Psychometric evaluation of the English version of the Düsseldorf Orthorexie Scale (DOS) and the prevalence of orthorexia nervosa among a U.S. student sample

Purpose Recently, the concept of orthorexia nervosa (ON) as a potential new variant of disordered eating behavior has gained popularity. However, published prevalence rates appear to be questionable given the lack of validity of the available questionnaires. The Düsseldorf Orthorexie Scale (DOS) is a validated questionnaire only available in German to measure orthorexic behavior. Methods The DOS was translated into English using the back-translation process. Cronbach’s alpha was used to establish internal consistency and an intra-class correlation coefficient was calculated to assess reliability. The Eating Habits Questionnaire (EHQ) was used to test construct validity and the Eating Disorders Inventory was used to test discriminant validity. Principal and confirmatory factor analyses were carried out to test the factor structure. The sample consists of 384 university students in the U.S. Results English (E)-DOS and EHQ were highly correlated ( r = 0.76, p