An Explorative Retrospective Video Analysis of Movement Quality in Infants Later Diagnosed with Developmental Coordination Disorder.

Developmental Coordination Disorder (DCD) is a neurodevelopmental condition affecting coordinated motor skill acquisition usually diagnosed after 5y. However, parents and clinicians report poorer movement quality at earlier ages. Using the 'Observable Movement Quality' scale (OMQ), we compared movement quality between children with typical development (TD), with DCD, and with DCD and Autism Spectrum Disorder (ASD). Using blinded retrospective video analysis, a trained physical therapist observed 5-min compilations of home videos at 6-12 m (n = 53), 12-18 m (n = 54), and 18-24 m (n = 47) followed by OMQ-scoring and a three-point scale for clinical judgement (will/might/will not develop DCD). A 15% sample was re-evaluated to assess intra-rater reliability using Spearman coefficients. OMQ group performance was assessed using Kruskal-Wallis tests, while dichotomized (good/poor quality) data were examined with Fisher exact tests. OMQ scores' association with later motor performance (MABC-2 and DCDQ) was analysed via Spearman coefficients. Cramer's V determined the strength of association between clinical judgment and diagnostic outcome. Intra-rater reliability for total OMQ score was strong (r = 0.79, p ≤ 0.001). Reduced movement quality was found at 18-24 m in children with DCD (median 69, interquartile range [IQR] 10) and DCD+ASD (median 69, IQR 14) compared to TD children (median 74, IQR 2) (p ≤ 0.001). Five times more compilations in the DCD groups demonstrated poor overall movement quality at 18-24 m. At 18-24 m, movement quality correlated strongly with MABC-2 (r = 0.66) and DCDQ (r = 0.67). The therapist correctly identified 63-67% of DCD and DCD+ASD children respectively (Cramer's V = 0.62, p ≤ 0.001). These findings underscore the importance of investigating movement quality as a potential early feature of DCD.