Official Statistics

Obesity Profile: statistical commentary December 2022

Published 6 December 2022

Applies to England

Introduction

The December 2022 update of the Obesity Profile presents the 2021 to 2022 academic year National Child Measurement Programme (NCMP) data for all current indicators. Headline findings from this data have already been published by NHS Digital on 2 November 2022 in the NCMP 2021 to 2022 school year report. This update of the Obesity Profile publishes the data at national, regional, upper and lower tier local authority level, and for integrated care boards (ICBs), Middle Super Output Areas (MSOAs) and electoral wards.

The NCMP is an annual programme that measures the height and weight of over 1 million children in reception (age 4 to 5 years) and year 6 (age 10 to 11 years) in primary schools across England. The data is used at national and local level to monitor the patterns and trends in child weight status, providing valuable evidence for planning and delivering policy measures and interventions.

New in this update

The following indicators have been updated with 2021 to 2022 NCMP data for national, regional, upper and lower tier local authorities and integrated care boards (ICBs):

• reception and year 6: prevalence of underweight

• reception and year 6: prevalence of healthy weight

• reception and year 6: prevalence of overweight (including obesity)

• reception and year 6: prevalence of overweight

• reception and year 6: prevalence of obesity (including severe obesity)

• reception and year 6: prevalence of severe obesity

• reception and year 6: prevalence of obesity (including severe obesity), 5 years of data combined

Local authority level inequalities data is available using the ‘reception and year 6: prevalence of obesity (including severe obesity), 5 years of data combined’ indicators.

Prevalence of obesity by sex, ethnic group and deprivation quintile can be examined for upper and lower tier local authorities in the inequalities data view of the Obesity Profile.

The following indicators have been updated in the NCMP small area data topic showing data for MSOAs and electoral wards, together with local authority and England figures for comparison.

• reception: prevalence of obesity (including severe obesity), 3 years of data combined

• reception: prevalence of overweight (including obesity), 3 years of data combined

• year 6: prevalence of obesity (including severe obesity), 3 years of data combined

• year 6: prevalence of overweight (including obesity), 3 years of data combined

The small area data is presented by area of child residence using 3 years of combined NCMP data to show small area trends from 2008 to 2009 up to 2021 to 2022. This data will assist planning and delivery of services for children and the targeting of resources at a local level to help reduce the prevalence of overweight and obesity.

The national patterns and trends in the child obesity data slide set has also been updated with 2021 to 2022 NCMP data and is available in the reports data view. Slide sets showing the patterns and trends in child obesity at regional and local authority levels are due to be published in February 2023.

This statistical commentary focuses on the data for small area geographies.

Main findings

• there is variation in the prevalence of overweight and obesity at small area level throughout England

• obesity prevalence is highest among children living in the most deprived areas of England

• it is important to consider the confidence intervals around the small area prevalence values when comparing between areas and over time

Interpreting the data

Prevalence of overweight and obesity varies across England. Analysis of national^{[footnote 1]} and local authority^{[footnote 2]} data shows that children resident in the most deprived areas in England are at the highest risk of being overweight or living with obesity.

In England, 9.9% of children in reception were living with obesity in the combined 3-year period 2018 to 2019, 2019 to 2020 and 2021 to 2022, varying from 4.0% to 13.9% at lower tier local authority level. Among children in year 6 in England, 21.6% were living with obesity in the same period, varying from 10.3% to 30.6% between lower tier local authorities. There is often considerable variation between neighbourhoods within each local authority.

This variation within local authorities can be examined using data for MSOAs and wards. The data published in the Obesity Profile will help to identify pockets of high overweight and obesity prevalence and enable changes in prevalence to be monitored over time. This may help to assist planning and delivery of services for children.

Figures 1 and 2 show examples of how the data can be examined to identify local patterns and trends in child obesity prevalence using the data at ward level.

When interpreting this small area level data it is important to consider the 95% confidence intervals for the values as they show the level of uncertainty in the prevalence estimates and provide a range that we can be 95% confident contains the true value.

In general, the greater the number of children measured within any analysis, the more reliable the resulting statistics (for example, the England and local authority figures). Analysis based on small areas (such as MSOA and ward level) may show more variation, and therefore the prevalence figure may not always provide a reliable estimate.

Figure 1 shows the prevalence of obesity among year 6 children in Coventry local authority by ward of child residence. Obesity prevalence varies between 14.8% up to 31.4% across all wards in Coventry.

In figure 1, Longford ward has the highest prevalence value in the local authority, of 31.4%, but the 95% confidence interval ranges from 27.9% to 34.4%. We can be confident that year 6 obesity prevalence in Longford ward is higher than the England and Coventry values as their confidence interval values do not overlap with that for Longford ward.

When making comparisons with other wards, however, we can only say with some certainty that prevalence in Longford ward is higher than the prevalence in 9 wards with the lowest prevalence, as in only these cases the confidence intervals do not overlap. For the other wards, the confidence intervals do overlap with those for Longford so we cannot be confident that the prevalence in Longford ward is higher than the prevalence in any of these wards.

The bars on figure 1 are shaded red (ward value higher than England value), amber (ward value similar to England value) and green (ward value lower than England value) to help compare the ward values to the England value.

Figure 1: prevalence of obesity among year 6 children (aged 10 to 11 years) in Coventry local authority by ward of residence, NCMP combined years 2018 to 2019, 2019 to 2020 and 2021 to 2022 with 95% confidence intervals

Figure 2 shows the trend in obesity prevalence among reception children for Coventry 001 as an example MSOA, compared with the local authority values. Obesity prevalence in this MSOA had been higher than the Coventry local authority value up to 2012 to 2013 to 2014 to 2015 and since then has been similar to the Coventry local authority value.

The data points in figure 2 are shaded red (higher), amber (similar) and green (lower) to help compare the MSOA values to the Coventry local authority values.

Figure 2: trend in prevalence of obesity among reception children (aged 4 to 5 years) for one MSOA in Coventry local authority, NCMP 2008 to 2009 up to 2021 to 2022 with 95% upper and lower confidence intervals (UCI and LCI) around MSOA data (benchmark is Coventry local authority)

Data quality

Previously the profile provided data for Clinical Commissioning Groups (CCGs) using 3-year combined NCMP data. The CCG geography has been removed from the profile and replaced with ICBs and sub-ICB locations. Indicators in the profile for ICB geographies use one year of NCMP data and are presented in the NCMP prevalence data topic.

Data from the 2020 to 2021 NCMP has not been included in the 5-year combined indicators used for local authority inequalities data. The 2020 to 2021 data collection had a delayed start due to the COVID-19 pandemic and local authorities were asked to collect a nationally representative sample of data. Around 300,000 children (25% of previous full measurement years) were measured, enabling robust prevalence estimates to be produced at national and regional level. However, the sample did not enable the production of comprehensive and robust local authority level data. The 5-year combined data that has been added to the profile in this update uses the following years: 2016 to 2017, 2017 to 2018, 2018 to 2019, 2019 to 2020 and 2021 to 2022.

The 2021 to 2022 NCMP was the first full year of data collection since the start of the COVID-19 pandemic; 1,171,322 children had their height and weight measured, amounting to 92% of all eligible children.

As described above, the 2020 to 2021 NCMP data cannot consistently be used to produce prevalence estimates below regional level. Therefore, the 3-year combined data for MSOA and ward level indicators that has been added in this update uses data from the following years: 2018 to 2019, 2019 to 2020 and 2021 to 2022.

School closures in March 2020 due to the COVID-19 pandemic meant that in 2019 to 2020 the number of children measured was around 75% of previous years. Analysis by NHS Digital shows that national and regional level data is reliable and comparable to previous years. The data at local authority level and below is not as robust. As a result, a small number of areas do not have published data for 2019 to 2020, and data for some areas has a reliability flag, indicating that figures need to be interpreted with caution. Further information can be downloaded from Fingertips and found in the NHS Digital 2019 to 2020 annual report.

In the 3-year grouped NCMP data for small areas we would expect around 33% of data from each contributing year. Values for areas where less than 20% of data is from 2019 to 2020 is flagged with an asterisk (*) and the following note: ‘Data for 2019 to 2020 is underrepresented due to paused measurements in March 2020 - see metadata for details’. The percentage contribution of 2019 to 2020 data to the 3-year data for each geographic area is available to download from Fingertips, as above. The overweight and obesity prevalence indicators at small area level that use the 2019 to 2020 data are still considered to be reliable even with the small amount of data from 2019 to 2020.

Background

Further information about this publication and the data used:

• the NCMP annually measures the height and weight of over 1 million children in England and provides robust data on rates of child overweight and obesity

• detailed metadata for each indicator is available in the definitions tab of the Obesity Profile

• in the 2006 to 2007 NCMP, 57.7% of records had a valid child postcode of residence; in 2007 to 2008 this figure had risen to 95.1%; in the NCMP since 2008 to 2009, over 99% of child records have a valid postcode, providing large enough coverage to produce reliable estimates at small area level

• the NCMP data for year 6 children from 2006 to 2007, 2007 to 2008 and 2008 to 2009 needs to be treated with caution as low participation levels in these years led to underestimation of overweight and obesity prevalence

• children with a body mass index (BMI) greater than or equal to the 95th centile of the British 1990 growth reference (UK90) BMI distribution have been classified as living with obesity for population monitoring purposes

• children with a BMI greater than or equal to the 85th centile of the British 1990 growth reference (UK90) BMI distribution have been classified as overweight (including living with obesity) for population monitoring purposes

• these population monitoring cut points for overweight and obesity are slightly lower than the clinical cut points used to assess individual children. This is to capture those children with an unhealthy BMI for their age and those at risk of moving to an unhealthy BMI. This helps ensure that adequate services are planned and delivered for the whole population

• these indicators can also be examined in the Office for Health Improvement and Disparities (OHID) Local Health tool; the latest data may not be available in Local Health due to different publication dates

• the statistics were produced using the national analysis dataset provided to OHID by NHS Digital

Responsible statistician, product lead: Caroline Hancock

For queries relating to this document, please contact: PHA-OHID@dhsc.gov.uk

1. National Child Measurement Programme: changes in children’s body mass index in England between 2006 to 2007 and 2018 to 2019. London: Public Health England, June 2020. ↩

2. Office for Health Improvement and Disparities, Obesity Profile. ↩