CO1.7: Overweight at age 15 by gender

Transcription

1 Definitions and methodology CO1.7: Overweight at age 15 by gender The Body Mass Index (BMI) is the most commonly used indicator for assessing excess weight among adolescents (aged 15+) and adults. This index is calculated as the weight in kilograms divided by height in meters squared (kg/m2). The World Health Organisation (WHO) defines individuals with a BMI equal to or greater than 25 as overweight. The data presented here is based on self-reporting data captured in the Health Behaviour in School Children (HBSC) survey. Such data can differ markedly from measured data. Overweight among youngsters might be associated with childhood diabetes and asthma (CO1.6) and psychological problems (low self-esteem). In the long term, it can be associated with cardiovascular diseases, hypertension, diabetes, high cholesterol and some forms of cancer (Currie et al, 2008). The HBSC survey collects information on many socio-economic factors that affect health behaviour among children. This indicator presents information on the prevalence of overweight children by family structure and family affluence. Family structure is defined by whether the child lives with both or just one parent, while family affluence is defined by the Family Affluence Scale (FAS) calculated based on responses to the survey. The FAS scale is based on a composite measure calculated for each surveyed student based on their response to questions about household possessions. A three point ordinal scale is used, where FAS low (score=0,1,2) indicates low affluence, FAS medium (score=3,4,5) indicates middle affluence, and FAS high (score=6,7,8,9) indicates high affluence. For more information please see Currie et al. (2012). Key findings In 2009/10, around 17% of 15 year-olds in OECD countries were considered to be overweight (Chart CO1.7.A). This proportion ranged from 10% in the Netherlands to around 34% in the United States. At 20% or above, overweight rates were also relatively high in Canada, Greece, Portugal and Slovenia. Countries with high overweight rates at age 15 also have high overweight rates among adults (OECD Health Data 2012). These results are based on self-reported data; BMI based on self-reported data tend to be smaller than BMI based on actual measurements (Elgar et al, 2005). Chart CO1.7.A: Overweight rates at age 15, 2009/2010 BMI equal or greater than 25; based on self-assessment by respondent. 1

2 Other relevant indicators: CO1/3: Low birth weight; CO1.5: Breastfeeding rates; CO1.6: Disease-based indicators: prevalence of diabetes and asthma among children; CO1.8: Risky behaviours among 15 year-olds by gender. Chart CO1.7.B presents the proportion of overweight 15 year-olds by gender. The data shows that boys are more likely to be overweight than girls in all countries for which data are available. Countries with the widest gender gaps (more than 12 percentage points) include the Czech Republic, Greece, Hungary, Italy and the Slovak Republic. Chart CO1.7.B: Overweight by gender at age 15, 2009/2010 BMI equal or greater than 25; based on self-assessment by respondent Countries are ranked in descending order of total prevalence rate. In all OECD countries for which data are available for 2001 and 2010, self-reported obesity rates for boys and girls aged 15 have increased during this period (see Chart CO1.7.C). Among boys, the average overweight rate increased from 13% in 2001 to 22% in 2010, while among girls, the average overweight rate increased from 8% to 13% over the same period. The largest increases were recorded in Austria, the Czech Republic, Poland and the United States among boys (greater than 12 percentage points), while it was largest in Portugal and the United States among girls (greater the 8 percentage points). 2

3 Chart CO1.7.C: Trends in overweight rates among 15 year-olds by gender, 2001 to 2010 Self-reported data Boys overweight rates in 2001/02 and 2009/10 Girls overweight rates in 2001/02 and 2009/ / /02 United States Greece Canada Portugal Italy Czech Republic Spain Austria Hungary Poland Norway Finland Germany United Kingdom Ireland Sweden Switzerland Belgium France Netherlands Denmark 2009/ /02 Source: Health Behaviour in School-aged Children 2001/2002 and 2009/2010 Prevalence of overweight children by socio-economic characteristics Chart CO1.7.D presents the prevalence of children aged 15 years who are overweight, by family structure based on whether the child lives with both parents or just one parent. The data show that in most countries, for which data are available, children living with two parents are less likely to be overweight than children living with just one parent; only in the OECD countries of Hungary, Poland and Sweden is the reverse true. The difference is particularly big, at more than 5 percentage points, in Germany, Greece and the United States. Chart CO1.7.D Overweight rates at age 15, by household structure, 2009/10 Percentage of children living with 1 1. Data is not available for children who do not live with either parent, often under foster care. 3

4 Chart CO1.8.D presents the prevalence of overweight children at age 15 years based on level of affluence using the HSBC FAS scale. The data show that children from low affluence families are more likely to be overweight than children from high affluence families in most OECD countries; in Poland and Turkey children from high affluence families are more likely to be overweight. The difference in the prevalence of smoking between high and low affluence children is particularly big, at over 10 percentage points, in Luxembourg, Norway and the United States. Chart CO1.7.E Overweight rates at age 15, by family affluence, 2009/10 Comparability and data issues Self-reported data on overweight have been taken from The Health Behaviour in School-aged Children survey (HBSC) 2005/06, a study which takes place every four years. Children are asked to provide their height (without shoes) and weight (without clothes). The last data collection covered 41 countries, including most OECD countries (except Australia, Japan, Korea, Mexico and New Zealand), and also includes information for the following new member countries of the EU (Bulgaria, Estonia, Latvia, Lithuania, Malta and Slovenia). The HBSC study collected data among children aged 11, 13 and 15. However, we present data for children aged 15 only, because of the reported high levels of missing data for 11 and 13 year olds. For 15 year-olds, Ireland was the only country with missing data for 30% of the sample, and results for this country should be interpreted with caution. The BMI values presented here were calculated using the International Obesity Task Force guidelines (Cole et al, 2000). HBSC data for Belgium and the United Kingdom were collected separately for the different communities/countries (Flemish- and French-speaking communities in Belgium and England, Wales and Scotland for the UK). This indicator presents one value per country on basis of a weighted population average. The International Obesity Task Force ( has compiled information from different country surveys which collect actual measurements of children s weight using professional anthropometric 4

5 equipment (see the notes in the xls file with Charts CO1.7.D and Chart CO1.7.E for this indicator on Such information was also taken from the National Health and Nutrition Survey 2006 (ENSANUT for its acronym in Spanish) for Mexico and the New Zealand Health Survey 2006/2007. Self-reported data was collected around the same year in all countries 2005/06. However, the year of reference for children s weight as measured varies across countries: 2007 for Australia and New Zealand; 2006 for France and Mexico; 2005 for the Czech Republic; 2004 for England and Scotland; 2003 for Greece and the Netherlands; 2002/03 for Germany; 2001 for Ireland and Turkey; and for Italy. The prevalence of overweight children by socio-economic groups are descriptive and are not regressed with control factors, thus the differences may not be directly and exclusively related to characteristics of the socio-economic groups defined here, but could also be due to other related factors. While the HBSC survey includes information on many factors, only the major socio-economic factors are presented where the difference in the prevalence of smoking is statistically significant across most countries. Sources and further reading: Cole T.J. E t al (2000) Establishing a standard definition for child overweight and obesity worldwide: international survey. British Medical Journal, 320: ; Currie C. et al (2008) Inequalities in Young People s Health: HBSC International Report. WHO Policy Series: Health policy for children and adolescents Issue 5, WHO Regional Office for Europe, Copenhagen; Elgar et al (2005) Validity of self-reported height and weight and predictors of bias in adolescents. Journal of Adolescent Health, 37(5):371:375; Sassi, F., M. Devaux, M. Cecchini and E. Rusticelli (2009) The Obesity Epidemic: Analysis of Past and Projected Future Trends in Selected OECD countries, OECD Health Working Papers, No. 45 ( OECD (2009), Society at a Glance, OECD; and Obesity and the Economics of Prevention, Fit not Fat,