When Eating Right, Is Measured Wrong! A Validation and Critical Examination of the ORTO-15 Questionnaire in German

RESEARCH ARTICLE When Eating Right, Is Measured Wrong! A Validation and Critical Examination of the ORTO-15 Questionnaire in German Benjamin Missbach1*, Barbara Hinterbuchinger2, Verena Dreiseitl1, Silvia Zellhofer1, Carina Kurz1, Jürgen König1 1 Department of Nutritional Sciences, University of Vienna, Vienna, Austria, 2 Department of Psychiatry and Psychotherapy, Division of Social Psychiatry, Medical University of Vienna, Vienna, Austria * Abstract OPEN ACCESS Citation: Missbach B, Hinterbuchinger B, Dreiseitl V, Zellhofer S, Kurz C, König J (2015) When Eating Right, Is Measured Wrong! A Validation and Critical Examination of the ORTO-15 Questionnaire in German. PLoS ONE 10(8): e0135772. doi:10.1371/ journal.pone.0135772 Editor: Emmanuel Manalo, Kyoto University, JAPAN Received: May 8, 2015 Accepted: July 24, 2015 Published: August 17, 2015 Copyright: © 2015 Missbach et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The characteristic trait of individuals developing a pathological obsession and preoccupation with healthy foods and a restrictive and avoidant eating behavior is described as orthorexia nervosa (ON). For ON, neither universal diagnosis criteria nor valid tools for largescale epidemiologic assessment are available in the literature. The aim of the current study is to analyze the psychometric properties of a translated German version of the ORTO-15 questionnaire. The German version of the ORTO-15, a eating behavior and dieting habits questionnaire were completed by 1029 German-speaking participants (74.6% female) aged between 19 and 70 years (M = 31.21 ± 10.43 years). Our results showed that after confirmatory factor analysis, the best fitting model of the original version is a single-factor structure (9-item shortened version: ORTO-9-GE). The final model showed only moderate internal consistency (Cronbach’s alpha = .67), even after omitting 40% of the original question. A total of 69.1% participants showed orthorectic tendencies. Orthorectic tendencies are associated with special eating behavior features (dieting frequency, vegetarian and vegan diet). Education level did not influence ON tendency and nutritional students did not show higher ON tendency compared to students from other disciplines. This study is the first attempt to translate and to evaluate the psychometric properties of a German version of the ORTO-15 questionnaire. The ORTO-9-GE questionnaire, however, is only a mediocre tool for assessing orthorectic tendencies in individuals and shows moderate reliability and internal consistency. Our research suggests, that future studies are needed to provide more reliable and valid assessment tools to investigate orthorexia nervosa. Data Availability Statement: Data are available at Figshare: http://dx.doi.org/10.6084/m9.figshare. 1451279. Funding: This article was supported by the Open Access Publishing Fund of the University of Vienna. Competing Interests: The authors have declared that no competing interests exist. Introduction There is a thin line between eating right and healthy and a pathological preoccupation with healthy foods. This appears paradox at first, because public health nutrition policies’ primary strategy is to promote healthy dietary choices and eating right to decrease diet-related PLOS ONE | DOI:10.1371/journal.pone.0135772 August 17, 2015 1 / 15 Orthorexia Nervosa Validation in German pathologies like overweight and obesity [1]. In contrast, there are mounting reports from eating disorder professionals who find themselves confronted with individuals who are pathologically preoccupied with healthy eating: a condition called orthorexia nervosa (ON) [2]. ON was first framed by Bratman and Knight [3] in the late 90’s, describing eating behavior associated with behavioral and psychiatric traits. Individuals with ON are typically concerned about food quality rather than food quantity. Nevertheless, there is still a lack of valid instruments for ON [4]. The aim of this study is to provide a validated measurement tool for ON in German language, based on the original (English) ORTO-15 questionnaire [5] and further contribute to our understanding of mediators for orthorectic eating and the identification of groups at risk to develop ON. Orthorexia Nervosa Symptoms and Diagnostics ON is an eating-related condition with obsessive eating directed at healthy foods. The healthfulness of foods can vary depending on individual’s preferences. ON can, in extreme cases, lead to a pathological preoccupation with pure and unprocessed foods and stringent eating plans, combined with significant psychopathological overlappings with anorexia nervosa (AN) and obsessive-compulsive disorders (OCD) [6]. Transgressing self-imposed dietary rules often lead to intense feelings of anxiety, guilt and shame followed by more stringent dietary restriction leading to a vicious cycle [7]. Different from common eating-related disorders, individuals with ON do not fear to gain weight and have clear, rationalized rules related to food intake [4]. Additionally, eating according to a fixed schedule and spending a lot of time to prepare meals [8–10], and unrealistic food beliefs are very prominent among individuals with ON [10]. Social isolation as a consequence of a constant daily domination of healthy eating and reduced stress by eating good and proper foods accompanied by spiritual feelings about foods have been reported [8]. At present, ON is not classified as a formal eating disorder neither by DSM-5 [11], nor by ICD-10 criteria [12]. Grading of ON is still a matter of debate and under current DSM-5 criteria, individuals with ON characteristics may best be classified in the broad category of Avoidant/Restrictive Food Intake Disorder (ARFID) [11]. Several medical consequences are described, which are very similar to other known eating disorders. For instance a shortage of essential nutrients, malnutrition, starvation and weight loss have been reported [13, 14]. Assessment, Epidemiology and Moderators for Orthorexia Nervosa To monitor the prevalence of ON and to investigate various subtypes of the condition, thorough assessment tools are needed. Previous investigations report several inconsistencies about the validity and internal reliability of commonly used questionnaires [15]. To date, two instruments were developed to identify individuals with ON: the 10-Item Bratman Scale [3] and the ORTO-15 questionnaire [5]. While the 10-Item Bratman Scale was widely disregarded by the scientific community, several language and item adaptations of the ORTO-15 questionnaires were developed (Polish, Hungarian, Turkish). The only adapted version showing good internal reliability is the Hungarian adaptation (11 items), Cronbach’s alpha = .82. The Polish version (9 items) and th (...truncated)