Editors: Peacock, W. Frank
Title: Short Stay Management of Heart Failure, 1st Edition
Copyright 2006 Lippincott Williams & Wilkins
> Table of Contents > 3 - Observation Unit Admission Inclusion and Exclusion Criteria
Observation Unit Admission Inclusion and Exclusion Criteria
Sean P. Collins
Heart failure (HF) is a disease of epidemic proportions. Hospitalization accounts for the largest expenditure for care; annual costs are estimated to be $27.9 billion per year, about 3% of the total national health care budget.1,2 and 3 In-hospital mortality ranges from 2% to 20% and 90-day recidivism in those discharged directly from the emergency department (ED) has been reported to be 61%.4,5 Current guidelines for disposition are based on little or no empirical evidence.6,7 and 8 As a direct result of the high-risk features of these patients and a lack of disposition guidance, the emergency physician's triage decisions are historically conservative; more than 80% of ED patients with acute decompensated heart failure (ADHF) are admitted to the hospital.9 It has been suggested that poor ED risk stratification, particularly overestimation of disease severity, is the fundamental cause of the overutilization of limited in-hospital resources for this rapidly growing patient population.10
A novel approach for ADHF is necessary to decrease the relative burden of this disease. Despite recent advances in diagnostic and therapeutic measures for HF, the admission rate has remained largely unchanged. The observation unit (OU) presents an opportunity for further risk stratification and treatment for up to 24 hours to better delineate the need for admission. Using the OU to avoid hospital admission (average cost $5,456 per admission3) in just a small percentage of patients is likely to have a profound effect on health care expenditures.
The evaluation and disposition of ED patients with ADHF resembles the approach to chest pain in the 1980s, prior to the advent of chest pain centers. As a result of extensive research over the last 2 decades, we have experienced a dramatic paradigm shift in ED chest pain patients: from a high proportion of admitted patients to a rapid OU protocol allowing further risk stratification and safe, early discharge.11,12 and 13 Preliminary research suggests a similar approach to ADHF may yield similar results.14,15
Observation Unit Management of Acute Decompensated Heart Failure
It has been suggested that appropriate candidates for the OU are those who have an expectation of (a) hospital stays less than 48 hours, (b) no diagnosis traditionally requiring hospitalization, (c) no procedure requiring hospitalization, and (d) no probability of death.16 Due to the multiple comorbidities of ADHF patients, identifying a cohort that will fulfill these criteria is inherently difficult. However, excluding subjects with high-risk features,5,17,18,19,20,21,22 and 23 as well as including subjects identified as proper candidates from previous OU research,15,24 and 25 lends some guidance in patient selection. Our OU protocol is a collaborative effort between the Department of Emergency Medicine and the Division of Cardiology at the University of Cincinnati. Inclusion and exclusion criteria were selected based on a review of previously derived retrospective risk data and an OU protocol, so as to identify what current practice suggests is a low- to moderate-risk patient (Table 3-1).5,15,17,18,19,20,21,22 and 23
An ED diagnosis of HF is often based on history and physical examination findings along with ancillary tests such as chest radiography and electrocar-diography. Distinguishing between cardiac and noncardiac causes of dyspnea by relying solely on these tests is difficult. The etiology is often determined after hospital admission based on right heart catheterization results or indirect measurement of ejection fraction via radionuclide scanning or echocar-diography. The use of these tests to determine OU inclusion is not practical because they are not routinely available in EDs and their cost is prohibitive for use as a standardized screening test.
However, with an ED diagnosis of ADHF we also require patients to fulfill a modification of the Framingham criteria (Table 3-2). The Framingham criteria, reported in 1971, is one of the tools used to predict HF.26,27 They were developed by following the natural history of HF over a 16-year period in more than 5,000 persons initially free of the disease. This tool uses major and minor criteria based on history, physical examination, and ancillary tests to categorize patients as definite, probable, and questionable HF. The Framingham criteria are well known for providing a useful probe-bilistic diagnosis of HF, and they are accepted criteria for establishing an eti ology of dyspnea before definitive studies have been performed.28 Furthermore, fulfillment of the Framingham criteria has not been shown to correlate with an increased risk of subsequent adverse events.29 Four of the Framingham criteria are not used as part of our modified criteria: (a) circulation time, (b) vital capacity, (c) weight loss in response to treatment, and (d) autopsy findings. Vital capacity and circulation time are two parameters that are not measured in the ED, and weight loss in response to treatment would only help with a retrospective diagnosis of HF. Inclusion of patients requires two major or one major and two minor criteria.
TABLE 3-1 Inclusion and Exclusion Criteria for ADHF OU Management
TABLE 3-2 The Modified Framingham Criteria
Patients are excluded for OU HF management if they have a feature that defines them as high risk (positive cardiac markers, systolic blood pressure <90 mm Hg) or have a concomitant illness that will make their discharge from the OU difficult (urgent need for dialysis, alternative diagnosis contributing to concurrent decompensation such as pneumonia). Based on its high sensitivity, a B-type natriuretic peptide (BNP) value less than 100 pg/mL is also used to exclude patients who are likely to not have AHDF as the underlying cause of their symptoms. Patients with new-onset ADHF can be managed in the OU; however, a facilitated workup will be needed as an outpatient.
We have been enrolling patients in our OU since May 2003 using the criteria listed in Table 3-1. Preliminary findings suggest it is safe and conserves hospital resources.14 We conducted an observational, sequential cohort study. Both cohorts satisfied the inclusion and exclusion criteria identified in Table 3-1. During enrollment of the first cohort, the OU was not operational, whereas in the second group the OU was available to treating physicians. The first cohort of 36 ED patients was enrolled from April 2002 to April 2003 and the second group of 28 ED patients was enrolled from May 2003 to September 2003. With the exception of heart rate (90 vs. 99 beats per minute, p = 0.02) the patients were similar with regard to demographics and presenting vital signs (p >0.10). Twenty percent of the first cohort was discharged from the ED, whereas 40% of the second cohort was discharged home after an OU stay. All patients in the first cohort were admitted to the hospital, whereas only 25% of patients in the second cohort were admitted to the hospital after an OU stay.
The OU represents an attractive alternative for further treatment and risk stratification of low- to medium-risk patients with ADHF. Safely avoiding hospitalization in a subset of patients is likely to result in a significant decrease in resource consumption. Current inclusion and exclusion criteria are based on what previous research has suggested are high-risk features in admitted patients, as well as on preliminary results of select OU protocols. Further prospective studies are needed to better characterize the safety and cost-effectiveness of the OU when compared with standard inpatient care.
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