OBJECTIVES: To evaluate body mass index trajectories over time and to evaluate common comorbidities across a large, nationally representative sample of youth with Down syndrome (DS). STUDY DESIGN: This retrospective study included children ages 2-18 years within the Cerner Health Facts database with a diagnosis of DS and a medical visit between 2010 and 2017. Comorbid conditions were mapped into PheCodes (ie, ≥1 International Classification of Diseases codes that combine into specific diseases or traits) and were included if they occurred in ≥1% (145 PheCodes) of the sample. RESULTS: Outcomes trajectories were analyzed through generalized additive mixed models. Estimated modified body mass index z-scores showed a general trend of nonlinear increasing weight by age, specifically an increase from age 2 through 5 years, then stabilization until age 10, thereafter increasing again. When comorbidities were included, some were associated with lower rates of weight gain, whereas others were associated with higher rates of weight gain. CONCLUSIONS: This study showed rapid weight gain in early years and early adolescence for youth with DS. This pattern of weight gain is consistent with same-age peers
however, youth with DS have difficulty recovering after these periods owing to several factors, such as not having the same height gain. Given these patterns, intervention and prevention should target periods of time when recovery is difficult.