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Use of the eating attitudes test and eating disorder inventory in adolescents
JOURNAL OF ADOLESCENT HEALTH CARE 1987;8:266-272
Use of the Eating Attitudes Test an Disorder Inventory in Adolescents RICKEY L. WILLIAM$ M.D.
The Eat@ Attitudes Test and the Eating DieorderInventorywere developed to measureabnormal eating attitudes mndbehavior6in patients with eating disorders. Thie report describes each of these self-reportquestionnaires and outlines their functions, limitations, and previoue use with adolescent subjects. KRY WORDS:
Eating Attitudes Test Eating Disorder Inventory Eating disorders Anorexia newosa Bulimia Appetite disorders
The Eating Attitudes Test
The eliagnch of an eating disorder, including anorexia nervosa and bulimia,is being made more frequently, especially in tenage and young adult
women (l-7). Physicians who care for adolescents to evaluatepabents with a suspected . In addition to the traditional history and physical examination, some physicians also use self-report questionnaires such as the Eating Attitudes Test and the Eating Disorder Inventory as part of their assessment. Patients with eating disorders have abnormal eating attitudes and behaviors. For example, patients with anorexia nervosa still exhibit an intense desire tolose weight even when they are emaciated. The patient may follow a ritualistic diet that avoids carbohydrates and red meats, eat the same foods day
ham fk
iIk!prtnunt of Pediufrics, University of Arizona Htwlth Center, &st.m, Atina. ms reprint requests to: Rickey L. Wilhms, M.D.. Department l!iOl North cmnpbelt Avenue, Tucson, AZ 85724. ubpt ucvxptedApril 29, 2986.
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after day, avoid eating with others, and be terrified that they will be unable to control their food intake once they start eating. Patients with bulimia frequently binge on high-calorie, easily digested food, then engage in purging behaviors with self-induced vomiting. The Eating Attitudes Test and Eating Disorder Inventory were developed to help measure some of these attitudes and behaviors.
The Eating Attitudes Test (EAT) was developed by Garner and GarEnkel(8). It is a IO-item self-administered questionnaire that originally was administered to patients with anorexia nervosa. Each of the 40 forced-choice Likert-scale items can be answered “always,” “very often,” “often,” “sometimes,” “rarely,” or “never.” A score of 3 is earned for an extreme response in the “anorexic” direction, with adjacent alternatives given a score of 2 or 1. For example (Table l), subject A receives a score of 3 on item 1, 2 on item 2, 1 on item 3, and 0 on items 4, 5, and 6; and subject B receives a score of 3 on item 6, 2 on item 5, 1 on item 4, and 0 on items 3, 2, and 1. The sum of the scores on all 40 items gives the total score for the EAT. Gamer and Garfinkel (8) applied the EAT to 65 female anorexia nervosa patients in various stages of therapy and 93 control subjects. The mean age of the subjects was 22 years. The mean total score on the EAT was 58.9 for patients with anorexia nervosa and 15.6 for normal controls. When a total score of 32 was used as a minimum cut-off point for anorexia nervosa, all patients with anorexia and only 7% of the normal controls scored 1 32. As patients with anorexia nervosa improved clinically, their total scores decreased into the normal range. Internal re0 Society for Adolescent Medicine, 1987
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May 1987
Table
1.
EATING-DISORDER
Selected Items from the Eating Attitudes
Test, with Responses
by Two
QUESTIONNAIRES
Hypothetical
Subjects,
267
A and B
Response EAT item
1.
Engage in dieting behavior
2.
Eat diet foods
3. Feel uncomfortable
Always
Very often
Often
Sometimes
A B
after eating sweets
A
B
B
A
I have eaten
6. Have gone on eating binges where not be able to stop
Never
B A
4. Have the impulse to vomit after meals 5. Vomit after
Rarely
B
A
I feel that I may
liability (Cronbach’s alpha) was reported as 0.79 for the anorexia nervosa subjects and 0.94 for the pooled sample of anorexics and normal controls. In a subsequent study using the EAT as a screening device to determine whether individuals whose profession focuses increased attention on a slim body shape are at risk for anorexia nervosa, a normal control group compared to ballet and fashion modeling students had significantly iower mean total scores (8). The EAT helped to identify 7% of the ballet and fashion modeling students who were subsequently diagnosed by clinical interview as having anorexia nervosa. Other investigators have used the EAT to screen for eating disorders. Button and Whitehouse (10) administered the test to 578 students (446 women and 132 men) at a technical college. The 28 students with total scores 2 32 were invited for an interview, as were 28 randomly selected students with scores < 32. The interviews were directed at eliciting detailed information of clinical relevance to anorexia nervosa. Although no cases of anorexia nervosa were found, high-scoring students tended to report a lower minimum weight (lowest since puberty) than did the low-scoring students. In addition, 39% of the high-scoring students but none of the lowscoring students reported self-induced vomiting. Szmukler (3) found that 65 (5%) of 1331 South London upper-class schoolgirls 14-18 years of age scored L 30 on the EAT. Subsequent clinical interviews disclosed that of those 65, 8 individuals had anorexia nervosa, 5 had bulimia, 25 had a partial syndrome of anorexia nervosa (that is, they showed most of the typical psychopathological features of anorexia nervosa), and 27 were normal dieters. Three cases of anorexia nervosa were not detected: one girl with known anorexia nervosa was excused
B
A
from the survey, one girl did not hand in her questionnaire, and one girl who was later referred to the author for treatment of anorexia nervosa admitted to lying on the questionnaire. In addition, some of the girls who scored < 30 were considered to show a partial syndrome of anorexij nervosa. There was no correlation between the EAT scores and age. Lowe and coworkers (11) administered the test to screen for eating disorders in 1514 New Zealand school girls (mean age 15 years). Fourteen percent scored > 30. Are all 40 items on the EAT necessary? To answer this question, Garner and coworkers (12) used factor analysis to show that 14 of the 40 original items on the EAT could be deleted and still maintain a high correlation (I’ = 0.98) with the original test. Standardized reliability coefficients (Cronbach’s alpha) for the EAT-26 total score were reported as 0.90 and 0.83, respectively, for the anorexia nervosa and female comparison groups. Mann and coworkers (13) administered the 26item EAT version to 262 15-year-old South London schoolgirls and found that 6.9% scored in the anorexic range of B 21. Compared with their peers, the girls who scored in the anorexic range reported missing more meals during the day and having more weight instability. The authors concluded that the 26-item EAT is an efficient screening instrument for abnormal eating attitudes and behaviors. Because two individuals can achieve the same total EAT score by answering every item differently (Table l), the patterns of relationships between items have been assessed to determine whether items can be grouped together in a small number of subscales representing an underlying construct. For example (Table l), items 1,2, and 3 could represent a dieting subscale, and items 4, 5, and 6 a bulimia
26s
JOURNAL OF ADOLESCENT HEALTH CARE Vol. 8, No. 3
WILLIAMS
subscale. Garner and coworkers (12) used factor analysis to define three EAT sobscales related to dieting, bulimia and food preoccupation, and oral control, They found that although the bulimic and restricter subsamples of their anorexia nervosa population did not differ in total test scores, there were significant differences in subscale scores between the two groups. Standardized reliability coefficients, for the three subscale scores ranged from 0.83 to 0.90 for their anorexia nervosa group and from 0.46 to 0.86 for their female comparison group. Subsequent investigators using adolescent subjects have confirmed that these subscales are useful in these patient groupings. Wells and coworkers (14) administered the 40sitem EAT to 749 teenage New Zealand schoolgirls. The mean EAT-40 score was 12.1, with 4.5% of the girls scoring Z 30, The mean EAT-26 score was 66. Factor analysis revealed that their Factor 1 contained 12 and 13 items of Garner and coworkers’ dieting factor, with the other subscales also being similar to those reported by Garner et al. (12) Williams and coworkers (1 S) administered the 40item EAT to 72 Tucson, Arizona, junior and senior high school women (mean age 15 years). The mean EAT-40 score for subjects classified as normal was 17.6, and the mean EAT-26 score was 10.7. F‘ictor analysis revealed results essentially identical tc the subscales of Garner and coworkers (12) (Table 2). In an attempt to evaluate the utility of the EAT alone as a screening device for the detection of anorexia nervosa and bulimia in a female college population, Garter and Moss (16) administered the EAT40 to 162 white females (mean age 19 years) and found that 21.6% of the subjects scored B 30. Only ) of56 selected subjects who underwent a struc-
tured interview could be classified as anorexic, and only 4 (7%) of the 56 subjects could be classified as bulimic. The authors reported the test-retest reliability coefficient of the EAT as 0.84.
The Eating Disorder inventory The Eating Disorder Inventory (EDI), developed by Garner and coworkers (17), is a 64-item, self-report, multiscale measure designed to assess the psychologic and behavioral traits common to anorexia nervosa and bulimia. It consists of eight subscales: 1) Drive for Thinness, 2) Bulimia, 3) Body Dissatisfaction, 4) Ineffectiveness, 5) Perfectionism, 6) Interpersonal Distrust, 7) Interoceptive Awareness, and 8) Maturity Fears. These subscales were derived from a large pool of items generated by clinicians familiar with the research and treatment of patients with anorexia nervosa. To be included in a subscale, an item had to be answered significantly differently by control patients compared to those with anorexia nervosa and had to be more highly correlated to the subscale to which it was intended to belong than to any other subscale. As a measure of internal consistency, the authors required coefficients of reliability (standardized Cronbach’s alpha) for each subscale to be above 0.80 for the anorexia nervosa samples. The format of the ED1 is similar to the EAT, Scoring is the same. In contrast to the EAT, the ED1 focuses more on the specific cognitive and behavioral dimensions to help differentiate patient subgroups, or those with serious psychopathokgy, from “extreme dieters.” Garner and coworkers applied the ED1 to subjects with “restricter” or “bulimia” subtypes of anorexia
Fable 2. Eating Attitudes Test Scores Reported in Previous Studies Bulimiaand Investi@ors
Population
Garner and Carfmkel Anorexia nervosa Control (7) Carnat et al. (It) Anorexia nervosa Control Wells et al. (13) Unselected Schoolgirls Williams et al. (14) Normals Dieters Suspected bulimics Szfiwkter (3) Schoolgirls Mann et al. (12) Schoolgirls
II 33 59 160 140 749 54 9 8 1331 262
Mean age (yr) 22 22 22 20 Range 12-18 15 15 16 16 15
“Totenumberin parentheses is the standard deviation.
EAT-40 58.9(13.3)” 15.6( 9.3) 52.9(23.0) 15.4(11.0) 12.2(-) 17.6( 18.7( 25.5( 10.7(
8.3) 7.1) 9.3) 9.3)
EAT-26 -
Dieting subscale -
Food Prcoccupation subscale -
Qral Control subscale -
36.1(17-O) 9.9( 9.2) 6.6(-)
19.9(10.9) 7.1( 7.2) -
8.0 (5.2) LO(2.1) -
8.3(5.8) 1.9(2-l) -
10.7( 6.6) 10.9( 6.6) 17.0( 7.0)
7.0( 5.4) 8.7( 5.5) 12.0( 4.5)
0.6(1.5) 0.5(1.1) 1.6(2.1)
3.1(3.0 1.7(1.5) 3.4(2.5)
9.6( 6.4)
May 1987
EATING-DISORDER QUESTIONNAIRES
269
Table 3. E,nting Disorder Inventory Scores Reported in Previous Studies Mean Investigdtors
Population
Garner e/i al.
Anorexia nervosa Restricters Bulimics Female comparison Recovered anorexia Male comparison Gp/rner et al. Anorexia nervosa (18) Weight preoccupied Not weight preoccupied Williams et al. Normals Dieters (14) Suspected bulimics Bulimic (16)
Drive for
Bulimia
Body Dissatisfaction
5.0(5.3)
2.7(3.8) 10.8(5.6) 2.0(3.4)
14.2(6.9) 17.4(8.1) 10.2(7.7)
23.9
3.6(5.4)
0.3(0.6)
6.3(6.2)
166
20.3
1.6(3.1)
l.O(l.8)
3.9(5.0)
50
21.9
15.1(4.2)
8.3(5.1)
18.5(7.8)
35
19.8
16.1(3.4)
6.2(4.1)
15.8(6.3)
134
20.2
O.Cq3.5)
O.li(4.3)
3.9(6.5)
54 9 8
15.4 15.3 15.9
4.8(5.2) 7.7(5.6) 8.9(4.9)
1.3(2.2) 2.1(3.4) 2.4(2.2)
9.7(7.3) 14.8(8.2) 12.6(8.1)
n
age (yr)
Thinness
113
21.8
15.4(5.3)”
48 65 577
21.0 22.4 19.9
17
1
17
18.0(-)
17.0(-)
ll.O(-)
“The number in parentheses is the standard deviation.
nervosa, bulimia, obesity, former obesity, and normal controls. Subscale scores differentiate between these groupings, with little overlap of subjects with an eating disorder and normals (Table 3). In a subsequent study, the ED1 was administered to 42 women with bulimia who had not met weightloss criteria for anorexia nervosa (18). Scores were compared with those obtained from 42 restricting and 42 bulimic anorectic patients. Normal-weight bulimic patients scored significantly higher than restricting anorectic patients on the Drive for Thinness and the Bulimia subscales. Normal-weight bulimic and bulimic anorectic patients scored similarly on all subscales. More recently, Garner and coworkers (19) have administered the ED1 to 237 female college students and 66 female ballet students. Women from these samples were then selected for inclusion in a weightpreoccupied group (N = 35) and a not weight-preoccupied group (N = 134) on the basis of their scores on the Drive for Thinness subscale. Cluster analysis of the weight-preoccupied women was performed using ED1 subscale scores. A 2-cluster solution identified one group of 11 women characterized by elevated scores on all of the subscales, and a second
group of 24 women with elevated scores only on the Drive for Thinness, Body Dissatisfaction, and Perfectionism subscales. Clinical interviews of a subsample of these women suggest that the first group had significant pyschopathology, whereas the second group were probably normal dieters. The authors conclude that “although there are some highly weight-preoccupied females who display psychopathology quite similar to anorexia nervosa, others only superficially resemble patients suffering from serious eating disorders.” Williams and coworkers (15) administered the ED1 to 72 randomly selected young women in a junior or senior high school in Tucson, Arizona. Subjects were classified by clinical interview as normal, dieter, suspected bulimia, and bulimia categories. T.,&e results of their ED1 subscale scores are shown in Table 3. Normal adolescents had similar scores to the normal subjects in previous studies (17, 19). Cooper and coworkers (20) questioned whether all eight subscales of the ED1 are specific for patients with eating disorders. The authors administered the EDI, EAT, and the General Health (GHQ) to 27 female psychiatric outpatients (age range 17-39 years) and found that only the Drive for
270
JOURNAL OF ADOLESCENT HEALTH CARE Vol. 8, No. 3
WILLIAMS
Table 3. (continued) Interoceptive Awareness
h4aturity Fears
Ineffectiveness
Perfectionism
Interpersonal Distrust
14.4(8.0)
10.0(5.0)
7.7(5.2)
12.5(11.7)
6.0(10.5)
2.0(3.6)
5.2(3.8)
2.2(2.9)
2.9(11.3)
2.5( 7.9)
3.1(3.9)
6.5(3.6)
1.9(2.3)
2.1( 3.5)
l.l( 1.3)
l.iq3.1)
6.2(3,9)
3.1(3.1)
1.4( 5.0)
2.7( 5.7)
13.7(7.6)
6.9(4.9)
9.5(5.9)
12.0( 6.1)
5.3( 5.7)
6.3(6.2)
3.5(4*0)
8.9(4.7)
7.8( 4.9)
4.7( 4.6)
1*1(6.3)
2.0(4. I)
5kq4.9)
l.l( 5.0)
2.2( 4.6)
3,1(4.2) 3.7(3.8) 4.5(3*3) ¶3.0(--)
5.3(3.8) 4.2(3.1) 7,2(5.6) 13.0(-)
3.5(4.2) 3.3(2.5) 3.6(3.6) 7.0(-)
4.4( 5.4) 4.3( 5.6) 5.2( 2.0) 23.O(-)
3.8( 3.2) 3.8( 3.4) 3.8( 4.2) 4.0(-)
Thinness, Bulimia, and Body Dissatisfaction
subscales were significantly correlated with the EAT total score. The Ineffectiveness, Interpersonal Distrust, and Interoceptive Awareness subscale scores were significantly correlated with the GHQ, leading the authors to speculate that some of the DI subscales assess dimensions of psychological common to patients with a variety of distur al disorders. psych
As with all self-report questionnaires, the EAT and EDI are vulnerable to distortion by inaccurate subject reporting. Vanderdeycken and Vanderlinden (21) found in administering the EAT-40 to 40 patients with anorexia nervosa (mean age 23) that 13 patients scored Q 30, presumably because they were denying their illness. Bven tho the EAT is reported to have a sensitivity of 9 and a specificity of 88% (9, 22), Williams and coworkers (22) cautioned against using as a screening instrument for anorexia se it is an uncommon illness. They state that the positive predictive value of the EAT is only 0.19, i.e. of 100 high scorers on the test, only 19 wilI actually have anorexia nervosa. Positive predictive value is the probability of dis-
ease in a patient with a positive (abnormal) test result (23). This value is determined by the sensitivity and specificity of the test and the prevalence of the disease in the population tested. Positive results even for a very specific test, when applied to subjects with a low likelihood of disease, will be largely false positives. Because the prevalence of anorexia nervosa in a high school population is less than l%, single screening tests should always yield a substantial number of false positives. Even a test with 99% specificity and 99% sensitivity has a positive predictive value of only 0.50 for a disease with a prevalence in the population of 1%. Several assumptions are made when the EAT and ED1 are scored as described by the original authors. The magnitude of the interval between the quasidimensional scores on individual items is not necessarily equal, yet a rating of “always” is assumed to be three times as important as a rating of “often.” Each item is weighted equally in the overall score. It is reasonable to suspect that some items may actually be more valuable than others in classifying subjects as normal or abnormal. To determine the importance of individual items in a multiple-item test, discriminant analysis is employed. Discriminant analysis is a family of statistical methods used to predict in which of several discrete groups (e.g., normal, bulimic) an individual subject
May 1987
should be classified (24). Williams and coworkers (15) performed a classical discriminant analysis of EAT and ED1 items to determine whether a combination of items could predict the classification of junior and senior high school students (n = 71, mean age 15 years) into one of three categories (normal, dieter, suspected bulimic) as predicted from a structured clinical interview. A preliminary equation was derived that correctly classified 86% of the subjects into the categories as determined from the interviews. A second discriminant analysis was performed, and the subjects were classified as normal (normal, dieter) or abnormal (suspected bulimic, bulimic). In this analysis, 96% of the subjects were correctly classified. Classification of abnormals using the discriminant score from this analysis had a sensitivity of 67%, a specificity of 966, and a positive predictive value of 100%. Further research will be necessary to validate and improve upon these findings before such a discriminant analysis technique can be recommended as a screening device for subjects with eating disorders. Finally, the original versions of the EAT and the ED1 were developed for college students; therefore some of the words used are not likely to be understood by younger patients or those with limited reading ability. Consequently, minor modifications in item wording may be necessary when administering these tests to adolescents.
Discussion How can practitioners benefit from usin;; self-report questionnaires such as the EAT and EDI in assessing adolescents with suspected eating disorders? The EAT and ED1 can be used to help confirm one’s clinical impression derived from a thorough history and physical examination. However, the benefits gained by using one or both of these tests must be weighed against the possible threat to the doctorpatient relationship caused by impersonal questionnaires. The EAT and ED1 can be used to help monitor a patient’s progress as studies of current and recovered anorexics (8,17) suggest that scores decrease with clinical improvement. Which EAT should the clinician use? Although the EAT-40 total score is frequently reported in studies of patients with eating disorders, one must be cautious in interpreting the result when reported alone. Recent studies have shown that the 26-item version of the EAT has a high correlation with the 40-item version. In addition, three subscales related to dieting, bulimia and food preoccupirtion, and oral con-
EATING-DISORDERQUESTIONNAIRES
271
trol can be derived from the 26-item test and may be useful in discriminating normals dram bulimics or anorectics. The additional information gained from determining EAT subscale scores suggests that the clinician may benefit from using these subscale scores as a supplement to the EAT-26 and EAT-40 total score. Selected items from these self-report questionnaires could be part of a screening program for eating disorders in adolescents, if properly developed. Although the clinical interview remains the “gold standard” for diagnosing eating disorders, the time and expense involved in conducting clinical interviews, combined with the relatively low occurrence of clinically significant eating disorders in the adolescent population, may make screening by clinical interview prohibitively expensive. Preliminary evidence (15) suggests that development of an effective self-report screening device for eating disorders in young women is feasible.
References 1. Willi J, Grossman S. Epidemiology of anorexia nervosa in a defined region of Switzerland. Am J Psychiatry 1983;140:5647. 2. Crisp AH, PalmerRL, Kalucy RS. How common is anorexia nervosa? A prevalence study. Br J Psychiatry 1976;128:54954. 3. SzmukIer GI. Weight and food preoccupation in a population of English schoolgirls. In Understanding anorexia nervosa and bulimia, Report of the Fourth Ross Conference on Medical Research. Columbus, OH: Koss Laboratories, 1983:21-B. 4. Pyle RL, Mitchell JR,EckertED, et al. The incidence of bulimia in freshman college students. Int J Eating Disord 1982;2:7585. 5. Halmi KA, Falk JR, Schwartz E. Binge-eating and vomiting: A survey of a college population. Psycho1 Med 1981;11:697706. 6. Johnson CL, Lewis C, Love S, et al. A descriptive survey of dieting and bulimic behavior in a female high school population. in Understanding anorexia nervosa and bulimia, Report of the Fourth Ross Conference on Medical Research. Columbus, OH: Ross Laboratories, 1983~14-20. 7. Killen JD, Taylor CB, Telch MJ, et al. Self-induced vomiting and laxative and diuretic use among teenagers: Precursorsof the binge-purge syndrome? JAMA1986;255:1447-9. 8. Gamer DM, Garfinkel PE. The Eating Attitudes Test: An index of the symptoms of anorexia nervosa. Psycho1 Med 1979;9:273-9. 9. Gamer DM, Garfinkel PE. Socio-cultural factors in the development of anorexia nervosa. Psycho1 Med 1980;10:647-56. 10. Button EJ, Whitehouse A. Subclinical anorexia nervosa. Psy chol Med 1981;11:509-16. 11. Lowe NC, Miles SW, Richards CG. Bating attitudes in an adolescent schoolgirl population. N Z Med J 1985;98:330-1. 12. Garner DM, Olmstead Ml’, Bohr Y, Garfinkel PE. The Eating Attitudes Test: Psychometric features and clinical correlates. Psycho1 Med 1982;12:871-8.
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WILLIAMS
13. Mann AH, WaLeling A, Wood K, et al. Screening for abnorma1 eating attitudes and psychiatric morbidity in an unselected population of 15 year-old schoolgirls. Psychol Med 1983; 13573-80. 14. Welts JE,Coope PA, Gabb DC, Pears RK. The factor structure of the Eating Attitudes Test with adolescent schoolgirls. Psyrho1 Med 1985;15:141-6. 15, Williams RL, Schaefer CA, Shisslak CM, Gronwaldt VH, Comerci CD. Eating attitudes and behaviors in adolescent women: Discrimination of normals, dieters, and suspected bulimics using the Eating Attitudes Test and Eating Disorder Inventory. lnt J Eating Disord 1986;5:879-94. 16. Carter PI, Moss RA. Screening for anorexia and bulimia nervosa in a college population: problemsand limitations. Addict Behav 1 ;9:417-9. 17, Garner DM, Olmstead MP, Polivy J. Development and validation of a multidimensional Eating Disorder Inventory for anorexia nervosa and bulimia. lnt J Eating Disord 1982;2:1534. 10. Gamer DM, Garfinkel PE, Q’ghaughnessy M. Clinical and psychometric comparison between bulimia in anorexia ner-
JOURNAL OF ADOLESCENT HEALTH CARE Vol. 8, No. 3
vosa and bulimia in normal-weight women. In Understanding anorexia nervosa and bulimia, Report of the Fourth Ross Conference on Medical Research. Columbus, OH: Ross Laboratories, 1983;6-13. 19. Gamer DM, Olmstead MP, Polivy J, Garfinkel PE. Compar ison between weight-preoccupied women and anorexia nervosa. Psychosom Med 1984;46:255-46. 20. Cooper Z, Cooper PJ, Fairbum CG. The specificity of the Eating Disorder Inventory. Br J Clin Psycho1 1985;24:129-30. 21. Vanderdeycken W, Vanderlinden J. Denial of illness and the use of self-reporting measures in anorexia nervosa patients. Int J Eating Disorcl 1983;2:101-7. 22. Williams P, Hand D, Tamopolsky A. The problem of screening for uncommon disorders==-A comment on the Eating Attitudes Test. Psycho1 Med 1982;12:431-4. 23. Fletcher RH, Fletcher SW, Wagner EH. Clinical epidemiology--The essentials. Baltimore, Williams and Wilkins, 1982;52-6. 24. Brown GW. Discriminant 19&4;138:395-400.
analysis.
Am J Dis Child
Use of the Eating Attitudes Test an Disorder Inventory in Adolescents RICKEY L. WILLIAM$ M.D.
The Eat@ Attitudes Test and the Eating DieorderInventorywere developed to measureabnormal eating attitudes mndbehavior6in patients with eating disorders. Thie report describes each of these self-reportquestionnaires and outlines their functions, limitations, and previoue use with adolescent subjects. KRY WORDS:
Eating Attitudes Test Eating Disorder Inventory Eating disorders Anorexia newosa Bulimia Appetite disorders
The Eating Attitudes Test
The eliagnch of an eating disorder, including anorexia nervosa and bulimia,is being made more frequently, especially in tenage and young adult
women (l-7). Physicians who care for adolescents to evaluatepabents with a suspected . In addition to the traditional history and physical examination, some physicians also use self-report questionnaires such as the Eating Attitudes Test and the Eating Disorder Inventory as part of their assessment. Patients with eating disorders have abnormal eating attitudes and behaviors. For example, patients with anorexia nervosa still exhibit an intense desire tolose weight even when they are emaciated. The patient may follow a ritualistic diet that avoids carbohydrates and red meats, eat the same foods day
ham fk
iIk!prtnunt of Pediufrics, University of Arizona Htwlth Center, &st.m, Atina. ms reprint requests to: Rickey L. Wilhms, M.D.. Department l!iOl North cmnpbelt Avenue, Tucson, AZ 85724. ubpt ucvxptedApril 29, 2986.
266 0191-/$3.50
after day, avoid eating with others, and be terrified that they will be unable to control their food intake once they start eating. Patients with bulimia frequently binge on high-calorie, easily digested food, then engage in purging behaviors with self-induced vomiting. The Eating Attitudes Test and Eating Disorder Inventory were developed to help measure some of these attitudes and behaviors.
The Eating Attitudes Test (EAT) was developed by Garner and GarEnkel(8). It is a IO-item self-administered questionnaire that originally was administered to patients with anorexia nervosa. Each of the 40 forced-choice Likert-scale items can be answered “always,” “very often,” “often,” “sometimes,” “rarely,” or “never.” A score of 3 is earned for an extreme response in the “anorexic” direction, with adjacent alternatives given a score of 2 or 1. For example (Table l), subject A receives a score of 3 on item 1, 2 on item 2, 1 on item 3, and 0 on items 4, 5, and 6; and subject B receives a score of 3 on item 6, 2 on item 5, 1 on item 4, and 0 on items 3, 2, and 1. The sum of the scores on all 40 items gives the total score for the EAT. Gamer and Garfinkel (8) applied the EAT to 65 female anorexia nervosa patients in various stages of therapy and 93 control subjects. The mean age of the subjects was 22 years. The mean total score on the EAT was 58.9 for patients with anorexia nervosa and 15.6 for normal controls. When a total score of 32 was used as a minimum cut-off point for anorexia nervosa, all patients with anorexia and only 7% of the normal controls scored 1 32. As patients with anorexia nervosa improved clinically, their total scores decreased into the normal range. Internal re0 Society for Adolescent Medicine, 1987
Pubfished by Elsevier
SciencePublishing Co., Inc., 52 Vanderbilt Ave., New York, NY 10017
May 1987
Table
1.
EATING-DISORDER
Selected Items from the Eating Attitudes
Test, with Responses
by Two
QUESTIONNAIRES
Hypothetical
Subjects,
267
A and B
Response EAT item
1.
Engage in dieting behavior
2.
Eat diet foods
3. Feel uncomfortable
Always
Very often
Often
Sometimes
A B
after eating sweets
A
B
B
A
I have eaten
6. Have gone on eating binges where not be able to stop
Never
B A
4. Have the impulse to vomit after meals 5. Vomit after
Rarely
B
A
I feel that I may
liability (Cronbach’s alpha) was reported as 0.79 for the anorexia nervosa subjects and 0.94 for the pooled sample of anorexics and normal controls. In a subsequent study using the EAT as a screening device to determine whether individuals whose profession focuses increased attention on a slim body shape are at risk for anorexia nervosa, a normal control group compared to ballet and fashion modeling students had significantly iower mean total scores (8). The EAT helped to identify 7% of the ballet and fashion modeling students who were subsequently diagnosed by clinical interview as having anorexia nervosa. Other investigators have used the EAT to screen for eating disorders. Button and Whitehouse (10) administered the test to 578 students (446 women and 132 men) at a technical college. The 28 students with total scores 2 32 were invited for an interview, as were 28 randomly selected students with scores < 32. The interviews were directed at eliciting detailed information of clinical relevance to anorexia nervosa. Although no cases of anorexia nervosa were found, high-scoring students tended to report a lower minimum weight (lowest since puberty) than did the low-scoring students. In addition, 39% of the high-scoring students but none of the lowscoring students reported self-induced vomiting. Szmukler (3) found that 65 (5%) of 1331 South London upper-class schoolgirls 14-18 years of age scored L 30 on the EAT. Subsequent clinical interviews disclosed that of those 65, 8 individuals had anorexia nervosa, 5 had bulimia, 25 had a partial syndrome of anorexia nervosa (that is, they showed most of the typical psychopathological features of anorexia nervosa), and 27 were normal dieters. Three cases of anorexia nervosa were not detected: one girl with known anorexia nervosa was excused
B
A
from the survey, one girl did not hand in her questionnaire, and one girl who was later referred to the author for treatment of anorexia nervosa admitted to lying on the questionnaire. In addition, some of the girls who scored < 30 were considered to show a partial syndrome of anorexij nervosa. There was no correlation between the EAT scores and age. Lowe and coworkers (11) administered the test to screen for eating disorders in 1514 New Zealand school girls (mean age 15 years). Fourteen percent scored > 30. Are all 40 items on the EAT necessary? To answer this question, Garner and coworkers (12) used factor analysis to show that 14 of the 40 original items on the EAT could be deleted and still maintain a high correlation (I’ = 0.98) with the original test. Standardized reliability coefficients (Cronbach’s alpha) for the EAT-26 total score were reported as 0.90 and 0.83, respectively, for the anorexia nervosa and female comparison groups. Mann and coworkers (13) administered the 26item EAT version to 262 15-year-old South London schoolgirls and found that 6.9% scored in the anorexic range of B 21. Compared with their peers, the girls who scored in the anorexic range reported missing more meals during the day and having more weight instability. The authors concluded that the 26-item EAT is an efficient screening instrument for abnormal eating attitudes and behaviors. Because two individuals can achieve the same total EAT score by answering every item differently (Table l), the patterns of relationships between items have been assessed to determine whether items can be grouped together in a small number of subscales representing an underlying construct. For example (Table l), items 1,2, and 3 could represent a dieting subscale, and items 4, 5, and 6 a bulimia
26s
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WILLIAMS
subscale. Garner and coworkers (12) used factor analysis to define three EAT sobscales related to dieting, bulimia and food preoccupation, and oral control, They found that although the bulimic and restricter subsamples of their anorexia nervosa population did not differ in total test scores, there were significant differences in subscale scores between the two groups. Standardized reliability coefficients, for the three subscale scores ranged from 0.83 to 0.90 for their anorexia nervosa group and from 0.46 to 0.86 for their female comparison group. Subsequent investigators using adolescent subjects have confirmed that these subscales are useful in these patient groupings. Wells and coworkers (14) administered the 40sitem EAT to 749 teenage New Zealand schoolgirls. The mean EAT-40 score was 12.1, with 4.5% of the girls scoring Z 30, The mean EAT-26 score was 66. Factor analysis revealed that their Factor 1 contained 12 and 13 items of Garner and coworkers’ dieting factor, with the other subscales also being similar to those reported by Garner et al. (12) Williams and coworkers (1 S) administered the 40item EAT to 72 Tucson, Arizona, junior and senior high school women (mean age 15 years). The mean EAT-40 score for subjects classified as normal was 17.6, and the mean EAT-26 score was 10.7. F‘ictor analysis revealed results essentially identical tc the subscales of Garner and coworkers (12) (Table 2). In an attempt to evaluate the utility of the EAT alone as a screening device for the detection of anorexia nervosa and bulimia in a female college population, Garter and Moss (16) administered the EAT40 to 162 white females (mean age 19 years) and found that 21.6% of the subjects scored B 30. Only ) of56 selected subjects who underwent a struc-
tured interview could be classified as anorexic, and only 4 (7%) of the 56 subjects could be classified as bulimic. The authors reported the test-retest reliability coefficient of the EAT as 0.84.
The Eating Disorder inventory The Eating Disorder Inventory (EDI), developed by Garner and coworkers (17), is a 64-item, self-report, multiscale measure designed to assess the psychologic and behavioral traits common to anorexia nervosa and bulimia. It consists of eight subscales: 1) Drive for Thinness, 2) Bulimia, 3) Body Dissatisfaction, 4) Ineffectiveness, 5) Perfectionism, 6) Interpersonal Distrust, 7) Interoceptive Awareness, and 8) Maturity Fears. These subscales were derived from a large pool of items generated by clinicians familiar with the research and treatment of patients with anorexia nervosa. To be included in a subscale, an item had to be answered significantly differently by control patients compared to those with anorexia nervosa and had to be more highly correlated to the subscale to which it was intended to belong than to any other subscale. As a measure of internal consistency, the authors required coefficients of reliability (standardized Cronbach’s alpha) for each subscale to be above 0.80 for the anorexia nervosa samples. The format of the ED1 is similar to the EAT, Scoring is the same. In contrast to the EAT, the ED1 focuses more on the specific cognitive and behavioral dimensions to help differentiate patient subgroups, or those with serious psychopathokgy, from “extreme dieters.” Garner and coworkers applied the ED1 to subjects with “restricter” or “bulimia” subtypes of anorexia
Fable 2. Eating Attitudes Test Scores Reported in Previous Studies Bulimiaand Investi@ors
Population
Garner and Carfmkel Anorexia nervosa Control (7) Carnat et al. (It) Anorexia nervosa Control Wells et al. (13) Unselected Schoolgirls Williams et al. (14) Normals Dieters Suspected bulimics Szfiwkter (3) Schoolgirls Mann et al. (12) Schoolgirls
II 33 59 160 140 749 54 9 8 1331 262
Mean age (yr) 22 22 22 20 Range 12-18 15 15 16 16 15
“Totenumberin parentheses is the standard deviation.
EAT-40 58.9(13.3)” 15.6( 9.3) 52.9(23.0) 15.4(11.0) 12.2(-) 17.6( 18.7( 25.5( 10.7(
8.3) 7.1) 9.3) 9.3)
EAT-26 -
Dieting subscale -
Food Prcoccupation subscale -
Qral Control subscale -
36.1(17-O) 9.9( 9.2) 6.6(-)
19.9(10.9) 7.1( 7.2) -
8.0 (5.2) LO(2.1) -
8.3(5.8) 1.9(2-l) -
10.7( 6.6) 10.9( 6.6) 17.0( 7.0)
7.0( 5.4) 8.7( 5.5) 12.0( 4.5)
0.6(1.5) 0.5(1.1) 1.6(2.1)
3.1(3.0 1.7(1.5) 3.4(2.5)
9.6( 6.4)
May 1987
EATING-DISORDER QUESTIONNAIRES
269
Table 3. E,nting Disorder Inventory Scores Reported in Previous Studies Mean Investigdtors
Population
Garner e/i al.
Anorexia nervosa Restricters Bulimics Female comparison Recovered anorexia Male comparison Gp/rner et al. Anorexia nervosa (18) Weight preoccupied Not weight preoccupied Williams et al. Normals Dieters (14) Suspected bulimics Bulimic (16)
Drive for
Bulimia
Body Dissatisfaction
5.0(5.3)
2.7(3.8) 10.8(5.6) 2.0(3.4)
14.2(6.9) 17.4(8.1) 10.2(7.7)
23.9
3.6(5.4)
0.3(0.6)
6.3(6.2)
166
20.3
1.6(3.1)
l.O(l.8)
3.9(5.0)
50
21.9
15.1(4.2)
8.3(5.1)
18.5(7.8)
35
19.8
16.1(3.4)
6.2(4.1)
15.8(6.3)
134
20.2
O.Cq3.5)
O.li(4.3)
3.9(6.5)
54 9 8
15.4 15.3 15.9
4.8(5.2) 7.7(5.6) 8.9(4.9)
1.3(2.2) 2.1(3.4) 2.4(2.2)
9.7(7.3) 14.8(8.2) 12.6(8.1)
n
age (yr)
Thinness
113
21.8
15.4(5.3)”
48 65 577
21.0 22.4 19.9
17
1
17
18.0(-)
17.0(-)
ll.O(-)
“The number in parentheses is the standard deviation.
nervosa, bulimia, obesity, former obesity, and normal controls. Subscale scores differentiate between these groupings, with little overlap of subjects with an eating disorder and normals (Table 3). In a subsequent study, the ED1 was administered to 42 women with bulimia who had not met weightloss criteria for anorexia nervosa (18). Scores were compared with those obtained from 42 restricting and 42 bulimic anorectic patients. Normal-weight bulimic patients scored significantly higher than restricting anorectic patients on the Drive for Thinness and the Bulimia subscales. Normal-weight bulimic and bulimic anorectic patients scored similarly on all subscales. More recently, Garner and coworkers (19) have administered the ED1 to 237 female college students and 66 female ballet students. Women from these samples were then selected for inclusion in a weightpreoccupied group (N = 35) and a not weight-preoccupied group (N = 134) on the basis of their scores on the Drive for Thinness subscale. Cluster analysis of the weight-preoccupied women was performed using ED1 subscale scores. A 2-cluster solution identified one group of 11 women characterized by elevated scores on all of the subscales, and a second
group of 24 women with elevated scores only on the Drive for Thinness, Body Dissatisfaction, and Perfectionism subscales. Clinical interviews of a subsample of these women suggest that the first group had significant pyschopathology, whereas the second group were probably normal dieters. The authors conclude that “although there are some highly weight-preoccupied females who display psychopathology quite similar to anorexia nervosa, others only superficially resemble patients suffering from serious eating disorders.” Williams and coworkers (15) administered the ED1 to 72 randomly selected young women in a junior or senior high school in Tucson, Arizona. Subjects were classified by clinical interview as normal, dieter, suspected bulimia, and bulimia categories. T.,&e results of their ED1 subscale scores are shown in Table 3. Normal adolescents had similar scores to the normal subjects in previous studies (17, 19). Cooper and coworkers (20) questioned whether all eight subscales of the ED1 are specific for patients with eating disorders. The authors administered the EDI, EAT, and the General Health (GHQ) to 27 female psychiatric outpatients (age range 17-39 years) and found that only the Drive for
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WILLIAMS
Table 3. (continued) Interoceptive Awareness
h4aturity Fears
Ineffectiveness
Perfectionism
Interpersonal Distrust
14.4(8.0)
10.0(5.0)
7.7(5.2)
12.5(11.7)
6.0(10.5)
2.0(3.6)
5.2(3.8)
2.2(2.9)
2.9(11.3)
2.5( 7.9)
3.1(3.9)
6.5(3.6)
1.9(2.3)
2.1( 3.5)
l.l( 1.3)
l.iq3.1)
6.2(3,9)
3.1(3.1)
1.4( 5.0)
2.7( 5.7)
13.7(7.6)
6.9(4.9)
9.5(5.9)
12.0( 6.1)
5.3( 5.7)
6.3(6.2)
3.5(4*0)
8.9(4.7)
7.8( 4.9)
4.7( 4.6)
1*1(6.3)
2.0(4. I)
5kq4.9)
l.l( 5.0)
2.2( 4.6)
3,1(4.2) 3.7(3.8) 4.5(3*3) ¶3.0(--)
5.3(3.8) 4.2(3.1) 7,2(5.6) 13.0(-)
3.5(4.2) 3.3(2.5) 3.6(3.6) 7.0(-)
4.4( 5.4) 4.3( 5.6) 5.2( 2.0) 23.O(-)
3.8( 3.2) 3.8( 3.4) 3.8( 4.2) 4.0(-)
Thinness, Bulimia, and Body Dissatisfaction
subscales were significantly correlated with the EAT total score. The Ineffectiveness, Interpersonal Distrust, and Interoceptive Awareness subscale scores were significantly correlated with the GHQ, leading the authors to speculate that some of the DI subscales assess dimensions of psychological common to patients with a variety of distur al disorders. psych
As with all self-report questionnaires, the EAT and EDI are vulnerable to distortion by inaccurate subject reporting. Vanderdeycken and Vanderlinden (21) found in administering the EAT-40 to 40 patients with anorexia nervosa (mean age 23) that 13 patients scored Q 30, presumably because they were denying their illness. Bven tho the EAT is reported to have a sensitivity of 9 and a specificity of 88% (9, 22), Williams and coworkers (22) cautioned against using as a screening instrument for anorexia se it is an uncommon illness. They state that the positive predictive value of the EAT is only 0.19, i.e. of 100 high scorers on the test, only 19 wilI actually have anorexia nervosa. Positive predictive value is the probability of dis-
ease in a patient with a positive (abnormal) test result (23). This value is determined by the sensitivity and specificity of the test and the prevalence of the disease in the population tested. Positive results even for a very specific test, when applied to subjects with a low likelihood of disease, will be largely false positives. Because the prevalence of anorexia nervosa in a high school population is less than l%, single screening tests should always yield a substantial number of false positives. Even a test with 99% specificity and 99% sensitivity has a positive predictive value of only 0.50 for a disease with a prevalence in the population of 1%. Several assumptions are made when the EAT and ED1 are scored as described by the original authors. The magnitude of the interval between the quasidimensional scores on individual items is not necessarily equal, yet a rating of “always” is assumed to be three times as important as a rating of “often.” Each item is weighted equally in the overall score. It is reasonable to suspect that some items may actually be more valuable than others in classifying subjects as normal or abnormal. To determine the importance of individual items in a multiple-item test, discriminant analysis is employed. Discriminant analysis is a family of statistical methods used to predict in which of several discrete groups (e.g., normal, bulimic) an individual subject
May 1987
should be classified (24). Williams and coworkers (15) performed a classical discriminant analysis of EAT and ED1 items to determine whether a combination of items could predict the classification of junior and senior high school students (n = 71, mean age 15 years) into one of three categories (normal, dieter, suspected bulimic) as predicted from a structured clinical interview. A preliminary equation was derived that correctly classified 86% of the subjects into the categories as determined from the interviews. A second discriminant analysis was performed, and the subjects were classified as normal (normal, dieter) or abnormal (suspected bulimic, bulimic). In this analysis, 96% of the subjects were correctly classified. Classification of abnormals using the discriminant score from this analysis had a sensitivity of 67%, a specificity of 966, and a positive predictive value of 100%. Further research will be necessary to validate and improve upon these findings before such a discriminant analysis technique can be recommended as a screening device for subjects with eating disorders. Finally, the original versions of the EAT and the ED1 were developed for college students; therefore some of the words used are not likely to be understood by younger patients or those with limited reading ability. Consequently, minor modifications in item wording may be necessary when administering these tests to adolescents.
Discussion How can practitioners benefit from usin;; self-report questionnaires such as the EAT and EDI in assessing adolescents with suspected eating disorders? The EAT and ED1 can be used to help confirm one’s clinical impression derived from a thorough history and physical examination. However, the benefits gained by using one or both of these tests must be weighed against the possible threat to the doctorpatient relationship caused by impersonal questionnaires. The EAT and ED1 can be used to help monitor a patient’s progress as studies of current and recovered anorexics (8,17) suggest that scores decrease with clinical improvement. Which EAT should the clinician use? Although the EAT-40 total score is frequently reported in studies of patients with eating disorders, one must be cautious in interpreting the result when reported alone. Recent studies have shown that the 26-item version of the EAT has a high correlation with the 40-item version. In addition, three subscales related to dieting, bulimia and food preoccupirtion, and oral con-
EATING-DISORDERQUESTIONNAIRES
271
trol can be derived from the 26-item test and may be useful in discriminating normals dram bulimics or anorectics. The additional information gained from determining EAT subscale scores suggests that the clinician may benefit from using these subscale scores as a supplement to the EAT-26 and EAT-40 total score. Selected items from these self-report questionnaires could be part of a screening program for eating disorders in adolescents, if properly developed. Although the clinical interview remains the “gold standard” for diagnosing eating disorders, the time and expense involved in conducting clinical interviews, combined with the relatively low occurrence of clinically significant eating disorders in the adolescent population, may make screening by clinical interview prohibitively expensive. Preliminary evidence (15) suggests that development of an effective self-report screening device for eating disorders in young women is feasible.
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vosa and bulimia in normal-weight women. In Understanding anorexia nervosa and bulimia, Report of the Fourth Ross Conference on Medical Research. Columbus, OH: Ross Laboratories, 1983;6-13. 19. Gamer DM, Olmstead MP, Polivy J, Garfinkel PE. Compar ison between weight-preoccupied women and anorexia nervosa. Psychosom Med 1984;46:255-46. 20. Cooper Z, Cooper PJ, Fairbum CG. The specificity of the Eating Disorder Inventory. Br J Clin Psycho1 1985;24:129-30. 21. Vanderdeycken W, Vanderlinden J. Denial of illness and the use of self-reporting measures in anorexia nervosa patients. Int J Eating Disorcl 1983;2:101-7. 22. Williams P, Hand D, Tamopolsky A. The problem of screening for uncommon disorders==-A comment on the Eating Attitudes Test. Psycho1 Med 1982;12:431-4. 23. Fletcher RH, Fletcher SW, Wagner EH. Clinical epidemiology--The essentials. Baltimore, Williams and Wilkins, 1982;52-6. 24. Brown GW. Discriminant 19&4;138:395-400.
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Am J Dis Child