Abstract
CONTEXT: Pediatric obesity affects endocrine conditions, which may alter growth. OBJECTIVE: This work aimed to investigate the effect of obesity severity and obesity treatment outcome on growth. METHODS: This prospective cohort study included children (aged 3-18 years) enrolled in the Swedish Childhood Obesity Treatment Register (BORIS) (1998-2020). Obesity was categorized as class I and class II obesity. Obesity treatment outcome was measured as body mass index (BMI) z score changes and categorized into good (BMI z score reduction of ≥0.25), intermediate, and poor (increasing BMI z score). Height for age z score, final height, and growth velocity were compared between class I and class II obesity. Further, the effect of obesity treatment outcome on growth velocity during 2-year follow-up was assessed. RESULTS: A total of 27 997 individuals (mean age 10.2 ± 3.6 years) were included. Individuals with class II obesity were on average taller than those with class I obesity during childhood. Among males, reduced growth spurt was observed in class I obesity, and even absent in class II obesity. Females exhibited a similar but less pronounced pattern. Good obesity treatment outcome yielded lower growth velocity at ages 3 to 9 years but higher growth velocity at ages 10 to 13 years compared to poor treatment outcome. CONCLUSION: Obesity severity is positively associated with height and growth velocity in childhood. A hampered growth spurt during puberty should be anticipated, particularly in adolescents with severe obesity. Therefore no difference in final height between class I and class II obesity is expected. Successful obesity treatment does not harm, but rather normalizes, the growth velocity pattern.