Horowitz Event Scales

Impact of Event Scale:

A Measure of Subjective Stress

MARDI HOROWITZ, MD, NANCY WILNER, BA, AND WILLIAM ALVAREZ, MA

Clinical, field, and experimental studies of response to potentially stressful life events giveconcordant findings: there is a general human tendency to undergo episodes of intrusive think-ing and periods of avoidance. A scale of current subjective distress, related to a specific event,was based on a list of items composed of commonly reported experiences of intrusion andavoidance. Responses of 66 persons admitted to an outpatient clinic for the treatment of stressresponse syndromes indicated that the scale had a useful degree of significance andhomogeneity. Empirical clusters supported the concept of subscores for intrusions and avoid-ance responses.

INTRODUCTION

Research on human response to stressrequires evaluation of both serious lifeevents and their subjective impact. Evalu-ation of life events is now possiblethrough questionnaires that list situa-tional changes and yield quantitative es-timates of the cumulative impact of suchepisodes on individuals or on groups(1—4). What is needed is an instrumentthat measures the current degree of sub-jective impact experienced as a result of aspecific event. With such an instrument,investigators can observe individuals overperiods of time following the occurrenceof an event, compare subgroups for degreeof subjective distress after a particular lifeevent, or contrast life events in terms oftheir relative impact on different popula-tions.

From the Department of Psychiatry, University ofCalifornia School of Medicine, San Francisco.

Address reprint requests to: Dr. Mardi J. Horowitz,Langley Porter Institute, 401 Parnassus Avenue, SanFrancisco, California 94143.

Received for publication April 28,1978; final revi-sion received January 11,1979.

Moos (5) reviewed methods in this areaand found no suitable measurement forthis purpose. Since then, however, an in-strument called the Texas Inventory ofGrief (6) has been reported. While it doesexplore the kind of conscious experiencesthat a person can describe, its use is lim-ited to a particular event; the study of be-reavement. We have developed a morebroadly applicable measure, the Impact ofEvent Scale, used to assess current subjec-tive distress for any life event. The word-ing is not anchored to a specific occur-rence, but to the particular qualities ofconscious experience that encompass allsuch events.

DEVELOPMENT OF THEINSTRUMENT

In studies of psychological responses tostressful life events, common qualities ofconscious experience were found amongpatients with different personality styles.Two major response sets, intrusion andavoidance, were abstracted from in-depthevaluation and psychotherapy interviews.These response sets, and the manner in

Psychosomatic Medicine Vol. 41 , No. 3 (May 1979)Copyrighte 1979 by the American PsychoPublished by Elsevier North Holland, Inc.

matic Society, Inc

209

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MARDI HOROWITZ etal.

which they were experienced, were alsoprominent in other reports of psychologi-cal reactions to stress (7-10). Intrusionwas characterized by unbidden thoughtsand images, troubled dreams, strongpangs or waves of feelings, and repetitivebehavior. Avoidance responses includedideational constriction, denial of themeanings and consequences of the event,blunted sensation, behavioral inhibitionor counterphobic activity, and awarenessof emotional numbness.

Items for this self-report instrumentwere derived from statements most fre-quently used to describe episodes of dis-tress by persons who had experienced re-cent life changes (11, 12). The list thatevolved in this way contained experi-ences of a particular quality, such as in-trusiveness, worded so that they mightapply to any event. To anchor the qual-ities of experience to a particular context,the life event specific to each person wasentered at the top of the form and servedas a referent for each of the statements onthe list.

Guided by clinical experience, the vari-ous items were divided into two sub-groups, intrusion and avoidance. The goalwas a scale that would provide subscoresfor these response sets, as well as a totalsubjective stress score. Since personscannot report the unconscious aspects ofthe denial process, but only the "felt"consequences, such as numbness, theterm "avoidance," rather than "denial" isused to describe this subscale.

Over a period of several years variousforms of this item list were given to psy-chotherapy patients with stress responsesyndromes, and to nonpatient volunteersexposed to serious life events. The word-ing and the format were revised duringthese trial runs, and it was determinedthrough this process that the best time

unit for clinically valid reports of a per-son's current response level was "the pastweek." Subjects reported forgetfulnessand less conviction about intervals longerthan a week, and a constriction in report-ing significant episodes felt to be markersof their current level of stress for a periodof less than a few days. Through examina-tion of the data it also became evident thatalthough we had asked for separate rat-ings of how often during the past week aparticular experience had occurred, andwhat the peak intensity of that episodehad been, the scores for frequency and in-tensity of episodes were relatively similar.In other words, the experience of a single,very intense intrusive image was similarin its effect to multiple experiences of lessintense and only mildly intrusive images.Therefore, although subjects were askedto respond to both variables in a study ofthe refined Impact of Event Scale, only thehigher score of either frequency or inten-sity was used as the indicator of the mag-nitude of the item.

The goals of the present study were 1)to determine the frequency of item en-dorsement by a new group of subjectsclinically diagnosed as suffering fromstress response syndromes after seriouslife events, 2) to test the internal reliabilityof the instrument by examining the fre-quency of response to each item and theintercorrelation of response items, and 3)to determine whether the logical subsetsof intrusion and avoidance items had em-pirical cohesion.

METHODS

ScaleIn its form after pilot studies, the scale consisted

of twenty items. Nine items described episodes ofintrusion, eleven described episodes of avoidance.

210 Psychosomatic Medicine Vol. 41 , No. 3 (May 1979)

IMPACT OF EVENT SCALE

The specific life event and the date of its occurrencewere recorded at the top of the page. The subject wasdirected to indicate whether or not each item hadbeen experienced within the past seven days. If herecalled such an experience, he rated it for both fre-quency (indicated as rarely, sometimes, and often)and intensity (indicated as mild, moderate, or se-vere). If he did not recall having such an experiencewithin the past seven days, he marked a separatecolumn included for this purpose.

Subject SampleThe Impact of Event Scale was given to 66 adults

who sought psychotherapy at the University ofCalifornia outpatient department as a result of reac-tions to a serious life event. These patients were re-ferred to a clinic for specialized treatment of stressresponse syndromes. This clinic accepted patientswith neurotic levels of psychopathology; those per-sons referred elsewhere had overt psychoses, drugdependence, alcoholism, or were unwilling to givewritten consent to research review of their records.

The inciting serious life event that preceded thedevelopment of a stress response syndrome varied inthis group. About half the patients (n = 34) had ex-perienced bereavement, the remainder had personalinjuries resulting from accidents, violence, illness,or surgery. When scales completed by bereaved sub-jects were compared with those of subjects who hadincurred personal injury, endorsements of itemswere found to be relatively similar despite disparateevents.

The subjects were 16 men and 50 women between20 and 75 years of age, with a mean age of 34. Theywere from a literate, lower-middle to middle classpopulation, with the diverse ethnic origins thatcharacterize San Francisco. The sex bias reflects theratio of men to women applicants to our specialclinic and resembles the ratio at this time of men towomen applicants to our university psychiatric out-patient clinic.

DesignEach subject completed the Impact of Event Scale

after the initial interview with a clinician. The recentserious life event reported as most significantlystressful was indicated as the referent for all scaleitems. The time from the occurrence of the event tothis first visit averaged 25 weeks, with a range from 1to 136 weeks.

Data AnalysisThe frequency of endorsement of a given experi-

ence as having occurred within the preceding weekwas calculated. Mean scores were also computed;these were based on an assigned weight for eachitem of zero for negative endorsement and one, three,or five for the three degrees of positive endorsementfor intensity and frequency. The higher score ofeither intensity or frequency ratings was used to cal-culate the means in the tables presented here. In ad-dition, the data were analyzed separately for the in-tensity and frequency ratings. The two categoriescorrelated well with each other and independentlyyielded essentially the same results.

RESULTS

All items were endorsed frequently.Those most often endorsed, "Things I sawor heard suddenly reminded me of it,"and "I got waves or pangs of intense ordeep feelings about it," were acknowl-edged by 85% of the subject sample (seeTable 1). Even the item with the lowestendorsement, "It seemed to me that I wasreacting less than would be expected,"was acknowledged by 38 % of the 66 sub-jects. All six of the most frequently re-ported items had a mean weighted scoreof three or more, indicating that as agroup these subjects experienced suchepisodes at a high level of frequency orintensity. This occurred even though theparticular stressful event had usually beenexperienced several months earlier (meanof 5V2 months) while the time frame forendorsement of any scale item was lim-ited to the past seven days.

Sex Differences

The mean scores for each item werecalculated separately for men and women,as well as for the total group. The sexesdiffered significantly in their degree offrequency or intensity on 3 of 20 items; in

Psychosomatic Medicine Vol. 41, No. 3 (May 1979) 211


TABLE 1. Impact of Event Scale: Frequency and Mean of Positive Report and Cluster Analysis of Items(n=66)

% Item LogicalItem Endorsement Mean (SD) to Cluster3

Subscale

Cluster 1:I had waves of strong feelings about it.Things I saw or heard suddenly reminded me of it.I thought about it when I didn't mean to.Images related to it popped into my mind.Any reminder brought back emotions related to it.I have difficulty falling asleep because of

images or thoughts related to the event.I had bad dreams related to the event.

Cluster 2:I knew that a lot of unresolved feelings were

still there, but I kept them under wraps.I avoided letting myself get emotional when I

thought about it or was reminded of it.I wished to banish it from my store of memories.I made an effort to avoid talking about it.My emotions related to it were kind of numb.I felt unrealistic about it, as if it hadn't

happened or as if it wasn't real.I stayed away from things or situations that

might remind me of it.I didn't let myself have thoughts related to it.

Cluster 3:I kept wondering why it had to happen to me or to

persons near me and not someone else.I used alcohol, drugs, or a lot of activity to

help me forget.It seemed to me that I was reacting less than would

be expected.

Cluster 4:I found myself almost waiting for something like

that to happen again.I found myself making plans and decisions which

were inappropriate in light of the event.

88 3.8 (1.9)85 3.7 (1.9)76 3.3 (2.2)76 3.2 (2.2)76 3.0 (2.1)

0.57b0.57b0.45 b

0.39b

0.62b

64 2.6 (2.4) 0.35b44 1.7 (2.2) 0.41b

71 3.0 (2.2) 0.466 A

70 2.8 (2.1) 0.626 A

65 2.8 (2.3) 0.49b A61 2.2 (2.0) 0.59b A

59 2.1 (2.1) 0.426 A

58 2.2 (2.3) 0.48b A

53 2.2 (2.3) 0.57b A

50 1.8 (2.2) 0.656 A

59 2.6 (2.3) 0.18 I

54 2.0 (2.2) 0.29 A

38 1.3 (2.0) 0.20 A

44 1.6 (2.1) 0.29 I

41 1.5 (2.0) 0.08 A

I: intrusion item; A: avoidance item.=p<0.01.

212 Psychosomatic Medicine Vol. 41, No. 3 (May 1979)


each instance, women indicated a higherlevel of endorsement than men. Theseitems were all in the avoidance category:"I knew that a lot of unresolved feelingswere still there, but I kept them underwraps," "I avoided letting myself get emo-tional when I thought about it or was re-minded of it," and "It seemed to me that Iwas reacting less than would be ex-pected." The total subjective stress scores,derived by adding the positive scores ofeach item were not significantly affectedby sex.

Cluster Analysis for Subscales

Clusters were determined by a correla-tional measure of association and an aver-age linkage algorithm (13). As shown inTable 1, the primary and secondary clus-ters included 15 of the 20 items, with 2smaller residual clusters containing 5items. The primary cluster containeditems from the clinically derived intru-sion subset, while the second cluster wascomposed of clinically derived avoidanceitems. This finding, added to the logicwith which items were initially selected,supports the use of intrusion and avoi-dance subscales.

Revision of Scale and InternalReliability

On the basis of these empirical findingswe concluded that the Impact of EventScale was a useful instrument, but thatadditional revisions were indicated. First,the number of items was reduced byselecting only those that empirically clus-tered and had significant item-to-subscalecorrelations beyond the 0.01 level of sig-nificance. Next, comparison of scores de-rived by frequency and by intensity indi-cated a degree of similarity that made dual

response for each item unnecessary. As aresult, only the frequency variable was re-tained, since subjects seemed able to scoreit more accurately than the intensity vari-able. Finally, wording of a few items wasslightly modified to further reduce am-biguity. This revised scale is presented inTable 2.

We are presenting this scale for the firsttime, in order that it may be used by otherinvestigators, and have, therefore, recal-culated the data on our sample of 66 per-sons with stress response syndromes, ac-cording to the condensed, revised version.The mean total stress score for 66 subjects,computed by adding the mean scores forfrequency for the 15 items, was 39.5 (SD =17.2, range 0-69). The mean intrusionsubscale score (items 1, 4, 5, 6, 10, 11, 14)was 21.4 (SD = 9.6, range 0-35), and themean avoidance subscale score (items 2,3, 7, 8, 9, 12, 13, 15) was 18.2 (SD = 10.8,range 0-38).

After reduction of the scale to the 15most powerful items, the split half relia-bility of the total scale was high (r = 0.86).Internal consistency of the subscales, ascalculated using Cronbach's Alpha, wasalso high (intrusion = 0.78, avoidance =0.82). A correlation of 0.42 (p > 0.0002)between the intrusion and avoidance sub-scale scores indicates that the two subsetsare associated, but do not measure identi-cal dimensions.

Test-Retest Reliability

The 15 item scale was given to a newsample, a beginning class of 25 physicaltherapy students; 20 women and 5 menwho had graduated from college and hada median age in the late twenties. Theyhad recently begun dissection of a cadaverand hence contact with death and sightsthat were usually taboo. The class as a

Psychosomatic Medicine Vol. 41 , No. 3 (May 1979) 213


TABLE 2. Revised Impact of Event Scale

On. . you experienced(date) ' ' (life event)

Below is a list of comments made by people after stressful lifeevents. Please check each item, indicating how frequentlythese comments were true for you DURING THE PAST SEVENDAYS. If they did not occur during that time, please mark the"not at all" column.

FREQUENCY

Not at All Rarely Sometimes Often

1. I thought about it when I didn't mean to.2. I avoided letting myself get upset when I thought about

it or was reminded of it.3. I tried to remove it from memory.4. I had trouble falling asleep or staying asleep,

because of pictures or thoughts about it that cameinto my mind.

5. I had waves of strong feelings about it.6.1 had dreams about it.7.1 stayed away from reminders of it.8. I felt as if it hadn't happened or it wasn't real.9. I tried not to talk about it.

10. Pictures about it popped into my mind.11. Other things kept making me think about it.12.1 was aware that I still had a lot of feelings about

it, but I didn't deal with them.13.1 tried not to think about it.14. Any reminder brought back feelings about it.15. My feelings about it were kind of numb.

Intrusion subset = 1, 4, 5, 6, 10,11,14; avoidance subset = 2, 3, 7,8,9, 12, 13, 15.

whole gave unanimous consent, and thencompleted the scale twice with an intervalof one week between each rating. Theydid not know there would be a second rat-ing until it was administered, but again allagreed to complete the scale. They hadseen and dissected a cadaver for the firsttime four weeks before initial administra-tion of the Impact of Event Scale. Whenthey were given the scale for the secondtime, a week later, they were asked toallow their answers to encompass the twopreceding weeks, which would cover thetime period included by the first scale,and allow for maximum overlap of previ-ously reported experiences. Inspection ofthe data indicated frequent endorsementof positive responses. Results indicated a

test-retest reliability of 0.87 for the totalstress scores, 0.89 for the intrusion sub-scale, and 0.79 for the avoidance subscale.

Sensitivity

This subjective distress scale is a self-report instrument that can be used for re-peated measurement over time. In order todetermine the suitability of this scale as asensitive indicator of such change, a sub-sample of the 66 patients with stressresponse syndromes was examined. Thissubsample of 32 patients completed thescale immediately before and after a brieftherapy aimed at relief of their stressresponse syndromes. The mean time be-tween the first and second administration

214 PsychosomaticMedicineVol.41,No. 3 (May 1979)


was 11 weeks (range 4 to 31 weeks). Clini-cal assessments and subjective reports in-dicated that about 80% of these patientsachieved beneficial levels of improve-ment. For most subjects, a sensitive scalewould show somewhat lower scores fourmonths after the termination of therapy,due to a combination of additional timesince the specific event and the effects oftherapy. As shown in Table 3, the signifi-cant change in scores on the Impact ofEvent Scale conformed to this predictionand the marked decline in item, subscale,and overall scores, supports its validity asa sensitive reflection of change.

A second index of sensitivity would bethe degree to which scores on the scalemight discriminate persons from differentpopulations who had experienced dif-ferent kinds of life events. A new group of110 medical students (75 men and 35women), in the early months of theirfreshman year, were given the Impact ofEvent Scale to relate to the experience oftheir first confrontation with cadaver dis-section. Their scores were contrasted withthe patient group, who we believed hadexperienced much more distressing lifeevents, and who were in all probabilitypersons more predisposed to symptom

TABLE 3. Change of Scores Over Time in 32 Persons Evaluated for Stress Response Syndromes before andafter Brief Therapy

ItemFrequency Present (%)Time 1 Time 2

Means (SD)Time 1 Time 2

Intrusion ItemsI had waves of strong feelings about it.Other things kept making me think about it.I thought about it when I didn't mean to.Pictures about it popped into my mind.Any reminder brought back feelings about it.I had trouble falling asleep or staying

asleep, because of pictures or thoughtsabout it that came into my mind.

I had dreams about it.

Intrusion Subscale

Avoidance ItemsI was aware that I still had a lot of feelings

about it, but I didn't deal with them.I avoided letting myself get upset when I

thought about it or was reminded of it.I tried to remove it from memory.I tried not to talk about it.My feelings about it were kind of numb.I felt as if it hadn't happened or it wasn't real.I stayed away from reminders of it.I tried not to think about it.

Avoidance Subscale

Total Scale

8872788181

6947

7566666262

2834

4.13.83.73.53.4

2.81.8

(1.9)(2.0)(2.2)(2.1)(2.1)

(2.3)(2.3)

2.62.82.32.22.0

1.01.0

(2.1)(1.9)(2.1)(2.1)(2.1)

(1.8)(1.7)

3.63.22.83.13.3

5.12.4

23.1 (9.4) 13.9(10.9) 5.5

78

78697562595350

62

66383847382834

3.6

3.22.92.72.12.22.21.8

(2.1)

(1.9)(2.4)(2.0)(2.1)(2.3)(2.3)

.8

>.O.3.1.2.2.0

(2.1) 0.8

(1.9)

(2.0)(1.9)(1.9)(1.8)(1.9)(1.7)(1.5)

3.7

2.53.74.52.01.93.32.4

20.6(11.0) 10.5(10.3) 4.8

43.7(17.2) 24.3(17.8) 5.8

1 All ts were significant atp < 0.05, one-tailed tests.

Psychosomatic Medicine Vol. 41, No. 3 (May 1979) 215

TABLE 4

. S

ensi

tivi

ty t

o P

opul

atio

nlE

vent

Dif

fere

nces

: S

core

s fr

om 6

6 S

tres

s C

linic

Pat

ien

ts v

ersu

s 110 M

edic

al S

tud

ents

Rea

ctin

g to

Cad

aver

D

isse

ctio

n

Fre

quen

cy P

rese

nt (%

I S

tress

Clin

ic P

atie

nts

Me

dic

al S

tude

nts

Stre

ss C

linic

P

atie

nts

Me

dic

al S

tude

nts

Item

M

ale

F

emal

e M

ale

F

emal

e M

ale

F

emal

e M

ale

F

emal

e (n

=1

6)

(n=

50

) (n

=7

5)

(n=

35

) M

ean

(SD

) M

ean

(SD

) M

ean

(SD

) M

ean

(SD

)

lntr

usi

on lt

ems

I had w

aves

of s

tron

g fe

elin

gs

about i

t.

Oth

er t

hin

gs

kept

maki

ng m

e th

ink

about i

t.

I thought a

bout

it w

hen I

did

n't

mea

n to

. P

ictu

res

abou

t it p

opped in

to m

y m

ind.

Any

rem

inder b

rought b

ack

feel

ings

about i

t.

I had tr

ouble

falli

ng a

slee

p or

stayi

ng

asle

ep,

beca

use

of p

ictu

res

or th

oughts

about i

t tha

t cam

e in

to m

y m

ind

. I h

ad d

ream

s ab

out i

t.

Intr

usi

on S

ubsc

ale

Avo

idance

ltem

s I w

as a

ware

that

I st

ill h

ad a

lot o

f feelin

gs

about i

t, b

ut I

did

n't

deal w

ith th

em

. I a

void

ed le

ttin

g m

yself

get u

pset

when I

thought a

bout i

t or

was

rem

inded o

f it.

I t

ried to

rem

ove

it fr

om

mem

ory

. I t

ried n

ot t

o ta

lk a

bout i

t. M

y fe

elin

gs

abou

t it w

ere

kin

d o

f num

b.

I felt

as i

f it

hadn't

happened o

r it

w

asn'

t re

al.

I sta

yed

aw

ay

from

rem

inders

of

it.

I tried n

ot t

o th

inka

bo

ut i

t.

Avo

idance

Sub

scal

e T

otal

Sca

le


development. The patient reports referredto their responses during the previousweek as related to an individually specificlife event that had occurred on an averageof 25 weeks earlier. The student reportsreferred to their reactions during the pre-vious week to a specific event (cadaverdissection) that began approximately fourweeks earlier.

On the intrusion subscale, the mean forthe patient sample was 21.0 for both menand women, while the mean for the stu-dent sample was 2.5 for men and 6.1 forwomen, a difference showing patientscores that were three to ten times as highas those of students. Patient means on theavoidance subscale were 35.3 for men and42.1 for women, while student meanswere 6.9 for men and 12.7 for women.Again the differences were sizable, as wellas statistically significant.

The detailed data on each item are ofinterest and are summarized in Table 4;both percents and means for items, sub-scales, and total subjective distress scoresare given. The major difference in effectsnoted was between the groups, as men-tioned (F = 212.1, p < 0.0001 for intru-sion; F = 73.0 p < 0.001 for avoidance; F= 170.8, p < 0.0001 for the total stressscore). The sex differences were also sig-nificant, with much lower size of effectand are largely accounted for by womenstudents reporting most intrusion itemsand all but a few avoidance items morefrequently. (The main exception, as notedin Table 4, was the higher men's score on"My feelings about it were kind ofnumb.") These statistical tests are shownin Table 5.

DISCUSSION

Items on the Impact of Event Scale werefrequently endorsed by a population seek-

TABLE 5. Two Way Analysis of Variance on Sub-scale and Total Scores Comparing 66 Patients and

110 Medical. Students by Group and Sex

Source df MS <P

Intrusion Subscale MeanGroup 1 9374.5 212.1 0.0001Sex 1 211.1 4.8 0.03Croup X Sex 1 86.0 1.9 NSP

Residual 172 44.2Total 175 119.2

Avoidance Subscale MeanGroupSexGroup X Sex

ResidualTotal

111

172175

5158.7485.5145.570.6

119.0

73.06.92.1

0.00010.01

NS

Total Distress MeanGroup 1 28441.6 170.9 0.0001Sex 1 1336.9 8.0 0.005

Group X Sex 1 7.8 0.0 NSResidual 172 166.5Total 175 408.2

aNS: not significant.

ing help for post-traumatic stress disor-der. This finding affirms the accomplish-ment of our original intent, to construct aninstrument suitable for obtaining reportsof characteristic experiences from personswith such syndromes. A further goal wasthe development of a scale that wouldyield subscores for intrusive and avoi-dance experiences. These subscales,based upon clinical observation and in-ference, were found to have empirical val-idity by the emergence of coherent clus-ters. The reliability of the scale was sup-ported by adequate test—retest results; itssensitivity was supported by indicationsof change in a population where clinicalimpressions by experienced observerssuggested such change and by relevantdifferences in the response to discrete lifeevents of varied magnitude. Naturally,

Psychosomatic Medicine Vol. 41 , No. 3 (May 1979) 217


additional studies would be helpful,especially as they might yield data fromstill more diverse populations, events,and time periods.

The avoidance subscale consists of re-ported episodes of conscious awareness. Itcannot be expected to include self-reportsof manifestations of successful inhibi-tions. Persons who have accomplishedmassive denial or repression may not haveepisodes of conscious experience, such asnumbing or ideational constriction. Inves-tigators who would regard this subscale asan indicator of denial processes would bebound to include some false negatives intheir results.

Finally, we would like to note that per-sons of various educational, economic,and cultural backgrounds have been ableto use the scale. They understand it, arecomfortable with it, and do not feel that it

probes excessively. Clinicians have foundthe Impact of Event Scale useful in follow-ing the trajectory of a person respondingto a specific traumatic life event over along period of time, since it can easily beused repetitively and anchored to thesame psychological trauma over the entiretime span.

This research was supported by a Men-tal Health Clinical Research Center Grantfrom the NationaJ Institute of MentalHealth (MH30899-02), a grant from theNational Institute on Aging (AG00002-05), and a University 0/ CaliforniaBiomedical Research Support Grant. Theauthors would like to acknowledge thecooperation of Michel Paglaolii MA, RPT,and Nancy Horowitz, RPT, in theTest -Retest Reliability study.

REFERENCES

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Wiley, 19743. Gunderson E, Rahe R (Eds.): Life Stress and Illness. Springfield, 111., Charles Thomas, 19744. Horowitz M, Schaefer C, Hiroto D, Wilner N, Levin G: Life event questionnaires for measuring presump-

tive stress. Psychosom Med 39:413-431, 19775. Moos R: Psychological techniques in the assessment of adaptive behavior, in Coping and Adaptation

(edited by GV Coelho, D Hamburg, and J Adams). New York, Basic Books. 1974, pp. 334-3996. Faschingbauer TR, Devaul RA, Zisvok S: Development of the Texas Inventory of Grief. Am J Psychiatry

134:6,19777. Horowitz MJ: Stress Response Syndromes. New York, Aronson, 19768. Janis I: Stress and Frustration. New York, Harcourt, Brace, Jovanovich, 19699. Lazarus RS: Psychological Stress and the Coping Process. New York: McGraw-Hill, 1966

10. Lindemann E: Symptomatology and the management of acute grief. Am J Psychiatry 101:141-148,1944

11. Horowitz MJ: Phase oriented treatment of stress response syndromes. Am J Psychother 27:506—515,1973

12. Horowitz MJ: Stress response syndromes: Character style and brief psychotherapy. Arch Gen Psychiatry31:768-781, 1974

13. Sokall RR, Sneath PHA: Numerical Taxonomy: The Principles and Practice of Numerical Classifica-tions. San Francisco, WH Freeman and Co., 1973

218 Psychosomatic Medicine Vol. 41, No. 3 (May 1979)

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Horowitz Event Scales