American Journal of Emergency Medicine 32 (2014) 1405–1407
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Brief Report
Predictors of hospital admission after ED observation unit care☆,☆☆,★ Anthony M. Napoli, MD, FACEP a,⁎, Peter M. Mullins, MA, MPH b, Jesse M. Pines, MD, MBA c, d a
Department of Emergency Medicine, Warren Alpert Medical School of Brown University, Providence, RI 02903 School of Continuing and Professional Studies, University of Virginia, 104 Midmont Lane, Charlottesville, VA 22904 c Office for Clinical Practice Innovation, Washington, DC d Departments of Emergency Medicine and Health Policy, George Washington School of Medicine and Health Sciences, 2030 M St NW Room 4044, Washington, DC 20037 b
a r t i c l e
i n f o
Article history: Received 15 July 2014 Accepted 14 August 2014
a b s t r a c t Background: Emergency department observation units (EDOUs) represent an opportunity to efficiently manage patients with common conditions requiring short-term hospital care. Understanding which patients are ultimately admitted to the hospital after care in an EDOU may enhance patient selection for EDOU care. Methods: We conducted a retrospective analysis of US emergency department visits resulting in admission to observation status using the National Hospital Ambulatory Care Survey (NHAMCS) from 2009 to 2010, a nationally representative sample. We used survey-weighted logistic regression to identify predictors at the patient level, visit level, and hospital level for inpatient hospital admission after EDOU care. Results: Between 2009 and 2010, there were 4.65 million patient visits (95% confidence interval [CI], 3.68-5.63) to EDOUs in the United States. Of those evaluated in an EDOU, 40.4% (95% CI, 34.5%-46.6%) were admitted to the hospital after EDOU care. Progressively older patient age was a strong predictor of hospital admission: patients age older than 65 years were more than 5 times more likely to be admitted than patients age younger than 18 years (odds ratio, 5.36; 95% CI, 2.26-12.73). The only other visit-level factor associated with admission was a reason for visit of chest pain; this was associated with a lower rate of hospital admission (odds ratio, 0.61; 95% CI, 0.41-0.91). Conclusion: Across the United States in 2009 to 2010, older patient age was a strong predictor of admission after EDOU care, suggesting that older patients are more likely to require inpatient hospital services after EDOU care than younger patients. © 2014 Elsevier Inc. All rights reserved.
1. Introduction The US emergency departments (EDs) and hospitals are under significant pressure to enhance value and quality, improve patient experience, and to reduce readmissions. The emergency department observation unit (EDOU) is an alternative to the 2 traditional dispositions (admission or discharge) for patients who present with complaints or diagnoses requiring short-term hospital care that exceeds the resources of an ED but does not require a full inpatient admission. Over an 8-year period between 2001 and 2009, there was a 4-fold increase in US EDOU usage [1]. Emergency department observation unit cases now account for 2% of all ED encounters and account for 12% of all hospital care [1]. The most common observation diagnoses are (in descending order) chest pain, abdominal pain, syncope, cardiac ☆ Conflicts of interest and source of funding: This study was supported by an intradepartmental grant from the Department of Emergency Medicine, Providence, RI and University Emergency Medicine Foundation, Warren Alpert Medical School of Brown University, Providence, RI. ☆☆ This study was designed and carried out at Rhode Island Hospital/Brown University (Providence, RI). ★ None of the authors has any conflict of interest. ⁎ Corresponding author. 593 Eddy St, Davol 142, Providence, RI 02903. Tel.: +1 401 444 2859; fax: +1 401 444 2922. E-mail address:
[email protected] (A.M. Napoli). http://dx.doi.org/10.1016/j.ajem.2014.08.039 0735-6757/© 2014 Elsevier Inc. All rights reserved.
dysrhythmias, mood disorders, skin and soft tissue infections, and congestive heart failure [1]. Studies of EDOUs for various clinical conditions demonstrate shorter length of stay, fewer adverse outcomes, and lower readmission rates [2,3]. Emergency department observation units have the potential to significantly decrease costs of care for a significant subset of patients admitted to the hospital [4,5]. An estimated 30% of observation admissions are amenable to EDOU care, and based on prior studies, approximately 80% of patients managed in an observation unit can be discharged home from that unit [1]. Identifying patient factors associated with admission after EDOU care is important because needed inpatient care may be more efficient when initiated directly after ED care rather than after an EDOU evaluation. We explored what factors predict when patients are ultimately admitted to the hospital after EDOU care in US EDs. 2. Materials and methods 2.1. Study design and protocol We conducted a retrospective analysis of ED visits resulting in admission to observation status found in the National Hospital Ambulatory Care Survey (NHAMCS) from 2009 to 2010. The NHAMCS is an annual multistage probabilistic sample of visits made to EDs in
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the United States conducted by the National Center for Health Statistics (NCHS). The survey is designed to produce survey-weighted national-level estimates. The NHAMCS collects patient-level data, including demographics, primary source of payment, reason for visit (RFV), diagnoses, services/medications provided, and patient disposition as well as hospital-level data, such as geographic region, metropolitan status, and hospital ownership. Data are publicly available and can be downloaded from the NCHS website. Additional information regarding the design and data collection procedures of NHAMCS is available elsewhere [6]. 2.2. Data analysis This study examined visits resulting in admission to EDOUs; specifically, we explored national rates of discharge and admission after EDOU care. Emergency department observation units care in NHAMCS was defined as admission to an observation unit for evaluation and management or to await an inpatient bed. We tabulated the proportion of observation visits resulting in discharge or admission by age, race, sex, triage acuity, primary payer, RFV, geographic region, hospital ownership, teaching status, and metropolitan status of the hospital. Age was divided into 4 categories: younger than 18, 18 to 34, 35 to 64, and 65 years and older. The imputed race variable in NHAMCS was used; this variable was divided into white and nonwhite for sample size reasons per NCHS guidelines [6]. Triage acuity was separated into urgent/emergent (triage levels 1 or 2) and nonurgent (levels 3-5). The 5 most common RFVs were included in the analyses (chest pain, abdominal pain, dizziness/ vertigo, dyspnea, and injury). To examine potential predictors of hospital admission after observation, we conducted a survey-weighted logistic regression analysis. We computed adjusted odds ratios (ORs) for admission after observation for each categorical variable described above. In addition, we conducted logistic regression analysis with age as a continuous independent variable. A P b .05 was considered statistically significant. All analyses were performed using Stata, version 12 (College Station, TX). This study used publicly available deidentified data and was therefore not considered human subjects research. 3. Results In 2009 and 2010, NHAMCS included 1626 patient visits in which the patient was treated in an EDOU. Of these, 640 visits resulted in hospital admission after observation. These visits represented 4.65 million (95% CI, 3.68-5.63) survey-weighted visits to EDOUs and 1.88 million (95% CI, 1.35-2.41) admissions after observation. The mean age of patients admitted to an EDOU was 50.5 years (95% CI, 48.4-52.6), whereas the mean age of patients admitted after observation was 54.1 years (95% CI, 51.6-56.7). Demographic and other patient-level and hospital-level features are in the Table. The overall EDOU hospital admission rate was 40.4% (95% CI, 34.5-46.6). There was a significant relationship between patient age categories and odds of hospital admission after EDOU care in all age categories compared with patients age 18 years and younger. There was a stepwise positive relationship between age categories and odds of admission. Patients age older than 65 years were more than 5 times more likely to be admitted after EDOU care compared with patients younger than 18 years (OR, 5.36; 95% CI, 2.26-12.73; P b .001). As a continuous variable, age was a significant predictor of observation failure (OR, 1.01; 95% CI, 1.00-1.02; P b .002); for each additional year of life, patients were 1.1% more likely to be admitted after EDOU care. A primary complaint of chest pain also was associated with lower odds of admission after EDOU care (OR, 0.61; 95% CI, 0.41-0.91; P b .014). No other patient or hospital demographic data were associated with EDOU failure.
Table Demographic and hospital features of observation unit admissions
Age
Race Sex Triage acuity Payer
RFV
Region
Hospital type
b18 18-34 35-64 65+ White Nonwhite Male Female 1 or 2 N2 Self-pay Medicare Medicaid Private Chest pain Abdominal pain Dizziness/vertigo Dyspnea Injury Northeast Midwest South West For profit Nonprofit Government Nonteaching Teaching Rural Urban
Observation admit
Observation discharge
Adjusted OR for admission
P
22.1% 39.2% 38.9% 49.1% 42.1% 36.0% 40.2% 40.6% 44.8% 38.9% 39.7% 45.3% 41.3% 38.0% 35.0% 40.4% 35.9% 40.4% 40.9% 42.4% 43.3% 37.1% 38.4% 39.1% 42.9% 29.3% 41.8% 36.6% 34.4% 41.0%
77.9% 60.1% 61.1% 50.9% 57.9% 64.0% 59.8% 59.4% 55.2% 61.2% 60.3% 54.7% 58.7% 62.0% 65.0% 59.6% 64.1% 59.6% 59.1% 57.6% 56.7% 62.9% 61.6% 60.9% 57.1% 70.7% 58.2% 63.4% 65.6% 59.1%
Reference 2.756 3.095 5.359 Ref 0.723 Ref 0.962 1.268 Ref Ref 0.761 1.199 0.731 0.612 0.904 0.631 0.918 0.990 Ref 0.977 0.847 0.831 Ref 1.306 0.649 Ref 0.869 Ref 1.868
– .006 .005 .001 – .079 – .775 .233 – – .236 .396 .104 .014 .683 .075 .718 .946 – .947 .665 .615 – .571 .421 – .666 – .081
4. Discussion Although previous studies have examined demographics, clinical outcomes, and costs of EDOUs, prior studies have not focused on EDOU failures: those patients ultimately admitted to the hospital from the EDOU. This study demonstrates, in a national survey, that older age is the most important demographic or visit-level variable as a predictor of admission after EDOU care and that an admission diagnosis of chest pain is a significant predictor of observation unit discharge. Observation unit utilization and admission rates are important; a key determinant of the operational success of such units is the efficient management and disposition of patients. Distinguishing features of patients likely to fail observation unit admission could be an important feature in improving the relative cost savings and operational flow benefit of EDOUs. Previous research has demonstrated that EDOU admission rates have traditionally been lower than we found in this study, generally approximately 20% [7,1]. However, this failure rate is increasing. A recent study demonstrated that observation unit failure rates are steadily on the rise; in 2008, the failure rate was 33% [1]. Our results, in the 2 years subsequent to this study, may reflect that increasing numbers of patients are being placed in ED observation units, particularly with recent trends toward increased scrutiny on short-term admission. Better discrimination of which patients are likely to fail EDOU may improve the efficiency and effectiveness of such units, as observation unit use increases, and observation failures are on the rise. Previous studies have explored EDOU failure, specifically, 1 study in advanced age chest pain patients concluded that appropriately screened patients are actually not at higher risk for observation failure [8]. However, the same group demonstrated a 3-fold higher rate of failed observation in patients with coronary artery disease vs those without [8]. Underlying comorbidities of older patients may be responsible for higher rates of EDOU failures in our study. The association between chest pain and higher discharge rates from EDOUs has been previously reported [1] and may demonstrate the
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efficiency of diagnostic protocols in lower risk subgroups, even those with many comordidities. Another single-center study including all EDOU diagnoses found results similar to Madsen et al [9]. Many studies of EDOUs have reported data in closed EDOUs units—units under ED administrative control with only ED physicians having admitting privileges. In the NHAMCS sample, most hospitals with observation units are in the ED, but we did not have data if these units were closed or who provided the administrative oversight. The association between age and EDOU failure found in this study raises the question of whether certain patients beyond a certain age should be admitted inpatient initially or whether they simply represent a higher risk cohort of EDOU patients requiring better pre-EDOU admission screening or more intensive services while admitted to the EDOU. Observation units are likely taking on higher risk patients, and further research may help identify those likely to fail observation, the reasons for failure, and the best ways to appropriately screen and direct admission practices, particularly in the older subgroups.
5. Limitations The primary limitations of the present study are related to the use of the NHAMCS database. Although NHAMCS is considered a valid and reliable data source due to a sophisticated multistage sampling strategy, the national-level estimates generated from the samples may contain inaccuracies. For instance, the classification of EDOUs as well as observation protocols may differ across hospitals, and this difference may not be reflected in the data set. In addition, other variables, such as patient race, may contain errors in coding. Finally, although NHAMCS' annual samples contain more than 30 000 patient visit records, admission to observation is a relatively rare outcome. Smaller sample
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sizes may result in biased estimates, although this study complied with NCHS guidelines for generating national-level estimates. 6. Conclusion Older age is a significant predictor of EDOU failure. Further research is necessary to identify patient-level characteristics, comorbidities, or admission diagnoses that may contribute to this failure and better predict ultimate disposition to ensure optimal efficiency of these units. References [1] Venkatesh AK, Geisler BP, Gibson Chambers JJ, Baugh CW, Bohan JS, Schuur JD. Use of observation care in US emergency departments, 2001 to 2008. PLoS One 2011;6 (9):e24326. [2] McDermott MF, Murphy DG, Zalenski RJ, Rydman RJ, McCarren M, Marder D, et al. A comparison between emergency diagnostic and treatment unit and inpatient care in the management of acute asthma. Arch Intern Med 1997;157(18):2055–62. [3] Decker WW, Smars PA, Vaidyanathan L, Goyal DG, Boie ET, Stead LG, et al. A prospective, randomized trial of an emergency department observation unit for acute onset atrial fibrillation. Ann Emerg Med 2008;52(4):322–8. [4] Baugh CW, Venkatesh AK, Hilton JA, Samuel PA, Schuur JD, Bohan JS. Making greater use of dedicated hospital observation units for many short-stay patients could save $3.1 billion a year. Health Aff 2012;31(10):2314–23. [5] Ross MA, Hockenberry JM, Mutter R, Barrett M, Wheatley M, Pitts SR. Protocoldriven emergency department observation units offer savings, shorter stays, and reduced admissions. Health Aff 2013;32(12):2149–56. [6] McCaig LF, Burt CW. Understanding and interpreting the National Hospital Ambulatory Medical Care Survey: key questions and answers. Ann Emerg Med 2012;60(6):716-721 e1. [7] Sieck S. Cost effectiveness of chest pain units. Cardiol Clin 2005;23(4):589–99. [8] Madsen T, Mallin M, Bledsoe J, Bossart P, Davis V, Gee C, et al. Utility of the emergency department observation unit in ensuring stress testing in low-risk chest pain patients. Crit Pathw Cardiol 2009;8(3):122–4. [9] Caterino JM, Hoover EM, Moseley MG. Effect of advanced age and vital signs on admission from an ED observation unit. Am J Emerg Med 2013;31(1):1–7.
