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Updated: Jun 26, 2025
Assessment of Child Anthropometry in a Large Epidemiologic Study
Published on: February 2, 2017
Children and young people's body mass index measures derived from routine data sources: A national data linkage study
Lucy J Griffiths1, James Rafferty1, Richard Fry1
1Swansea University Medical School, Swansea, United Kingdom.
Insights
General practice Body Mass Index (BMI) records are not representative of child populations. Linking national Child Measurement Programme (CMP) data to GP records can aid clinical discussions but doesn't offer population-level insights for healthy weight gain.
Area of Science:
- Public Health
- Epidemiology
- Child Health Surveillance
Background:
- Routine monitoring of Body Mass Index (BMI) is crucial for managing childhood weight.
- General practice electronic health records (GP-BMI) and national Child Measurement Programme (CMP-BMI) data are key sources.
- Assessing the representativeness and feasibility of combining these datasets is vital for accurate surveillance.
Purpose of the Study:
- To compare the presence and representativeness of children's BMI data in GP records versus the CMP.
- To evaluate the potential for combining GP-BMI and CMP-BMI data for longitudinal analyses.
- To understand how these datasets reflect the broader population of children and young people.
Main Methods:
- Utilized de-identified population-level GP-BMI and CMP-BMI data from 2011-2019.
- Analyzed the proportion and socio-demographic distribution of GP-BMI records.
- Compared BMI distributions between GP-BMI and CMP-BMI datasets and assessed follow-up record linkage.
Main Results:
- GP-BMI records were found for 41% of children, with higher proportions in females, infants, and adolescents.
- No significant difference in deprivation profile was observed for children with GP-BMI measurements.
- Children with extreme BMIs (underweight/very overweight) or from deprived areas were more likely to have follow-up GP-BMI records.
Conclusions:
- Childhood weight status records from general practice are not representative and are biased by weight status.
- Linking national programme data to GP records can improve point-of-care discussions but not population estimates.
- A second Child Measurement Programme measurement is recommended for Wales to improve data representativeness.
Background:
Routine monitoring of Body Mass Index (BMI) in general practice, and via national surveillance programmes, is essential for the identification, prevention, and management of unhealthy childhood weight. We examined and compared the presence and representativeness of children and young people's (CYPs) BMI recorded in two routinely collected administrative datasets: general practice electronic health records (GP-BMI) and the Child Measurement Programme for Wales (CMP-BMI), which measures height and weight in 4-5-year-old school children. We also assessed the feasibility of combining GP-BMI and CMP-BMI data for longitudinal analyses.
Methods:
We accessed de-identified population-level GP-BMI data for calendar years 2011 to 2019 for 246,817 CYP, and CMP-BMI measures for 222,772 CYP, held within the Secure Anonymised Information Linkage Databank. We examined the proportion of CYP in Wales with at least one GP-BMI record, its distribution by child socio-demographic characteristics, and trends over time. We compared GP-BMI and CMP-BMI distributions. We quantified the proportion of children with a CMP-BMI measure and a follow-up GP-BMI recorded at an older age and explored the representativeness of these measures.
Results:
We identified a GP-BMI record in 246,817 (41%) CYP, present in a higher proportion of females (54.2%), infants (20.7%) and adolescents. There was no difference in the deprivation profile of those with a GP-BMI measurement. 31,521 CYP with a CMP-BMI had at least one follow-up GP-BMI; those with a CMP-BMI considered underweight or very overweight were 87% and 70% more likely to have at least one follow-up GP-BMI record respectively compared to those with a healthy weight, as were males and CYP living in the most deprived areas of Wales.
Conclusions:
Records of childhood weight status extracted from general practice are not representative of the population and are biased with respect to weight status. Linkage of information from the national programme to GP records has the potential to enhance discussions around healthy weight at the point of care but does not provide a representative estimate of population level weight trajectories, essential to provide insights into factors determining a healthy weight gain across the early life course. A second CMP measurement is required in Wales.
