Background: This systematic review synthesizes the literature on incidence of obesity during childhood.
Methods: We searched PubMed, Excerpta Medica database (EMBASE), and Cumulative Index to Nursing and Allied Health Literature (CINAHL), and used the Web of Science tool in June 2015. Studies were included if they were published in English, presented results from primary or secondary analyses, used data about children in the US, provided obesity incidence data on children 0 to 18 years born after 1970, and did not pertain to clinically defined populations (disease, medication use, etc.). Author(s), study year, study design, location, sample size, age, and obesity incidence estimates were abstracted.
Results: Nineteen studies were included, three of which used nationally representative data. The median study-specific annual obesity incidences among studies using U.S. Centers for Disease Control and Prevention (CDC) growth charts were 4.0%, 3.2%, and 1.8% for preschool (2.0-4.9 years), school aged (5.0-12.9 years), and adolescence (13.0-18.0 years), respectively. This pattern of declining obesity incidence with age was consistent between and within studies.
Conclusions: Studies of childhood obesity in the US indicate declining incidence with age. Childhood obesity prevention efforts should be targeted to ages before obesity onset. Longitudinal data and consistent obesity definitions that correlate with long-term morbidity are needed to better characterize the life history of obesity.