Psychometric Properties of the Persian Version of the Orthorexia Nervosa Scale (ORTO-15)

The aim of this study was to prepare the Persian version of the orthorexia nervosa Scale and evaluate its psychometric properties.

The sample of the present study consisted of 639 people aged 18 to 65 years living in Tehran who were tested using the available sampling method. The Persian version of the orthorexia nervosa Scale was prepared after the translation-retranslation process and was administered along with the eating attitude test (EAT-26) and Reef psychological well-being questionnaire (REEF-18). The validity of the scale was assessed using construct,  convergent and divergent validity was evaluated through Pearson correlation. Moreover, to assess its reliability, Cronbach's alpha calculation method and composite reliability were used.

The results of exploratory factor analysis indicated the existence of three factors: cognitive, emotional and clinical, and the results of confirmatory factor analysis indicated the goodness of fit and eligibility of the obtained model. Significant correlations between the obtained factors with the eating attitude test and Reef psychological well-being questionnaire also confirmed the convergent and divergent validity of the orthorexia nervosa scale. The reliability of the scale was calculated using Cronbach's alpha coefficient and obtained 0.811 for the all scales and ranged 0.69 to 0.735 for specific scales. Moreover, the composite reliability of the scales ranged between 0.78 and 0.82.

In general, it can be said that the Persian version of the orthorexia nervosa Scale has a three-factor structure and has the adequate validity and reliability for use in psychological research in the Iranian sample.