Page last updated: 16-DEC-2008

Childhood Obesity

ONS kitemarkStatistical Publication Notice

16 December 2008

Childhood Obesity: Primary 1 statistics for school year 2007/08

INTRODUCTION

There is continued concern over the levels of obesity among children in Scotland. Obesity during childhood is a health concern in itself, but can also lead to physical and mental health problems in later life, such as heart disease, diabetes, osteoarthritis, back pain, increased risk of cancer, low self-esteem and depression. Obesity develops as a result of an imbalance between energy consumption and energy expenditure.
 
Measuring Obesity in Children
 
Body Mass Index (BMI) is one of the most widely used methods for assessing body composition or estimating levels of body fat.  BMI is calculated by dividing an individual's weight (in kilograms) by their height (in metres) squared and gives an indication of whether weight is in proportion to height.  In adults there are static cut off values for BMI between normal weight, overweight and obesity, however these are not appropriate for children.  The normal BMI range for children changes substantially with age and is different between boys and girls.  A certain BMI at one age may be the norm but at another age the same BMI may be unusually high or low.  Interpretation of BMI values in children therefore depends on comparison with age- and sex-specific growth reference charts.  These provide thresholds or cut-off points in the BMI distribution (BMI centiles), which can be used to estimate levels of obesity, overweight and underweight in children.  Statistics in this release were derived using the UK 1990 growth reference for BMI (the standard approach in the UK).
 
The BMI centile cut-offs used to derive the percentages classified as overweight, obese and severely obese are those recommended for the purposes of population monitoring and epidemiological research.  The statistics do not represent the percentage of children clinically classified as overweight, obese or severely obese.  Use of the cut-offs recommended for clinical practice would result in lower percentages for overweight, obese and severely obese and BMI centile would be only one of a variety of factors taken into consideration before any clinical diagnosis is made.
 
The release updates annual statistics on high and low body mass index (BMI) for Primary 1 school children, and includes data to school year 2007/08.  The statistics are derived from height and weight measurements recorded at routine health reviews for ten NHS Boards in Scotland which participate in the CHSP-School system.  Statistics are presented by: participating NHS Board, Council Area, Community Health Partnership, gender and Scottish Index of Multiple Deprivation (SIMD) quintile. 

KEY POINTS

Based on centile cut-offs on the 1990 UK growth reference charts used for population monitoring purposes:
  • In 2007/08, among the ten participating NHS Boards, 20.0% of Primary 1 children were classified as overweight, including 7.9% obese and 3.9% severely obese.
  • Levels of high BMI increased slightly, and very gradually, between 2000/01 and 2005/06. Over the last two years, levels of high BMI have decreased slightly and the percentages for 2007/08 are similar to those for 2000/01 (19.7% overweight, including 8.0% obese and 3.9% severely obese).  As the number of NHS Boards submitting data has increased since 2000/01 (from four to ten Boards) the trend for ‘All participating NHS Boards’ should be interpreted with a degree of caution.  However, a similar trend is observed among the Boards participating throughout the eight year period.

INTERPRETATION

Statistics in this release are derived from centiles, using the 1990 UK growth reference standards. These growth reference charts are based on data collected between 1978 and 1990 from UK surveys (they therefore represent children's weight relative to height before the recent rise in levels of obesity in children). Cut-off points for population monitoring purposes, based on these studies, define overweight as children whose BMI is in the top 15% of the UK 1990 reference range for their age and sex. Obese and severely obese children are defined as those whose BMI is in the top 5% and 2% of the reference range respectively.  Children with a BMI within the 5th -  85th centile range are considered to be in the normal range (although BMI may incorrectly categorise a small minority of children with heavy musculature as being overweight or obese).  These statistics classify underweight and very underweight as children with a BMI in the bottom 5% and 2% of the reference range respectively.
 
All NHS Boards in Scotland provide a Child Health Surveillance Programme where children are offered routine reviews at various stages of their life. The majority of Boards record these reviews using the Child Health Systems Programme (CHSP). Statistics in this release are derived from height and weight measurements collected at routine health reviews in Primary 1 through the CHSP-School system. As CHSP-School is implemented in the majority of NHS Boards, data from this system can be used to estimate prevalence of over- and under- weight children in Scotland.  Data for NHS Grampian, NHS Orkney, NHS Shetland, NHS Highland and the former NHS Greater Glasgow are not included.  The BMI statistics cover approximately 88% of children in Primary 1 among the ten participating NHS Boards, and approximately 52% of children in Primary 1 across Scotland.
 
Figures for Community Health Partnerships, Council Areas and NHS Boards with small numbers of reviews should be interpreted with care as the small numbers may result in fluctuations in the percentages from year to year etc. The smaller the number of reviews, the poorer the precision of the estimate (percentage) and the wider the associated confidence interval.

DETAILED FINDINGS


Based on centile cut-offs on the 1990 UK growth reference charts used for population monitoring purposes:
  • In 2007/08, among the ten participating NHS Boards, 20.0% of Primary 1 children were classified as overweight, including 7.9% obese and 3.9% severely obese.
  • Levels of high BMI increased slightly, and very gradually, between 2000/01 and 2005/06. Over the last two years, levels of high BMI have decreased slightly and the percentages for 2007/08 are similar to those for 2000/01 (19.7% overweight, including 8.0% obese and 3.9% severely obese).  As the number of NHS Boards submitting data has increased since 2000/01 (from four to ten Boards) the trend for ‘All participating NHS Boards’ should be interpreted with a degree of caution.  However, a similar trend is observed among the Boards participating throughout the eight year period.
  • In Primary 1, levels of high BMI amongst boys tend to be slightly higher than those for girls.  In school year 2007/08, 20.5% of boys were classified as overweight (including 8.2% obese and 4.1% severely obese) compared to 19.6% of girls (including 7.6% obese and 3.6% severely obese).
  • Primary 1 figures for 2007/08 indicate that the most deprived areas have the highest percentage of children classified as overweight, obese and severely obese (21.7% overweight, including 9.2% obese and 4.5% severely obese) while the least deprived areas had the lowest percentage (18.1% overweight, including 6.3% obese and 3.0% severely obese), however this pattern is not clearly observed for all previous years.
  • The percentage of Primary 1 school children with low BMI (classified as underweight) was 3.2% in 2007/08.  Levels of low BMI have remained relatively stable at around 3% in recent years.

-----------------------------------------------------------------

MAIN CONTACTS:

Dr Jim Chalmers (Consultant in Public Health Medicine)
Head of Programme
Women and Children’s Health Information Programme
0131 275 6136
Jim.Chalmers@isd.csa.scot.nhs.uk

Judith Tait
Child Health Information Team Leader
0131 275 6833
Judith.Tait@isd.csa.scot.nhs.uk

-----------------------------------------------------------------

GLOSSARY:

BMI : Body Mass Index [weight (in Kg) divided by height (in m) squared]
CHSP-PS : Child Health Systems Programme  - Pre-School
CHSP-S : Child Health Systems Programme – School
Hall4 : Health For All Children 4 – Guidance on Implementation in Scotland
 
-----------------------------------------------------------------

PRE-RELEASE ACCESS TO THIS PUBLICATION WAS GIVEN TO:

Scottish Government Health Directorates
Directors of Public Health
Chairs of the Child Health Systems Programme National User Groups and Project Board
NHS Board Chief Executives
 
-----------------------------------------------------------------

HISTORY OF THIS PUBLICATION:

Last Published: 18/12/2007
Next Due: December 2009
Data Avaliable Since: School year 2000/01 for children in primary 1

 


Main contact: Email Jim Chalmers