Supplementary Material for: Prevalence of childhood obesity in the United States 1999-2018: a 20-year analysis

Background
Obesity is a public health crisis in the US. This study aims to estimate the prevalence of obesity and severe obesity in US children and adolescents and identify novel targetable risk factors associated with childhood obesity.

Methods
From the US National Health and Nutrition Examination Survey from 1999-2018, 35,907 children aged 2-19 with body mass index (BMI) data were included. Obesity and severe obesity were defined as BMI ≥95th percentile and ≥120% of 95th percentile of US Centers for Disease Control and Prevention growth charts, respectively. Trends in prevalence of obesity and subgroup analyses according to socio-economic factors and language used in interview, were analyzed.

Results
The prevalence of obesity and severe obesity increased from 14.7 [95%CI: 12.9-17.0]% to 19.2 [17.2-21.0]% and 3.9 [2.9-5.0]% to 6.1 [4.8-8.0]% in 1999-2018, respectively (p=0.001 and p=0.014, respectively). In 2017-8, the prevalence of obesity among children from Spanish-speaking households was 24.4 [22.4-27.0]%, higher than children from English-speaking households (p=0.027).

Conclusions
The prevalence of childhood obesity kept increasing in 1999-2018. The problem is worse in children from Spanish-speaking households. Novel and targeted public health intervention strategies are urgently warranted to effectively halt the rising epidemic of childhood obesity.