Purpose/Hypothesis: The purpose of this study was to investigate infants and toddlers with Down Syndrome (DS) to determine: 1) interrater, intrarater, and live versus video reliability of the Segmental Assessment of Trunk Control (SATCo), 2) concurrent validity of the SATCo with the Gross Motor Function Measure (GMFM), and 3) whether a model of staggered entry with age and SATCo score predicts GMFM score.
Number of Subjects: 18 children with DS between 6 to 23 months (mean = 13.67, SD = 5.31) participated. Materials and Methods: The SATCo is a dichotomous scale to assess 7 discrete levels of trunk control in children with neuromotor disabilities. At each level, the child is tested on static, active, and reactive trunk control for a possible total score of 20. The GMFM was developed to measure gross motor function in children with cerebral palsy and can be used for children with DS under 6 years old. The examiner scores a child’s capabilities across 5 dimensions of functional movement, each consisting of several items (88 total) with a total possible score of 264. Experienced pediatric PTs were recruited as raters. Each child was tested (and videorecorded) on the SATCo by 2 PT raters at least 30 minutes apart. One PT rater also administered GMFM to all participants. After 2 weeks, the PT raters re-scored their video- recorded SATCo testing sessions. A third PT rater, who did not perform live testing sessions, also scored the SATCo videos.
Results: Interrater reliability of the SATCo was moderate to good among all 3 raters (ICC (2,1) = 0.50 to 0.85, p ≤ 0.013). The SATCo had good to excellent intrarater reliability (ICC (2,1) = 0.77 to 0.94, p < 0.001). The interrater reliability between Rater 1 and Rater 2 reflected the lowest overall scores (ICC (2,1) ≤ 0.686, p ≤ 0.008). Highest scores were found in the intrarater reliability of Rater 1 (ICC (2,1) ≥ 0.806, p < 0.001). Spearman’s rho correlations revealed good to excellent significant relationships (r > 0.75, p < 0.001) for every category of the SATCo, SATCo total score, and SATCo level with GMFM Dimension B score (sitting ability) and GMFM total score. Regression showed that age accounted for 63% of the variation in GMFM total score and SATCo total score accounted for an additional 17%. There was a significant regression equation (F[2,15] = 30.45, p < 0.001) as follows: GMFM = -53.22 + (6.40 x SATCo total score) + (3.61 x Age). Block entry of the single predictors of age (R = 0.82, R = 0.67, F[1,16] = 31.89, p < 0.001) and SATCo total score (R = 0.86, R = 0.74, F[1,16] = 46.599, p < 0.001) had a significant predictive effect on dimension B (sitting) of the GMFM.
Conclusions: Three PT raters who had no prior experience with the SATCo were able to administer and score this outcome measure in infants and toddlers with DS. Trunk control appears to play a central role in the gross motor function of infants and toddlers with DS. The SATCo was found to have good psychometric properties in infants and toddlers with DS.
Clinical Relevance: This study contributes to the literature on the psychometric properties of the SATCo and supports its use to measure trunk control in infants and toddlers with DS.
Flores M, Mitchell K, Da Silva C, Bickley C. Psychometric Properties of Segmental Assessment of Trunk Control in Infants and Toddlers with Down Syndrome. 2020.