Any overlap between orthorexia nervosa and obsessive–compulsive disorder in Lebanese adults? Results of a cross-sectional study and validation of the 12-item and 4-item obsessive–compulsive inventory (OCI-12 and OCI-4)

Background: Orthorexia Nervosa (ON), a compulsive obsession with vigorous eating, has increasingly caught researchers' attention. Although Orthorexia Nervosa has not been labeled an eating disorder, research about ON highlighted a strong link with anorexia nervosa or obsessive–compulsive disorder (OCD). Therefore, this study aimed to (1) validate the Arabic version of the Obsession-Compulsion Inventory (OCI-12 and OCI-4) and (2) check if there is an overlap between ON and OCD among a sample of Lebanese adults. Methods: This cross-sectional study involved 487 Lebanese participants between July and August 2021. The Dusseldorf Orthorexia Scale (DOS) was used to assess ON; scores between 25 and 29 indicate probable ON, whereas scores ≥ 30 indicate ON tendencies. A confirmatory factor analysis (CFA) was carried out using SPSS AMOS v.24 on the OCI-12 and OCI-4 scales’ items. The root mean square error of approximation (RMSEA) statistic, the Tucker Lewis Index (TLI) and the comparative fit index (CFI) were used to evaluate the goodness-of-fit of the model. Results: The CFA results indicated an excellent fit of the model: the Maximum Likelihood Chi-Square = 147.73 and Degrees of Freedom = 48, which gave a χ2/df = 3.08, TLI = 0.934, CFI = 0.952, and RMSEA = 0.065 [95% CI 0.054–0.078]. The fit indices of the one-factor structure of the OCI-4 were excellent as well: χ2/df = 6.15/2 = 3.08, TLI = 0.95, CFI = 0.98 and RMSEA = 0.065 [95% CI 0.007–0.127]. The Area Under the Curve was 0.600 [95% CI 0.524–0.674]. There was no cutoff value that showed good sensitivity or specificity at the same time. At the DOS cutoff of 25, sensitivity was 19.1%, whereas the specificity was 90.6%. The positive and negative predictive values (PPV and NPV) at this cutoff value were 24.4% and 88.7% respectively. At the DOS cutoff of 30, sensitivity was 8.8%, whereas the specificity was 94.3%. The PPV and NPV at this cutoff value were 10.6% and 92.5% respectively. The results showed that higher total OCD scores (Beta = 0.15) were significantly associated with more ON tendencies. Moreover, higher OCD washing scores (Beta = 0.52), physical activity index (Beta = 0.06), and Body Mass Index (Beta = 0.17) were significantly associated with more ON tendencies. Conclusion: The present results suggest that ON, as measured by the DOS, shares more common features with disordered eating and cannot adequately predict the presence of OCD symptoms.