SPECIAL CONTRIBUTION
Frequent Users of Emergency Department Services: Gaps in Knowledge and a Proposed Research Agenda Jesse M. Pines, MD, MBA, MSCE, Brent R. Asplin, MD, MPH, Amy H. Kaji, MD, PhD, Robert A. Lowe, MD, MPH, David J. Magid, MD, Maria Raven, MD, Ellen J. Weber, MD, and Donald M. Yealy, MD
Abstract Frequent use of emergency department (ED) services is often perceived to be a potentially preventable misuse of resources. The underlying assumption is that similar and more appropriate care can be delivered outside of EDs at a lower cost. To reduce costs and incentivize more appropriate use of services, there have been efforts to design interventions to transition health care utilization of frequent users from EDs to other settings such as outpatient clinics. Many of these efforts have succeeded in smaller trials, but wider use remains elusive for varying reasons. There are also some fundamental problems with the assumption that all or even the majority of frequent ED use is misuse and invoking reasons for that excessive use. These tenuous assumptions become evident when frequent users as a group are compared to less frequent users. Specifically, frequent users tend to have high levels of frequent ED use, have a higher severity of illness, be older, have fewer personal resources, be chronically ill, present for pain-related complaints, and have government insurance (Medicare or Medicaid). Because of the unique characteristics of the population of frequent users, we propose a research agenda that aims to increase the understanding of frequent ED use, by: 1) creating an accepted categorization system for frequent users, 2) predicting which patients are at risk for becoming or remaining frequent users, 3) implementing both ED- and non–ED-based interventions, and 4) conducting qualitative studies of frequent ED users to explore reasons and identify factors that are subject to intervention and explore specific differences among populations by condition, such as mental illness and heart failure. ACADEMIC EMERGENCY MEDICINE 2011; 18:e64–e69 ª 2011 by the Society for Academic Emergency Medicine
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ver the past decades, there have been increases in the utilization of U.S. emergency departments (EDs). According to the Centers for Disease Control and Prevention, there were 117 million ED visits in 2007, compared with 96 million in 1997.1 A con-
siderable proportion of the visits are by individuals who visit the ED two or more times in a year. According to one study, 63% of individuals who reported an ED visit reported visiting the ED two or more times in the past year.2 Patients who use ED services often are termed
From the Departments of Emergency Medicine and Health Policy, George Washington University Medical Center (JMP), Washington, DC; the Department of Emergency Medicine, Mayo Clinic College of Medicine (BRA), Rochester, MN; the Department of Emergency Medicine, Harbor-UCLA Medical Center, David Geffen School of Medicine, University of California (AHK), Los Angeles, CA; the Department of Emergency Medicine, Oregon Health Sciences University (RAL), Portland, OR; the Institute for Health Research, Kaiser Permanente Colorado and the Departments of Emergency Medicine and Preventive Medicine and Biometrics, University of Colorado Health Sciences Center (DJ), Denver, CO; the Department of Emergency Medicine, New York University School of Medicine (MR), New York, NY; the Department of Emergency Medicine, University of California at San Francisco (EJW), San Francisco, CA; and the Department of Emergency Medicine, University of Pittsburgh School of Medicine (DMY), Pittsburgh, PA. Dr. Asplin is currently at the Fairview Medical Group, St. Paul, MN. Received August 5, 2010; revision received October 12, 2010; accepted October 15, 2010. Funding for this conference was made possible (in part) by 1R13HS018114–01 from the Agency for Healthcare Research and Quality (AHRQ). The views expressed in written conference materials or publications and by speakers and moderators do not necessarily reflect the official policies of the Department of Health and Human Services, nor does mention of trade names, commercial practices, or organizations imply endorsement by the U.S. Government. The authors have no potential conflicts of interest to disclose. Supervising Editor: Lawrence M. Lewis, MD. Address for correspondence and reprints: Jesse M. Pines, MD, MBA, MSCE; e-mail:
[email protected].
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ISSN 1069-6563 PII ISSN 1069-6563583
ª 2011 by the Society for Academic Emergency Medicine doi: 10.1111/j.1553-2712.2011.01086.x
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‘‘frequent users.’’ One estimate is that 8% of ED patients are frequent users, accounting for up to 28% of all visits.2 In the same study, the authors found that frequent users were more likely to be female than male, older (35 to 64 years vs. 18 to 34 years), below the poverty threshold, report poor health status, have Medicaid insurance, and have a regular source of care. Frequent use of ED services is often perceived to be a potentially preventable misuse of resources. There is a common perception that similar and more appropriate medical services can be delivered outside of EDs at a lower cost.3 There have been many efforts to better understand who frequent ED users are and design interventions to transition their health care utilization from EDs to other settings, such as outpatient clinics. There are some fundamental problems with equating frequent use with misuse. High users of ED services are also high users of non-ED services, indicating that patient-level factors, such as disease burden, are important drivers of frequent ED utilization.4,5 The purpose of this article is to describe several issues in the epidemiologic study of frequent ED use, identify gaps in knowledge, and propose several potential areas for future research to improve the understanding of frequent use and, where appropriate, reduce it. The process of generating this review and resulting research agenda was conducted through a series of conference calls among the authors culminating in an in-person discussion at the October 2009 conference titled, ‘‘Emergency Care Across the Continuum: A Systems Approach.’’ During development, a nonsystematic literature review was conducted by the authors. Relevant work that was found during the course of this review is included in the following article. It is framed to present the current state of knowledge about frequent ED use and where the logical next steps are to advance our understanding of this phenomenon. While the health systems and EDs differ tremendously between countries, there are similar themes in non-U.S. studies on frequent use. Therefore, we have integrated studies conducted both within the United States and outside the United States into the discussion together, as we describe this worldwide phenomenon. DEFINITION OF FREQUENT ED USE Currently, no standard or uniform definition of what constitutes frequent use exists, making it difficult to compare or aggregate studies. The number of visits to the ED for patients over any time period tends to follow a Poisson distribution, which requires any investigator to define the time period in question (e.g., 1 month, 6 months, 1 year), and a cut-point between regular use and persistent versus time-limited frequent use. Researchers have variably defined this cutoff for frequent ED use, ranging from more than three to as many as 20 visits in any given year or three times in any given month.6–15 Among these studies, the most common definition for frequent users is four or more ED visits in a 1-year period. Others define additional subsets of frequent user as ‘‘hyperusers’’ as 10–20 visits in a year.16 While an elevated threshold for frequent use defines groups with unquestionably higher use
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patterns, it also reduces the population to study and potential interventions. However, some authors have found commonalities in groups stratified by visit number; for example, one study found that frequent users with 3–20 visits in a year were more likely to be admitted, while those with 20 or more visits were less likely to be admitted.17 Another observation in the current literature on frequent use is that some studies investigate frequent users as a whole, while others have studied specific populations, either identified by specific reasons for visit, such as substance abuse, or by patients with various comorbid conditions. We find value in both approaches. However, it is important to recognize that the true reasons for frequent use might be better elucidated in condition-specific populations, while the demographic factors and interactions between factors may be better understood in datasets where heterogeneous populations are combined. For example, the reasons for frequent use among patients with heart failure, chronic pain, and mental illness might be tremendously different. However, understanding commonalities between the groups is important in understanding the greater phenomenon, for example, that particular demographic groups, income brackets, education levels, types of insurance, or regional factors may predispose to a higher or lower likelihood of frequent use. Other issues not addressed in the literature include the distribution of use over time and pattern of use. Populations of ED frequent users are typically described over a specific time period. However, there have been few attempts to describe in more detail whether the visits occur over a short period (such as three visits spaced evenly over a month or a year) or whether they cluster around particular events, such as an acute medical illness, a traumatic injury, or a change in insurance status. No studies to our knowledge have distinguished between different patterns of use. For example, one patient may have an acute injury and visit an ED five times over several months, and then rarely thereafter, while another patient may consistently visit the ED once or twice every few months for exacerbation of a chronic illness, such as asthma, heart failure, or sickle cell disease. While many investigators have asked why frequent users use the ED instead of other sources of care, there are few studies examining what services frequent users receive in the ED, notably laboratory, imaging, or specific medications.17 We also know little beyond visit number about other features that subcategorize frequent use based on the likelihood of hospital admission. Hospital admission results in higher health expenditures on average than outpatient ED visits. Therefore, frequent ED users who are also frequently admitted may represent the highest cost group, and these patients may differ from the frequent ED user who is usually discharged. It is also unknown whether different patterns of frequent use are related to the choice of a particular ED site for care. Frequent users of specific types of ED services may choose to visit the same ED for all their care or visit several different EDs. For example, a patient with a complex medical condition, like cancer, may use
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one ED because his or her oncologists practice at the same hospital. In contrast, those who exhibit nontherapeutic drug-seeking behavior, or use the ED for social service needs, may choose to visit a variety of EDs within a region. This may be guided by the knowledge that few EDs have interoperable medical records and more of their needs are met by using services in disparate locations. Developing databases that can assess repeat ED use among different EDs may help quantify this phenomenon. Frequent use may not be just about numbers of visits, which is how it has traditionally been defined and studied in the literature. There is a need to improve the understanding of frequent use by creating more meaningful categories of frequent use based on actual usage, patterns over time, types of ED services used, and whether more than one ED is used. CHARACTERISTICS OF FREQUENT USERS Various studies describe patient-level factors associated with being a frequent ED user. In general, frequent users tend to have a higher severity of illness, be older, and have less financial resources. They are more likely to have health insurance, be chronically ill, and have a pain-related visit. The following section describes the literature and interprets the factors in the context of future research on frequent use. Severity of Illness Using a Massachusetts database to compare frequent users (five or more visits in a year) with less frequent users, frequent users were more likely to die after their last visit (2.6% of frequent users vs. 1.1% of infrequent users), were hospitalized at higher rates (18.8% vs. 14.2%), and were transported to the ED more frequently by ambulance (18.6% vs. 12.1%).18 Another study reported a 28% admission rate to the hospital among frequent ED users compared to 16% for the general ED population.7 In addition, the mortality rate among frequent ED users has been reported to be high (18.6%) over a 1-year period in Spain.19 The most common causes of death reported among frequent ED users are cancer, ischemic heart disease, drug intoxication, and suicides.20 Understanding the causes of death among particular types of frequent ED users may be helpful in directed programs aimed at reducing potentially preventable causes, such as intoxication and suicide. Age Patients in older age groups are associated with a higher odds ratio (OR; 2.4, 95% confidence interval [CI] = 2.3 to 2.6) of being a frequent user compared to younger age groups.18 The increased use may be due to the declining health of older adults in need of more frequent medical attention. Older adults (>65 years) have access to insurance through the Medicare program. The older frequent ED user may be a good target for focused efforts to move certain care from the ED to a primary care provider. Similarly, coordinated medical homes or outpatient support for those with chronic illnesses like heart failure, chronic obstructive pulmonary
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disease, or diabetes may help keep older adults out of the ED and hospital, decreasing cost. More importantly, care coordination for older adults outside of ED settings may improve outcomes such as survival and quality of life. However, some recent studies have challenged the notion that access to primary care may not actually improve chronic disease control in frequent users, because primary care follow-up rates may be lower than expected.6,21 Income According to the data from the Medical Expenditure Panel Survey (MEPS), 27% of frequent ED users were below the federal poverty level compared to 16% of infrequent users.22 Another study demonstrated the following demographic associations with frequent ED use: being a single parent, single or divorced marital status, high school education or less, and an annual income of less than $10,000.18 When household income is below the federal poverty level, the odds of frequent use are significantly higher (OR = 2.4, 95% CI = 1.7 to 3.3), compared to households whose income is above the federal poverty level.2 Among frequent visitors to a Canadian psychiatric ED, the majority were described as ‘‘economically impaired’’; however, there is considerable selection bias in a psychiatric ED with regard to the lack of employment and reported poverty.14 Health Insurance Status There is a common perception that frequent ED users are more often uninsured and without a usual source of health care, such as a primary care physician. Current data do not support this notion; according to MEPS, frequent ED users were more likely to have Medicare (28% vs. 18%) or Medicaid (23% vs. 12%) coverage.22 Another study found that uninsured and privately insured adults had the same risk of being frequent users, but that publicly insured adults were twice as likely to be frequent users.10 Among pediatric frequent ED users, 38% had private insurance, 60% had Medicaid or state assistance, and 1.4% were uninsured.9 Because those with government insurance are at higher risk for being frequent users, interventions aimed at reducing frequent use may be best targeted at individuals with government insurance, specifically Medicaid. Health Status According to the MEPS database, frequent ED users are more likely to be living with at least one physical or mental chronic condition (84% vs. 64%).22 Clinical factors associated with frequent ED use include having a chronic disease (OR = 3.1, 95% CI = 1.8 to 5.3), cancer (OR = 4.2, 95% CI = 1.3 to 13.4), gastrointestinal disease (OR = 6.3, 95% CI = 2.0 to 20.2), cardiovascular disease (OR = 8.4, 95% CI = 2.5 to 28.1), or pulmonary disease (OR = 4.2, 95% CI = 1.0 to 17.0).23 Another study found a high prevalence of mental health issues among ED frequent users, as measured by the 12-item General Health Questionnaire score.24 Among children, chronic conditions most associated with frequent use were wheezing, neurologic conditions, gastrointestinal complaints, and endocrine problems.9 Typically, patients with chronic conditions also receive medical care
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outside of EDs, suggesting that interventions to reduce frequent ED use among this population may be formulated for care outside the ED. Reason for ED Visit While also very common among nonfrequent users, pain or pain-related complaints are the most commonly cited reason for the ED visit among frequent ED users.25 In addition, psychiatric complaints were found to be more common among frequent ED users compared to other ED users in Canada.26 In that study, 93% of frequent ED users had at least one DSM-IV psychiatric diagnosis, compared to 50% of random users matched for the same chief presenting complaint. In addition, the most common diagnoses among these frequent users were major depression, anxiety disorder, somatoform disorder, pain disorder, and substance abuse and dependence.26 Another study reported that patients with 11 or more annual visits were more likely to be diagnosed with schizophrenia.15 The high prevalence of mental disorders among frequent ED users suggests that this particular population may be a good target for both ED-based and non–ED-based interventions to reduce frequent use. This also suggests the merit of studying reasons and designing condition-specific interventions for frequent use among conditionspecific populations because of the myriad different reasons that each population may frequent the ED. Access to Other Health Care Services Another common perception is that frequent use of ED services is caused by limited access to primary care. One study found that individuals who lack a usual source of care were actually less likely to be frequent users.2 Irish investigators reported that frequent ED users made more visits to their general practitioners in the year of study compared to control patients (median = 12 vs. 3 visits), and a higher proportion of these individuals also used community welfare services, social work, addiction counseling, and psychiatric services.24 Lucas and Sanford6 found that 73% of frequent users reported having a usual source of medical care other than the ED and only 27% said they had difficulty in seeing a primary care physician. Adults who made three or more visits to their primary care doctors were five times more likely to be frequent ED users than those who made no such visits.2,22 Clearly, many frequent users are not obtaining medical services exclusively in the ED. This suggests that interventions to reduce frequent ED use should also be targeted at primary care sites, among patients known to be frequent users or at risk for frequent use. Cost of Care Because frequent users by definition have higher health care utilization in the ED than other patients, costs of care may be seen as an outcome measure. Cost is a particularly important outcome, since much of the literature on frequent ED use reports that a primary care– based medical home may reduce expenditures for these patients. In light of the previous discussion that frequent users are older, have higher severities of illness, chronic illness, and higher rates of primary care use,
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costs should be considered a major outcome in moving the care of frequent users to other settings. Also key to any future analysis is a broader look at costs that includes those associated with care outside of the ED and whether overall societal costs vary based on the care setting. While the ED is often assumed to be ‘‘higher cost,’’ true cost versus charge data are often lacking in comparisons across settings. For some, the intensive evaluation and care in an ED visit could actually lessen future costs, making cost analyses challenging. In addition, because EDs are available at night and on weekends, overall costs of care (including missed work) should be considered. INTERVENTIONS AIMED AT REDUCING FREQUENT USE Several published studies aimed to reduce frequent ED use through interventions tailored to specific populations of frequent users. These studies occurred within individual EDs and regional managed care organizations. One large program, called the Civilian Health and Medical Program of Uniformed Services (CHAMPUS) reform initiative, aimed to actively find non-ED care locations for approximately 1.2 million beneficiaries in California and Hawaii.27 ED use among patients with diabetes, hypertension, and asthma was significantly reduced (from 55% to 41%), and allowed charges dropped nearly 50%.27 One recent ED-based study reported on a randomized trial of a housing and case management program for chronically ill homeless adults in a public teaching hospital, finding a reduction in ED visits and hospitalizations.28 A similar ED-based randomized trial found that case management was associated with reductions in both ED use and overall costs of care in a broader group of frequent ED users.29 Similar studies found reductions in ED use after an intervention using before–after designs.30 However, other studies have not been universally positive. One pilot study did not demonstrate a reduction in ED visits,31 and another EDbased randomized trial detected no difference in ED use among frequent ED users when a multidisciplinary team created individualized treatment plans.32 Another study found that an expedited referral to a federally qualified health center resulted in very low attendance.21 Overall, the results of both managed care based and ED-based trials aimed at reducing frequent use have been positive, indicating that efforts to reduce frequent ED use and the costs of health care can be effective. However, the managed care studies have mostly focused on specific disease management, indicating that the interventions at the plan level may be more effective if focused on particular conditions, rather than frequent users as a whole. FUTURE DIRECTIONS AND RESEARCH AGENDA Based on our review of existing data, we identified several areas for study that may improve the understanding of frequent ED use, identify the populations at risk, and help develop interventions to decrease frequent ED use.
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Better Categorization System for Frequent Users Recent studies have debunked many of the myths of frequent ED users. However, a limitation in these studies is the arbitrary definitions used to classify frequent users. The first step in advancing the literature on frequent use is to better define specific categories of frequent users along several domains, including overall frequency and pattern of use, insurance status, specific services received in the ED, specific disease states, and use of one or more EDs as regular sources of care. Overall frequency and patterns of use should move beyond the general classification of frequent users as four to five or more visits in a year. Potential classifications may include short-term versus long-term versus periodic frequent users. Specific services received in the ED may include classifying patients as frequent admitters versus infrequent admitters. Those who use one ED versus many EDs should be classified separately, and likely represent different populations. By creating a taxonomy of frequent use, we may better understand some of the epidemiologic patterns observed in studies that pool frequent users into one category. Any taxonomy of frequent use should consider stratification by comorbid conditions, such as heart failure, asthma, mental illness, or other conditionspecific factors that may predispose people to frequent ED use. Potential sources for study include large administrative databases such as National Emergency Department Sample (NEDS) or Healthcare Cost and Utilization Project (HCUP) or data from large insurers, such as Medicare, Medicaid, or private companies. However, if interventions are to be tested, this would require large, ideally regional multicenter studies. Identifying Predictors of Frequent ED Use The majority of existing research focuses on curbing future ED use among those with frequent antecedent use. We believe that in addition to this approach, efforts are needed to identify individuals or groups at risk for future frequent ED use before it occurs. Specifically, what factors predict who will become a frequent ED user during an initial medical illness or after a traumatic injury? A longitudinal study may be helpful to identify these populations. In addition, among frequent users, understanding which patients will remain frequent users may be similarly helpful in identifying groups for interventions. Study the Effects of Non–ED-based Interventions: Primary Care or Managed Care Based Because frequent ED users also have high rates of primary care use, interventions aimed at curbing frequent ED use may be better designed in primary care settings or managed care organizations where patients can be followed longitudinally. In addition, the degree to which suboptimal primary care management leads to frequent ED use has not been well explored. Many EDbased interventions that have reported positive results have required considerable additional resources, such as case managers. Unfortunately, case managers may not be available outside of research settings, thus limiting the generalizability and feasibility of implementing a study intervention. Thus, broad-based interventions
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to increase primary care access or develop care management plans outside the ED may be most effective at reducing frequent ED use. The effects of such primary care based interventions may be greatest for individuals with chronic illness such as asthma, chronic obstructive pulmonary disease, congestive heart failure, and sickle cell disease. Qualitative Studies of Frequent Users That Explore Potentially Preventable Reasons for ED Use While reasons for frequent use could vary based on individual and group factors, qualitative studies aimed at uncovering the reasons select patients frequently use the ED may provide insight into how to best address the issue. Specifically, questions aimed at identifying potentially preventable versus nonpreventable reasons for use should be sought. These studies would likely be best done identifying specific conditions or groups of patients, as the reasons for frequent use will likely be more similar between conditions than among them. CONCLUSIONS Much research has been devoted to understanding frequent ED use. Current literature suggests that frequent ED users are more severely ill, older, more likely to have government insurance, more likely to have certain comorbid conditions, more likely to have poor health status, do have regular sources of care, and are more likely to experience poor outcomes, including mortality. Several gaps exist in the literature related to frequent ED use. Specifically, a better categorization system, longitudinal studies, primary care–based interventions, and qualitative studies aimed at identifying preventable reasons for frequent use are some of the next steps to better understanding and learning how to potentially reduce frequent ED use. References 1. Niska R, Bhuiya F, Xu J. National Hospital Ambulatory Medical Care Survey: 2007 emergency department summary. Natl Health Stat Report. 2010; 6:1–31. 2. Hunt KA, Weber EJ, Showstack JA. Characteristics of frequent users of emergency departments. Ann Emerg Med. 2006; 48:1–8. 3. Carret ML, Fassa AG, Kawachi I. Demand for emergency health service: factors associated with inappropriate use. BMC Health Serv Res. 2007; 7:e131. 4. Lacalle E, Rabin E. Frequent users of emergency departments: the myths, the data, and the policy implications. Ann Emerg Med. 2010; 56:42–8. 5. Hansagi H, Olsson M, Sjöberg S, et al. Frequent use of the hospital emergency department is indicative of high use of other health care services. Ann Emerg Med. 2001; 37:561–7. 6. Lucas RH, Sanford SM. An analysis of frequent users of emergency care at an urban university hospital. Ann Emerg Med. 1998; 32:563–8. 7. Locker TE, Baston S, Mason SM, Nicholl J. Defining frequent use of an urban emergency department. Emerg Med J. 2007; 24:398–401.
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8. Okuyemi KS, Frey B. Describing and predicting frequent users of an emergency department. J Assoc Acad Minor Phys. 2001; 12:119–23. 9. Yamamoto LG, Zimemrman KR, Butts RJ, et al. Characteristics of frequent pediatric emergency department users. Pediatr Emerg Care. 1995; 11: 340–6. 10. Zuckerman S, Shen YC. Characteristics of occasional and frequent emergency department users: do insurance coverage and access to care matter? Med Care. 2004; 42:176–82. 11. Mandelberg JH, Kuhn RE, Kohn MA. Epidemiologic analysis of an urban, public emergency department’s frequent users. Acad Emerg Med. 2000; 7:637–46. 12. Milbrett P, Halm M. Characteristics and predictors of frequent utilization of emergency services. J Emerg Nurs. 2009; 35:191–8. 13. Chaput YJ, Lebel MJ. Demographic and clinical profiles of patients who make multiple visits to psychiatric emergency services. Psychiatr Serv. 2007; 58:335–41. 14. Sun BC, Burstin HR, Brennan TA. Predictors and outcomes of frequent emergency department users. Acad Emerg Med. 2003; 10:320–8. 15. Pines JM, Buford K. Predictors of frequent emergency department utilization in Southeastern Pennsylvania. J Asthma. 2006; 43:219–23. 16. Oliveira A. Hyperusers and emergency. Acta Med Port. 2008; 21:553–8. 17. Ruger JP, Richter CJ, Spitznagel EL, et al. Analysis of costs, length of stay, and utilization of emergency department services by frequent users: implications for health policy. Acad Emerg Med. 2004; 11:1311– 7. 18. Fuda KK, Immekus R. Frequent users of Massachusetts emergency departments: a statewide analysis. Ann Emerg Med. 2006; 48:9–16. 19. Salazar A, Bardes I, Juan A, et al. High mortality rates from medical problems of frequent emergency department users at a university hospital tertiary care center. Eur J Emerg Med. 2005; 12:2–5. 20. Gunnarsdottir OS, Rafnsson V. Mortality of the users of a hospital emergency department. Emerg Med J. 2006; 23:269–73. 21. Scherer TM, Lewis LM. Follow-up to a federally qualified health center and subsequent emergency department utilization. Acad Emerg Med. 2010; 17:55–62.
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22. Kaiser Family Foundation. Characteristics of Frequent Emergency Department Users. Available at: http://www.kff.org/insurance/upload/7696.pdf. Accessed Mar 27, 2011. 23. Huang JA, Tsai WC, Chen YC, et al. Factors associated with frequent use of emergency services in a medical center. J Formos Med Assoc. 2003; 102: 222–8. 24. Byrne M, Murphy AW, Plunkett PK, et al. Frequent attenders to an emergency department: a study of primary health care use, medical profile, and psychosocial characteristics. Ann Emerg Med. 2003; 41:309–18. 25. Blank FS, Li H, Henneman PL, et al. A descriptive study of heavy emergency department users at an academic emergency department reveals heavy ED users have better access to care than average users. J Emerg Nurs. 2005; 31:139–44. 26. Mehl-Madrona LE. Prevalence of psychiatric diagnoses among frequent users of rural emergency medical services. Can J Rural Med. 2008; 13:22–30. 27. Kravitz RL, Zwanziger J, Hosek S, Polich S, Sloss E, McCaffrey D. Effect of a large managed care program on emergency department use: results from the CHAMPUS reform initiative evaluation. Ann Emerg Med. 1998; 31:741–8. 28. Sadowski LS, Kee RA, VanderWeele TJ, Buchanan D. Effect of a housing and case management program on emergency department visits and hospitalizations among chronically ill homeless adults: a randomized trial. JAMA. 2009; 301:1771–8. 29. Shumway M, Boccellari A, O’Brien K, Okin RL. Cost-effectiveness of clinical case management for ED frequent users: results of a randomized trial. Am J Emerg Med. 2008; 26:155–64. 30. Pope D, Fernandes CM, Bouthillette F, Etherington J. Frequent users of the emergency department: a program to improve care and reduce visits. CMAJ. 2000; 162:1017–20. 31. Lee KH, Davenport L. Can case management interventions reduce the number of emergency department visits by frequent users? Health Care Manag (Frederick). 2006; 25:155–9. 32. Spillane LL, Lumb EW, Cobaugh DJ, Wilcox SR, Clark JS, Schneider SM. Frequent users of the emergency department: can we intervene? Acad Emerg Med. 1997; 4:574–80.
