Development and Pilot Validation of the Romanian Antioxidant Cosmetics and Nutrition Questionnaire (RO-ACNQ): A Simulation-Based Multicenter Benchmark with an Observed Pilot Sample

Oxidative stress contributes substantially to skin aging, while antioxidant-based cosmetics and nutrition-oriented “skin-from-within” strategies are increasingly popular among young adults. However, no validated Romanian instrument integrates antioxidant-related knowledge, attitudes, nutrition/lifestyle behaviors, and cosmetic-use intentions. This study developed the 61-item Romanian Antioxidant Cosmetics and Nutrition Questionnaire (RO-ACNQ), including a 36-item psychometric core covering four hypothesized domains: Knowledge, Attitudes, Behavioral Intention, and Nutrition/Lifestyle. Initial psychometric evaluation used a unified dataset (N = 1013) comprising a reproducible synthetic multicenter benchmark (n = 957) and an observed pilot sample (n = 56). Exploratory factor analysis (KMO = 0.943) identified eight weak or structurally inconsistent items, yielding a refined 28-item, four-factor model with acceptable-to-good internal consistency (α = 0.70–0.89) and good fit in an internal, same-sample CFA evaluation (χ2/df = 1.43, CFI = 0.984, TLI = 0.982, RMSEA = 0.021, SRMR = 0.033). Discriminant validity was generally supported (HTMT ≤ 0.74), although convergent validity remained partial. Within the simulation-based benchmark, theoretically expected known-groups patterns, high synthetic test–retest stability (ICC ≥ 0.97), and a Knowledge → Attitudes → Intention pathway were reproduced. Importantly, the refined domains showed encouraging internal consistency in the observed participants (α = 0.78–0.89; total α = 0.91), while differences between observed and synthetic response distributions identified areas requiring further calibration. These findings support the RO-ACNQ as a promising candidate instrument and establish a refined 28-item structure for prospective multicenter validation in participant-derived data.