Validity of the Greek Eating Disorder Examination Questionnaire 6.0 (EDE-Q-6.0) among Greek adolescents.

The aim of this study is to examine the validity of the Greek version of the Eating Disorder Examination Questionnaire 6.0 (EDE-Q-6.0) in a sample of adolescent pupils. EDE-Q is a self- report instrument that assesses attitudes and behaviors related to Eating Disorders (EDs). A two-stage identification protocol has been applied to the 16 schools that agreed to participate in the present study. Initially, 2058 adolescents, in class under the supervision of one research assistant and one teacher, completed a Questionnaire on socio-demographic data, the Greek EDE-Q-6.0 and the Greek Eating Attitudes Test (EAT-26) while their weight and height were measured. Six-hundred and twenty six participants, who had scores on EAT-26≥20 and/or were underweight or overweight, were considered as "possible-cases" while the remaining 1432 pupils of the sample were thought as "non-possible cases". At the second stage, parents of 66 of the participants identified as possible-cases as well as parents of 72 participants from 358 controls randomly selected from the sample of "non-possible cases" agreed that their children would be examined by means of Best Estimate Diagnostic Procedure. Participants meeting DSM-IV-TR Eating Disorders criteria were identified. Receiver Operating Characteristics (ROC) analysis was applied to reveal EDE-Q's criterion validity. The kappa statistic test was used as measure of agreement between categorical variables at EDE-Q and at interview (the presence of objective binge eating episode, of self-induced vomiting, the use of laxatives and of excessive exercise). The Discriminant and Convergent validity were assessed using the non-parametric Mann-Whitney U test and by means of the Spearman's correlation coefficient, respectively. Nineteen cases of EDs were identified [one case of Anorexia Nervosa (AN), 13 cases of Eating Disorder Not Otherwise Specified (EDNOS), 5 cases of Binge Eating Disorder (BED)]. At the cut off point of 2.6125 on the EDE-Q's global scale the instrument screens with a sensitivity (Se) of 89.5% and a specificity (Sp) of 73.1%, a Positive Predictive Value (PPV) of 34.7% and a Negative Predictive Value (NPV) of 97.8% The same analyses for both sexes revealed a cut-off point of 2.612 for females and of 3.125 for males on the global EDE-Q-6.0 score (Se=84.62%, Sp=73.33% for females and Se=83.33%, Sp= 84.09% for males), yielding a PPV and a NPV of 35.5% and of 96.5% for females and 41.7% and 97.4% for males, respectively. A very low agreement level, between EDE-Q and interview, was observed regarding the presence of objective bulimic episodes (OBEs) [k=0.191 (SE=0.057)] and the unhealthy weight control behaviors [k=0.295 (SE=0.073)]. Positive correlations were found between EAT-26 and EDE-Q-6.0 for both global scale and subscales (rho=0.50-0.57). The results suggest that EDE-Q-6.0, when using its global score, appears to be a proper screening tool for assessing the core psychopathology of eating disorders in community samples in two-stage screening studies since it distinguishes very well the cases from the non-cases. However, the assessment of the presence and frequency of pathological behaviours which characterize EDs appears to be problematic since adolescents, especially the younger ones, misunderstood terms like large amount of food and loss of control or misinterpret the motivation for excessive exercise. Therefore, marked discrepancies were observed between pathological behaviors self-reported at questionnaire and those detected at interview. We may assume that giving participants more information regarding the definition of these concepts may increase the accuracy with which the participants report these behaviors.