Cross-cultural adaptation and psychometric validation of the Spanish version of the Orthorexia Nervosa Inventory...

Orthorexia nervosa (ON) has gained increasing attention as a maladaptive pattern of rigid health-oriented eating characterized by cognitive preoccupation, behavioral restriction, and functional impairment. The Orthorexia Nervosa Inventory (ONI) was developed as a multidimensional instrument to assess orthorexic tendencies; however, further cross-cultural validations are needed to ensure its applicability across different linguistic and cultural contexts.

To translate, culturally adapt, and evaluate the psychometric properties of the Spanish version of the Orthorexia Nervosa Inventory (ONI-ES) in a general adult population in Spain.

A two-phase validation study was conducted. Phase 1 involved forward-backward translation and expert panel evaluation to assess content validity using Aiken's V coefficient. Phase 2 examined construct validity and reliability in two independent samples (EFA: n = 272; CFA: n = 257; total N = 529). Exploratory factor analysis (EFA) was performed using Principal Axis Factoring with oblimin rotation, followed by confirmatory factor analysis (CFA) using maximum likelihood estimation. Internal consistency was assessed using Cronbach's alpha and McDonald's ω, and temporal stability was evaluated through test-retest reliability using the intraclass correlation coefficient (ICC).

All items demonstrated adequate content validity (Aiken's V range: 0.71-0.96). EFA supported a three-factor structure-orthorexic behaviors, emotional attitudes toward food, and social/functional impairment-accounting for 41.9% of the total variance. CFA confirmed the adequacy of the three-factor model (CFI = 0.905; TLI = 0.891; RMSEA = 0.066). The ONI-ES showed excellent internal consistency (α = 0.91) and good to excellent temporal stability (ICC = 0.824-0.903). Convergent validity was supported by a positive correlation with EAT-26 scores (r = 0.586, p < 0.001).

The ONI-ES demonstrates solid psychometric properties and replicates the original three-factor structure in a Spanish general population. These findings support its reliability, structural validity, and cross-cultural applicability as a multidimensional measure of orthorexic symptomatology.