Evaluation of a German version of a brief diagnosis questionnaire of symptoms of orthorexia nervosa in patients with mental disorders (Ortho-10)

Purpose In recent years, a new term—orthorexia nervosa (ON)—has been introduced in the field of clinical assessment and psychotherapy. Orthorexia nervosa is defined as a fixation on healthy food and a pathological obsession to eat food with more natural, higher quality ingredients. Although instruments to measure ON are available, no study on the psychometric properties of the original developed instrument by Bratman (Orthorexia nervosa: Overcoming the obsession with healthful eating, Broadway Books, New York, 2000) in a large clinical sample exists until now. Methods The study was conducted in a large clinic in Germany. The study sample consisted of N = 1122 inpatients, 70% were female, and the mean age was 41 years (SD = 14 years). The main diagnoses at the end of treatment were affective disorders (46%), followed by eating disorders (13%), anxiety disorders (10%), and personality disorders (10%). The patients filled out several instruments, like the Ortho-10, the 10-item version of the orthorexia nervosa instrument, and other construct-related, disorder-specific and construct-distant instruments. Results The exploratory factor analysis revealed a two-factor structure: an eating disorder-specific factor and an orthorexia-nervosa specific factor. The eating disorder factor showed good convergent and discriminative validity in which patients with eating disorders and those without could correctly be classified. However, the orthorexia-nervosa specific factor revealed no informational gain compared to the eating disorder-specific factor in this clinical sample. Conclusions Further investigation is necessary to approach the concept of ON and its sense in clinical samples. Level of evidence Level II: evidence obtained from well-designed controlled trials without randomization.