Association Between Toe Walking and Repetitive Behaviors in Children with Autism Spectrum Disorder: A Cross-Sectional Phenotypic Analysis.

Background and Objectives: Toe walking (TW) is frequently observed in children with Autism Spectrum Disorder (ASD), yet its clinical significance remains incompletely understood. While previous studies have linked TW to ASD severity and multisystem involvement, its relationship with the behavioral phenotype of repetitive behaviors has not been systematically explored. Materials and Methods: This study analyzed a cohort of 289 children with ASD who underwent comprehensive clinical assessment, including motor evaluation, sleep assessment using the Sleep Disturbance Scale for Children (SDSC), feeding behavior using the Brief Autism Mealtime Behavior Inventory (BAMBI), and detailed behavioral characterization through the Repetitive Behavior Scale-Revised (RBS-R) at the item level. Statistical analyses included non-parametric group comparisons, Spearman correlation analyses, and multivariable regression models. Results: TW was observed in 27.3% of participants. Children with TW showed significantly higher scores in stereotyped behaviors (7.71 ± 2.09 vs. 4.26 ± 2.06, r = 0.756, pFDR < 0.001), ritualistic/sameness behaviors (11.78 ± 3.21 vs. 7.05 ± 3.03, r = 0.709, pFDR < 0.001), and total RBS-R scores (25.52 ± 4.51 vs. 15.88 ± 4.64, r = 0.867, pFDR < 0.001). Correlation analyses revealed a strong association between TW and stereotyped behaviors (ρ = 0.588, p < 0.001) and a moderate association with ritualistic/sameness behaviors (ρ = 0.549, p < 0.001). RBS-R total scores were also correlated with sleep disturbances (ρ = 0.532, p < 0.001). In the multivariate linear model, TW was associated with an adjusted mean increase of 7.77 points in the RBS-R Total Score (B = 7.771, 95% CI 6.603-8.939, p < 0.001, β = 0.551). In the multivariate logistic model, the combined Ritualistic/Sameness behavior domain independently predicted the presence of TW (OR = 1.549, 95% CI 1.366-1.757, p < 0.001). Conclusions: In children with ASD, TW was associated with specific domains of repetitive behavior, particularly stereotyped and ritualistic/sameness patterns. These cross-sectional findings suggest a phenotypic association between motor and behavioral features, without establishing specificity, causality, or a shared underlying mechanism. This multidimensional perspective may support future studies investigating the clinical and biological correlates of TW in ASD.