jsa.1999.60.705

Screeningfor Alcohol Problemsin the U.S. General
Population:A Comparisonof the CAGE and TWEAK by
Gender, Ethnicity, and ServicesUtilization*
CHERYL J. CHERPITEL, DR.P.H.
Western
Consortium
for PublicHealth,Alcohol
Research
Group,2000HearstAvenue,
Berkeley,
California
94709
ABSTRACT:Objective:
Thepurpose
ofthisstudy
wastocompare
the
performance
of twoscreening
instruments
for alcoholproblems,
the
CAGE andtheTWEAK, against
ICD-10 andDSM-IV criteriafor alcohol dependence
by genderandethnicity,andto evaluatewhetherchar-
acteristics
associated
withhealthservices
utilizationmayaffectthe
performance
ofscreening
instruments,
inarepresentative
sample
ofthe
U.S. adultgeneralpopulation.
Method:DataarefromtheAlcoholResearch
Group's1995National
AlcoholSurvey;
thesewereweighted
to
account
for thedesign
effectinherent
in multistage
clustersampling
andoversampling
of blacksandHispanics.
Effectivesample
sizewas
2,443:797blacks,
642Hispanics
and1,004whites
andothers
(primarily AsianandNativeAmerican).
Sensitivity
andspecificity
wereexaminedfor bothscreening
instruments.
Logisticregression
wasusedto
evaluatethepredictive
value,separately,
for theCAGE andTWEAK,
controlling
for gender,ethnicity,
regionof thecountryandserviceuse
(primarycareandemergency
room).Results:The TWEAK wasmore
sensitive
for menthanfor women,but no differences
werefoundby
serviceuse,while the CAGE was more sensitivefor men who had used
the emergency
roomduringthe preceding
yearcompared
with those
whohadnot.TheTWEAK wasmoresensitive
thantheCAGEamong
whiteandHispanic
men,amongmenwhohadnotusedtheemergency
room and amongwhiteswho had no serviceuse.Performanceof nei-
therthe CAGE nor theTWEAK wasfoundto varyby regionof the
country.Conclusions:
Data suggestthat while the performance
of
screening
instruments
mayvaryacrossdemographic
subgroups
in the
generalpopulation,
instruments
mayperformequallywellfor identifyingproblemdrinkers
in generalpopulations
asin clinicalpopulations.
(J. Stud.Alcohol60:705-711, 1999)
NUMBER
OFrelatively
shortscreening
instrumentsmary care samplesthan in the generalpopulationfrom
havebeendeveloped
for usein clinicalpopulations
to
identifyalcoholdependence
or alcoholabuse/harmful
drink-
ing.The validityof theseinstruments,
basedon diagnostic
criteria(International
Classification
of Diseases
[ICD] orDiagnostic
andStatistical
Manualof MentalDisorders
[DSM])
for problemdrinking,hasbeentestedprimarilyin clinical
populations
comprised
largelyof whitemalepatients.
The
performance
of screening
instruments
is lesswell establishedamongwomenandethnicminorities,
or in general
populations.
Theprevalence
of problem
drinking
in primary
careandemergency
room(ER) settings
hasrecentlygained
considerable
attention(Buchsbaum
et al., 1991b;Chanet al.,
1994a;Cherpitel,1993,1994;FlemingandBarry,1991b;
Magruder-Habib
et al., 1991;Soderstrom
et al., 1992),and
theneedforevaluating
easilyadministered
screening
instrumentsto identifythosepatients
whomaybenefitfroma brief
intervention
or referralfor problemdrinkinghasbecome
evident(Buchsbaum
et al., 1991a;Cherpitel,1997, 1998;
'FlemingandBarry,1991a;Volk et al., 1997).
Althoughtheprevalence
of alcohol-related
problems
has
beenfoundto be higherin bothemergency
roomandpri-
Received:June30, 1997. Revision:November10, 1997.
*Thisresearch
wassupported
byNational
Alcohol
Research
Center
grant
AA 05595 from the National Instituteon Alcohol Abuse and Alcoholism.
705
whichtheycome(Cherpitel,1991,1995a),theprevalence
of
alcoholdependence
in thegeneralpopulation,
nevertheless,
hasnotbeenfoundto beinconsequential.
The 1988National
HealthInterviewSurveyfoundthat9% of Americanadults
met DSM-III-R
criteria for current alcohol abuse and de-
pendence(Grant et al., 1991), while the 1990 National Al-
cohol Survey found 4% positive for current alcohol
dependence
alone,accordingto DSM-IV criteria,and5.5%
according
to ICD-10 criteria,withhighestratesfor Hispanics followedby blacksandthenwhiteson bothdiagnostic
schemes(CaetanoandTam, 1995).The 1992NationalLongitudinal
AlcoholEpidemiologic
Surveyalsofound4% positive for currentalcoholdependence
basedon DSM-IV and
ICD-10 criteria,and7% and4.6% positiveon DSM-IV and
ICD-10 criteria,respectively,for alcoholabuseand/ordependence(Grant, 1996).
Relativelyfew studies,
however,haveexaminedtheper-
formance
of screening
instruments
for identifying
problem
drinkingin generalpopulations.
Onestudyexamined
sensitivity of theCAGE,Brief MichiganAlcoholism
Screening
Test(BMAST)andTWEAK against
a past-year
diagnosis
of
alcoholdependence,
usingDSM-III-R criteria,in a primary
carepopulation
compared
witha sampleof thegeneralpopulationfromthesamemetropolitan
area,andfoundsensitivity for theseinstruments
to be higherin the primarycare
sample(Chan et al., 1993, 1994a,b).No studyto date,
706
JOURNAL
OF STUDIES
ON ALCOHOL
however,hasreportedthe performanceof screeninginstrumentsin a representative
sampleof the U.S. population,nor
have manyof thesestudiesanalyzedscreenerperformance
acrossgenderand ethnicgroupsin the generalpopulation.
While the useof standarddiagnosticinstrumentswould be
preferablefor establishing
the prevalenceof alcoholdependence in nonclinicalpopulations,such instrumentsare
lengthy,andthe useof shorterscreeners
would seemadvantageousin this regard. Additionally, such short screeners
wouldbe usefulas a first-stagescreeningdevicein general
populationsurveysto identify those who would then be
givena standarddiagnosticinstrument.
Screeninginstruments
may notbe expectedto performas
well in the generalpopulationasin clinicalpopulations,
due
to a lower prevalenceof alcoholdependence
and harmful
drinking/abuse
in nonclinicalsamples.The Epidemiological
CatchmentArea studyfounda higherproportionof thosein
clinical populationshad a symptomcountfor alcoholdependence
well abovethediagnostic
threshold
compared
with
thosein the generalpopulation,while thosein the general
populationwere morelikely to havea symptomcountright
at the diagnosticthreshold(Helzer et al., 1985). Differences
in characteristics
betweenthosein the generalpopulation
andmorefrequentusersof clinicalservices
(whowouldhave
a greaterprobabilityof falling into suchsamplesthan less
frequentusersof thesehealthcare services),may alsoexplain differentialperformanceof screeninginstruments
in
the generalpopulationcomparedto clinical populations.
However,a priorcomparison
of drinkingpatternsandproblem and demographiccharacteristics
betweena representative sample of ER patients in a large HMO and a
representative
sampleof the generalpopulationof the same
countywhoreportedmembership
in theHMO foundthemajor differencebetweenthetwo samples
wasthefrequencyof
ER use(Cherpitel,1992).
To fill thisgapin our knowledgeandexaminethe performanceof screeninginstruments
in nonclinicalpopulations,
the sensitivityandspecificityof theCAGE andTWEAK are
comparedacrossgenderand ethnicgroupsfor black,Hispanic and white/otherrespondents
from a U.S. national
household
probabilitysampleof adults.To evaluatewhether
characteristics
associated with
health
services utilization
may affecttheperformance
of screeninginstruments,
analysis alsoincludeswhetherthe respondentreportedusingprimary care and/or ER servicesin the year precedingthe
interview.
Both ICD-10
and DSM-IV
criteria for current al-
cohol dependenceare used as the gold standardagainst
which the performanceof screeninginstrumentsis compared.Logisticregression
analysisis usedto evaluatethe
predictivevalueof the CAGE and the TWEAK on alcohol
dependence,
controllingfor demographic
characteristics,
regionof the countryandserviceuse(ER andprimarycare).
Theseanalysesareimportantin determiningthosescreeners that may be most effective for identifyingproblem
drinkersin nonclinicalpopulations.
/ SEPTEMBER
1999
Method
Sample
The dataarefromtheAlcoholResearchGroup's 1995NationalAlcohol Survey.Fieldworkfor the studywas subcontracted to the Institute for Survey Researchat Temple
University.The sampleconsisted
of adults18yearsandolder
living in householdswithin the 48 contiguousstates.A multistagearea-probabilitysamplewas drawn, using 100 primary samplingunits, with an oversamplingof blacksand
Hispanics.Completedinterviewswere obtainedon 1,587
black, 1,598 Hispanic and 1,740 white/other (primarily
AsianandNative American)respondents,
representing
completionratesof 77% for blacksandHispanics,and76% for
whites/other.Noninterviewswere dueto refusals(13%), and
incapacitation,
languagebarhersandfailureto locatetherespondent
(10%). Datawereweightedto reflectthenumberof
adultsliving in a selectedhouseholdandthe interviewcompletionratein a givenarea.Data were alsoweightedto take
into accountthe designeffect inherentin the useof multistageclustersampling,using an approachoriginally suggestedby Kish(1965) for estimatinga designeffectaverage.
The averagedesigneffectwas 1.99 for blacks,2.49 for Hispanicsand1.73for whites/others,
using48 variablesfromsix
domainsof the questionnaire,
whichresultedin an effective
samplesize (N = 2,443; 52% women) of 797 blacks,642
Hispanicsand 1,004 whites/othersfor analysis."Others"in
thislattercategoryincluded29 Asians,22 NativeAmericans
and 5 of mixed race.
Table 1 showsdemographiccharacteristics
of the sample
by ethnicity.Whites/others
weremorelikely to be older,better educated and to be current drinkers than blacks or His-
panics,and lesslikely to have neverbeen married,to be
unemployedandto havenohealthinsurance.They werealso
morelikelyto haveusedprimarycareservices
in thelastyear
thanblacksor Hispanics,whileHispanicswerelesslikely to
haveusedthe ER duringthe lastyearcomparedwith whites
or blacks. No differences
were found in the rate of alcohol
dependence
acrossthe threegroups.
Data collection
Interviews
were conducted with informed
consent in the
respondents'
homesby trainedinterviewers
usingstructured
interview schedules(questionnaires)
of about 1 hour in
length.Hispanicrespondents
were given a choiceof being
interviewedin English,or in Spanishwith a bilingualinterviewer.The Spanishversionof the questionnaire
underwent
a processof translationandindependent
backtranslation.
Respondents
who self-identifiedas either "white of Hispanic
origin"or "blackof Hispanicorigin"(Latino,Mexican,Central or SouthAmerican,or any otherHispanicorigin) were
classifiedas Hispanic.Respondentswho self-identifiedas
"black, not of Hispanicorigin" were categorizedas black.
CHERPITEL
T^BI•œ1. Demographic
characteristics
by ethnicity(in percent)
White/other
Black
Hispanic
(n = 1,004)
(n = 797)
(n = 642)
48
52
45
55
50
50
19
44
37
27 a
46
27 a
34 b
45
22 b
5
10
37
25
23
8•
17•
38
24
13•
27•
18•
29•
17•
9b
Marriage/marriage-like
relationship
Separated/divorced
69
10
49•
14a
68
9
Widowed
Never married
7
14
8
29 •
3•
200
Gender
Men
Women
<-8th grade
Somehigh school
High schoolgraduate
Somecollege
Collegegraduate
Marital
status
Unemployed
4
10"
No health insurance
11
20"
38•
UsedER in lastyear
Usedprimarycarein lastyear
11
34
12
20"
8•
200
Current drinker
67
54 •
54 b
5
4
5
5
5
6
Alcoholdependence-ICD-10
Alcoholdependence-DSM-IV
Region
8•
East
21
16 •
14 •
South
32
57 a
33
Central
West
27
20
19 •
8•
7•
46 •
"p < .05, comparisonof proportionsbetweenblacksandwhites.
Op< .05, comparison
of proportions
betweenHispanicsandwhites.
All otherrespondents
are includedin the "white and other"
categoryfor analysesreportedhere.
Instruments
Among other questions,respondents
were askeditems
comprisingthe CAGE andTWEAK screening
instruments,
itemsrelatedto alcoholdependence,
useof emergency
room
or primary care servicesduringthe last year, and demographiccharacteristics
includingregionof thecountrywhere
the respondentlived (East, South,Central,West).
Both the CAGE
and the TWEAK
are mnemonics.
(Beresford et al., 1990: Bernadt et al., 1982; Bush et al.,
1987).The CAGE hasbeenusedextensivelyin clinicalpopulations,in bothwrittenandverbalform;however,relatively
little dataare availableon its performanceacrossgenderand
ethnic minorities.
Age
18-29
30-49
50+
Education
707
The
CAGE (Ewing, 1984)wasdesignedfor rapidverbalscreeningfor alcoholdependence
in clinicalpracticeandis derived
from the followingfour items:(1) Have you ever felt you
shouldcutdownonyourdrinking?(2) Havepeopleannoyed
youaboutyourdrinking?(3) Haveyoueverfelt bador guilty
aboutyour drinking?(4) Have you ever had a drink first
thingin the morningto steadyyour nervesor get rid of a
hangover(eye-opener)?Validity of the CAGE was establishedin relationto a diagnosisof alcoholdependence
based
on psychiatric
evaluationin a VeteransAdministration
psychiatricinpatientpopulation(Mayfield andJohnston,1981;
Mayfield et al., 1974). Basedon a positiveresponseto two
or more items, the CAGE has been found to have a sensitiv-
ity rangingfrom 72-91%, and a specificityfrom 77-96%
The TWEAK is a recentlydevelopedinstrumentdesigned
to identify"atrisk"drinkingin prenatalpopulations
(Russell
et al., 1994),andasksquestions
havingto do with tolerance
(holdingmorethanfive drinks),friendsor relativesworried
abouta person'sdrinking,takinga drink first thingin the
morning(eye-opener),blackouts(amnesia),and felt a need
to c(k)utdownondrinking.Two of theTWEAK itemswere
taken from the CAGE (eye-openerand cut down) and two
(worriedandamnesia),from the full MichiganAlcoholism
Screening
Test(MAST) (Selzer,1971).Usinga cutpointof
2 (whena weightof 2 is appliedto toleranceandworry,and
a weightof 1 to theremainingthreeitems),theTWEAK was
foundto havea sensitivityof 79% anda specificityof 83%
in prenatalpopulations
againsta criterionof drinkingoneor
more ouncesof absolutealcoholper day (Russellet al.,
1994).Usinga cutpointof 3, asusedin thepresentstudy,the
TWEAK hasbeenfoundto havea sensitivityrangingfrom
94-84% (Chan et al., 1993; Cherpitel,1995b) and a specificity from 89-81% (Chan et al., 1993; Cherpitel, 1998)
againstdiagnostic
criteriafor alcoholdependence
in clinical
samples.The questionhavingto do with the numberof
drinksone can hold (tolerance)presumablymakesthis instrumentmore sensitiveto identifying alcohol problems
amongwomensinceit cantakeintoaccounta lowerthresholdfor women(Russell,1994).OnequestionontheTWEAK
andall four CAGE questionswereaskedon a lifetime basis.
If respondents
were positiveon theselifetimebasedquestions,theywereaskedagainregardingthelast 12 months.
Alcoholdependence
duringthelastyearwasmeasured
by
24 items similar to those in the Alcohol Section of the Com-
posite InternationalDiagnostic Interview (CIDI) core
(Wittchenet al., 1991),whichoperationalized
bothICD- 10
(World HealthOrganization,1992)andDSM-IV (American
PsychiatricAssociation,1994)criteria(CaetanoandRoom,
1994).Thesesameitemshavebeenusedto operationalizealcoholdependence
in prior NationalAlcoholSurveys(Caetano and Tam, 1995; Caetano et al., 1997). Items which
operationalized
ICD-10 includedquestions
relatedto thesix
domainsof craving, impaired capacity to control, withdrawal,tolerance,neglectof interests,andcontinuedusedespiteproblems;whileDSM-IV includedquestions
relatedto
the sevendomainsof tolerance,withdrawal,drinkingmore
thanintended,unsuccessful
effortsto control,givinguppleasuresor intereststo drink, spendinga greatdeal of time in
drinkingactivities,and continueduse despiteproblems.A
respondent
wasconsidered
alcoholdependentif positiveon
threeor more domainsin either of the diagnosticschemes
considered
separately.
The standardagainstwhichsensitivity of thescreening
instruments
wasanalyzedwascomprised
of thosepositiveon eitheror bothof the diagnosticschemes.
708
JOURNAL
OF STUDIES
ON ALCOHOL
/ SEPTEMBER
1999
T^SL•. 2. Sensitivity(S) and specificity(SP) for the CAGE and TWEAK by genderand ethnicityamongcurrent
drinkers
Total
CAGE
TWEAK
Men
Women
S
SP
S
SP
(141)
(1,297)
(1,04)
61
79 a
95
89
59
83 a
White
Hispanic
S
SP
S
SP
S
SP
S
SP
(686)
37
(611)
(52)
(620)
(47)
(376)
(42)
(301)
94
86
70
66 b
97
93
56
77 a
97
91
70
83
95
91
60
76
93
83
White
Black
Men
CAGE
TWEAK
Black
Women
Men
Hispanic
Women
Men
Women
S
SP
S
SP
S
SP
S
SP
S
SP
S
SP
(39)
(316)
(13)
(304)
(33)
(194)
(14)
(183)
O1)
(175)
(11)
(124)
97
89
62
58
97
94
70
85
94
89
17
77
95
92
89
76
73
64
98
94
54
83 a
55
81 a
Note:WeightedN's are in parentheses;
subgroup
N's may notsumto totalbecauseof weighting.
ap< .05, comparison
of proportions
of sensitivitybetweenCAGE andTWEAIC
bp< .05,comparison
of proportions
of sensitivity
of CAGE andTWEAK betweengenders
andbetweenethnicgroups.
Amongcurrentdrinkers(thosewho reportedhavingany alcoholicbeverageduringthe past 12 months)20% reported
consumingeightor moredrinkson at least1 day duringthe
lastyear,and65% of thosepositiveon eitheror bothof the
diagnosticschemes
reporteddoingso.
sensitivityare alsoreportedfor thosewho madean ER visit
(Table 3) andthosewho madea primarycarevisit (Table 4)
duringtheprevious12 monthscomparedwith thosewho did
not, within genderand ethnicsubgroups
for the CAGE and
TWEAK, and for the CAGE comparedto the TWEAK
within serviceuseand demographic
subgroups.
The datain
the tables will be discussed further in the Results section
Data analysis
which follows.
The sensitivity(percentagecorrectlyclassifiedas having
thecondition)andspecificity(percentage
correctlyclassified
as nothavingthe condition)for currentalcohoIdependence
(ICD-10 and/orDSM-IV criteria)arereportedat a cutpoint
of 2 for theCAGE and3 for theTWEAK for reportingthese
experiences
as havingoccurredduringthe precedingyear.
Two-tailedtestsof significantdifferencesbelweenproportionsof sensitivityacrossgenderand ethnicsubgroups
are
reportedfor theCAGE andtheTWEAK, andfor theCAGE
comparedto the TWEAK within demographicsubgroups
(Table 2). Significantdifferencesbetween proportionsof
Logisticregression
(SPSS,1996),with simultaneous
entry
of variables,wasthenusedto analyzethepredictivevalueon
alcoholdependence,separatelyfrom the CAGE and the
TWEAK, controllinggender,ethnicity,regionof thecountry,
andserviceuse(ER andprimarycare).CAGE, TWEAK, and
genderwere codeddichotomously.
Men were comparedto
womenas the referencecategory.Both ethnicityandregion
were coded as indicator contrasts,with whites/othersas the
referencegroupto which blacksand Hispanicswere contrasted,andWestas thereferencegroupto East,Southand
Centralwerecontrasted.
The interactiontermof screeningin-
T^aLE 3. Sensitivity(S) and specificity(SP) for the CAGE andTWEAK by ER useduringthe lastyear
amongcurrentdrinkers
Total
Men
Yes
CAGE
TWEAK
No
No
Yes
No
S
SP
S
SP
S
SP
S
SP
S
SP
S
SP
(21)
(142)
(121)
(1,154)
(14)
(78)
(91)
(607)
(7)
(64)
(30)
(547)
76
80
94
89
59 •
79•
95
89
84
81
92
84
55 b
83 a
94
86
63
74
97
95
71
64
97
93
White/other
Yes
CAGE
TWEAK
Women
Yes
Black
No
Yes
Hispanic
No
Yes
No
S
SP
S
SP
S
SP
S
SP
S
SP
S
SP
(5)
(67)
(47)
(553)
(11)
(46)
(36)
(330)
(5)
(29)
(38)
(271)
81
78
98
90
53
70:
97
93
81
81
92
95
66
84
95
90
61
25
90
77
60
76
93
84
Note:WeightedN's are in parentheses;
subgroup
N's may notsumto totalbecauseof weighting.
ap < .05, comparison
of proportions
of sensitivitybetweenCAGE andTWEAK.
•p < .05, comparison
of proportions
of sensitivity
of CAGE andTWEAK betweenthosewhodid anddid not
usetheER duringthelastyearwith genderandethnicgroups.
CHERPITEL
709
TABLE4. Sensitivity(S) andspecificity(SP) for the CAGE andTWEAK by primarycareuseduringthe last
yearamongcurrentdrinkers
Total
Men
Yes
CAGE
TWEAK
No
No
Yes
No
S
SP
S
SP
S
SP
S
SP
S
SP
S
SP
(40)
(346)
(102)
(950)
(29)
(154)
(75)
(531)
(11)
(191)
(26)
(420)
55
78 a
96
91
64
79 a
95
89
51
82 a
95
86
62
83 a
94
85
69
63
97
94
70
68
97
93
White/other
Yes
CAGE
TWEAK
Women
Yes
Black
No
Yes
Hispanic
No
Yes
No
S
SP
S
SP
S
SP
S
SP
S
SP
S
SP
(19)
(218)
(33)
(402)
(13)
(68)
(35)
(308)
(9)
(59)
(33)
(241)
58
74
97
92
54
78 a
97
91
65
90
96
94
71
81
94
90
38
64
92
82
65
79
93
84
Note:WeightedN's arein parentheses;
subgroup
N's maynotsumto totalbecause
of weighting.
ap< .05, comparison
of proportions
of sensitivity
betweenCAGE andTWEAK.
strument(CAGE or TWEAK) by regionwasalsoenteredinto
an additionalregressionfor each instrument,with region
codedas a deviationcontrast,comparingeachregionto the
overalleffectof theotherregions.Oddsratios(ORs) arereportedfor eachvariablein theequation.ORsgive thelikelihood,for example,thata respondent
with a positiveCAGE
comparedwith a respondent
with a negativeCAGE will be
positivefor alcoholdependence,
controllingfor all othervariablesin theequation.The 95% confidenceinterval(CI) is reportedfor eachvariablethatreachedstatisticalsignificance.
Analysisis cardedout on currentdrinkers,sincethisis the
population
considered
tobeatriskforcurrentproblemdrinking.
Results
for men regardlessof primary careuse, and was alsobetter
amongwhitesfor thosewhodidnotmakea primarycarevisit
duringtheprecedingyear.
Table 5 showsthe predictive value, separatelyfor the
CAGE andtheTWEAK, on alcoholdependence,
controlling
for gender,ethnicity,regionof thecountry,andER treatment
and primarycare treatmentduringthe last year. Both the
CAGE andTWEAK werehighly predictiveof alcoholdependence:thosepositiveon the CAGE were 37 timesmore
likely than thosenegativeto be alcoholdependent,while
thosepositiveon the TWEAK were30 timesmorelikely to
be alcoholdependentthan thosenegativeon the TWEAK.
Genderwas alsofoundto be a significantpredictorof alcohol dependencewhen CAGE statuswas controlled,but not
when TWEAK
Table2 showsthesensitivityandspecificityfor theCAGE
and TWEAK within genderand ethnicsubgroups.
No differenceswerefoundacrosssubgroups
for the CAGE, while
sensitivityof theTWEAK wasfoundto be significantlybetter amongmenthanamongwomen.Comparedto theCAGE,
sensitivityof theTWEAK wasfoundto be bestamongwhite
andHispanicmales.
Sensitivityand specificityof the CAGE and TWEAK
werethencomparedfor thosewho did andthosewho did not
reportan ER visit duringthepreceding12 months.As seen
in Table 3, sensitivityof the CAGE wasbetteramongmen
who had attendedthe ER duringthe last year (84%) than
amongthosewhohadnot(55%), butnodifferencewasfound
amongwomen,or within ethnicgroups.Sensitivityfor the
TWEAK wasnot foundto differ significantlyin relationto
whetheranER visit wasmadeduringtheprecedingyear,but
was foundto be significantlybetterthanthe CAGE among
men andamongwhiteswhodid notmakean ER visit.
As seenin Table4, no differencewasfoundin sensitivity
of theseinstrumentswithin genderor demographicsubgroupsin relationto primarycareserviceuseduringthelast
year. Sensitivityof the TWEAK was betterthanthe CAGE
status was controlled, with men almost 3
timesmorelikely thanwomento be alcoholdependent.
Regionof the countrywas alsofoundto be significantin both
equations,
with thoseliving in theEastandCentralregions
only a thirdaslikely asthoselivingin theWestto be alcohol
TABLE5. Oddsratios(OR) andconfidence
intervals(CI) for demographic
characteristics,
healthservicesuseandscreeneron alcoholdependence
CAGE as screener
TWEAK
(n = 940)a
OR
Screener(positive)
Gender(male)
Ethnicity
(white/other)
Black
37.14*
2.67*
CI
20.24-68.17
1.42-4.92
0.80
Hispanic
Region(West)
1.11
East
South
Central
ER treatment
PC treatment
0.32*
0.62
0.38*
0.76
1.07
as screener
(n = 932)b
OR
CI
30.75*
1.69
16.98-55.71
0.79
1.42
0.13-0.80
0.17-0.90
0.36*
0.69
0.38*
0.92
1.22
0.14-0.89
0.17o0.87
aExcludes
threerespondents
on whomall datawerenotobtained.
bExcludes
ninerespondents
on whomall datawerenotobtained.
*p < .05 (X2 with 1 df); *p < .01 (X2 with 1 df).
710
JOURNAL
OF STUDIES
ON ALCOHOL
dependent.Neitherethnicitynorhealthservicesusewaspredictiveof alcoholdependence
in eitherequation.Additional
regressions
were examinedfor the CAGE andTWEAK includingthe interactionterm of screeninginstrumentby region(not shown),thatwasnotfoundto be significant.
Discussion
Differenceswere found by gender,ethnicityand service
use in sensitivityof both the CAGE and TWEAK. The
TWEAK
was found to be more sensitive for men than for
women, while the CAGE was more sensitive for men and
whiteswhohadnotusedtheER duringtheyearprecedingthe
interviewcomparedwith thosewho had.Differencesin sensitivitywerealsofoundbetweentheCAGE andtheTWEAK,
with the TWEAK performingbetterthanthe CAGE among
whites and Hispanicmen (but not black men), amongmen
who had not usedthe ER during the last year, and among
whiteswho hadnotusedtheER or primarycareservicesduring the precedingyear.It is importantto noteherethatmultiple comparisons
were cardedout on thesedata, thereby
increasingtheprobabilitythatsomeof thedifferencesfound
mayhaveoccurredby chancealone.On theotherhand,small
samplesizesin someof the gender/ethnic/service
usecategoriesmay haveprecludedthedetectionof additionaldifferencesin instrumentperformance
acrosssubgroups.
Orderingof thetwo instruments
may alsohaveinfluenced
their relative performance,to somedegree(the CAGE was
administeredfirst, followedby the TWEAK). Both instruments were administered rather late in the interview, after
numerousquestions
hadbeenaskedregardingquantityand
frequencyof drinkingand drinkingpatternsand problems,
includingquestions
whichobtainedan ICD-10 or DSM-IV
diagnosisfor alcoholdependence.
This,too,may haveinfluencedinstrument
performance--apriorstudyfoundthatsensitivity of the CAGE was reduced when precededby
questionsrelated to defining quantity and frequencyof
drinking(SteinwegandWorth, 1993).
While the prevalenceof alcoholdependencein this general populationsampleis similarto that foundin othernational alcohol surveys(Caetano and Tam, 1995; Grant,
1996), it is substantiallylower than that found in clinical
populations,
andthismay alsohaveaffectedinstrumentperformance.Usingthe samediagnosticcriteriafor alcoholdependence as that used here, prevalence of alcohol
dependence
rangedfrom 10% amongHispanicpatientsto
16% amongwhite/otherpatientsin a CaliforniaER sample
(Cherpitel,1998) and 9% for black patientsand 12% for
whitepatientsin a MississippiER sample(Cherpitel,1997).
A comparison
of thesensitivityof theCAGE andTWEAK
reportedherewith that from thesetwo ER studies,usingthe
samegold standard,
foundbothinstruments
performedbetter within the samegender/ethnicsubgroups
in the ER samplesthan in this nationalprobabilitysampleof the general
population(Cherpitel,1997,1998).Priorprimarycareclinic
/ SEPTEMBER
1999
studiesalso report higher sensitivityfor the CAGE and
TWEAK than that found here, althoughthesestudieshave
not examinedinstrumentperformance
within gender/ethnic
subgroups
(Chan et al., 1993, 1994a:Flemingand Barry,
1991a;Liskow et al., 1995).
Few significant
differences
in theperformance
of theseinstruments
by ER andprimarycareusewerefound,possibly
dueto smallsamplesizesasmentionedabove;andcontrary
to what might be expected,with one exceptiondifferences
foundsuggestthatthe sensitivityof the CAGE andTWEAK
maybe betterfor thosenotusingtheER or primarycareservicesduringthe precedingyear thanfor thosewho did use
suchservices.The lack of significantdifferencesfoundby
services
usemayalsoberelatedto thefactthatthosewhoreporteduse of suchservicesin the precedingyear may not
necessarily
be heavyusersof theseservices,as are manyof
thosesampledin theseclinicalsettings,andwho thushavea
greaterlikelihoodof falling into suchsamples.Serviceuse
wasbasedhereon reportingevenonevisit to an ER or primary careclinicduringthe previousyear.
A comparisonof the performanceof screeninginstrumentsin the two ER studiesdescribedabove(Cherpitel,
1997, 1998)foundthatwhileregionof the country(Southvs
West)wasnotanimportantpredictorof alcoholdependence,
regionaldifferencesin the performanceof screeninginstrumentsmay exist,even whenethnicityis takeninto account.
Logistic regressionanalysisreportedhere, however, suggeststhat regionis an importantpredictorof alcoholdependence,with thoseliving in the East andCentralregionsless
likely to be alcoholdependent
comparedto thosein theWest,
but performanceof neitherthe CAGE nor the TWEAK varied by region.
Data reportedheresuggest
thatwhile the performance
of
screeninginstrumentsmay vary acrossdemographicsubgroupsin the generalpopulation,instruments
may, nevertheless,performequallywell for identifyingproblemdrinkersin
generalpopulationsas in clinical populations.Furtherresearch is needed in order to determine
the usefulness of
screeninginstrumentsfor problem drinking within gender
andethnicsubgroups
in nonclinicalpopulations,
andwhether
regionaldifferences,
beyondethnicity,in theperformance
of
screeninginstruments
existin the generalpopulation.
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