Body Composition Changes and Catch-up Growth in Pre-pubertal Children with Short Stature: A Longitudinal Retrospective Cross-sectional Cohort Study

Objective: Predicting whether children with pre-pubertal short stature will achieve catch-up growth to a normal height or remain short remains a clinical challenge. As body composition plays a vital role in growth, we aimed to compare longitudinal body composition changes in children with short stature who either achieved normal height by the onset of the growth spurt or remained short. Methods: This longitudinal, retrospective, cross-sectional, cohort study analyzed anthropometric and body composition data of children aged 8 and 12 years, allowing for both longitudinal tracking and cross-sectional comparisons. Participants were categorized into three groups: short-to-short statured (short stature at 8 and 12 years, n=177), short-to-normal statured (short stature at age 8 and normal stature at 12, n=90), and control (normal stature at both ages, n=7,195). Height, weight, body fat mass (BFM), skeletal muscle mass (SMM), body mass index (BMI), BFM index (BFMI), and SMM index (SMMI) were assessed. Growth variations were examined using a difference-in-difference estimator. Results: Cross-sectional analysis showed the short-to-short group had significantly lower weight, BFM, SMM, BMI, BFMI, and SMMI compared to controls at both ages. Longitudinally, the short-to-normal group exhibited significantly greater increases in height [0.87 and 0.95 standard deviation scores (SDS) for boys and girls, respectively], weight (0.59 and 0.68 SDS), and SMMI (0.75 and 0.50 SDS) compared to the short-to-short group. However, BFMI increases were not significant. Conclusion: Children with pre-pubertal short stature who achieved a normal height showed the most significant increase in SMMI. Children with lower increases in SMMI may require further assessment for continued short stature.