1362 McCusker et al. d DETERMINANTS OF ED VISITS

Determinants of Emergency Department Visits byOlder Adults: A Systematic Review

Jane McCusker, MD, DrPH, Igor Karp, MD, MPH, Sylvie Cardin, PhD,Pierre Durand, MD, Jacques Morin, MD

AbstractObjectives: To conduct a systematic review of the literatureon the determinants of hospital emergency department(ED) visits by elders, using a modification of the Andersenbehavioral model of health services, adapted to explainED utilization. Methods: Relevant articles were identifiedthrough MEDLINE and a search of reference lists andpersonal files. Studies of populations aged 65 or older inwhich ED visits were a study outcome were included ifthey were: original, not restricted to a particular medicalcondition, written in English or French, and investigatedone or more determinants. Data were abstracted andchecked by two authors using a standard protocol. Results:Fourteen studies (reported in 15 articles) were reviewed, 10community-based and four using clinical samples. Among

ten studies that measured multiple determinants, determi-nants reported from multivariate analyses included mea-sures of need (perceived and evaluated health status, priorutilization), predisposing factors (health beliefs and socio-demographic variables), and enabling factors (physicianavailability, regular source of care, family resources, geo-graphical access to services). Conclusions: Need is usuallythe primary determinant of ED visits in older people.Controlling for need, predisposing and enabling factorsthat promote access to primary medical care are associatedwith reduced ED utilization. Key words: emergencymedical services; aged; utilization; review literature; meta-analysis. ACADEMIC EMERGENCY MEDICINE 2003;10:1362–1370.

The emergency department (ED) is a crucial interfacebetween the hospital and community. There is an on-going debate about the role that the ED should play inthe health care system, not only in its traditional roleas provider of emergency care, but as part of theprimary care system, where it may function as a safetynet for those without adequate access to primarycare.1 Older people constitute an increasingly impor-tant population served by the ED, a populationcharacterized by multiple comorbid medical condi-tions, cognitive and functional impairment, andrelated social problems.2,3 A recent review of the

literature found that, compared with younger per-sons, older adults use emergency services at a higherrate, their visits have a greater level of urgency, theyhave longer stays in the ED, they are more likely tobe admitted or to have repeat ED visits, and theyexperience higher rates of adverse health outcomesafter discharge.4 Research has indicated many defi-ciencies in the care of this high-risk population,including failure to recognize problems that couldbenefit from more careful assessment (either in theED or another setting), failure to refer to appropriatecommunity services, and failure to communicate tothe primary physician in a timely fashion the prob-lems identified and interventions implemented at theED visit.5–9 These problems may reflect uncertaintyabout the appropriate role of ED care in this popula-tion, whether as provider of urgent medical care and/or primary care for those without access to suchservices.

According to Andersen’s behavioral model (theconceptual model most frequently used to explainvariation in the use of health services), utilization ofhealth services results from the combined effects ofneed, predisposing, and enabling factors.10 Priorresearch has evaluated the ability of this model toexplain variations in the use of health services amongolder adults.8,11–13 Need, both perceived and pro-fessionally evaluated, appears to be the proximateand, in most contexts, the primary determinant ofutilization of various services in older adults, in-cluding hospitalization, physician visits, and home

From the Department of Clinical Epidemiology and CommunityStudies, St. Mary’s Hospital, Montreal, Quebec, Canada (JMcC);Department of Epidemiology and Biostatistics, McGill University,Montreal, Quebec, Canada (JMcC, IK); Departements de medecinefamiliale et medecine sociale et preventive, Centre de recherche duCentre Hospitalier de l’Universite de Montreal, Montreal, Quebec,Canada (SC); Unite en recherche en geriatrie de l’Universite Laval,Quebec, Quebec, Canada (PD); and Departement de geriatrie del’Hopital Enfant-Jesus, Quebec, Quebec, Canada (JM).Received December 20, 2002; revision received May 8, 2003;accepted May 16, 2003.Presented at the Annual Meeting of the American Geriatric Society,Baltimore, MD, May 2003.Supported by a grant from the Fonds de la Recherche en Sante duQuebec to the Network on Geriatrics/Gerontology.Address for correspondence and reprints: Jane McCusker, MD,DrPH, Department of Clinical Epidemiology and CommunityStudies, St. Mary’s Hospital Center, 3830 Lacombe Avenue, Room2508, Montreal, Quebec, Canada H3T 1M5. Fax: 514-734-2652;e-mail: jane.mccusker@mcgill.ca.doi:10.1197/S1069-6563(03)00539-6

health care.14 Predisposing factors include sociodemo-graphic characteristics (age, sex, marital status, etc.),and health beliefs, which predispose the individual touse services for an illness. Enabling factors includethose family and community resources that facilitateor impede access to services, such as income, healthinsurance, a regular source of care, availability ofphysicians, and rural vs. urban residence. Use of thebehavioral model to explain health services utilizationin a particular context allows an examination of theequity of access to health services and the identifica-tion of underserved populations. Access to servicescan be judged to be equitable if need is the primarydeterminant of utilization. Conversely, in populationsin which predisposing and enabling factors explaina significant proportion of the variance of utilization,there is inequitable access to services.Reviews of the performance of the behavioral

model have not explicitly investigated its ability toexplain ED utilization among older adults, nor havethe determinants of ED utilization been differentiatedfrom the determinants of the utilization of other typesof services. When applied to ED utilization, the behav-ioral model requires some modification (Figure 1). Ingeneral, need for care and certain predisposing andenabling factors (e.g., age) might be expected to in-

crease the use of a variety of health services, includingboth primary care and emergency medical services.However, if ED utilization results at least in part fromreduced access to primary care, enabling factors thatincrease utilization of primary medical care servicesshould be associated with reduced ED utilization. Forexample, controlling for need, greater availability ofphysicians might be expected to increase the utiliza-tion of primary medical care, but also to reduce EDutilization.15 Also, certain health beliefs that are asso-ciatedwith reduced utilization of primary care servicesmay predispose toward increased ED utilization.

To better understand the determinants of EDutilization in older people, including need, predispos-ing, and enabling factors, and to test our proposedmodification of the Andersen model, we conducteda systematic review of the literature.

METHODS

Study Design. The study design was a systematicreview of published studies in English or French onthe determinants of ED utilization among older pop-ulations.

Study Protocol. The search strategy for relevantstudies focused on published studies identifiedthrough computerized databases and handsearchesof the bibliographies of relevant studies and reviewarticles. The MEDLINE database was searched for theyears 1965 to 2001 using a strategy to identify studiesthat were conducted in elders, and investigated one ormore predictors of ED utilization. Search terms usedincluded: elderly, health services utilization, emer-gency room utilization (or visit), emergency utiliza-tion (or service), emergency department utilization (orvisit), emergency medical services, and health ser-vices for the aged.

The abstract of each article identified through thesearch was screened. Articles were excluded for thefollowing reasons: they did not report data from anoriginal study; they were restricted to a particularmedical condition or procedure (e.g., a surgical case-series); the study population included patients youn-ger than age of 65 (unless the results for those aged 65and older were presented separately); no determinantwas investigated; the study outcomes did not includea measure of ED utilization; or the article was writtenin a language other than English or French.

Measurements. Data were abstracted from eligiblearticles by one author (IK) and checked by the firstauthor (JM). The following data were abstracted: studysetting (community vs. clinical); study design (cross-sectional or longitudinal, use of a control group);sample size for the analysis; characteristics of the studypopulation (population-based vs. clinical sample, un-selected or high-risk); definition, reference time period,

Figure 1. Modified Andersen model of emergency medicalservices.

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and data source for ED utilization outcome variable;and data source(s) for determinants.

The determinants were classified as measures ofneed, predisposing factors, and enabling factors.Measures of need included evaluated need (medicalproblems, symptoms) and perceived need (self-re-ported health or functional status). We classified priorED or hospital utilization as measures of need. Pre-disposing factors included social and demographicfactors and health beliefs. Enabling factors includedincome, health insurance, regular source of primarycare, and availability of primary care.

Data Analysis. The method of analysis was classi-fied as univariate or multivariable. Variables that werestatistically significant predictors (p \ 0.05) of EDutilization (in either univariate or multivariableanalyses) were noted.

RESULTS

Identification of Studies. A total of 15 relevantarticles were found,16–30 of which two reported on thesame study,19,29 for a total of 14 studies. Methodologicfeatures of the studies are shown in Table 1. Of these,10 used population-based samples,16–24,30 and fourused samples from clinical settings.25–28 Most studies(9) were cross-sectional; five used a prospective de-sign.

Measurement of ED Utilization. Measures of EDutilization were either dichotomous (e.g., any vs. nouse) or the total number of ED visits. These trackeduse during a reference time period that for the cross-sectional studies was between 6 and 18 months beforethe collection of data on predictors, and for theprospective studies was between 3 and an average of15 months after data collection. Some of the studiesused several measures of utilization: Ginsberg18

analyzed two different outcomes: any vs. no use asthe primary outcome, and secondary analyses of thenumber of ED visits among users. The study reportedby Lishner19 and Rosenblatt29 conducted separateanalyses of the number of visits per year and of anyvs. no use per year; multivariate analyses wereperformed only for the second outcome. Two of theclinical studies focused on the determinants of repeatED visits after an index visit.25,26 Because the patternof repeat ED visits after an index visit is not uniformover time, one of these studies investigated both thedeterminants of early return to the ED (during themonth after the index ED visit) and frequent overallED utilization (three or more visits during the 6months after the index ED visit).26

Data sources for these measures of ED utilizationincluded questionnaires (seven studies), medical re-cord review (three studies), and administrative data-bases (four studies).

Measurement of Determinants. Four studies in-vestigated only one or two determinants of EDutilization: restricted activity,20 age and gender,22

retirement status,17 and appropriateness of medica-tions.28 Three of these studies conducted only univar-iate analyses; the study that conducted multivariateanalyses reported only adjusted analyses for the pri-mary determinant (retirement status) and did not ex-plicitly report the effects of the covariates.22

The other 10 studies investigated multiple determi-nants of ED utilization, six of them based explicitly onthe Andersen model of health service utilization, cat-egorizing determinants as measures of need, predis-posing, or enabling factors.16,21,23,24,27,30

Data sources for the measures of determinants werevaried; most studies (eight) used questionnaires only,two used a combination of questionnaires and ad-ministrative databases, two used administrative data-bases, and two used professional assessments.

Results of Multivariate Analyses. Table 2 showsthe statistically significant (p\ 0.05) determinants ofED utilization identified in the 10 studies in whichmultiple determinants were investigated using mul-tivariate methods. Measures of need were investi-gated in all of these studies; at least one measure ofneed in each study predicted ED utilization. Perceivedpoor health status was a statistically significantdeterminant of ED utilization in four studies.16,18,21,23

Evaluated health status was assessed in several ways,including self-reports of medically diagnosed prob-lems, symptoms, or impaired functional status, andcomposite measures of comorbidity based on admin-istrative data. Statistically significant measures ofevaluated health status included: heart disorder,16,18

diabetes,26 visual problems,16,26 nocturia,18 psychiatricproblems,18 depression,26 respiratory diagnosis,26

greater comorbidity,21,23 diagnostic group,29 impair-ment in activities of daily living (ADL),21,25 low phys-ical activity,23 and homebound status.18

Four studies reported that either previous hospitalor ED utilization, or both of these measures, werestatistically significant determinants of ED utilization:previous hospitalization in three studies,19,26,27 andprevious ED utilization in two studies.26,30

One study also assessed a composite measure ofneed: a six-item self-report screening tool, developedfor the prediction of functional decline (Identificationof Seniors At Risk [ISAR]), and found it to bea significant predictor of both early and frequentreturn visits to the ED.26

Predisposing variables investigated in these studiesincluded sociodemographic characteristics and healthbeliefs. Although older age was associated with in-creased ED utilization in most studies in univariateanalyses, it was a significant multivariate predictor inonly three studies.19,21,30 Gender was a significantmultivariable predictor in only one study, with men

1364 McCusker et al. d DETERMINANTS OF ED VISITS

TABLE 1. Methodological Features of Studies of Determinants of Emergency Department (ED) Utilization, by Study Setting

Author(Year) Country Design

StudyPopulation

Sample Sizeand Sampling

MethodsOutcomeVariable

Data Sourcefor Outcome

DeterminantsExamined

Data Source forDeterminants

Population-basedstudies

Bazargan (1998)16 USA Cross-sectional

Urban, AfricanAmericansage 62þ

998 Volunteersfrom randomsample ofsenior centers

Number of ED visits inpast 6 months

Questionnaire PredisposingEnablingNeed

Questionnaire

Gill (2001)17 USA Prospective Health planmembers(nondisabled)

754 Rate of ED visitsduring follow-up(median ¼ 15months)

Telephonefollow-upquestionnaire

Restricted activity Homeassessment

Ginsberg (1996)18 Israel Cross-sectional

Urban residents(includinginstitutionalpopulation)age 69–71

759 Systematicsample

1 or more EDvisits in past12 months(secondaryanalysis ofnumber ofvisits per user)

Questionnaire SociodemographicUtilization Healthinsurance coverageAccess to health

careHealth practicesSupport networkSocial networksMedicalADL

Questionnaire

Hansell (1991)30 USA Prospective HMO membersage 62þ

667 Age-stratifiedrandomsample

Number of EDvisits insubsequentyear

Medicalrecords

Body awarenessDemographicStressful life eventsFinancial statusHealth limitations

on activitiesDepressed mood

Questionnaire

Lishner (2000)19

and Rosenblatt(2000)29

USA Cross-sectional

Health insurancedatabase,age 65þ

354,782 1) Annual EDvisit rate

2) 1 or more EDvisits/year

Administrativedatabase

DemographicLocationSource of careHealth care utilizationInsuranceCasemix

Administrativedatabase

Murphy (1996)20 USA Cross-sectional

Urban HMOmembers,age 66–69

759 Randomsample

Number of EDvisits during18 months

Medicalrecords

AgeGender

Administrativedatabase

Shah (2001)21 USA Cross-sectionalsurvey

Health insuranceenrollees aged66þ (MedicareCurrentBeneficiary Survey)

9,784 1 or more EDclaims in 1993

Administrativedatabase

PredisposingEnablingNeed

QuestionnaireAdministrativedata (CharlsonComorbidityIndex)

Soghikian(1991)22

USA Cross-sectional

HMO membersaged 60–66

1,073 Number of EDvisits/year

Medicalrecords

Retirement status QuestionnaireAdministrativedata(hospitalization)

continued

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more likely to make repeat ED visits.25 Other sta-tistically significant sociodemographic determinantsincluded: African American vs. other race21 and lowereducation.21 Conflicting results on living arrange-ment/marital status were found. Three studies foundthat individuals who lived alone,21,25 or were wid-owed,24 were more likely to make ED visits. On theother hand, one study reported that individuals wholived with a spouse were more likely to utilize theED.23 Statistically significant measures of healthbeliefs included: health locus of control (those whobelieved that their health is determined by chance ora powerful other entity rather than by their personalactions were more likely to visit the ED),16 lack of faithin doctors,18 and positive attitudes toward healthservices use.27 One study found that increasedawareness of bodily symptoms and stressful lifeevents were statistically significant determinants ofED utilization.30

Among the enabling factors investigated, statisti-cally significant measures of primary medical careincluded: perceived low availability of physicians,16

lack of a principal care or regular physician,19,24 andhaving more than one source of health care.27

Conflicting results on family social resources werefound. Perceived tangible support (including assis-tance with transport and finances)16 and ability todrive a car18 were associated with increased EDutilization in two studies. In a third study, perceivedlack of support in case of need was associated withincreased ED utilization.26 Other enabling factorsassociated with increased ED utilization reported insingle studies included: inadequate income and Medi-caid insurance coverage18 and residence in urban vs.rural areas.19

The relative importance of need, predisposing, andenabling factors was addressed in some of thesestudies. Most studies reported a larger number of de-terminants related to need than to predisposing or en-abling characteristics. However, one study conductedin an inner-city, African American population re-ported that more than 60% of the explained variancein ED utilization was related to predisposing and en-abling factors.16

Four of the studies included in this review examinedthe determinants of the utilization of other types ofhealth services, thus allowing a comparison of thedeterminants of utilization of the ED vs. other services.In Bazargan’s study of inner-city African Americans,external locus of control was associated with the use ofother ambulatory services.16 In Hansell’s study ofolder HMO members, older age and stressful lifeevents also predicted increased initial and follow-upclinic visits.30 Increased body awareness predictedincreased patient-initiated, but not physician-initiated,clinic visits. In Walter-Ginzburg’s study of an Israelipopulation, all measures of need predicted physicianutilization as well as ED visits, but living alone didTA

BLE

1.MethodologicalFe

aturesofStudiesofDeterm

inants

ofEm

ergencyDepartment(ED)Utilizatio

n,byStudySe

tting

(cont.)

Author

(Year)

Country

Design

Study

Population

Sample

Size

and

Sampling

Methods

Outcome

Varia

ble

Data

Source

forOutcome

Determ

inants

Exa

mined

Data

Sourcefor

Determ

inants

Walter-Ginzb

urg

(2001)2

3Israel

Cross-

sectional

survey

Community-

dwelling

Jews,

aged

75–9

4

1,487

Stratifie

drandom

sample

1ormore

ED

visitsin

past

year

Questionnaire

Predisposing

Enablin

gNeed

Questionnaire

Wolin

sky

(1983)2

4USA

Cross-

sectional

survey

Communityresidents

aged

65þ

4012-sta

ge

random

sample

NumberofED

visitsin

past

year

Questionnaire

Predisposing

Enablin

gNeed

Questionnaire

Clin

icalstudies

McCusker

(1997)2

5Canada

Prosp

ective

cohort

ED

use

rsatone

hosp

ital,

age75þ

113

Convenience

sample

Return

visitin

90days

Administrative

data

base

Sociodemographic

Functional

Clin

ical

Questionnaire

McCusker

(2000)2

6Canada

Prosp

ective

cohort

Release

dfrom

ED

of4hosp

itals

age65þ

1,122

Represe

nta

tive

sample

1)30dayreturn

toED

2)3þ

visitsin

6months

Administrative

data

base

Sociodemographic

Functional

Clin

ical

Questionnaire

Parboosingh

(1987)2

7Canada

Cross-

sectional

survey

ED

use

rsatone

hosp

ital,

age65þ

75

Random

sample

NumberofED

visitsin

past

6months

Questionnaire

Predisposing

Enablin

gNeed

Questionnaire

Schmader

(1997)2

8USA

Prosp

ective

cohort

High-riskpatients

from

RCTatgen-

eralmedicalclin

icforveterans

208

Unsc

heduled

ambulatory

orED

visitdurin

g12-m

onth

follo

w-up

Questionnaire

Medication

appropria

teness

Pharm

acist

assessment

ADL¼activitiesofdaily

living;ED¼emergencydepartment;RCT¼randomized

controlle

dtrial.

1366 McCusker et al. d DETERMINANTS OF ED VISITS

not.23 Wolinsky found that nutritional risk predictedtotal doctor visits and hospital episodes in addition toED visits.24 A regular source of care was positivelyassociated with preventive medical contact and totaldoctor visits, but was inversely related to ED visits.Being widowed was not associated with use ofservices other than the ED.

DISCUSSION

This systematic review of the literature attempted toidentify the determinants of ED utilization among ol-der populations, using a modification of the Andersenmodel of health services utilization, adapted to ex-

plainvariations inEDutilization. The reviewwasbasedon 14 studies, of which 10 reported the results on mul-tiple determinants.

Methodologic differences between the studies mayhave accounted for some of the differences in theresults. The most important differences were in thespecific determinants investigated. Some of the stud-ies proposed explicitly to use the Andersen modeland measured a variety of need, predisposing, andenabling factors. Other studies examined a more lim-ited set of variables. For example, two of the ED-basedstudies of the determinants of repeat ED visits focusedon identifying the individual patient characteristics,particularly measures of need and sociodemographic

TABLE 2. Statistically Significant Determinants of Increased ED Utilization from Multivariate Analyses

Author (Year) Need Predisposing Factors Enabling Factors

Population-based studiesBazargan (1998)16 Perceived poor health status

Heart conditionsEye problems

Locus of control(chance, powerfulothers)

Perceived lowavailability ofphysicians

Perceived tangiblesupport (e.g.,transportation,financial)

Ginsberg (1996)18 Heart disorderNocturiaPsychiatric problemsPerceived poor health statusHomebound

No faith in doctors Inadequate incomeDriving a car

Hansell (1991)30 Previous ED utilization Older ageBody awarenessStressful life events

Lishner (2000)19 andRosenblatt (2000)29

CasemixHospitalization

Older age Urban residenceMedicaid insuranceNo principal carephysician

Shah (2002)21 Fair or poor self-reported healthADL impairmentComorbidities

Age $ 85 yearsEducation\12 yearsAfrican AmericanLiving alone

Walter-Ginsberg (2001)23 ComorbiditiesPerceived poor health statusLow physical activity

Living with spouse

Wolinsky (1983)22 Nutritional risk Widowed Lack of regularphysician

Clinical studiesMcCusker (1997)25 Number of functional problems Male

Living aloneMcCusker (2000)26

1) Determinants of3þ visits/6 months

DiabetesED visit in past monthHospitalized in past 6 monthsDepressionRespiratory diagnosis

Lack of supportin case of need

2) Determinants of 30-dayreturn visit

Heart diseaseHospitalized in past 6 monthsDepressionAlcohol less than dailyDigestive system diagnosisComposite screening tool (ISAR)

Ever married

Parboosingh (1987)27 Number of hospital admissions Positive attitude tohealth services

More than onesource of care

ADL¼activities of daily living; ED¼emergency department; ISAR¼ Identification of Seniors at Risk.

ACAD EMERG MED d December 2003, Vol. 10, No. 12 d www.aemj.org 1367

predisposing factors; enabling factors were not as-sessed. Other methodologic characteristics, includingstudy design (prospective vs. cross-sectional), studysetting (community vs. clinical), measures of ED utili-zation (any use vs. number of visits per unit time),and data sources (questionnaire vs. medical records)may also account for differences in the results, but thesmall number of studies reviewed did not permit fur-ther exploration of these issues.

The substantive findings of this review support, ingeneral, our adaptation of the behavioral model toexplain ED utilization in older people. In this model(Figure 1), measures of need for care predict the use ofa variety of health services, including ED services.Measures of need include perceived and evaluatedhealth status. Perceived health status was perhaps themost consistent predictor of ED utilization in multi-variate analyses, in four of six studies in which it wasmeasured. Measures of evaluated health status alsowere consistent predictors of ED utilization; theseincluded specific diagnoses (heart disease, diabetes,psychiatric) and composite measures of comorbidityor case-mix. Other measures of need found in severalstudies included functional status, both perceived andevaluated, measured in various ways, and previoushospitalization and/or ED visits. Miscellaneous mea-sures of need reported from only one study includednutritional risk and alcohol consumption less thandaily. The latter may be a proxy measure of chronicillness, because individuals with chronic illness maybe advised to reduce their alcohol consumption. Mostof these measures of need are inter-related, and somethat predicted ED utilization in the univariateanalyses were dropped from the final model. Never-theless, among studies that assessed multiple mea-sures of need, many of these measures remained inthe final model. The use of composite measures ofcomorbidity reduces the number of disease-specificmeasures that are needed. Because of the importanceof need in explaining ED utilization, it is essential tocontrol for need (preferably using multiple measuresof need and including perceived health status,functional limitations, comorbidity, and previousutilization) when examining other possible predictorsof ED utilization. Lack of adequate control for healthstatus is a limitation of several studies in this review,particularly those using only administrative data.

Predisposing factors included sociodemographicvariables and health beliefs. Older age, an indepen-dent predictor of ED utilization in three studies, maybe a proxy for unmeasured needs. Living arrange-ment or marital status was an independent predictorof ED utilization in four studies, although the di-rection of the association was not consistent. Theseinconsistent findings may reflect the variable path-ways and temporal sequences by which marital statuscan affect the use of services. Presence of a spousemay provide instrumental support, for example,

assisting in transport to the ED; conversely, loss ofa spouse may be associated with depression, whichtends to increase service utilization. Another expla-nation is that, in some settings, older people who livealone are more likely to receive home care servicesthat reduce the need for an ED visit.

African Americans and those with less educationhad increased rates of ED utilization in one study.These populations may lack information about al-ternative community services, or may have limitedaccess to nonemergency services, because of lack ofhealth insurance, or financial or other resourcesneeded to obtain this care. Thus, low socioeconomicstatus may be a proxy indicator of lack of enablingfactors to access primary medical care.

Health beliefs that predispose toward utilization ofhealth services were addressed by several studies inthis review. However, variability in the specific healthbeliefs assessed and in the method of measurementmay have contributed toward differences in the results.Of interest was that several health beliefs that shouldpredispose toward utilization of primary care serviceswere associated with reduced ED utilization: faith indoctors and internal health locus of control. However,another study found that a positive attitude towardhealth services was associated with increased EDutilization.27 One study reported that heightenedawareness of bodily symptoms and stressful life eventspredicted increased ED utilization.30 These factors alsopredisposed to non-ED visits in the same population.30

The hypothesized relationships between factorsthat enable access to primary care and lower EDutilization were, in general, confirmed among thosestudies that adjusted for at least one measure of need.Enabling factors that were associated with increasedED utilization included measures of lack of familyresources, suggesting that older people may benefitfrom social support to help them to appropriatelyaccess community services.16,23–26 Also, perceived lowavailability of physicians,16 lack of a principal care orregular physician or having a specialist rather thangeneralist as the principal care physician,19,24 andhaving more than one source of health care27 wereassociated with increased ED use. This relationshiphas potentially important practical as well as theoret-ical implications, suggesting that ED utilizationamong elders in a community may be used as anindicator of access to primary care for this popula-tion.1 This relationship and application should bevalidated in different settings.

The results of this review support our modificationof the Andersen behavioral model of health serviceutilization for use in examining the determinants ofED utilization.10,14 Need remains an important, per-haps the primary, determinant of ED utilization inmost of the studies reviewed. However, predisposingand enabling factors that predict increased utilizationof primary care and other community services appear

1368 McCusker et al. d DETERMINANTS OF ED VISITS

to have the opposite relationship to ED utilization,because of the association between ED utilization andpoor access to primary and community health ser-vices, described above.

LIMITATIONS

Potential limitations of this review include thefollowing: incomplete identification of relevant stud-ies, publication bias, exclusion of studies in lan-guages other than English or French, missinginformation, and possibly incorrect interpretation ofarticles. Our search strategy included studies ofhealth services utilization in which results related toED utilization might not be reported in the study titleor abstract, or captured in key words designed tocapture ED utilization. We also searched in bibliog-raphies of relevant articles. Several of the studyauthors (JM and SC) have published research on EDutilization in older populations and are familiar withmuch of the literature in this area. It therefore seemsunlikely that relevant studies were overlooked in thisreview.Another important limitation of these nonexperi-

mental studies is confounding. Because perceivedand/or evaluated health status appears to be a primarypredictor of ED utilization, the associations of otherpredictors of utilization identified in these studies maybe due to incomplete control of confounding by healthstatus. For example, the associations of various mea-sures of low socioeconomic status (SES) may be due, atleast in part, to the association of poor health with lowSES. Another example of a possibly spurious associ-ation is widowhood, often associated with depression,which leads to increased utilization.This review found conflicting results with regard

to the role of social factors as determinants of EDutilization. Future research should address the spe-cific pathways through which these factors (e.g.,marital status and social support) affect the use ofservices; prospective studies will be needed todetermine the temporal sequences of these relation-ships.Although these studies have identified multiple

determinants of ED utilization, much work remainsto be done. In general, studies of health serviceutilization among older adults find that much of thevariance in utilization of services remains unex-plained by multivariate analyses models based onthe Andersen behavioral model.24 Important areasfor future research include identification of the healthbeliefs of older adults in relation to their decision toseek care in general, and to use the ED rather thananother type of service.15 The ways in which healthservices for older adults can meet their needs moreappropriately also should be investigated. Theorganization and delivery of services for older adultsin hospitals and their EDs (e.g., availability of

geriatric liaison staff) may affect subsequent patternsof ED visits. The effects of alternative sources of care(e.g., drop-in clinics that are open evenings andweekends) upon ED utilization should be investi-gated.

CONCLUSIONS

This review, despite the relatively small number ofstudies and their methodologic heterogeneity, ingeneral provides evidence in support of our modifi-cation of the behavioral model to explain EDutilization. The strength of this model is that it allowsthe equity of access to services to be examined ina particular context. If access to services is equitable,need should be the primary determinant of EDutilization; predisposing and enabling factors shouldaccount for a small proportion of the variance in EDvisits.

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