Psychometric Validation of the SNAP-IV Rating Scale in Amblyopic Children at High AD/HD Risk: Structural Validity and Measurement Invariance

Lu Pan¹Meng Ru²Yuxing Huang³Wuqiang LUO³Lili Li³Yan Luo³Enwei Lin³Min Kong³Qi Chen³Yali Luo⁴Hairun Liu³Siyan Huang³Jin Zeng⁵Fei Han²Xin Xiao^3*

• ¹Guilin Medical University, Guilin, China
• ²Guangxi Medical University, Nanning, China
• ³People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, China
• ⁴GuangXi University of Chinese Medicine, Nanning, China
• ⁵Guangdong Provincial People's Hospital, Guangzhou, China

Objective: To validate the psychometric properties of the Swanson, Nolan, and Pelham Rating Scale (SNAP-IV) in amblyopic children at high AD/HD risk and establish its clinical utility for comorbid AD/HD screening. Methods: This cross-sectional study utilized baseline data from the China Amblyopia Behavioral Cohort (CABC), which comprises 465 amblyopic children (aged 4–17 years). The reliability of the SNAP-IV was comprehensively assessed using Cronbach's alpha and the split-half coefficient. The validity of the SNAP-IV was evaluated using criterion validity with the Conners' parent rating scale (CPRS) and construct validity via confirmatory factor analysis (CFA). The measurement invariance of the SNAP-IV across gender and age groups was also investigated. Results: The SNAP-IV demonstrated exceptional internal consistency (Cronbach's α = 0.965 [95% CI: 0.958–0.972], split-half coefficient = 0.891) and strong criterion validity with the CPRS domains, particularly with respect to the oppositional factor of the SNAP-IV scale, which showed the highest correlation with the conduct problem factor of the Conners' Parent Rating Scale (CPRS) (rₛ = 0.837, 95% CI: 0.807–0.863, p < 0.001, large effect). The findings indicated a substantial correlation between inattention and learning problems (rₛ = 0.808, 95% CI: 0.767–0.834, p < 0.001, large effect) and conduct problems (rₛ = 0.719, 95% CI: 0.675–0.765, p < 0.001, large effect). Confirmatory factor analysis confirmed a three-factor structure (inattention, hyperactivity-impulsivity, oppositional) with robust fit indices (χ²/(291) = 1033.4, χ²/df = 3.551, RMSEA = 0.074, CFI = 0.92, IFI = 0.92), with full measurement invariance confirmed across gender and age groups. Conclusions: This study constitutes the first systematic validation of the SNAP-IV in amblyopic children, thereby establishing its robustness for AD/HD screening in visually impaired populations. The scale's standardized application has the potential to enhance the screening of early AD/HD-amblyopia comorbidity and the development of multidisciplinary intervention strategies for integrating visual and behavioral rehabilitation.