Soc, Sci. & Med., Vol. 13A, pp. 495 to 498 Pergamon Press Ltd 1979. Printed in Great Brilain

RESEARCH N O T E

THE E M E R G E N C Y D E P A R T M E N T AS A S C R E E N I N G P O I N T FOR H O S P I T A L SPECIALTY SERVICES:

I N C L U S I O N A R Y VS E X C L U S I O N A R Y STRATEGIES*

GEOFFREY GIBSON

Health Services Research and Development Center, Department of Emergency Medicine, The Johns Hopkins University and Medical Institutions

Abstracl--The screening function performed by the emergency department for hospital specialty units varies greatly and is important in understanding the complex relationship between emergency medical services and the wider health care environment. Two organizational postures define the extremes in screening variations. Under an Inclusionary Strategy the emergency department seeks at all costs to minimize the number of false negative cases (those that should have been referred to the specialty clinic/unit but who were incorrectly discharged from the E.R. instead) by over-referring a high level of false positives (those who should have been discharged from the emergency department but who were incorrectly referred to the specialty clinic/unit). Under an Exclusionary Strategy the emergency department does the opposite, that is, it minimizes false positive referrals by under referring and toler- ating a high level of false negatives. The adoption of an Inclusionary or Exclusionary Strategy or any intermediate posture has important causes and consequences for occupancy rates of specialty units, the level of diagnostic ability required in the emergency department and therefore its clinical attractiveness for physicians, staffing ratios and training levels for nurses and physicians in the emer- gency department and specialty clinics/units, and the risk taking behavior of preferring a false positive to a false negative or vice versa. Since this typology and the model on which it is based are seen as a means by which EMS research can move from observation to description and through explanation to prediction, both are used to deduce hypotheses on the causes and consequence of emergency depart- ment screening selectively for early testing of the model.

AN EMERGENCY DEPARTMENT

T Y P O L O G Y F O R SCREENING

The hospital is a complex and highly specialized social system separated from the environment by a boundary crossing which are several different entry points w i t h varying levels of selectivity. Thus, a patient may not walk into a hospital and climb into a bed or walk in to a specialized out-patient clinic. Entry points are admission procedures which, depending on the type of hospital, occupancy rates and perceived mandate, impose different selection. criteria based on the potential patient's clinical con- dition, insurance coverage, and even veteran status. Outpatient clinics may screen on the basis of clinical condition, area of residence, internal and external physician referral factors, economic status, etc. The emergency department differs from Other entry points in not being able to deny or delay treatment, in the diagnostic diversity, range of severity and volume of input, as well as being accessible at all times.

The emergency department acts not only as an entry point to the hospital (accounting for approxi- mately one-fifth of admissions and one-third of in- patient days as well as about two-thirds of all in i t i a l outpatient referral visits [1] but as a screen to reduce

* Presentation at American Public Health Association annual meetings, November, 1977, Washington, D.C. Sup- ported by Grant HS 01907 from the National Center for Health Services Research to the Health Services Research and Development Center, The Johns Hopkins Medical In- stitutions.

the volume, and diversity of the rate of input to the more specialized inpatient and outpatient units within the hospital. These specialty units require protective screening from the emergency department in order to maintain an appropriate balance between their high technology and degree of specialization and the input they are expected to process. In this screening function, any given emergency department may be characterized by its position along a continuum defined by the polar postures relative to the specialty unit being referred to. One extreme (the Inclusionary Strategy) seeks at all costs to minimize the number of false negative cases (those that should have been referred to the specialty clinic/unit but who were in- correctly discharged from the emergency department instead) by over referring and tolerating a high level of false positives (those who should have been dis- charged from the emergency department but who were incorrectly referred to the specialty clinic/unit). The opposite extreme (the Exclusionary Strategy) seeks to minimize false positive referrals by under referring and tolerating a high level of false nega- tives. The adoption of either strategy or any inter- mediate position by an emergency department has important catises and consequences for occupancy rates of specialty units, the level of diagnostic ability required in the emergency department, the scope of treatment given there and therefore, its clinical attractiveness for physicians, staffing ratios and train- ing levels for nurses and physicians in the emergency department and specialty units/clinics and the risk- taking behavior of preferring a false positive to a false negative or vice versa.

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496 Research N o t e

The Inclusionary Strategy avoids inappropriate dis- charges by over-referring to the specialty unit and running the risk of generating a high level of inappro- priate referrals. In general, this posture minimizes the diagnostic workup activities performed in the emer- gency department which this mainly acts as a non- screening processing unit or even "sign post". Rela- tively low staffing ratios of nurses and physicians are required under this strategy and indeed a high degree of nurse substitution for physicians is allowable since this exclusionary strategy requires little clinical de- cision making as cases in doubt are resolved by admitting or referring to the specialty unit. This stra- tegy maximizes admission and occupancy rates and minimizes the risk of inappropriate discharges. It reduces the volume and intensity of the emergency department diagnostic work load but not the clinical attractiveness of service there nor its training value. In turn, this stance imposes a heavy diagnostic burden on the specialty units to perform their own screening and selection and requires high staffing ratios and a well developed triage ability. Inevitably it results in some misallocation of specialized resources to inappropriate patients as a price for a confident assurance that all appropriate patients have been referred and treated. Indeed, it is often the con- cern by the specialty units themselves (both in-patient and out-patient) about "false negatives" that have led them to request or even insist that the emergency department adopt the inclusionary posture. This strategy is well sutied for community hospitals where attending physicians may be concerned about the emergency department doing too much and referring too little. It is relatively unattractive for a teaching hospital from the perspective of the self-screening required of specialty units and particularly so from the perspective of training for surgical and medical house officers, to say nothing of the newly emerging emergency medicine residency programs.

The Exclusionary Strategy avoids inappropriate referrals by under referring to the specialty unit and running the risk of generating a high level of inappro- priate discharges. This posture maximizes the diag- nostic work-up activities in the emergency depart- ment even though the specialty unit may choose to repeat the work-up when they admit the patient. This stance requires high staff ratios of nurses and physicians at a sufficiently advanced training level to screen appropriately and for their judgment to be credible to the specialty unit. The Exclusionary Strategy necessitates much decision making and, because cases in doubt are resolved by discharging from the emergency department, runs certain legal and clinical risks. This stance may remove some of the diagnostic burden from the specialty units and may allow them lower staffing ratios depending on whether the specialty unit confidence in the emer- gency department decision persuades them that they likely and as a result an emergency department exclu- sionary strategy may not obviate the specialty unit doing its own screening and repeating the work-up. At the aggregate leve ! , however, this strategy does assure the specialty unit of appropriate referrals although i t may be at the cost of inappropriate dis- charges. The specialty unit may or may not be aware and/or concerned about such "false negatives" and

it may insist that the emergency department become more inclusionary and less exclusionary. Indeed, since the Exclusionary Strategy minimizes admission and occupancy rates, the specialty units may insist on more inclusion from their important perspective of wanting more patients and filling specialty beds. The introduction of planning and regulatory disincentives for low occupancy rates will clearly increase the pres- sure of the specialty units on the emergency depart- ment for more inclusionary strategies. This strategy is not well suited for community hospitals since it may involve a more expanded role for and by the emergency department than the attending staff think appropriate. In contrast it is well suited for teaching hospitals, but this depends largely on the often diver- gent service and training emphases of the specialty units Vs the emergency department. This strategy pro- vides excellent training opportunities in the emer- gency department and makes it an attractive clinical setting for service.

CASE EXAMPLES OF EMERGENCY

DEPARTMENT SCREENING

To illustrate this screening typology and to lay the basis for several concluding hypotheses, it is instruc- tive to consider two examples of selective screening by the emergency department for hospital specialty units: hypertension and chest pain.

First, with regard to hypertension, several emer- gency departments are screening for hypertension since inner-city, poverty level individuals using emer- gency departments are at high risk of being unde- tected hypertensives and are least likely to have an alternative regular source of health care to screen and treat them. In implementing screening, complex and important issues are faced by emergency departments in determining how inclusionary or exclusionary their screening ought to be of hypertensives, how complete a work-up should be undertaken in the emergency department, and how selective ought the referrals to be to hypertension management clinics. Thus, some emergency departments adopt an inclusionary strat- egy and refer to hypertension clinic all patients with an elevated blood pressure on one reading. This rela- tively unselective screening tends to be associated with high "no-show" rates at the hypertension clinic, a high volume of referrals, substanntial proportions of false positives, and criticism by hypertension clinics that emergency departments are over-referring, per- forming inadequate work-ups, ignoring risk factors, and routing to them a wide diversity of patients vary- ing as to clinical complexity, behavioral compliance, natural history, and even as to whether they are pre- sently under care for hypertension somewhere else. By contrast, other emergency departments adopt an exclusionary posture and take several blood pressure readings during the patients initial visit, attempt to bring the patient back to the mergency room for a second series of blood pressure readings and even may choose to manage behaviorally or clinically un- complicated hypertensives through emergency depart- ment nurse practitioners or physicians, while referring complicated hypertensives who have passed both screening series and been worked up in the emergency department with detailed attention to individual risk

Research Note 497

factors, onto an out patient hypertension clinic. This highly selective screening strategy results in fewer and more homogeneous referrals to the hypertension clinic, low proportions of false positives referrals, an increased probability of false negative discharges from the emergency department, and a much greater and diagnostically more demanding volume of ~ork-ups in the emergency department.

The second example has to do with the emergency department screening criteria for patients presenting with chest pain, a symptom which ranges in etiology and from the immediate life-threatening to the clini- cally mundane [2]. As we have indicated elsewhere [3]

"the clinical signs and symptoms as well as the basic laboratory assessment are noted for lack of sensitivity and specificity. The patient with atypical moderate pain and a normal electrocardiogram (EKG) and chest X-ray film may be having unstable angina and be at risk of sudden death. On the other hand, a patient with typical "ischemic" pain and nonspecific EKG abnormalities may merely have a "chest-wall syndrome". [4-5] "Killip et al. [6] found a 25% mortality rate for patients with myocardial infarction following admisstion to a coron- ary care unit (CCU). Norris et al. [7] evaluated 530 patients following CCU discharge and found a 33% 3 year mortality rate. Balancing these profound risks is the fact that CCU care may cost as much as $300 to $400 per day and may have serious psychological and medical com- plications. "Emergency department personnel know of individuals dis- charged only to return shortly with an evident myocardial infarction or DOA. CCU staff are generally concerned that too many patients are being "unnecessarily" admitted for monitoring as "rule out myocardial (MI)" or "chest pain of unknown etiology". This latter circumstance may hamper CCU effectiveness, depending on occupancy rate and the severity in the census. "Admitting enough as opposed to not admitting too many is a fine line. Schor e t al. [8] evaluated the emergency department treatments in Israel of 1,578 cases referred for possible MI. Ten per cent of admissions were subsequently judged unnecessary."

Again, emergency departments vary in their screen- ing posture for patients presenting with chest pain. On the one hand, inclusionary emergency depart- ments refer most such patients to the Coronary Care Unit (CCU) for further evaluation and do so quickly and non-selectively. Such a strategy is associated with low false negative rate, a high volume of CCU refer- rals and of inappropriate admissions. The exclusion- ary strategy, by contrast, involves a larger diagnostic role for the emergency department, a smaller but more homogenously severe set of referrals to the CCU, and a higher probability of fewer false positives at the price of more false negatives.

The screening role of emergency departments are influenced by both internal factors and the attitudes of the specialty units being referred to since that unit will have and seek to impose on the emergency department a particular set of referral expectations. Thus, although hypertension clinics at a hospital will probably seek fewer rather than many referrals, and homogenous as to clinical severity rather than hetro- genous, they vary in terms of how comprehensive a work-up they see as appropriate in the emergency department and how much decision making as to diagnosis and therapy they will concede to the emer-

gency department. Similarly, CCUs vary as to their perception as to how appropriate a comprehensive an E.R. work-up is and in their tolerance of false positives and false negatives.

SUMMARY AND DISCUSSION

This paper has pointed to the often neglected rela- tionship between the emergency department and other hospital in-patient and out-patient units as well as the wider ambulatory health care system. This neg- lect results from a theoretic and programmatic iso- lation of EMS from other health care perspectives and in turn has prevented our understanding of EMS moving from description to explanation to prediction. A key mechanism to facilitate an integrated view of EMS within health care as well as to systematize our understanding of EMS, is a conceptual model and typotogies and hypotheses based thereon. A social system model has been suggested and applied to emergency departments in specifying their screening behavior relative to hospital in-patient and out- patient specialty units. The model focussed on the role of the emergency department as an entry point across a boundary between environment and hospital system and on its role as an ingester and input trans- ducer in protecting highly specialized units by filter- ing input to be within appropriate qualitative and quantitative tolerance limits. In particular, the emer- gency department seems to perform an adaptive and homeostatic function in reducing disequilibrating im- balances elsewhere in the system.

From this model a typology has been developed to characterize an emergency department by placing its screening behavior on a continuum defined by two polar extremes. Under an Inclusionary Strategy the emergency department seeks at all costs to minimize the number of false negative cases (those that should .have been referred to the specialty clinic/unit but who were incorrectly discharged from the emergency room instead) by over-referring a high level of false positives (those who should have been discharged from the emergency department but who were incorrectly referred to the specialty clinic/unit). Under an Ex- clusionary Strategy the emergency department does the opposite, that is, it minimizes false positive refer- rals by under referring and tolerating a high level of false negatives. The adoption of an Inclusionary or Exclusionary Strategy or any intermediate posture has important causes and consequences for occu- pancy rates of specialty units, the level of diagnostic ability required in the emergency department and, therefore, its clinical attractiveness for" physicians, staffing ratios and training levels for nurses and phys- icians in the emergency department and specialty clinics/units and the risk taking behavior of preferring a false positive to a false negative or vice versa.

Table 1 indicates the typology and the causes and consequences of the emergency department screening behavior it attempt to characterize. Thus, screening behavior of the emergency department is seen as ranging along a continuum defined (like other screen- ing functions) by false positive/negative rates. The other aspects of the typology maybe summarized in

498 Research Note

Table 1. Typology of emergency department screening and associated causes and consequences

Causes -~ Emergency Department Screening = Consequences

Hospital Factors: Occupancy rates

Teaching involvement Type of residency program Presence/influence of private

attending staff Degree of specialization

(inpatient and out patient units)

Specialty Unit~Factors: Awareness/concern about

false negative Clinical/legal consequences

of false negatives Clinical/resource consuming

consequences of false positive

Perceived trade off between false negative and false positive

Confidence in E.D. diagnostic capacity

Inclusionary Strategy Emergency Department Hi false positive - - low false negative Scope of practice

rates - - rates - - Degree of work-up - - Staffing ratios - - Clinical attractiveness

Low false - - hi false negative positive rate rate

Exclusionary Strategy

specialty Units Volume and type of referrals Case mix

the form of hypotheses which are advanced for early typology and the hypotheses derived from it. If the testing: hypotheses are confirmed they will allow causes and

effect to be linked so that description may become 1. Hospital emergency departments systematically explanation in our understanding of emergency

vary in their screening behavior and may be charac- departments and our resulting predictive capacity terized by their false positive/negative levels. ,, enhanced.

2. The false positive/negative rates of emergency~ departments screening are determined and vary sys- tematically with such hospital factors as occupancy rates, teaching involvement, type of residency pro- grams, presence/influence of private attending staff, degree of specialization (in patient and out-patient units) and such specialty unit factors as awareness/ concern about false negatives, clinical/legal conse- quences of false negatives, clinical/resource consum- ing consequences of false positives, perceived trade- offs between false negatives and false positives, and confidence in emergency department diagnostic capa- city.

3. The false positive/negative rates of emergency department screening in part determines such emer- gency department factors as scope of practice, degree of work-up staffing ratios, clinical attractiveness and such specialty unit factors as volume and type of refer- rals and case mix.

A typology is useful only to the extent that it draws attention to important systematic differences and gen- erates hypotheses that are confirmed. The value of this typology and these hypotheses should be tested by applying them to hospital emergency departments which vary in their screening behavior and in the hypothesized determinants of that behavior. Specifi- cally, community vs teaching hospital comparisons are likely to be the initial arena for testing this

R E F E R E N C E S

1. Gibson G. The Social System of Emergency Medical Care. In Emergency Medical Services. Behavioral aml Planning Perspectives (Edited by Noble J.). Behavioral Publication, New York, 1973.

2. Lichstein E. and Seckler S. Evaluation of Acute Chest Pain. Med. Clins N. Am. 57, 1481-1490, 1973.

3. Slosberg B., Fink N. and Gibson G. Comparative analysis of emergency department treatment of patients with chest pain. J. Am. Coll. Emergency Phys- icians 445-448, 1977.

4. Braunwall E. and Harrison T. R. Principles of Internal Medicine. 8th ed~ McGra~v-]-Iill, New York, 28-33, 1977.

5. Conti C. R., Griffith L. and Ross R. Thoratic pain and angina pectoris. In Principles and Practice of Medicine. Appleton-Century Crofts, New York, 325- 340, 1976.

6. Killip T. and Kimball J. T. A survey of the coronary unit. Concepts and results. Prog. cardiovas. Dis. 11, 45, 1968.

7. Norris R. M., Caughey D. and Mercer C. Coronary prognostic index for predicting survival after recovery from acute myocardial infarction. Lancet 2, 485, 1970.

8. Shor S., Behar S. and Moda B. Disposition of pre- sumed coronary patients from an emergency room. J. Am. med. Ass. 236, 941-943, 1976.