is analyses that are limited to diagnoses and the reported to of will an of diagnoses that to in the of conditions, as in children the of of discharge for some of child The of an HCUP designed to analyses of children's to this MEPS data reported on report of health and use of a research is needed to reports in the HC with other to the of the important of this report is the of information on patterns of care at the state MEPS does not state-based As a of the large sample size in the most states, there be a to derive estimates to all by the In this MEPS also allows for that include state in to estimate the of these on care In HCUP is a for state level at least for states that are current in the are to expand the number of states included in HCUP and future reports in this series will include on state-based estimates have important for of children's growth in financing children's health care, of national data collection to at the state level is in the of reports as this is the of annual reports that of children's the most of which National of or these reports on the the health This the to use and these we future reports from these important datasets, we from the of the that the of analyses and datasets will be if they are to the by for children and youth.

Barbara Kass

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