Prevalence, incidence and prospective risk factors for eating disorders

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1 Acta Psychiatr Scand 2001: 104: 122±130 Printed in UK. All rights reserved Copyright # Munksgaard 2001 ACTA PSYCHIATRICA SCANDINAVICA ISSN X Prevalence, incidence and prospective risk factors for eating disorders Ghaderi A, Scott B. Prevalence, incidence and prospective risk factors for eating disorders. Acta Psychiatr Scand 2001: 104: 122±130. # Munksgaard Objective: To examine the prevalence, incidence and prospective risk factors for eating disorders (ED) among young adult females. Method: Using a prospective design, a randomly selected sample of 1157 females (18-30 years) from the general population was examined with questionnaires for establishing ED diagnoses, self-esteem, body concern, coping and perceived social support. Results: The prevalence of ED was 3.2% and the 2-year rst-time incidence was (n=8). Subjects in the extended incidence group (n=34) reported signi cantly lower self-esteem and perceived social support, and higher body concern and relative use of escape-avoidance coping, at the onset of the study in 1997, compared to controls (n=643). Furthermore, they reported a signi cant increase in body concern and relative use of escape-avoidance coping, and a signi cant decrease in selfesteem compared to controls from 1997 to Conclusion: These factors may be considered as risk factors for later development of ED among young adult women. Ata Ghaderi, Berit Scott Department of Psychology, Uppsala University, Uppsala, Sweden Key words: eating disorders; bulimia; anorexia; risk factors; incidence; prevalence Ata Ghaderi, Department of Psychology, Box 1225, SE Uppsala, Sweden Accepted for publication February 12, 2001 Introduction Although the aetiology of eating disorders (ED) is not known, there is a consensus that a multifactorial approach comprising biological, psychological and social factors is most valuable in explaining the development and maintenance of ED (1, 2). ED are dif cult to treat, and because of the high morbidity and mortality rates, early detection of cases is called for (3). Furthermore, effective prevention strategies and powerful therapeutic interventions should be implemented according to the knowledge of risk and buffering factors for ED. Dieting has been considered a major risk factor for development of ED (4), but when considering the uniformly negative results of attempts to reduce the prevalence of dieting among young girls (e.g. (5, 6)), it seems even more important to study other risk factors than dieting which can be modi ed and thus implemented in prevention programmes and early treatment. There are several studies investigating risk factors for ED. Most of these studies are cross-sectional in design (e.g. (7, 8)) with restricted samples, but there are also a few community-based, case±control studies of risk factors of ED (e.g. (9, 10)). Twin studies have provided some evidence of genetic involvement in the development of ED (e.g. (11)) but it cannot solely explain why some subjects develop ED and some do not. Findings from prospective studies which de ne risk on the basis of attenuated eating symptoms clearly points to the insidious nature of ED (10). By de ning risk on the basis of early attenuated symptoms, one is likely to pick up individuals who are already caught up in a pathological process (10). A potential problem in the prospective studies of risk factors is that the variables and theories that are considered to be important at the beginning of the study may be outdated later. Thus, it seems reasonable to avoid strong theoretical biases and it may be better to select potential risk variables that are relatively eclectic and empirically robust (10). Earlier research had suggested that factors such as self-esteem (12, 13), social support and social adjustment (e.g. (14)), coping (2, 15), and preoccupation about body image and body dissatisfaction (e.g. (16)) may be considered as factors of importance for the development and maintenance 122

2 of ED. In contrast to factors such as personality traits, these variables can be targeted in prevention interventions if they show to be prospective risk factors for ED. Accordingly, investigating these factors might be justi ed both theoretically and from a cost-effectiveness perspective. However, most of the studies are cross-sectional in nature and the populations being investigated are in most cases schoolgirls, college students or other selected samples. The need for well-planned prospective epidemiological studies of risk factors for ED, investigating subjects in the general population, has been proposed by many researchers in the eld (10, 17, 18). There are a few prospective studies concerning risk factors for ED or eating problems (19±21). The generalization of the accumulated knowledge from these studies is limited because of the restrictions in the samples being studied. There is to our knowledge no prospective study investigating risk factors for ED among young adult women in the general population, although the modal age of onset for bulimia is 18 (22) and the onset of the target symptoms of ED occurs after the age of 17 among nearly half the subjects who develop a diagnosable ED (23). The aim of the present study was to identify operating risk factors in the development of ED prospectively in a randomly selected sample of young adult females in the general population. Material and methods Subjects and procedure Sample characteristics. The present study comprises the population investigated in 1997 (24). Thus, the same 1157 respondents in 1997 who were selected randomly from the general population of females (18±30 years) in Sweden were included. The random selection of participants was conducted by Sema Goup Info data from the national register of population in Sweden. The selection is age-strati ed in order to ensure that the proportion of selected subjects within each age category (13 categories: 18±30 years) represents the actual proportion of subjects in respective age group. Thirty- ve subjects could not be included in the follow-up study due to various reasons (one death, six refusal, seven unknown addresses, three protected addresses, four being abroad and 14 had emigrated) giving a total sample of 1122 potential respondents. Of those, a total of 826 subjects (73.6%) completed the same questionnaire as in 1997 after two reminders were sent out. Attrition. The subjects who did not participate in the follow-up study (attrition group, n=296) were compared to the respondents concerning age, marital status, education and work situation. There were no signi cant group differences concerning age, marital status and work situation (t(1, 1119)=x0.06, P=0.95; x 2 (3, 1121)=0.39, P=0.94; x 2 (4, 1120)=5.8, P=0.21), but a signi cant difference was found for education (x 2 (3, 1121)=12.6, P=0.01). The highest grade of education obtained for the majority of respondents (65%) and subjects in the attrition group (62%) was completed high school. Among the respondents, 3% reported having uncompleted primary school and 14% had completed primary school. The corresponding gures for the attrition group were 6% and 19%. The proportion of vocational studies was almost identical for the groups (2%, and 3%, respectively) while about 11% in the attrition group reported having completed college or university studies compared to 15% of the respondents. Thus, subjects in the attrition group had on average a slightly lower level of education compared to controls. There were no differences between the respondents and the attrition group concerning body mass index (BMI) (t(1113)=x0.60, P=0.55) or lifetime history of ED (x 2 (1,1110)=0.37, P=0.55). Instruments Diagnostic questionnaire according to DSM-IV. The same modi ed self-report questionnaire (Survey for Eating Disorders: SEDs) used in 1997 (24) was employed. The modi ed version of SEDs consists of 46 questions, including six demographic questions. Before presenting any questions about occurrence of binge eating, a de nition of binge eating according to DSM-IV (25) is presented. The procedure of establishing the diagnoses was identical to the procedure and DSM-IV criteria used in the earlier study 1997 (39). For example, a subject diagnosed as having bulimia nervosa had to report repeated bingeeating episodes characterized by eating in a discrete period of time (e.g. within any 2-hour period), substantial intake of food that is de nitely larger than most people would eat during the same period of time and under similar circumstances, and a sense of loss of control over eating during the episode. Further, it was required that the subject reported recurrent inappropriate compensatory behaviour in order to prevent weight gain. The binge eating and the inappropriate compensatory behaviours must occur on average at least twice a week for 3 months. In addition to these behavioural criteria, if the 123

3 Ghaderi and Scott subject also reported that her self-evaluation is always (or very often) unduly in uenced by body shape and weight, then she would be diagnosed with bulimia nervosa according to DSM-IV. An equally stringent procedure was used to establish diagnoses of anorexia nervosa, binge eating disorder and eating disorders not otherwise speci ed. The reliability and validity of the SEDs was established by comparing the results of SEDs in a student sample (n=124) with their scores on the Eating Disorder Inventory (26), and by comparing the SEDs with the Eating Disorder Examination (EDE) (27) in a clinical sample (n=45). In the clinical sample, the results showed a very high concordance between the EDE and the SEDs in regard to the diagnoses of bulimia nervosa, binge eating disorder and eating disorders not otherwise speci ed. The SEDs yielded only two false positive cases of the total of 45 women that were assessed for participation in the effectiveness study (i.e. a positive predictive value of 0.96). These women had reported objective bulimic episodes on the SEDs that turned out to be subjective episodes when assessed with the EDE. In the student sample, the SEDs showed impressively high 2-week test±retest reliability. Students with a current diagnosis of ED (n=5) according to SEDs had high scores on the EDI (26) subscales of drive for thinness (M=13.6) and bulimia (M=7.4) compared to the students with no diagnoses of ED (M=1.3 and M=0.3, respectively). Self-Concept questionnaire (SCQ). The Self- Concept Questionnaire (SCQ) is a self-report questionnaire measuring self-esteem, constructed by Robson (28). It consists of 30 items (e.g. `I am a reliable person,' `If I really try I can overcome most of my problems'). Subjects are asked to respond on a seven-point scale, ranging from `completely disagree' to `completely agree'. High reliability (Cronbach's alpha of 0.89) and good validity (clinical validity of 0.70) have been reported for SCQ (28). The reliability in our study 1997 (24) also showed high homogeneity (Cronbach's alpha 0.89) and the corresponding value in the present study was Split-half reliability was 0.87 at 1997 and 0.89 at Body Shape questionnaire (BSQ). The Body Shape Questionnaire (BSQ), developed by Cooper et al. (29), is a self-report questionnaire comprising 34 questions measuring the extent of psychopathology of concerns about body shape, in particular the phenomenal experience of `feeling fat'. An item example is: `Have you noticed the shape of other women and felt that your own shape compared unfavourably?' The questions refer to the subjects' state over the past four weeks and are answered on a six-point scale, from `never' to `always.' The BSQ has shown to have good concurrent and discriminative validity (29). Reliability by means of Cronbach's alpha was 0.97 in both of our studies (1997 and 1999) and the corresponding split-half reliability was 0.97 and 0.96, respectively. Perceived social support from the family (PSSFa). This self-report questionnaire was developed by Procidano and Heller (30). It consists of 20 items for measuring the extent to which an individual perceives that his or her needs for support, feedback and interaction are ful lled by family (PSSFa). An item example is: `My family gives me the moral support I need.' The response categories in the original version were `yes', `no' and `don't know'. To increase the sensitivity of response categories, a ve-point scale from `always' to `never' was introduced (24). PSSFa have proved to have high internal consistency (Cronbach's alpha of 0.90), and construct validity (30, 31). Cronbach's alpha was 0.93 at rst study (1997) and 0.94 at in the present study. Further, the spilt-half reliability was 0.93 and 0.94, respectively. Ways of Coping questionnaire (WCQ). The revised version of Ways of Coping questionnaire (WCQ), developed by Folkman and Lazarus (32), is a self-report questionnaire assessing thoughts and actions used by individuals to cope with the stressful encounters of everyday life. The internal consistency of the subscales, measured by Cronbach's alpha, is regarded as more satisfactory than most of the measures of the coping process, and the same applies to reliability (32). Furthermore, the face and construct validity of WCQ are supported to the extent that the ndings are consistent with the theoretical predictions (32). Five factors from the WCQ were used at T 1, as these were considered to cover the topics found in other studies; confrontive coping, self-controlling, seeking social support, escapeavoidance and planful problem solving. Subjects were asked to think of a current stressor and to indicate on a four-point scale, from `Not used at all' to `Used very much' the degree to which each of the items was used to deal with the stressor. Relative scores of coping strategies were then obtained, that is, the degree to which each subscale (factor) was used relative to all the others. This is calculated by dividing the mean for each coping strategy by the sum of the means for 124

4 all coping strategies. In line with earlier studies (33), only the scores on the relative use of escapeavoidance coping was used in the group comparisons. Data analysis Demographic data were analysed by means of the chi-square and analysis of variance (ANOVA). Investigation of group differences was performed by means of multivariate analysis of variance (MANOVA) with time as within-subjects factor. MANOVA provides a distinct advantage over separate ANOVAs because the MANOVA test considers the correlations between the variables. The Tukey post hoc test for unequal group sizes (Spjotvoll Stoline HSD test) was then used for establishing group differences. To test that the assumption of homogeneity of variance is met, the distribution of variance was examined by Bartlett chi-square test to ensure the validity of the analyses. In the two-group comparisons, the only analysis where the smaller group had a signi cantly larger variance concerned SCQ (Bartlett chi-square=4.91, P=0.027). In this case the H 0 -hypothesis was examined by the Welch tk-test (34). The analyses showed that the true probability of type I-error in the two-group comparisons was not greater than the nominal, and the results of the MANOVA are thus reliable. Grouping in order to investigate risk factors Two distinct groups. Of all the potential respondents who were assessed during April±June 1997 (T 1 ), 826 were reassessed during April±June 1999 (T 2 ). In order to identify risk factors for ED, an extended incidence group was formed. This group comprised all the subjects who developed eating disorder after T 1 (n=28; seven with bulimia nervosa, 13 with binge eating disorder, one with anorexia nervosa and seven with eating disorders not otherwise speci ed according to the DSM-IV), and six subjects who met all the criteria for BN but reported that their selfevaluation is often unduly in uenced by body shape and weight. This incidence group was compared to controls, that is subjects who never reported any clinical symptoms of ED (C97C99; n=643). [Only subjects who reported that their self-evaluation was always or very often unduly in uenced by body shape and weight were considered to ful l the D-criterion of bulimia nervosa when the diagnosis was established strictly according to DSM-IV.] Exhaustive grouping. Some subjects (n=155) could not be classi ed into either the extended incidence group or the control group. In order to investigate the course and development of EDsymptoms for all the subjects in relation to the investigated psychological variables self-esteem, body concern, relative use of escape-avoidance coping and perceived social support from the family, a more comprehensive grouping was made. Subjects were divided into seven groups according to the level of ED-symptoms and EDdiagnosis. These groups were: 1) subjects with no history or symptoms of ED in T 1 and T 2 (C97C99; C means control, n=643): this is the control group; 2) symptomatic subjects not entirely ful lling the criteria for any diagnoses of ED (S97S99; S means symptom, n=84); 3) subjects with an ED-diagnosis in T 1 who reported fewer or less severe symptoms in T 2 and thereby did not ful l the criteria for any ED-diagnoses in T 2 (CR97C99; CR means current ED in 97 and C99 means that subjects have no ED in 99, n=7). This is the improved group; 4) subjects with an ED-diagnosis in T 1 and T 2 (CR97ED99; these subjects had an ED in 97 and still have a ED-diagnosis in 99, n=14); ED have been maintained in this group; 5) subjects with an ED-diagnosis before T 1 (and not in T 1 ) who did not ful l an ED-diagnosis in T 2 (PA97C99; PA (Past) means an EDdiagnosis before 97, n=31); 6) subjects with an ED-diagnosis before T 1 (and not in T 1 ) who did ful l an ED-diagnosis in T 2 (PA97ED99, n=13); this is the relapse group; 7) subjects with no diagnosis of ED before or in T 1 who met an ED-diagnosis in T 2 (C97ED99: this group is the same as the incidence group in the two-group comparisons, n=34). Results Prevalence and incidence of eating disorders Table 1 shows the prevalence and incidence of different diagnoses of ED according to DSM-IV in the follow-up in 1999 among females (20±32 years) from the general population of Sweden. The total prevalence of ED is slightly higher than the corresponding rate in First-time incidence, which is the number of subjects who developed an episode of ED for the rst time in their lives divided by the number of subjects who had never had the disorder, was (n=5) which is evidently less 125

5 Ghaderi and Scott Table 1. Prevalence and 1-year incidence at follow-up for females aged 20±32 with different diagnoses of eating disorders Diagnoses than the total incidence of (Table 1). The total 2-year rst time incidence was (n=8). Demographic characteristics Prevalence 1-year incidence % n Proportion n Anorexia nervosa (AN) Bulimia nervosa (BN) Binge eating disorder (BED) Eating disorders not otherwise speci ed Total eating disorders There were no signi cant differences between the control group and the extended incidence group concerning marital status, education or work situation in T 1 (x 2 (3677)=1.14, P=0.77; x 2 (4677)=1.14, P=0.32; x 2 (3677)=8.88, P=0.21, respectively), or in T 2 (x 2 (3677)=3.77, P=0.29; x 2 (4677)=8.35, P=0.08; x 2 (3677)=2.68, P=0.61, respectively). There were no signi cant differences concerning body mass index (BMI) between the groups at either of the assessment points (F(1,675)=0.02, P=0.88) although the control group reported a slight increase in BMI from T 1 to T 2 (22.40±22.94) and the extended incidence group reported a slight decrease during the same time period (22.88±22.66). To investigate the risk factors for ED, the extended incidence group (n=34) was compared to control subjects who never reported any symptoms of ED (n=643) in T 1 and T 2. The main effects (MANOVA) were signi cant for grouping (Wilks' lambda=0.84, df=4, 672, P= ), and time (Wilks' lambda=0.95, df=4, 672, P= ). Furthermore, there was a signi cant interaction (Wilks' lambda=0.96, df=4, 672, P= ) between grouping and time. The signi cant interaction concerned self-esteem, body concern and relative use of escape-avoidance coping (P=0.005, P=0.000 and P=0.048, respectively). The means and standard deviations for each group in T 1 and T 2 are shown in Table 2. As can be seen in Table 2, the incidence group reported signi cantly lower self-esteem and higher body concern (post hoc test: P= and P= , respectively) compared to controls in T 1. There were no signi cant changes in selfesteem and body concern for controls between T 1 and T 2 (post-hoc test: P=0.54 and P=0.99, respectively) while there was a tendency toward a Table 2. Mean and standard deviation for the control group and the extended incidence group in T 1 (1997) and T 2 (1999) concerning SCQ, BSQ, WCQ: E-A and PSSFa Variables T 1 Control group T 2 Extended incidence group T 1 T 2 M(SD) SCQ (17.5) (19.8) (22.6) (19.5) BSQ6 9.5 (25.4) 69.8 (26.3) (26.0) (27.7) WCQ:E-A (%) 14.7 (6.9) 15.5 (8.8) 19.7 (7.6) 23.6 (9.2) PSSFa 75.8 (11.9) 77.1 (12.6) 65.3 (14.5) 67.0 (12.6) signi cant change in self-esteem and a signi cant change in body concern for the incidence group between T 1 and T 2 (post-hoc test: P=0.05 and P=0.001, respectively). These signi cant changes between T 1 and T 2 resulted in the signi cant interactions (grouping r time) concerning selfesteem and body concern. These interactions are illustrated in Fig. 1. As Fig. 1 shows, the level of self-esteem and body concern is quite stable from T 1 to T 2 for controls, while the incidence group with lower self-esteem and higher body concern in T 1 reported further decrease in self-esteem and increased body concern in T 2. Concerning relative use of escape-avoidance coping, the same pattern as for body concern can be seen (Table 2). There were signi cant differences between the incidence group and the control group in T 1 and T 2 (post-hoc test: P=0.007 and P=0.000, respectively), indicating that elevated relative use of escape-avoidance coping may be a risk factor for the development of an eating disorder. There is an increase in the perceived social support from the family for both the control group and the incidence group from T 1 to T 2, respectively (Table 1) (post-hoc test: P=0.007, P=0.80). Although there is no signi cant interaction for grouping and time concerning PSSFa, there are signi cant group differences both in T 1 and T 2 (post-hoc test: P=0.0000, P=0.0000, respectively) indicating that low perceived social support may be a risk factor for development of ED. In order to investigate the course and development of ED-symptoms for all the subjects, a sevengroup comparison concerning the putative risk factors was done (see Method; Data analysis; Exhaustive grouping). The mean and standard deviations for these groups concerning the putative risk factors are shown in Table 3. As Table 3 shows, there is a marked stability in these variables for the control group (C97C99) from T 1 to T 2. The symptomatic group (S97S99) reported slightly less SCQ and PSSFa and higher body concern (BSQ) and more use of escape-avoidance coping compared to C97C99. There is a clear 126

6 Fig. 1. Two-way interaction for self-esteem (SCQ) and body concern (BSQ) for the incidence group and the control group with time as within-subjects factor. C97C99: subjects with no symptom of ED in 1997 and C97ED99: the extended incidence group. pattern of differences between these two groups and the groups with different ED-status in both T 1 and T 2. Figure 2 illustrates the group differences and the change over time concerning self-esteem. As Fig. 2 shows, subjects with no symptoms of ED in T 1 and T 2 (C97C99) reported the highest level of self-esteem followed by those who only reported some ED-symptoms (S97S99), while the lowest level of self-esteem was reported by subjects who had an ED-diagnosis in both T 1 and T 2 (CR97ED99). Subjects with no ED-diagnosis in T 1 who developed ED at T 2 (C97ED99) reported decreased self-esteem at T 2 while subjects with a past or current diagnosis of ED in T 1 who reported fewer ED-symptoms in T 2 (PA97C99 and CR97C99) reported increased selfesteem at T 2. A corresponding pattern of results was obtained concerning body concern (BSQ) and relative use of escape-avoidance coping (WCQ:E-A). [Copies of the illustrative gures concerning seven-group comparisons for these variables are available from the corresponding author.] Concerning the relative use of escape-avoidance coping, the C97C99 and S97S99 reported low levels of relative use of escapeavoidance coping in T 1 with no signi cant change from T 1 to T 2 (Table 3). The groups with ED in T 1, or earlier, which did not ful l any ED-diagnosis in T 2 (CR97C99 and PA97C99) reported a substantial decrease in the relative use of escape-avoidance coping from T 1 to T 2. Those groups who developed ED in T 2 reported a signi cant increase from T 1 to T 2. The change from T 1 to T 2 was somewhat more complicated concerning perceived social support from the family (PSSFa). The highest level of PSSFa in T 1 was reported by C97C99 followed by S97S99, CR97C99 and PA97C99 (Table 3). Lowest level of PSSFa in T 1 was reported by CR97ED99, while PA97ED99 and C97ED99 reported slightly higher PSSFa than CR97ED99. In T 2, the C97C99 and S97S99 reported slightly higher PSSFa compared to T 1 and, as expected, PA97C99 reported a considerable increase in PSSFa in T 2 compared to T 1. The two groups with ED-diagnosis in T 2 (PA97ED99 and CR97ED99) reported an increase in PSSFa in T 2. Finally, the CR97C99 reported an increase in PSSFa from T 1 to T 2. Discussion The reported total prevalence of ED in T 2 (3.15%) was slightly higher than the obtained prevalence in T 1 (2.56%) (24). The increase may be due partly to an actual increase of ED in the studied population and due partly to the attrition, or statistical uctuation in point prevalence rate, as the incidence Table 3. Means and standard deviations concerning self-esteem (SCQ), body concern (BSQ), relative use of escape-avoidance coping (WCQ:E-A) and perceived social support from the family (PSSFa) for the seven groups classi ed according to the history of ED-diagnoses in T 1 and T 2 Groups SCQ BSQ WCQ:E-A M% (SD) PSSFa T 1 T 2 T 1 T 2 T 1 T 2 T 1 T 2 C97C (17) 156 (20) 70 (25) 70 (26) 15 (0.07) 15 (0.09) 76 (12) 77 (13) S97S (21) 148 (22) 93 (33) 91 (31) 17 (0.08) 18 (0.09) 17 (14) 74 (15) C97ED (23) 133 (20) 103 (26) 122 (28) 20 (0.09) 24 (0.09) 65 (15) 70 (13) PA97C (23) 147 (23) 111 (36) 95 (35) 19 (0.07) 17 (0.08) 69 (15) 74 (15) PA97ED (29) 131 (27) 124 (38) 134 (38) 18 (0.10) 23 (0.10) 63 (20) 72 (16) CR97C (21) 142 (26) 130 (21) 108 (28) 24 (0.12) 20 (0.07) 69 (25) 65 (24) CR97ED (21) 133 (28) 140 (21) 134 (32) 24 (0.05) 25 (0.11) 61 (21) 68 (17) 127

7 Ghaderi and Scott Fig. 2. Two-way interaction concerning self-esteem for the seven group comparison with time as within-subjects factor. and transition of symptoms are high and the underlying sample is not big enough to compensate for it. The attrition analysis showed that there was a signi cant difference between the respondents and the attrition group concerning education. However, the impact of attrition and the discrepancy in education is limited in explaining the increased prevalence. The effect of statistical uctuations when measuring point prevalence in relatively small samples and an actual increase in the prevalence rate seem to be more plausible explanations. The prevalence of ED in T 2 (0.035) is, however, within the 95% con dence interval for the prevalence rate in T 1 (95% CI=0.17±0.035). The present study showed that the incidence of ED among young adult women (0.016) in the general population is quite high in relation to the prevalence. This nding is supported by others however, as shown in a review of the epidemiological studies (3) where the author found that the incidence of ED seems to be increasing. In the present study, the rst-time incidence was (n=5). Thus, a large part of the total incidence (n=8) consisted of relapses among subjects who had ED before T 1. Longitudinal studies have demonstrated that in many cases, ED-symptoms wax and wane in severity (e.g. (35)). The high incidence rate in relation to the prevalence in the general population and the transition of symptoms among a subgroup of subjects may partly explain why only a small percentage of subjects with ED seek treatment. In the present study low self-esteem, high body concern, high relative use of escape-avoidance coping and low perceived social support were found to be prospective risk factors for ED, given the results of the comparisons between the extended incidence group and the control group. In the seven-group comparisons, the incidence and the relapse groups reported a decrease in selfesteem from T 1 to T 2. The groups that reported an improvement in their ED-status (i.e. PA97C99 and CR97C99) showed increased self-esteem from T 1 to T 2. The control group followed by the symptomatic control group (S97S99) in both T 1 and T 2 reported the highest level of self-esteem. On the other hand, the lowest self-esteem in T 1 was reported by CR97ED99, and in T 2 by subjects who had relapsed at T 2 (PA97ED99). Similar patterns of results were observed for body concern. This pattern of results demonstrates the ability of SCQ and BSQ as instruments capturing the changes in self-esteem and body concern between the groups and over time. The relative use of coping among the groups and over time showed an expected pattern between the groups at each assessment point and in the pattern of change from T 1 to T 2. Concerning perceived social support from the family, the incidence group, the relapse group and the group with maintained ED (CR97ED99) reported an increase in social support from T 1 to T 2. This nding may be interpreted as a result of increased attention toward the individual from the family due to ED-symptoms. These groups had low mean scores on PSSFa in both T 1 and T 2 while the control group and the S97S99 had the highest on both occasions. There was an unexpected nding concerning perceived social support from the family. The CR97C99 reported a decrease in the perceived social support from the family from T 1 to T 2. However, this is in accordance with the clinical experience suggesting that, when behavioural symptoms of ED start to vanish, many patients report perceiving their families as less supportive and more critical. The critical comments generally re ect the decreased tolerance among the family members concerning different expressions of EDrelated problems because of the desire and expectation of the total recovery when behavioural symptoms are not prominent. Some major limitations of the present study should be noted. Questionnaire-based studies of ED have been criticized by leading researchers in the eld (3, 36). One of the main problems is that some items on the questionnaire (e.g. `binge eating') may be interpreted differently by different populations. Another major problem is the relatively low positive 128

8 prediction value of the screening questionnaires. In order to handle these potential shortcomings, dif cult items have been avoided in the diagnostic questionnaire and a de nition of `binge eating' was presented before this item was used in any question. Another issue is the validity and reliability of the diagnostic questionnaire (SEDs). The cross-validation of the SEDs with the clinical interview (Eating Disorders Examination) in a clinical sample (n=43) and the results of the investigation of the reliability and validity by comparing the SEDs with the EDI in a student sample (n=124) show positive results. Further investigation of the psychometric properties of the SEDs in a larger clinical sample of subjects is under progress. Another limitation of the current study is that data from only two measurement points are available. Data from more than two measurements (i.e. several follow-up periods) may show a more clear and stable picture of the importance, effect and the interactions of putative risk factors for ED. Finally, since the occurrence of other psychiatric disorders was not investigated in the current study, and the incidence group was not compared to a psychiatric sample, the identi ed risk factors can not be regarded as speci c risk factors for ED. Due to these limitations, the ndings must be interpreted cautiously. In summary, the current study simultaneously investigated the prevalence, incidence and prospective risk factors for ED among young adult women in the general population, and it showed a consistent change in the psychological variables such as self-esteem, body concern, perceived social support and use of coping strategies in different subgroup of subjects in the various stages of the development or recovery from ED. The value of the ndings is therefore signi cant for our understanding of the risk factors for ED, for prevention as well as for treatment of ED. References 1. STRIEGEL MOORE R. Psychological factors in the etiology of binge eating. Addict Behav 1995;20:713± TOBIN DL, GRIFFING AS. Coping and depression in bulimia nervosa. Int J Eat Dis 1995;18:359± HSU LK. Epidemiology of the eating disorders. Psychiatr Clin North Am 1996;19:681± HSU LK. Can dieting cause an eating disorder? [editorial]. Psychol Med 1997;27:509± KILLEN JD, TAYLOR CB, HAMMER LD et al. An attempt to modify unhealthful eating attitudes and weight regulation practices of young adolescent girls. Int J Eat Dis 1993;13: 369± PAXTON SJ. A prevention program for disturbed eating and body dissatisfaction in adolescent girls: a 1 year follow-up. Health Educ Res 1993;8:43± LEON GR, FULKERSON JA, PERRY CL, CUDECK R. Personality and behavioral vulnerabilities associated with risk status for eating disorders in adolescent girls. J Abnorm Psychol 1993;102:438± WILLIAMSON DA, NETEMEYER RG, JACKMAN LP, ANDERSON DA, FUNSCH CL, RABALAIS JY. Structural equation modelling of risk factors for the development of eating disorder symptoms in female athletes. Int J Eat Dis 1995;17:387± FAIRBURN CG, WELCH SL, DOLL HA, DAVIES BA, O'CONNOR ME. Risk factors for bulimia nervosa. A community-based case±control study. Arch Gen Psychiatry 1997;103:509± LEUNG F, GELLER J, KATZMAN M. Issues and concerns associated with different risk models for eating disorders. Int J Eat Dis 1996;19:249± KENDLER KS, MACLEAN C, NEALE M, KESSLER R, HEATH A, EAVES L. The genetic epidemiology of bulimia nervosa. Am J Psychiatry 1991:1627± SILVERSTONE PH. Low self-esteem in different psychiatric conditions. Br J Clin Psychol 1991;30:185± GRUBB HJ, SELLERS MI, WALIGROSKI K. Factors related to depression and eating disorders: self-esteem, body image, and attractiveness. Psychol Rep 1993;72:1003± GRISSETT NI, NORVELL NK. Perceived social support, social skills, and quality of relationships in bulimic women. J Consult Clin Psychol 1992;60:293± TROOP NA, HOLBREY A, TROWLER R, TREASURE JL. Ways of coping in women with eating disorders. J Nerv Ment Dis 1994;182:535± SLADE P, BRODIE D. Body-image distortion and eating disorder: a reconceptualazation based on the recent literature. Eat Dis Rev 1994;2:59± GARFINKEL PE, GARNER DM, GOLDBLOOM DS. Eating disorders: implications for the 1990s. Can J Psychiatry 1987;32:624± GILLBERG C. Whither research in anorexia and bulimia nervosa? Br J Hosp Med 1994;51:209± KILLEN JD, TAYLOR CB, HAYWARD C et al. Pursuit of thinness and onset of eating disorder symptoms in a community sample of adolescent girls: a three-year prospective analysis. Int J Eat Dis 1994;16:227± PATTON GC, JOHNSON SABINE E, WOOD K, MANN AH, WAKELING A. Abnormal eating attitudes in London schoolgirls Ð a prospective epidemiological study: outcome at twelve month follow-up. Psychol Med 1990;20:383± SHISSLAK CM, CRAGO M, GRAY N et al. The McKnight Foundation prospective study of risk factors for the development of eating disorders. In: VANDEREYCKEN W, NOORDENBOS G, eds. The prevention of eating disorders. New York: New York University Press, MITCHELL JE, HATSUKAMI D, PYLE RL, ECKERT ED. The bulimia syndrome: course of the illness and associated problems. Compr Psychiatry 1986;27:165± WOODSIDE DB, GARFINKEL P-E. Age of onset in eating disorders. International J Eat Dis 1992;12:31± GHADERI A, SCOTT B. Prevalence and psychological correlates of eating disorders among females aged 18±30 years in the general population. Acta Psychiatr Scand 1999;99:261± American Psychiatric Association. Diagnostic and statistical manual of mental disorders, 4th edn. Washington, DC: American Psychiatric Press, GARNER DM, OLMSTED MP, POLIVY J. The eating disorder inventory: a measure of cognitive behavioral dimensions of anorexia nervosa and bulimia. In: DARBY PL, GARFINKEL PE, GARNER DM, eds. Anorexia nervosa: recent developments in research. New York: Allan R. Liss, 1984:173± COOPER Z, COOPER PJ, FAIRBURN CG. The validity of the eating disorder examination and its subscales. Br J Psychiatry 1989;154:807±

9 Ghaderi and Scott 28. ROBSON P. Development of a new self-report questionnaire to measure self esteem. Psychol Med 1989;19:513± COOPER PJ, TAYLOR MJ, COOPER Z, FAIRBURN CG. The development and validation of the Body Shape Questionnaire. Int J Eat Dis 1987;6:485± PROCIDANO ME, HELLER K. Measures of perceived social support from friends and from family: three validation studies. Am J Commun Psychol 1983;11:1± SARASON BR, SHEARIN EN, PIERCE GR, SARASON IG. Interrelations of social support measures: theoretical and practical implications. J Pers Soc Psychol 1987;52:813± FOLKMAN S, LAZARUS RS. Ways of coping questionnaire, permission set, manual, test booklets, scoring key. Palo Alto, California: Consulting Psychologists Press, GHADERI A, SCOTT B. Coping in dieting and eating disorders: a population-based study. J Nerv Ment Dis 2000;188: 273± GLASS GV, HOPKINSKD. Statistical methods in education and psychology, 3rd edn. Boston, MA: Allyn and Bacon, STRIEGEL MOORE RH, SILBERSTEIN LR, FRENSCH P, RODIN J. A prospective study of disordered eating among college students. Int J Eat Dis 1989;8:499± FAIRBURN CG, BEGLIN SJ. Studies of the epidemiology of bulimia nervosa. Am J Psychiatry 1990;147:401±