School sociodemographic characteristics and obesity in schoolchildren: does the obesity definition matter?

Silvia Bel-Serrat,Mirjam M Heinen,John Mehegan,Sarah O’Brien,Nazih Eldin,Cecily C Kelleher,Celine M Murrin

doi:10.1186/s12889-018-5246-7

Abstract

BackgroundExisting evidence on the role of sociodemographic variables as risk factors for overweight and obesity in school-aged children is inconsistent. Furthermore, findings seem to be influenced by the obesity definition applied. Therefore, this study aimed to investigate if school sociodemographic indicators were associated with weight status in Irish primary schoolchildren and whether this association was sensitive to different obesity classification systems.MethodsA nationally representative cross-sectional sample of 7542 Irish children (53.9% girls), mean age 10.4 (±1.2SD) years, participating in the Childhood Obesity Surveillance Initiative in the 2010, 2012/2013 or 2015/2016 waves were included. Height, weight and waist circumference were objectively measured. Five definitions of obesity were employed using different approaches for either body mass index (BMI) or abdominal obesity. Associations between overweight and obesity and sociodemographic variables were investigated using adjusted multilevel logistic regression analyses.ResultsChildren attending disadvantaged schools were more likely to be overweight and obese than their peers attending non-disadvantaged schools, regardless of the obesity classification system used. Associations remained significant for the BMI-based obesity definitions when the sample was stratified by sex and age group, except for boys aged 8–10.5 years. Only boys aged ≥10.5 years in disadvantaged schools had higher odds of abdominal obesity (UK 1990 waist circumference growth charts: OR = 1.56, 95%CI = 1.09–2.24; waist-to-height ratio: OR = 1.78, 95%CI = 1.14–2.79) than those in non-disadvantaged schools. No associations were observed for school urbanisation level.ConclusionsSchool socioeconomic status was a strong determinant of overweight and obesity in Irish schoolchildren, and these associations were age- and sex-dependent. School location was not associated with overweight or obesity. There remains a need to intervene with school-aged children in disadvantaged schools, specifically among those approaching adolescence, to prevent a trajectory of obesity into adult life.

Highlights

Existing evidence on the role of sociodemographic variables as risk factors for overweight and obesity in school-aged children is inconsistent
The second wave of the Childhood Obesity Surveillance Initiative (COSI) conducted in 2009/2010 showed that the prevalence of overweight and obesity, assessed according to the International Obesity Task Force (IOTF) cut-offs [2, 3], in European children aged between 6 and 9 years ranged from 10.8% to 45.1%, with the lowest rates observed in countries such as Belgium, Latvia and Lithuania, and the highest in Mediterranean countries such as Greece, Italy, Portugal or Spain [4]
Focusing on body mass index (BMI) cut-off points, the prevalence of overweight and obesity was higher with the World Health Organisation (WHO) 2007 definition (35.5%–28.5%) as compared with either the IOTF (27.2%–18.4%) or the Centers for Disease Control and Prevention (CDC) 2000 (27.5%–20.3%) cut-offs, which yielded similar estimates

Summary

Introduction

Existing evidence on the role of sociodemographic variables as risk factors for overweight and obesity in school-aged children is inconsistent. In 2013, 23.2% of children and adolescents in developed countries aged between 2 and 19 years were overweight or obese [1]. The second wave of the Childhood Obesity Surveillance Initiative (COSI) conducted in 2009/2010 showed that the prevalence of overweight and obesity, assessed according to the International Obesity Task Force (IOTF) cut-offs [2, 3], in European children aged between 6 and 9 years ranged from 10.8% to 45.1%, with the lowest rates observed in countries such as Belgium, Latvia and Lithuania, and the highest in Mediterranean countries such as Greece, Italy, Portugal or Spain [4]. According to the latest COSI wave conducted in the Republic of Ireland in 2015/2016, one in five children aged 6–12 years were overweight or obese [5]. It is well known that overweight and obesity during childhood and adolescence track into adulthood and are associated with moderately increased risks of adult obesity-related morbidity, such as cardiovascular disease, cancer, and premature death [9]

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