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Logo of nihpaAbout Author manuscriptsSubmit a manuscriptHHS Public Access; Author Manuscript; Accepted for publication in peer reviewed journal;
J Hosp Med. Author manuscript; available in PMC 2011 March 1.
Published in final edited form as:
PMCID: PMC2860021

Pediatric Observation Units in the US: A Systematic Review

Michelle L. Macy, MD,*# Christopher S. Kim, MD, MBA,^ Comilla Sasson, MD,# Marie M. Lozon, MD,# and Matthew M. Davis, MD, MAPP*^



As the United States' (US) health system seeks more efficient and value-based care models, geographically distinct observation units (OUs) may become an integral part of hospital-based care for children.


To systematically review the literature and evaluate the structure and function of pediatric OUs in the US.

Data Sources

Searches were conducted in Medline, Web of Science, CINAHL, HCAB, Lexis Nexis, National Guideline Clearinghouse and Cochrane Reviews through February 2009, with review of select bibliographies.

Study Selection

English language peer-reviewed publications on pediatric OU care in the US.

Data Extraction

Two authors independently determined study eligibility. Studies were graded using a 5-level quality assessment tool. Data were extracted using a standardized form.

Data Synthesis

21 studies met inclusion criteria: 2 randomized trials, 2 prospective observational, 12 retrospective cohort, 2 before and after, and 3 descriptive studies. Studies present data on more than 22,000 children cared for in OUs, most at large academic centers. This systematic review provides a descriptive overview of the structure and function of pediatric OUs in the US. Despite seemingly straightforward outcomes for OU care, significant heterogeneity in the reporting of length of stay, admission rates, return visit rates, and costs precluded our ability to conduct meta-analyses. We propose standard outcome measures and future directions for pediatric OU research.


Future research using consistent outcome measures will be critical to determining whether OUs can improve the quality and cost of providing care to children requiring observation-length stays.

Keywords: Hospitalization, Emergency Department, Observation Unit, Pediatric, Review


The first observation units were implemented over 40 years ago with the goal of reducing the number and duration of inpatient stays. Since then, observation units (OUs) have evolved as a safe alternative to hospitalization (14) for the delivery of finite periods of care, typically less than 24 hours (58). Observation services allow for time to determine the need for hospitalization in cases that are unclear after their initial evaluation and treatment (9). Observation status is an administrative classification related to reimbursement that can be applied to patients whose diagnosis, treatment, stabilization, and discharge can reasonably be expected within 24 hours (10, 11). The site of care for observation is dependent in part upon existing facility structures; some institutions utilize “virtual” OUs within the emergency department (ED) or hospital ward, while others have dedicated, geographically distinct OUs, which may function as an extension of either the ED or inpatient settings (9).

OUs have been instrumental in providing care to adult patients with chest pain, asthma, and acute infections (1218). Recently, there has been an increase in the number of publications from pediatric OUs in the United States (US) and abroad. Observation may be a preferred model of care for select pediatric patients, as hospitalized children often experience brief stays (1921). Previous reviews on this model of care have combined adult and pediatric literature and have included research from countries with health care structures that differ considerably from the US (2224). To date, no systematic review has summarized the pediatric OU literature with a focus on the US health care system.

As payers and hospitals seek cost effective alternatives to traditional inpatient care, geographically distinct OUs may become integral to the future of health care delivery for children. This systematic review provides a descriptive overview of the structure and function of pediatric OUs in the US. We also scrutinize the outcome measures presented in the included publications and propose future directions for research to improve both observation unit care as well as the care delivered to patients under observation status within general inpatient or ED settings.


Literature Search

With the assistance of a health services librarian, a search of the following electronic databases from January 1, 1950 through February 5, 2009 was conducted: Medline, Web of Science, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Health Care Advisory Board (HCAB), Lexis Nexis, National Guideline Clearinghouse and Cochrane Reviews. Key words used for the Boolean search are included in Appendix A. In addition, we conducted a manual search of reference lists from reviews, guidelines, and articles meeting inclusion criteria.

We included English language peer-reviewed publications that reported on pediatric OU care in the US. Studies were included if they reported outcomes including lengths of stay, admission from observation rates, return visit rates, costs or charges. Descriptive publications of pediatric OU structure and function were also included. Studies were excluded if they were conducted outside the US, evaluated psychiatric or intensive care, reported on observation status in an ED without an OU or observation status on a traditional inpatient ward. Two reviewers (MM and CK) identified articles for inclusion. Any disagreements between the reviewers were resolved by discussion and consensus agreement. Inter-rater reliability was assessed using the kappa statistic.

Quality Assessment

The quality of each study was rated using the Oxford Centre for Evidence-Based Medicine levels of evidence (25). With this system, levels of evidence range from 1a (homogeneous systematic review of randomized, controlled trials) to 5 (expert opinion without explicit critical appraisal).

Data Synthesis

Data on study design, OU characteristics, patient populations, and outcomes were extracted using a standardized form. Heterogeneity of study design, interventions, and outcomes precluded the ability to conduct meta-analyses.


A systematic search of the electronic databases identified 222 unique citations (Figure). One hundred seven abstracts were evaluated. We identified 48 articles for full text review of which 18 met inclusion criteria. Hand search of references yielded 24 additional articles of which 3 met inclusion criteria. Inter-rater agreement for selected articles was high at 98% (kappa = 0.85).

Literature Search

Observation Unit Characteristics

The majority of research on OUs has been conducted at large academic pediatric centers. One publication was from a community hospital (26). These studies present data on more than 22,000 children cared for in OUs of 11 hospitals over a 32 year time span. Most studies were level 2 evidence: 2b - retrospective cohort studies and low quality randomized, controlled trials or 2c - “outcomes” research. Three were descriptive and not assigned a formal evidence level (2729).

Table 1 highlights general features of US pediatric OUs. Five institutions renovated or expanded clinical space in order to open the OU (27, 2932). Units ranged in size from 3 to 23 beds. The OU was located in or near the emergency department (ED) in all but 2 hospitals, which had ward-based units. The ED was the primary entry point into the OU with only 2 open model units accepting patients from other settings (5, 32). The annual number of observation cases ranged from 1,000 to 3,000 in children's hospitals. Approximately 500 ward-based observation cases per year were cared for in the single community hospital studied. Three reports included time trends showing increased OU utilization over study years (5, 30, 31).

Table 1
General Description of US Pediatric Observation Units

Staffing and Workflow

Staffing models varied and have undergone transitions over time. Prior to 1997, general pediatricians primarily provided physician services. In more recent years, OUs have utilized pediatric emergency medicine (PEM) providers. Three of the 11 units allowed for direct patient care by sub-specialists (5, 6, 32). One OU was staffed by nurse practitioners (29). OU nursing backgrounds included pediatrics, emergency medicine, or PEM.

Five institutions assembled multidisciplinary teams to define the unit's role and establish policies and procedures (7, 27, 2931). Workflow in the OU focused on optimizing efficiency through standardized orders, condition specific treatment protocols, and bedside charting (7, 26, 33). Several units emphasized the importance of ongoing evaluations by attending physicians who could immediately respond to patient needs. Rounds occurred as often as every 4 hours (5, 7). Two centers utilized combined physician-nursing rounds to enhance provider communication (7, 34). No publications reported on patient transitions between sites of care or at shift changes.

Criteria for Observation

All 11 hospitals have developed protocols to guide OU admissions (Table 2). Nine publications from four OUs commented on treatments delivered prior to observation (33, 3542). The most commonly cited criteria for admission was approval by the unit's supervising physician. Utilization review was not mentioned as an element in the OU admission decision. Common OU exclusions were the need for intensive care or monitoring while awaiting an inpatient bed; however these were not universal. Eight centers placed bounds around the duration of OU stays, with minimum stays of 2 hours and maximum stays of 8 to 24 hours.

Table 2
Observation Unit Entry Criteria

Ages of Children under Observation

Seven of 11 hospitals reported the age range of patients accepted in their OU (Table 2). All but one unit accepted children from infants to young adults, 18 to 21 years of age (43). In the 6 units that reported the age distribution of their OU population, roughly 20% were <1 year, more than 50% were <5 years, and fewer than 30% fell into an adolescent age range (5, 6, 26, 32, 34, 43).

Conditions under Observation

Many conditions under observation were common across time and location (Table 3). The list of conditions cared for in OUs has expanded in recent years. Medical conditions predominated over surgical. While the majority of observation cases required acute care, nearly half of the units accepted children with scheduled care needs (e.g., routine post-operative care, procedures requiring sedation, infusions, and extended evaluations such as electroencephalograms or pH probes). These scheduled cases, cared for within the OU structure, provided more steady demand for OU services.

Table 3
Conditions Cared for in US Pediatric Observation Units


One publication highlighted the special billing rules that must be considered for observation care (27). In three studies, payers recognized cost-savings associated with the OU's ability to provide outpatient management for cases that would traditionally require inpatient care (31, 35, 38).

Observation Unit Outcomes

Outcomes reported for pediatric OU stays fall into four major categories: length of stay (LOS), admission rates, return visit rates, and costs. Despite these seemingly straightforward groupings, there was significant heterogeneity in reporting these outcomes.

Length of stay

The start time for OU LOS is not clearly defined in the articles included in this review. While the start of an observation period is assumed to begin at the time the order for observation is placed, it is possible that the LOS reported in these publications began at the time of ED arrival or the time the patient was physically transferred to the OU. The average LOS for individual OUs ranged from 10 to 15 hours (5, 6, 26, 30, 35, 38, 40, 41, 43). One ward-based and one ED-based unit reported LOS extending beyond 24 hours (7, 30), with averages of 35 and 9 hours respectively. Two units limited the duration of care to <10 hours (31, 38).

For studies that included a comparison group, OU stays were consistently shorter than a traditional inpatient stay by 6 to 110 hours (7, 36, 38, 39, 42). No significant differences in clinical parameters between groups were reported. There was appreciable variation in the average LOS across institutions for similar conditions, 12 to 35 hours for asthma (5, 7, 34, 35), and 9 to 18 hours for dehydration (5, 34, 36, 38).

Admission rates

Rates of hospital admission after observation from the 9 OUs reporting this outcome are presented in Table 4. Three publications from a single institution counted hospital admission in the 48–72 hours following discharge from the OU as though the patient were admitted to the hospital directly from the index OU stay (33, 40, 41). Conditions with the lowest admission rates, <10%, included croup, neurologic conditions, ingestions, trauma, and orthopedic injuries. The highest admission rates, >50%, were for respiratory conditions including asthma, pneumonia, and bronchiolitis.

Table 4
Condition Specific Rates of Inpatient Admission following Observation Unit Care

Return visit rates

Unscheduled return visit rates were reported in 9 publications from 6 institutions and ranged from 0.01% to 5% (7, 26, 33, 3537, 3941). Follow-up timeframes ranged from 48 hours to 1 month. Return visits were inconsistently defined. In most studies, rates were measured in terms of ED visits (26, 33, 3537, 39, 41). One ward-based unit counted only hospital readmissions toward return visit rates (7). Three publications, from ED-based units, counted hospital readmissions in the 2 to 5 days following observation toward admission rates and not as return visits (33, 40, 41). In most studies, data on return visits were collected from patient logs or patient tracking systems. Three studies contacted patients by phone and counted return visits to clinic (3537). No studies reported on adherence to scheduled visits following observation.


Seven studies reported financial benefits of OU care when compared with traditional hospital care (7, 30, 31, 35, 37, 38, 42). Two centers admitted patients to inpatient care if their observation period reached a set time limit, after which cost savings were no longer realized (31, 35). Cost savings associated with the OU treatment of asthma and dehydration were attributed to lower charges for an OU bed (35, 38). Decreased charges for the OU treatment of croup were related to shorter LOS (42).


In the 40 years since the first studies of pediatric OUs, several US health systems have extended observation services to children. This model of care may be expanding, as suggested by an increase in the number of publications in the past ten years. However, the number of centers within the US reporting on their OU experience remains small. Our systematic review identified a recurrent theme related to OUs - the opportunity to improve operational processes of care compared with the traditional inpatient alternative. We have identified the need to standardize OU outcomes and propose measures for future OU research.

Observation Unit Operations

The OU care model expands outpatient management of acute conditions to include children who are neither ready for discharge nor clear candidates for inpatient admission. OUs have demonstrated the ability to care for patients across the pediatric age spectrum. Over the decades spanning these publications, advances in medical therapy such as anti-emetics for gastroenteritis and early administration of systemic steroids for asthma may have resulted in lower admission rates or shorter time to recovery (44, 45). Despite these advances, there are marked consistencies in the conditions cared for within OUs over time. The data summarized here may help guide institutions as they consider specific pediatric conditions amenable to observation care.

The hospitals included in this review either added physical space or revised services within existing structures to establish their OU. Hospitals facing physical constraints may look to underutilized areas, such as recovery rooms, to provide observation care, as observation does not require the use of licensed inpatient beds. Several units have responded to daily fluctuations in unscheduled observation cases by also serving patients who require outpatient procedures, brief therapeutic interventions, and diagnostic testing. By caring for patients with these scheduled care needs during the day, there is a more steady flow of patients into the OU. While hospitals traditionally have used post-anesthesia care units and treatment rooms for scheduled cases, OUs appear to benefit from the consistent resource allocation associated with a constant demand for services.

To date, the vast majority of pediatric OUs in the published literature have emerged as an extension of ED services. Now, with the expansion of pediatric hospitalist services and movement toward 24/7 inpatient physician coverage, there may be increased development of ward-based OUs and the designation of inpatient observation status. While ward-based OUs managed by pediatric hospitalists may be well established, we were not able to identify published reports on this structure of care. A national survey of health systems should be undertaken to gather information regarding the current state of pediatric observation services.

When creating policies and procedures for OUs, input should be sought from stakeholders including hospitalists, PEM providers, primary care providers, sub-specialists, mid-level providers, nurses, and ancillary staff. As patients requiring observation level of care do not neatly fit an outpatient or inpatient designation, they present an opportunity for hospitalist and PEM physician groups to collaborate (4648). Calling on the clinical experiences of inpatient and ED providers could offer unique perspectives leading to the development of innovative observation care models.

This review focused on institutions with dedicated observation services, which in all but one study (26) consisted of a defined geographic unit. It is possible that the practices implemented in an OU could have hospital-wide impact. For example, one study reported reduction in LOS for all asthma cases after opening a ward-based unit (7). Further, pediatric hospitalist services have been associated with shorter LOS (49) and increased use of observation status beds compared with traditional ward services (50). As pediatric hospitalists expand their scope of practice to include both observation and inpatient care, clinical practice may be enhanced across these care areas. It follows that the impact of observation protocols on care in the ward setting should be independently evaluated.

The costs associated with the establishment and daily operations of an OU were not addressed in the reviewed publications. Assertions that observation provides a cost-effective alternative to inpatient care (4, 7, 23, 42) should be balanced by the possibility that OUs extend care for patients who could otherwise be discharged directly home. Studies have not evaluated the cost of OU care compared with ED care alone. Research is also needed to assess variations in testing and treatment intensity in OUs compared with the ED and inpatient alternatives. Reimbursement for observation is dependent in part upon institutional contracts with payers. A full discussion of reimbursement issues around observation services is beyond the scope of this review.

Observation Unit Outcomes

Length of stay

Although most studies reported LOS, direct comparisons across institutions are difficult given the lack of a consistently referenced start to the observation period. Without this, LOS could begin at the time of ED arrival, time of first treatment, or time of admission to the OU. Identifying and reporting the elements contributing to LOS for observation care is necessary. The time of OU admission is important for billing considerations; the time of first treatment is important to understanding the patient's response to medical interventions; the time of ED arrival is important to evaluating ED efficiency. Each of these LOS measures should be reported in future studies.

Direct comparisons of LOS are further complicated by variability in the maximum permissible duration of an OU stay, ranging from 8 to 24 hours in the included studies. Despite these limits, some OU care will extend beyond set limits due to structural bottlenecks. For example, once the inpatient setting reaches capacity, observation LOS for patients who require admission will be prolonged. The best evaluation of LOS would come from prospective study design utilizing either randomization or quality improvement methods.

Defining Success and Failure in Observation Care

In the reviewed literature, “observation failures” have been defined in terms of admission after observation and unscheduled return visit rates. Admission rates are heavily dependent on appropriate selection of cases for observation. Although some observation cases are expected to require inpatient admission, OUs should question the validity of their unit's acceptance guidelines if the rate of admission is >30% (51). High rates could be the result of inadequate treatment or the selection of children too sick to improve within 24 hours. Low rates could indicate over-utilization of observation for children who could be discharged directly home. Full reporting on the number of children presenting with a given condition and the different disposition pathways for each is needed to evaluate the success of OUs. Condition-specific benchmarks for admission after observation rates could guide hospitals in their continuous improvement processes.

Unscheduled return visits may reflect premature discharge from care, diagnostic errors, or development of a new illness. OU care may influence patient adherence to scheduled follow-up care but this has not been evaluated to date. In future research, both scheduled and unscheduled return visits following ED visits, observation stays, and brief inpatient admissions for similar disease states should be reported for comparison. Standard methodology for identifying return visits should include medical record review, claims analyses, and direct patient contact.

As hospitals function at or near capacity (52, 53), it becomes important to delineate the appropriate length of time to monitor for response to treatments in a given setting. Limited capacity was a frequently cited reason for opening a pediatric OU; however the impact of OUs on capacity has not yet been evaluated. Operations research methods could be used to model OU services' potential to expand hospital capacity. This research could be guided by evaluation of administrative data from across institutions to identify current best practices for pediatric OU and observation status care.

OU benchmarking in the US has begun with a small number of adult units participating in the ED OU Benchmark Alliance (EDOBA) (54). In Table 5 we propose dashboard measures for pediatric OU continuous quality improvement. The proposed measures emphasize the role of observation along the continuum of care for acute conditions, from the ED through the OU with or without an inpatient stay to clinic follow-up. Depending on the structure of observation services, individual institutions may select to monitor different dashboard measures from the proposed list. Patient safety and quality of care measures for the conditions commonly receiving pediatric OU care should also be developed.

Table 5
Suggested Dashboard Measures for Pediatric Observation Units


The most important limitations to this review are the heterogeneity in interventions and reporting of outcomes, which precluded our ability to combine data or conduct meta-analyses. We attempted to organize the outcomes data into clear and consistent groupings. However, we could not compare the performance of one center with another due to differences in OU structure, function and design.

In order to focus this systematic review, we chose to include only peer reviewed publications that describe pediatric OUs within the US. This excludes expert guidelines, which may be of value to institutions developing observation services.

Our search found only a small number of centers that utilize OUs and have published their experience. Thus our review is likely subject to publication bias. Along this line, we identified 9 additional publications where children were cared for alongside adults within a general OU (5563). This suggests an unmeasured group of children under observation in general EDs, where more than 90% of US children receive acute care (64). These articles were excluded because we were unable to distinguish pediatric specific outcomes from the larger study population.

Finally, retrospective study design is subject to information bias. Without a comparable control group, it is difficult to understand the effects of OUs. Patients directly admitted or discharged from the ED and patients who require admission after observation all differ from patients discharged from observation in ways that should be controlled for with a randomized study design.


Observation units have emerged to provide treatment at the intersection of outpatient and inpatient care during a time of dramatic change in both emergency and hospital medicine. As hospitalists expand their scope of practice to include observation care, opportunities will arise to collaborate with ED physicians and share their growing expertise in quality and efficiency of hospital care delivery to improve observation services for children. OUs have been established with laudable goals - to reduce inpatient admissions, increase patient safety, improve efficiency, and control costs. The current evidence is not adequate to determine if this model of health care delivery achieves these goals for children. Through synthesis of existing data, we have identified a need for standard reporting for OU outcomes and propose consistent measures for future observation care research. Only through prospective evaluation of comparable outcomes can we appraise the performance of pediatric OUs across institutions.


Supported by the National Institute of Child Health and Human Development T32 HD007534.


Observation Unit
Emergency Department
Cumulative Index to Nursing and Allied Health Literature
Health Care Advisory Board
pediatric emergency medicine
length of stay

Appendix A

Search terms:

MeSH terms in bold.

Observation, short stay, assessment, hybrid, holding, admission - unit/ward
Observation level of care, observation status
Emergency Services, Hospital or Emergency Medicine
Hospital Units
Length of stay (LOS)
Fees and Charges
Costs and Cost Analysis
Outcome (and Process) Assessment
Patient Admission
Patient Readmission
Patient Transfer
Patient Satisfaction
Return visit
Limits - All child, English language
Intensive Care Unit


This work has not been presented previously. The authors have no conflicts of interest to disclose.


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