Objective. To measure the impact of asthma on the use and cost of health care by children in a managed care organization.
Design. Population-based historical cohort study.
Setting. A medium-sized staff model health maintenance organization in western Washington state.
Subjects. All 71 818 children, between age 1 to 17 years, who were enrolled and used services during 1992.
Outcome Measures. Children were identified with one or more asthma diagnoses during 1992 using automated encounter data. Nonurgent outpatient visits, pharmacy fills, urgent care visits, and hospital days, as well as associated costs were measured. All services were categorized as asthma care or nonasthma care. Multivariate regression analysis was used to compute marginal cost for asthma (difference in total cost between children with asthma and other children using services, adjusted for covariates).
Results. Treated prevalence of asthma was 4.9%. Children with asthma incurred 88% more costs ($1060.32 vs $563.81/yr), filled 2.77 times as many prescriptions (11.59 vs 4.19/yr), made 65% more nonurgent outpatient visits (5.75 vs 3.48/yr), and had twice as many inpatient days (.23 vs .11/yr) compared with the general population of children using services. Asthma care represented 37% of all health care received by children with asthma, while the remaining 63% were for nonasthma services. Almost two-thirds of asthma-related costs were attributable to nonurgent outpatient care and prescriptions; only one third was attributable to urgent care and hospitalizations. Controlling for age, sex, and comorbidities, the marginal cost of asthma was $615.17/yr (95% confidence interval $502.73, $727.61), which includes asthma as well as nonasthma services. This marginal cost represents 58% of all health care costs for children with asthma.
Conclusions. Children with asthma use significantly more health services (and incur significantly more costs) than other children using services, attributable largely to asthma care. The majority of all health care costs for children with asthma were for nonasthma services. Urgent care visits and hospitalizations are less important components of asthma costs in this managed care organization than has been found in other national studies.
Asthma is the most common chronic illness of childhood and has a prevalence of 3% to 7%.1,2 Asthma accounts for an estimated 13 million doctor visits and 200 000 hospitalizations per year in United States children.3 Children with asthma have three times the rate of school absences as children without the disease.4 The increasing prevalence of asthma over the last two decades2 and the rising numbers of children with asthma requiring acute services5,6 have further focused attention on asthma. Although asthma can negatively impact quality of life, lead to costly emergency department (ED) and hospital utilization, and result in potentially life-threatening exacerbations, many of these poor outcomes are preventable with appropriate outpatient management.7
Managed care organizations and other health care providers have begun to take a population-based preventive approach to managing children with asthma8 by ensuring delivery of sustained preventive services to this population. Public and private health care insurers have recognized the impact of pediatric asthma on health care utilization, motivating efforts to minimize total costs for children with asthma by decreasing ED and hospital use.9 However, the components of total health care costs for children with asthma have not been well studied and an overall understanding of the health care utilization patterns in this population is lacking.10 Such an understanding is essential for developing cost-effective strategies for asthma management.11
Several investigators have studied asthma care from a population perspective. Large administrative databases have been used to track hospitalization trends,12-15 medication use,16-18 and outpatient care.19 Weiss and colleagues used a variety of national data sources to compute the magnitude of the national economic burden of asthma.20 A recent study of four independent practice organizations estimated charges incurred specifically for asthma care and selected respiratory conditions but did not report total health care costs of children with asthma.21
Each of the above studies suffers from one or more of the following limitations, often due to the unavailability of the necessary data: lack of a denominator of individuals with asthma (ie, not truly population based); failure to consider the entire spectrum of asthma care (including primary, specialty, pharmacy, urgent, and inpatient); exclusive focus on asthma-related care while ignoring nonasthma care received by persons with asthma; use of charges rather than actual direct costs; and mingling of costs or charges from different health care systems.
Group Health Cooperative of Puget Sound (GHC) provided a unique setting in which we were able to study the health care use patterns of a defined population of children with asthma in a closed-panel setting, using outpatient diagnostic and cost data. We studied the health care utilization and cost of a cohort of children with asthma at GHC in order to:
Measure health care cost and utilization for children with asthma compared with the general population of children,
Measure the difference in total cost attributable specifically to asthma care and the cost due to other services,
Determine the distribution of utilization across categories of service (nonurgent outpatient care, pharmacy, urgent care, and inpatient care), and
Compare unadjusted cost differences to a multivariate model-based estimate of the marginal cost. Marginal cost refers to the estimated cost of care accounted for by the diagnosis of asthma after adjusting for age, sex, and comorbidities.
Established in 1947, GHC is a staff model HMO that serves approximately 380 000 enrollees in western Washington state. GHC is the country's largest consumer-governed health care organization. GHC has slightly fewer nonwhite enrollees (approximately 9%) and slightly more highly-educated enrollees than the Puget Sound population. GHC's 650 staff physicians provide health services through its 28 primary care clinics, two specialty centers, and two hospitals. In addition, GHC has contractual relationships with external facilities and health care professionals who also provide services to GHC enrollees.
Information and Costing Systems
GHC information systems capture basic demographic data, and diagnostic and procedural data on all ambulatory and inpatient care provided internally or from contracted providers. GHC's Decision Support System (DSS) contains data on the true cost of services through a system which fully allocates all health service delivery costs to individuals on a monthly basis.22
DSS automatically links the general ledger to a clinical and financial data repository through a cost accounting system. It uses an activity-based accounting approach that allocates all overhead costs to each service level department (eg, medical staff, nursing pharmacy, laboratory, and so forth). Each department has its own unit of service that serves as an activity basis for costing (eg, time-weighted outpatient visits for medical staff and technical Relative Value Units for radiology). The cost per unit that results from this cost-accounting system reflects the actual costs of medical personnel and supplies to provide the services as well as overhead costs. Outside services (including hospitalizations, urgent and nonurgent outpatient care, and pharmacy) are allocated based on Group Health's payment to those providers so that costs are equal to GHC's liability. Costs to the enrollee (in the form of copays) are not recorded on DSS.
Systematic verification of the automated data occurs through on-line edits, automatic prompts to data entry clerks if information is incomplete, and monthly comparisons of the system output and departmental level data. Internal controls also systematically compare the total of all outputs against the general ledger and transaction systems, such as the hospital information system and registration. Independent audits of system output were also conducted by auditors representing Medicare, Medicaid, and the Joint Commission on Accreditation of Healthcare Organizations. These auditors used standard procedures, such as statistical sampling of detailed variables and verification against source data, to ensure accuracy and completeness.22
We conducted a historical cohort study, collecting automated utilization data for all children between ages 1 to 17 years who were continuously enrolled at GHC between January 1 and December 31, 1992. Children were included in the cohort if they had at least one visit or admission (any diagnosis) during 1992. We excluded children under 1 year because of the difficulty in distinguishing between bronchiolitis and asthma in this age group. Also excluded were 80 children with cancer who had extremely high health care utilization. During the study period, no system-wide changes were instituted in the delivery of asthma care.
This study cohort was divided into the asthma group (“children with asthma”) and the control group (“children without asthma”). The asthma group consisted of all children with at least one diagnosis of asthma (International Classification of Diseases Code-9 of 493.XX) listed for an outpatient visit or hospitalization during 1992 (ie, provider-diagnosed asthma). A maximum of 2 outpatient and 10 inpatient diagnoses could be listed. Medical record review of a random sample of 150 children in the asthma group demonstrated that clinical documentation supported the diagnosis of asthma in 92% of cases (data not shown). The control group consisted of all children not in the asthma group. Because the total cohort was restricted to utilizers only, the control and asthma groups were comparable in being utilizers of services.
In addition to reporting results separately for the asthma and control groups, we included the entire cohort (“all children”) as a comparison group in Tables 1, 2, and 3, in order to make these comparisons more interpretable from the perspective of the health care provider or the health care organization.
The main outcomes of interest were utilization and cost. These were divided in two ways: (1) asthma services versus nonasthma services, and (2) by category of service. We divided encounters into asthma services and nonasthma services according to ICD-9 and drug codes. Drugs categorized as asthma medications included β-agonists, cromolyn, oral and inhaled steroids, and theophylline. We included oral steroids because we felt that the incidence of their use for nonasthma illnesses (eg, arthritis, Crohn disease) to be negligible in comparison to their use for asthma. Note that because the asthma group was defined only by diagnosis code, there were some children in the control group who received asthma medications during the study year, but did not have an encounter with an asthma diagnosis during that year. Costs for asthma and nonasthma services were computed as the sum of all costs corresponding to encounters in those categories.
Encounters were also classified into four categories of service: nonurgent outpatient visit, pharmacy fill, urgent care visit, and hospitalization. Nonurgent outpatient visits were defined as visits to outpatient clinics during normal business hours (7:30am to 5:30 pm on weekdays). Nonurgent outpatient visits which occurred at GHC facilities were subdivided into primary and specialty care visits using provider codes. Twelve percent of nonurgent outpatient visits were to external providers and could not be classified as primary or specialty visits. Pharmacy fills include initial dispensings and refills of all prescription medications as well as any over-the-counter medications covered by the pharmacy benefit, such as antihistamines and cold remedies. Urgent care visits were defined as either visits to one of GHC's two hospital-based emergency departments or visits to outpatient clinics on weekends or on weekdays after 5:30 pm Several types of services were not included in the four categories of service: laboratory, radiology, mental health, and physical therapy. Together, these services accounted for only 5% of all health care utilization in our cohort.
Per capita cost and utilization variables were expressed as visits, fills, hospitalizations, or dollars per child per year. These rates were compared between children with and without asthma using the Wilcoxon rank sum test with normal approximation and continuity correction of .5. Because of the low hospitalization rates, we also compared proportion of children hospitalized in the two groups using the χ2 test. In addition, cost and utilization ratios were expressed as per capita cost (or utilization) for children with asthma divided by per capita cost (or utilization) for all children.
Per capita cost and utilization differences (total and for each category of service) between the asthma and control groups were computed using two distinct methods: unadjusted and marginal (multivariate). The unadjusted cost and utilization differences represent the differences in use of resources between children with and without asthma. Unadjusted differences were computed by subtracting the per capita means for the control group from the per capita means for the asthma group.
Marginal costs represent the difference in health care cost accounted for by the diagnosis of asthma, adjusting for age, sex, and comorbidity in a multivariate regression model. By definition, marginal costs include the cost attributed specifically to asthma plus any increase in costs of nonasthma care (relative to children without asthma) incurred by children with asthma. Our choice of regression model was guided by the distribution of health services costs. The nonnormal distribution of health care costs results in error terms that are not independently and identically distributed, a key assumption with ordinary least squares. Therefore, the coefficients of an ordinary least squares regression would yield inefficient estimates of marginal cost, precluding calculation of standard errors and confidence intervals for specific cost estimates.
For this reason, we chose to estimate marginal costs for total health services using estimated generalized or weighted least squares. Weighted least squares is a family of approaches which weights or transforms the dependent variable in an ordinary least squares regression so that residuals are homoscedastic and coefficients are asymptotically efficient.23 A single equation approach is appropriate for our estimates of marginal cost for total health services costs because every child in the sample had used services during the year. Marginal cost estimates within the four categories of service were estimated with a two equation model which adjusts costs by age, sex, comorbidity, and the probability that the subject will have costs in each particular category.24,25 A two equation approach is appropriate for the categories of service because for any one category, there was a substantial number of children who used no services.
In order to control for comorbidity in multivariate models, we developed a general measure of chronic illness using a modification of the Ambulatory Diagnostic Groups (ADGs), a morbidity measure based on outpatient diagnosis codes.26 We selected the ten ADGs (from a total of 34 groups) which encompassed chronic conditions and excluded the ADG for asthma. We removed the codes indicating myopia and other refractory errors from the ADG for stable ophthalmologic conditions because these conditions had a high recorded prevalence in our population (13%) and would have heavily weighted our measure of comorbidity. Using this “chronic ADG score,” the prevalence of comorbidity in the study population was 10% among children without asthma and 21% among children with asthma.
There were 349 039 persons continuously enrolled during 1992 of which 71 818 were between ages 1 to 17 years (20.6%). (We excluded 17% of child enrollees because they did not use any health services during that year.) The period prevalence of treated asthma in our population of 1- to 17-year-old enrollees who used health care was 4.9% (n = 3531). There was a predominance of males (58.3%) and a slightly younger age distribution than the general population (Table1). Race is not coded on our database; however, data from other sources indicate that approximately 9% of Group Health patients are nonwhite (with 3% being African-American).27
Children with asthma made 1.65 times as many nonurgent outpatient visits (5.75 vs 3.48 visits) and filled 2.77 times as many prescriptions (11.59 vs 4.19 fills) as the general population of children. Children with asthma made 1.71 times as many urgent care visits (1.52 vs .89 visits) and had 2.09 times as many hospital days (0.23 vs .11) as the general population of children (Table2). The utilization differences between children with and without asthma were statistically significant (P = .0001) for each category, by the Wilcoxon rank sum test. The proportion of children hospitalized was 6.06% in the asthma group and 2.01% in the nonasthma group, and this difference was statistically significant (P = .001) by the χ2 test.
Among nonurgent outpatient visits within GHC, children with asthma made 4.30 primary care visits and .86 specialty visits, whereas all children made 2.58 primary care visits and .50 specialty visits. The ratio of primary to specialty care was 5.0 among children with asthma and 5.2 among the general population. (Provider type was not known for the 12% of nonurgent care visits that were made to providers outside GHC.)
During 1992, 2.2% (1592) of children in the general population and 6.1% (214) of children with asthma had at least one hospitalization. For children admitted at least once during 1992, the average number of admissions was 1.22 for the general population and 1.25 for children with asthma. The average length of stay for asthma hospitalizations was 2.12 days, compared with 4.30 days for nonasthma hospitalizations.
Children with asthma incurred 1.88 times the cost of the average child ($1060.32 vs 563.81; Table 3). Cost ratios (for children with asthma compared with all children) within categories of service ranged from 1.62 for nonurgent outpatient visits to 3.44 for pharmacy fills. The cost differences between children with and without asthma were statistically significant (P = .0001) for each category and for total costs, by the Wilcoxon rank sum test.
Figure 1 shows the mean per capita health care costs for the children with asthma (on the left) and children without asthma (on the right) divided into asthma-related services and nonasthma related services. Asthma-related care accounted for 37% of the total cost for children with asthma while the remaining 63% were for nonasthma services. Nonasthma care for children with asthma represented a 25% higher per capita cost than for children without asthma ($670.74 vs $536.58, P = .0002). Children with asthma incurred more than twice as much cost for nonasthma medication as children without asthma ($100.91 vs $46.45 per child per year, P < .0001). Most of the difference in total cost was accounted for by asthma-related services (Fig 1). (Note that asthma medications used by children without an asthma visit or hospitalization represent a negligible amount of charges.)
Within each category of service, asthma-related services accounted for between one-third and one-half of the cost of care for children with asthma (Table 4).
Figure 2 shows asthma-related costs for children with asthma by category of service. Nonurgent outpatient care and pharmacy services accounted for 62% of asthma-related costs for children with asthma. Hospital costs and urgent care visits accounted for only 26% and 11%, respectively. The distribution of total costs is quite similar to that of asthma-related costs: nonurgent outpatient care (48%) and pharmacy services (17%) accounted for 65% of total costs, and urgent care (14%) and hospitalizations (21%) accounted for 35% of total costs.
The unadjusted per capita cost difference between children with and without asthma was $522.19 ($1060.32 − $538.13), as shown in Table 5. Asthma-related care accounted for $389.57 for children with asthma, representing 75% of this total cost difference. The remaining 25% of this cost difference was, by definition, attributable to nonasthma care. Within each category of service, the overwhelming majority of the cost difference (60.1% to 91.5%) was attributable to asthma-related services (Table 5).
The distribution of the cost difference across categories of service was very similar to the distribution of total costs shown in Fig 2: nonurgent outpatient care, 39%; pharmacy, 26%; urgent care, 13%; and hospitalizations, 22%.
The cost and utilization differences presented thus far have been unadjusted differences (computed from per capita means without adjusting for covariates). Table 6 shows the unadjusted cost and utilization differences for children with asthma compared with children without asthma. In addition, this table presents the marginal costs estimated using multivariate models controlling for age, sex, and comorbidity. For our study population, the unadjusted cost differences lie within (or very close to) the respective confidence intervals for marginal cost (for overall cost and for nonurgent outpatient, pharmacy, and urgent care categories). The marginal cost of inpatient care was not computed because relatively the low admission rate resulted in poor model fit. The marginal cost of asthma (for all categories of service) was $615.17 (95% CI $502.73, $727.61), representing 58% of all health care costs for children with asthma. The marginal cost of asthma was $217.66 for nonurgent outpatient visits, $150.30 for prescriptions, and $76.46 for urgent care visits. By definition, both marginal cost and the unadjusted cost difference include asthma-related services as well as non-asthma care.
During 1992, the average child with asthma at GHC made approximately six nonurgent outpatient visits, filled 12 prescriptions, made 1.5 urgent care visits, and spent .23 days in the hospital (Table2). Health care for children with asthma at GHC cost 88% more per capita than for all children who were continuously enrolled and used services during that year. This represented approximately $2 million per year in this HMO of 380 000 enrollees. Asthma care accounted for 30 to 45% of all services received by children with asthma. The preponderance of the marginal cost of asthma was for services which were specifically for asthma. Children with asthma had 25% higher use of nonasthma services than the general population. Two-thirds of the cost of asthma care were attributable to nonurgent outpatient care and prescriptions; only one third was attributable to urgent care and hospitalizations. We believe that these results are generalizable to other similar HMO populations. Of course, health care administrators and policy makers should not extrapolate our findings to entire populations of enrolled children without taking into account the fraction of their population who are nonusers of health care.
The total cost of asthma-related health care in our population was comparable to the total charges reported by Stempel and colleagues for children with asthma in a recent study of four managed-care organizations ($389.57 in our study, vs $472.02 in theirs).21 The distribution of cost for asthma-related care was similar with the exception that asthma medications accounted for a larger proportion of costs in the study by Stempel and colleagues (21% vs 38%) probably reflecting that study's use of two or more asthma prescriptions as an inclusion criteria.21 The same study reported an increase in ED and inpatient care among adolescent girls (compared with males, young girls and adult women), and although we found similar trends in our data, they did not approach statistical significance (data not shown).
We believe our study has five methodologic advantages over earlier studies:
It is population-based and measures utilization based on a defined denominator of children with asthma.
We considered the entire spectrum of asthma care (nonurgent outpatient care, pharmacy services, urgent care, and hospitalizations) and we were able to measure the relative contribution of these categories of services to overall utilization and cost.
We chose to examine all health care costs and utilization rather than just asthma-related costs. This is important because most health care utilization by children with asthma was for nonasthma services.
Our estimates are based on true costs rather than charges. The problems with using charges as a proxy for costs have been well documented.28 These concerns are heightened in a marketplace which places payers at a competitive advantage with respect to providers, resulting in cost estimates which reflect negotiated discounts that drive a wedge between charges and costs. GHC's cost accounting system allows us to study cost estimates that directly reflect the health care system's use of resources.
Our subjects received care in an integrated delivery system, thus optimizing data capture and comparability across the study cohort.
There are four main limitations of this study. First, the demographics of our study population represents fewer nonwhite patients and a higher socioeconomic status than other metropolitan areas. However, it is relatively representative of the Puget Sound employed population.27 Secondly, GHC is an established nonprofit HMO with a reputation for clinical excellence among HMOs. Although it could be argued that this makes the utilization patterns of its enrollees atypical, there were no coordinated changes in asthma management underway during the study period and thus we would argue that these results are generalizable to other similarly structured HMOs. The third limitation is that these data were from 1992, the first year in which diagnoses for ambulatory visits were recorded on Group Health's automated data. For this reason, we were concerned about possible misclassification of our subjects. In fact, chart review revealed that 92% of children with at least one an automated diagnosis of asthma had a clinical course highly consistent with asthma during the study period. Lastly, we were unable to measure out-of-pocket expenditures or control for differences in health care coverage, including copays. However, we were unable to find any substantial differences in asthma prevalence among study subjects in different employer groups and in groups of varying sizes. This suggests that it is unlikely that differences in coverage account for the observed differences in utilization between children with and without asthma.
The implications from our findings are threefold:
The impact of asthma on health care utilization was primarily on asthma-related services, although there was a 25% increase in nonasthma care among children with asthma.Furthermore, nonasthma care accounted for two-thirds of all health care received by children with asthma. For these reasons, we recommend that cost-effectiveness evaluations of asthma interventions take into account all health care utilization and cost, not only that which is coded as asthma. The fact that children with asthma have higher health care costs for nonasthma conditions is not surprising. Reasons for this may include higher use of ambulatory care and medications for conditions that can act synergistically with asthma (such as allergic rhinitis, sinusitis, otitis, respiratory infections; data not shown), higher health care use in general, and misclassification of asthma-related encounters as “non-asthma.”
Urgent care and hospitalization are less prominent in the cost distribution than might be suggested by national data. Our data differ substantially from national data on asthma-related health care costs which have shown ED and hospital costs to be the driving force behind national asthma expenditures. Note that, unlike national studies, we included urgent care and ED visits in the same category. In an analysis of 1985 data from a variety of national sources,20 hospitalization and ED expenses represented 78% of all asthma costs excluding medications (age-specific medication data were not available in that study). In our population, the comparable figure would be 47% (ie, hospitalization and urgent care asthma-related costs as a fraction of all inpatient and outpatient asthma-related care excluding medications). Similarly, analysis of the 1987 National Medical Expenditure Survey suggests that hospitalization and ED expenses accounted for 61% of total costs for asthma (unpublished data), compared with 37% in our study (ie, hospitalizations and urgent care asthma-related costs as a fraction of all asthma-related costs). Although such comparisons are flawed by the somewhat different definitions of asthma and disparate data collection methods used, the predominance of ED and hospital charges in the national data is in striking contrast to the predominance of nonurgent outpatient and pharmacy costs in our staff-model HMO.
One explanation for the difference between our results and national data could be that GHC enrollees have better access to preventive asthma care than the patients in these national samples, resulting in fewer acute exacerbations requiring ED visits or hospitalizations. It is also important to bear in mind that African-Americans, who have been shown to bear a disproportionate burden of asthma morbidity, are under represented in the GHC (and western Washington) populations.
An alternative explanation could be that primary care providers in this HMO may be playing a large role in acute asthma care, perhaps as a result of an organizational emphasis on primary care as well as various triage mechanisms that discourage patients' use of EDs and urgent care clinics. (Acute asthma visits to primary care providers are difficult to distinguish from chronic asthma care using our automated data.) If this were true, then measuring urgent visits and hospitalizations for asthma would seriously underestimate the rate of acute asthma exacerbations in settings such as ours.
Furthermore, our findings suggest that although prevention of urgent care visits and hospitalizations for asthma remains an important goal, it may not necessarily lead to a large cost reduction for health care delivery systems in which primary care providers already provide such a large proportion of asthma care. In contrast, in populations with poor access to care and fragmented asthma services, there is likely to be a greater potential for cost savings through interventions which reduce the need for acute asthma care. Accurate measurement of acute asthma visits to primary care may be important for future studies of health outcomes and cost in managed-care settings such as ours. Asthma interventions aimed at reducing morbidity and cost in managed-care environments will benefit from realistic expectations about potential cost savings in asthma care. These expectations must be based on a setting-specific understanding of the patterns of health care utilization for children with asthma.
The marginal cost method has potential advantages over the unadjusted cost difference estimates. Both marginal cost and unadjusted cost methods include the cost attributed specifically to asthma services as well as the increase in costs of nonasthma care (relative to children without asthma) incurred by children with asthma. However, the marginal cost approach uses multivariate techniques which allow us to control for patient demographics and comorbidity. This approach may be particularly useful in clinical trials or observational studies where covariates may differ substantially between study groups.
In conclusion, children with asthma in this HMO had substantially greater health care cost and utilization than the general population of enrolled children, with the bulk of the difference being due to asthma care. Compared with national estimates, hospitalizations and urgent care visits represented a smaller portion of asthma-related costs. We are currently examining the populations of children with asthma at GHC in an attempt to characterize those children who contribute most to health care utilization and cost. Replicating this study in other settings would further enhance our understanding of health care utilization and cost for children with asthma, inform the improvement of asthma management and guide rational cost-reduction efforts. We recommend that future cost evaluations of asthma interventions measure total costs (not just asthma-related costs) as well as measuring all four categories of service discussed here, and that researchers consider employing a marginal cost approach.
The research was funded by Glaxo Wellcome, Inc and the Poncin Foundation.
The authors gratefully acknowledge the contributions of Willard Manning and Carolyn Rutter to the marginal cost analysis and those of David Goodman to the medical record review instrument.
- Received June 28, 1996.
- Accepted October 10, 1996.
Reprint requests to (P.L.) Center for Health Studies, Suite 1600, Group Health Cooperative of Puget Sound, 1730 Minor Ave, Seattle, WA 98101.
- ED =
- emergency department •
- GHC =
- Group Health Cooperative of Puget Sound •
- HMO =
- health maintenance organization •
- DSS =
- Decision Support System •
- ADG =
- Ambulatory Diagnostic Groups
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- Copyright © 1997 American Academy of Pediatrics