psychometric properties -clinical anxiety-beck.pdf

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JournalofConsulting and Clinical Psychology1988,Vol.56, No. 6,893-897 Copyright 1988by theAmericanPsychologicalAssociation,Inc.0022-006X/88/$00.75

AnInventoryforMeasuring Clinical Anxiety:Psychometric PropertiesAaronT.Beck

DepartmentofPsychiatryUniversity ofPennsylvaniaGaryBrown

Department ofPsychiatryUniversity of Pennsylvania

NormanEpsteinDepartment of Family and Community DevelopmentUniversityof Maryland

RobertA.SteerDepartment ofPsychiatry,SchoolofOsteopathicMedicine

University of Medicine and Dentistry of New Jersey

Thedevelopmentof a21-item self-report inventoryformeasuringtheseverityofanxietyinpsychiat-ricpopulationsisdescribed. Theinitial item poolof 86itemswasdrawnfrom three preexistingscales: the Anxiety Checklist, the Physician's DeskReferenceChecklist, and theSituationalAnxietyChecklist. Aseriesofanalyseswasusedtoreducetheitem pool.Theresulting BeckAnxietyInven-tory(BAI)is a21-item scale that showed high internal consistency(a t=.92)andtest-retestreliabilityover1week,r(81) =.75.The BAIdiscriminated anxious diagnostic groups (panic disorder, general-izedanxiety disorder,etc.)fromnonanxious diagnostic groups(majordepression, dysthymicdisor-der,etc).Inaddition,the BAI wasmoderately correlatedwiththerevised Hamilton Anxiety RatingScale,r(150) =.51,and wasonlymildly correlated withtherevised Hamilton Depression RatingScale, r(153) = .25.

Studies addressingthe distinctiveness ofanxietyanddepres-sion dependon theavailabilityofreliableandvalid assessmentinstruments.However,a number of studieshavereported highcorrelations r > .50) between thewidelyused rating scalesof anxiety and depression (e.g., Dobson, 1985; Mendels,Weinstein, &Cochrane,1972;Moumjoy&Roth, 1982;Prusoff& Klerman, 1974; Riskind, Beck,Brown, & Steer, 1987; Ta-naka-Matsumi & Kameoka, 1986). Thesefindingsraise thequestion,Are thehigh correlationsdue to agenuine sharedsymptomatology, or do they simplyreflect a lack of discrimi-nant validity? Consequently,to theextentthatagivenstudyfailsto differentiate anxiety from depression,it is notpossible toknowwhether anxiety and depression aretrulyindistinguish-ableorwhethertheresults simply reflecttheshortcomingsoftheinstruments usedtomeasurethe twosyndromes.

Apossible contributing factor to the lack of discriminant va-lidity is the inclusion of anxiety and depression symptoms onmeasures ofbothsyndromes (Lipman, 1982; Riskind, Beck,Brown,&Steer, 1987). Whenemphasisisplacedontheoretical(e.g.,Spielberger,Gorsuch,& Lushene,1970)and clinical (e.g.,Hamilton,1959, 1960; Zung,1971)considerations in the earlystages of clinicaltestconstruction, the discriminant validity ofeach test item isoftenoverlooked. Discriminant validity is fre-quently addressedin thelater stagesoftest construction whenattentionhasshifted tototalscores andawayfrom individualtestitems (e.g., Zung,1971 ).

Aposthocapproachtoreducing overlapping symptomatol-

This study was supported by National Institute of Mental HealthGrant MH38843toAaronT.Beckand by theFoundationforCognitiveTherapy. WegratefullyacknowledgethecontributionofPaul McDer-mott.

Correspondence concerningthisarticle should be addressed toAaronT.Beck, Center for Cognitive Therapy, Room602,133 South 36thStreet, Philadelphia, Pennsylvania19104.

ogyacrossmeasures of anxiety and depression has involvedshifting itemsto themore relevantscalebyusingapplicableexternalcriteria.Forexample, Riskind, Beck, Brown,andSteer(1987)foundthatthe Hamilton Rating Scales for Anxiety andDepression (Hamilton, 1959, 1960)contained overlappingitemsandproduced significantly correlated scores.Whentheauthors revisedthescalesbydeletingnondiscriminatingitemsandtransferringotheritemstomoreappropriate scales,the newscales were less correlatedand discriminatedbetterbetweenpa-tientswith primary anxietyanddepressiondiagnoses.

Ontheassumption that validity shouldbebuiltintothetestfromtheoutset, other test constructorshaveuseda sequentialor multistage approachto test construction (Anastasi, 1986;Jackson,1970;Millon, 1983). This strategy wasfollowedin thepresent studytodevelopa newinstrumentforthe measurementofclinical anxiety, the BeckAnxietyInventory(BAI).The BAIwasdevelopedtoaddresstheneedfor aninstrumentthatwouldreliably discriminate anxietyfromdepressionwhile displayingconvergent validity. Suchaninstrumentwouldofferadvantagesforclinical and research purposes over existing self-report mea-sures of anxiety, such as theState-TraitAnxiety Inventory(STAI;Spielberger etal., 1970)and the Self-Rating AnxietyScale (SRAS; Zung, 1971), which have not been shown todifferentiateanxietyfromdepression adequately (e.g.,Dobson,1985;Tanaka-Matsumi&Kameoka, 1986).

MethodSubjects

Three samplesofpsychiatric outpatients were drawnfrom consecu-tiveroutine evaluationsat theCenterforCognitive TherapyinPhiladel-phia, Pennsylvania,from successive time periods beginninginearly1980and lasting until late1986.The total sample size was 1,086. Thepatients were either self-referred or referred by other professionals.Therewere456 men(42%; meanage =36.35,SD = 12.41)and 630

893


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894 BECK, EPSTEIN, BROWN, AND STEERwomen(58%; meanage =35.69,SD =12.12).Thepatientshadpre-dominantlyaffectiveand anxiety disorders, although a variety of otherdiagnoseswererepresented. Less than 1 of thesamplewasdiagnosedaspsychotic.

The finalsubsample(n=160),on which extensive validation of thefinalBAIwascarriedout,wasmadeup ofgroups with primary diagno-ses ofmajordepressive disorder(n =40); dysthymic disorder and atypi-caldepression( = 11);panic disorder(n=45);generalized anxietydisorder ( =18);agoraphobia with panic attacks(n =18);social andsimple phobia(n =12);andmiscellaneousnonanxiety, nondepressiondisorders such as academic problems and adjustment disorders(n =16).ItemPool

Theinitialpool of 86 items comprised the contents of three self-re-port questionnaires administered routinely during intake evaluationsatthe center. These instruments were designed to cover thewiderange ofsymptoms reported by patients diagnosed ashavingananxietydisorder.Each instrumentwasdevelopedfor aspecificpurpose but containeditems judged to be relevant to the assessment of anxiety.

Anxiety Checklist. The AnxietyChecklist (ACL; Beck, Steer, &Brown,1985)wasdevelopedtoassesstheseverityofanxiety symptomsindepressed patients. The 21itemswereselected toreflect somatic,affective,and cognitive symptoms that are characteristic of anxiety butnot of depression. The ACL exhibited good internal consistency (a =.92)andtest-retestreliability,r(S&) - .75,over 1week(Becketal.,1985).

PDRChecklist.This checklist (PDR; Beck,1978)provides26symp-tomsof thecommon sideeffects ofanti-anxietyandantidepressantmedications describedin thePhysician s DeskReference (Medical Eco-nomics, 1977). The PDR itemswereincluded in the presentstudybe-cause a number of them (e.g., heart pounding,dizziness)also occur inanxietystates.In addition, the PDRitemsthat occur only as medicationsideeffects (e.g., strangetaste,skinrash) served as a control on itemselection: Content validitywassupportedwhenthesenonanxietyitemswereeliminated statistically.Situational Anxiety Checklist. The Situational Anxiety Checklist(SAC;Beck,1982)is an experimental measure of the severity of somaticandcognitive symptomsof anxiety,bothingeneraland in thecontextoftwospecificsituations (public speaking and a problem situationpro-vided by the respondent). The SAC was developed to assess the range ofcognitive and somatic symptoms of anxiety that are notrepresentedinexisting anxiety measures and to assess the possible situation specificityofthese symptoms.Clinical Evaluation

Beginning with the last two subsamples(n =116andn =160), weused the Structured ClinicalInterviewforDSM-III (SCID;Spitzer &Williams,1983)to aid inarrivingat adiagnosis.TheSCID providesastandardizedformatforquestioning patients about their symptoms, andthe sequence of questions approximates theDiagnosticand StatisticalManual ofMentalDisorders(DSM-III; American Psychiatric Associa-tion,1980)decision rules.TheDSM-III criteriaareembedded directlyin the interview,thus ensuring adequate coverage of the relevantcri-teria.

The SCID was administered by postdoctoral clinical psychologists.Evidencefor thereliabilityofSQD-baseddiagnoseson aportionofthepresent sample(n =75) wasprovidedby Riskind,Beck, Berchick,Brown,andSteer(1987), whoreported kappacoefficientsof .72 formajordepressionand .79 forgeneralizedanxietydisorder.CriterionMeasures

Hamiltonrating scales. Each patientwasratedby aclinicianon theHamilton Rating Scales forAnxiety(Hamilton, 1959) and Depression

(Hamilton, 1960). Because the standard scales overlap substantially,theywererescoredas suggested by Riskind et al.(1987)to enhance thediscrimination of anxiety and depressiondisorders.The alpha coeffi-cientswere.73 and .83 for therevised depression(HRSD-R)andanxiety(HARS-R)scales, respectively.

BeckDepression Inventory. TheBeck Depression Inventory(BDI;Beck,Rush,Shaw,&Emery,1979)is awidely used measure of theseverity of depression. The psychometricpropertiesof the BDIhavebeen reviewedbyBeck, Steer,andGarbin(1988).

Hopelessness Scale. The Hopelessness Scale(HS;Beck,Weissman,Lester, &Trexler,1974)is a self-report instrument assessing the expecta-tion that onewillnot be able to overcome an unpleasant lifesituationorattainthethings thatonevalues.In asampleofhospitalized patientswhohad made suicide attempts, theRuder-Richardsonreliabilityco-efficientwas.93.The HS was includedasa measure theoretically relatedto depression but not to anxiety.

Cognition Checklist. The Cognition Checklist (CCL; Beck, Brown,Steer, Eidelson, & Riskind,1987)is a measure of thefrequencyof auto-matic thoughts that occur during the course of depression and anxietydisorders. Both theAnxiety(CCL-A)and the Depression (CCL-D)subscaleshavehigh internal consistency (a=.92 and.90,respectively),and both subscales exhibited good, r(64)=.76,test-retest reliabilitycoefficientsoverIweek.

ProcedureDuringthepatient's initial telephone contact,a20-minscreeningin-

terviewwas conducted by astaffmember to provide the caller with in-formationaboutthetreatment program providedat thecenterand toscreen inappropriate subjects. Reasons for exclusion includedclearevi-dence of an organic disorder, of the manic phase of a bipolar disorderwithno medication, or of a condition requiring immediate hospitaliza-tion(e.g., acutesuicidalityor psychosis).

Individuals whowere appropriatefortreatment werescheduled foranintake interviewwitha clinician. On the date of theinterview,thepatientfirst metwithanintakecoordinator,whoadministeredtheACL,the PDR, and theSACaspartof a comprehensive psychometric evalua-tion.On completion of the self-report battery, the patient was inter-viewedby a clinician, who administered the Hamilton scales and madea diagnosis. The diagnostician did nothaveaccessto the results of theself-reporttests.The diagnosis wasreviewedby astaffpsychologistwhoconfirmedthat all diagnostic criteriaweremet or suggested modifica-tions.

ResultsOverview

ArchivaldatafromtheACL,thePDR,andtheSAC wereusedto generate an initial pool of 86items,and various item analysisstrategieswereusedon the firstsubsample n =810)toelimi-nate inappropriate and redundant items. An intermediate 37-itemscale based on the items that had not been eliminated tothispointwasadministeredto asecond subsample n - 116),and further item analyseswereusedtoproducethe final21-item BAI. The final scale was administered to the last subsam-ple n= 160), and reliability and validity analyses were con-ducted.

Phase One: ReductionoftheItemPoolOftheinitial86items,20wereeliminated becausethey were

eitheridentical orverysimilar to another item. Successive iter-


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ANXIETY INVENTORY 895Table1Means,StandardDeviations,andCorrectedItem-TotalCorrelationsorBAIItems

Factorloading

Item SDNumbnessortinglingFeelinghotWobblinessinlegsUnabletorelaxFearof theworst

happeningDizzyor lightheadedHeartpounding or racingUnsteadyTerrifiedNervousFeelingsofchokingHands tremblingShakyFear oflosingcontrolDifficultybreathingFearof dyingScaredIndigestionordiscomfort

in abdomenFaintFace flushedSweating (notdue to

heat)

.68

.86

.611.89.74.00.18.96.15.89.39.77

1.011.54.87.90

1.661.10.68.69.80

.80

.87

.83

.781.03.95.98.99

1.14.84.80.85.94

1.071.051.11.97.98.91.85.97

.30

.63

.54

.61

.59

.63

.55

.71

.63

.60

.46

.55

.67

.64

.53

.50

.68

.42

.67

.59

.60

246544

624265

7182

76

676768

6087

686132

754141

29

Note.BAI = BeckAnxietyInventory.N=160.Cronbach's alpha= .92.Eigenvalues are7.87forFactor1 and 1.38 forFactor2.Decimalpointsare omitted from standardized regressioncoefficients. Secondary co-efficientslessthan.30 are not shown.Interfactorcorrelation= .56.

ated principal factor analyseson the firstsubsample(n =810)led to theeliminationof anadditional19items.The 47itemsthatremainedatthis pointwereeach subjectedto aseriesofvalidity analyses (including correlations with criterion mea-sures and comparisons of means scores between diagnostic andother criterion groups) on the basis of which aninterim37-itemscale was constructed. The 37-item interim scale was adminis-tered to a new sample of116patients.Further item validity andreliability analyses yielded the finalscale.'

The final scale consists of 21 items, each describing a com-monsymptomofanxiety.Therespondentisaskedtoratehowmuchhe or she hasbeen botheredbyeach symptom overthepastweekon a 4-point scale rangingfrom0(Not at all)to 3(SeverelyI could barelystand it).Theitemsaresummed toobtain atotalscore that canrange from0 to 63.PhaseTwo:FinalPsychometric Properties

Reliability. The final 21-item BAI was administered to thelast subsample(= 160).The scale had high internal consis-tency(a =.92) anditem-totalcorrelations rangingfrom .30 to.71 (median = .60; see Table1).Asubsampleofpatients(n=83)completed the BAIafter 1week,and thecorrelation be-tweenintakeand1-weekBAIscoreswas .75(df= 81).

Factorial validity. An iterated principal factor analysiswas

performed on theintercorrelationsof the21BAIitems.Ascreeplot indicated that twounderlying dimensions described thecorrelationmatrix.Thefactorpatternafterpromaxrotationisshown inTable 1.The firstfactor comprised somatic symptomsandthe second factor comprised subjective anxiety and panicsymptoms.Toconfirm that these dimensions were distinctfromdepression, the21BAI and21BDIitems were intercorrelatedand subjected to an iterated principal factor analysisfollowedbyvarimaxrotation. Four factors wereretainedon the basis ofa screeplot.Threefactors were made up of BAI items and oneofBDI items. Only one BAI item ( terrified ) loaded on theDepression factor,and it had asecondary loading.

Convergent anddiscriminantvalidity ofthe final scale. Wetested the ability of the BAI todiscriminatehomogeneous andheterogeneous diagnostic groups byforming three successivegroupingsof thesample (Table2).

The first comparison was between patients with a primaryDSM-II1anxiety disorderand nosecondary depression disor-der(n= 82) and patients with a primaryDSM-IH depressiondisorder and no anxietydisorder(n =30). The second compari-son was between patients with a primary diagnosis of an anxietydisorder (whether or not there was a secondary depression disor-der,n =95) andpatientswitha primarydepression disorder(whetheror nottherewas asecondary anxiety disorder,n =49).The third and final comparison was between patients diagnosedwithananxiety disorder, whether primaryorsecondary (n =114)anddepressed patients withoutananxiety disorder (n=30). Each comparison also included a group of control patientswithneither an anxiety nor a depressiondisorder(n =16).One-wayanalysesofvariance ANOVAS)followed byTukey's testsin-dicated that the mean BAI score wassignificantlyhigher in theanxious group than in either the depressed or the controlgroups, whichdid not differfromeach other. Table2also showsthe results for theBDI.The mean BDI scores weresignificantlyhigher in the pure and primary depressed groups.

Therewasonlymoderateoverlap betweenthe BAIscoresofthe pure anxious and depressed groups. The scores of the anx-ious group(n= 82)rangedfrom 2 to 58(median=24),whereasthescoresof thedepressed group(n =30)rangedfrom 1 to 31(median= 13).Approximately25% of theanxious grouphadscores that were higher than the highest score in the depressedgroup.

Thecorrelations ofthe BAIwitha set ofself-reportandclini-cian-ratedscales are shown in Table 3. The correlations withtheHARS-RandHRSD-Rwere.51(df= 150)and .25(df= 153),respectively.The correlation of the BAI with the BDI was .48(df= 158).

Correlations were also computed between the BAI and non-symptom constructs theoretically relatedtoanxietyor depres-sion. The correlation of the BAI with theCCL-A(Beck etal.,1987)was.51(d/=151),whereasthecorrelation with the CCL-D was .22(df= 150). The BAI also had a correlation of .15(df= 158)withtheHS(Becketal.,1974),whichistheoreticallyrelated to depression but not to anxiety (Beck, 1976), as con-trastedwiththe BDIcorrelationof.59(df= 158)withthe HS.

1Copies of unpublishedtests,manuscripts, anddescriptionsof analy-ses notdescribedinthis articledue tospace limitationscan be obtainedbywritingtoAaronT.Beck.


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896 BECK EPSTEIN, BROWN AND STEERTable2Analysesof VarianceforDSM-IIl DiagnosticGroupings

AnxietyGroup

Pure'BAIBDFPrimary11

BAIBDP

AllAnxiety*1BAIbBDI

n M

82 24.5915.18

95 25.3917.09

114 25.7619.28

SD n

11.41 308.46

11.48 499.56

11.42 3010.40

DepressionM

13.2721.30

18.8424.76

13.2621.30

SD

8.369.31

11.819.51

8.369.31

F

13.77**5.02*

8.34**11.01**

18.601.44

Note.DSM-IH = Diagnostic andStatisticalManual ofMentalDisor-ders.N= 159. Forcontrol group,n - 16. BAImean= 15.88,SD-11.81;BDImean=15.88,57)= 11.81.Pure = no secondarydiagnosis.Primaryanxietyordepressionwithpossible secondary diagnosis.Allanxiety= anxiety, whetherprimaryorsecondary. df = 2,125. With Tukey'shonestly significant difference (HSD),anxiety>depressionandcontrol. eWithTukey'sHSD,depression>anxiety. ddF =2,157. With Tukey'sHSD,depression>anxietyandcontrol.*p


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ANXIETY INVENTORY 897thatseveralSRASitemshadhighercorrelationswiththeBDIthan with thetotalSRASscore,contributingto a .59(df= 118)correlationbetweenthe twomeasures.

In summary, theBAIis a new measure ofanxietythatwascarefully constructed to avoid confounding withdepression.Preliminaryvaliditydata supportitssuitabilityfor use in psy-chiatricpopulations as acriterionandoutcomemeasure. To-getherwiththe revisedHamilton ratingscales(Riskind,Beck,Brown,&Steer, 1987) withtheBDI, andwithimproveddiag-nostic procedures(Riskind,Beck,Berchick,Brown,&Steer,1987),thescaleprovides researchers andclinicianswith a setofreliableand valid criteriathatcan be used tohelp furtherdifferentiatebetweenanxietyanddepressionand toclarify out-come research andtheoretical investigationsof the two syn-dromes.

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Blanchard,E. B. (1986). Co-morbidity and depression among theanxietydisorder: Issuesindiagnosisandclassification.Journalo fNer-vousandMentalDisease, 174,63-72.

Beck,A. T.(1976).Cognitivetherapyandtheemotionaldisorders.NewYork:InternationalUniversities Press.

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Beck, A. T., Brown, G., Steei; R.A.,Eidelson, J. I., & Riskind, J. H.(1987).Differentiating anxietyfromdepression:Atestof the cogni-tivecontent-specificity hypothesis.JournalofAbnormal Psychology,96,179-183.

Beck, A. T, Rush,A.J.,Shaw, B. F., & Emery, G.(1979). Cognitivetherapy ofdepression.New York:GuilfordPress.

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Beck,A. X, Weissman,A.,Lester,D.,&Trexler,L. (1974). The mea-surementofpessimism:TheHopelessness Scale.JournalofConsult-ingandClinicalP sychology, 42,861-865.

Brown,G.,&Beck,A. T.(1987).An evaluation ofthepsychometricpropertiesoftheZungSelf-RatingAnxiety Scale.Unpublished manu-script,University of Pennsylvania.

Dobson,K. S.(1985).The relationship between anxiety and depression.ClinicalPsychologyReview, 5,307-324.

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Jackson, D. N. (1970). A sequential system for personality scale devel-opment.In C. D.Spielberger(Ed.),Currenttopicsinclinicaland com-munitypsychology(Vol.2, pp.61-96).NewYork:Academic Press.Lipman,R. S. (1982).Differentiatinganxiety and depression in anxietydisorders: Use of rating scales.PsychopharmacologyBulletin,18,69-77.

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ReceivedJuly21, 1987RevisionreceivedFebruary2, 1988AcceptedApriU,1988

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psychometric properties -clinical anxiety-beck.pdf