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Journal of Public Health Advance Access originally published online on October 30, 2006
Journal of Public Health 2006 28(4):330-336; doi:10.1093/pubmed/fdl070
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© The Author 2006, Published by Oxford University Press on behalf of Faculty of Public Health. All rights reserved.

Measuring children and monitoring obesity: surveys of English Primary Care Trusts 2004–06



Lesley Patterson, Research Associate1

Paul Jarvis, PhD Student1

Arpana Verma, Specialist Registrar1

Roger Harrison, Senior Research Fellow1,2

Iain Buchan, Director & Clinical Senior Lecturer1
1 Medical School, University of Manchester, Stopford Building, Oxford Road, Manchester M13 9PT, UK
2 Bolton Primary Care Trust, St. Peter’s House, Silverwell Street, Bolton BL1 1PP, UK

Address correspondence to Iain Buchan, E-mail: buchan{at}manchester.ac.uk

Background Child obesity has unclear determinants and consequences. A precautionary approach requires best-guess interventions and large-scale surveillance. This study was to determine the current measurement activities and the information systems required for child obesity surveillance.

Methods Design: Questionnaire-based surveys. Setting:Primary Care Trusts (PCTs) in United Kingdom. Participants: Two hundred and forty-seven (82%) PCTs in 2004 and 240 (79%) in 2006. Main measures: Children’s ages at which height and weight are routinely measured, the type of personnel taking the measurements, arrangements for recording data, information systems and uses of the data.

Results PCTs measure height/length and weight most commonly at 6 weeks (74%) and 5 years (74%)—also at 6–12 months (58%), 1.5–2.5 years (50%), 2.5–4 years (40%), 11 years (18%) and 7 years (11%). Seventy-seven per cent of PCTs transferred the measurements to a database—26 different information systems were named. Six per cent of PCTs in 2004, rising to 34% in 2006, used the data to produce public health reports.

Conclusions Body mass index (BMI) surveillance requires new arrangements in 25% of PCTs at school entry and 80% at transfer to senior school. Important aspects of child obesity surveillance not yet addressed are pre-school measurement, longitudinal assessment and the public health requirements of (child) electronic health records.

Keywords: child health, obesity, surveillance


   Introduction
TOP
 Introduction
Participants and methods
 Results
 Discussion
 Conflicts of interest
 Acknowledgements
 References
 
There is a global epidemic of obesity affecting all age groups1: its consequences are difficult to estimate but are likely to be as great a threat to the public’s health as tobacco.2

It is difficult to define a cut-off level of adiposity at which children start to accumulate harm associated with obesity. Therefore, in this article, we define ‘obesity surveillance’ as the systematic collection, collation, analysis and dissemination of information on child population adiposity to inform public health decision-making.

Children are an especially important group on which to focus obesity prevention because (i) the life-long risk of obesity is partly determined early in life3–6 and (ii) children’s adiposity reflects obesogenic environments in families and communities.7

Evidence of effective interventions for reducing population obesity in children is sparse, and the area is under-researched.8 Health policies for tackling obesity are therefore being set using an incomplete evidence base and extrapolation from basic biological knowledge. The UK government has set a target to ‘halt the year-on-year rise in obesity among children under 11 by 2010 (from the 2002 baseline) in the context of a broader strategy to tackle obesity in the population as a whole’.9 To measure the performance of public services in meeting this target, there is a need to (i) monitor child population adiposity; (ii) capture details of relevant interventions and (iii) accelerate research into the causes, prevention and treatments of obesity. The government recently initiated a national scheme to measure all children at entry to infant school (~5 years) and at transfer to senior school (~11 years).

Like many western countries, for more than half a century, the United Kingdom has recorded the heights and weights of children for monitoring their growth.10 The primary purpose of these measurements has been for detecting children with abnormal growth patterns and referring them for appropriate healthcare; the secondary purpose has been for public health surveillance. A public health measure of adiposity from these data, the mean body mass index (BMI), is a useful measure of population adiposity.11

Screening of children for growth retardation has been rationalized in the United Kingdom recently to bring practice in line with accepted screening criteria.12 We suspected that there might be conflicts of purpose in organizing the measurement of children between the clinical screening for growth retardation and the monitoring of adiposity to inform public health actions. We therefore surveyed the child measurement and information practices in English Primary Care Trusts (PCTs).


   Participants and methods
TOP
 Introduction
 Participants and methods
Results
 Discussion
 Conflicts of interest
 Acknowledgements
 References
 
Two surveys were conducted: Survey ‘2004’ between July and October 2004 and Survey ‘2006’ between November 2005 and February 2006.

The public health lead for each PCT was identified through a current database of National Health Service (NHS) organizations,13 and a postal questionnaire was sent to them with a covering letter. The questionnaire was kept short (single page) to maximize the response rate. Survey 2004 focused on the measurement of children up to school entry (~5 years). Survey 2006 extended to children transferring to senior school (~11 years).

The questionnaire presented a matrix of age ranges, plus an open section for ‘other periods’, and asked whether height/length and weight are measured, who does the measuring [health visitor, school nurse, general practitioner (GP) or other] and to specify any selection criteria used. We then asked whether the measurements were held in the child’s medical (GP held) record, the Personal Child Health Record, a central location in the PCT/locality and an electronic database. In addition, we asked respondents to specify the name of any information system used whether the data had been used to produce public health reports in the past 5 years.

Non-responders were followed up with a reminder letter, then a telephone call.


   Results
TOP
 Introduction
 Participants and methods
 Results
Discussion
 Conflicts of interest
 Acknowledgements
 References
 
Response
The response rate was 82% in 2004 and 79% in 2006 based on a denominator of 303 PCTs. However, some PCTs have merged public health functions; therefore, the true response rate was higher. The respondents represented a wide variety of public health and clinical roles, mostly in children’s services. Just 8% of respondents were directors or assistant directors of Public Health. All regions were strongly represented, with the lowest returns in 2004 from Eastern (72%) and London (76%) and the highest from Northwest (92%) and Southeast (88%). Survey 2006 was not geographically coded. Both the surveys gave rise to a large number of unsolicited telephone calls and e-mails, indicating a high level of interest in the topic.

Ages at which children being measured
Table 1 summarizes the frequency of height and weight measurements reported in 2004 for different stages of child development up to infant school entry. Just over three quarters of PCTs measured both height and weight at 6 weeks to 8 months and at infant school entry. The PCTs reporting measurements at 6 weeks to 8 months were more likely (P < 0.001) to report a further measurement before infant school entry. Most PCTs appeared to be following routine measurement schedules in the pre-school period, apart from 15 (6%) who took no routine measurements and 26 (11%) who started at infant school entry. Just under half of PCTs reported, no measurement between 8 months and infant school entry. Only 63 (26%) measured routinely across at all stages.


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  		Table 1 Child height/length and weight measurements taken by Primary Care Trusts (PCTs, n = 247) in 2004

 

Table 2 summarizes the frequency of height and weight measurements reported in 2006 for an extended set of stages of child development up to transfer to senior school. The most frequent measurement periods were around 6 weeks and infant school entry, little changed from 2004. An additional question about the 6–12-month period in the 2006 survey showed that most PCTs were measuring at two stages of post-neonatal infancy. The least commonly reported measurements were at the transfers to junior school (11%) and senior school (18%). Eight (3%) PCTs reported not taking any routine measurements from 6 weeks to 10–11 years.


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  		Table 2 Child height/length and weight measurements taken by Primary Care Trusts (PCTs, n = 240) in 2006

 

Who measures children
Table 3 summarizes the roles of people reported by PCTs as routinely measuring children in 2004 up to infant school entry. Over 90% of PCTs used health visitors to carry out pre-school measurements. School nurses measured >90% of children on entry to infant school. GPs were duplicating measurements of health visitors in the 6-week to 8-month period in half of the PCTs. A small proportion of other measurers included ‘health visitor assistants’, ‘nurse assistants’ and ‘nursery assistants’.


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  		Table 3 Personnel taking child height and weight measurements in Primary Care Trusts (PCTs) in 2004

 

Table 4 summarizes the roles of people measuring children in 2006 but for an extended set of stages/ages of development. As for 2004, health-visiting measurements predominate in the pre-school period, and largely duplicate GP measurements are clustered ~6 weeks. Around a third of the measurements in schools were taken by someone other than a school nurse—where this was specified the role was usually ‘school nurse assistant’. Between 2004 and 2006, 20% [95% confidence interval (95% CI) 12–28] of infant school entry measurements shifted from school nurses to other personnel.


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  		Table 4 Personnel taking child height and weight measurements in Primary Care Trusts (PCTs) in 2006

 

Data organization
Figure 1 illustrates the responses of PCTs to questions about the recording, storage and use of child height and weight data in their locality: almost all reported that the parent-held child record was used, just under half reported that these data were also held in general practice medical records, ~80% of PCTs collated the data centrally and almost all these reported holding the data on a database accessible to the PCT. Little had changed between 2004 and 2006 in the recording of data. There was, however, a large change in the use of the data: in 2004, just 15 (6%) PCTs said they used the data for public health reports; by 2006, this had risen to 82 (34%)—an increase of 28% (95% CI 21–35).


Figure 1
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  		Fig. 1 Organization of height and weight measurements in Primary Care Trusts (PCTs) in 2004 and 2006. Parent, data recorded in parent-held child record; GP, data recorded in child’s medical record in primary care; PCT, measurements sent to central location in PCT; e-central, data stored on a central database; reported, data used for public health reports.

 

The 2006 survey asked respondents to name the child health information systems used: 19 (8%) did not name a system, 25 (11%) gave a non-specific answer such as ‘child health system’ and the remainder named 26 different information systems of which the most commonly named were Child Health 2000 (22), Swift (21), Comwise (20) and McKesson Child Health (9).

Population coverage at infant school entry
PCTs were asked to specify the proportion of all children at infant school entry on which they can access height and weight records for the school years 2003–04 and 2004–05: for 2003–04, 71 (30%) did not answer the question, 34 (14%) stated that they did not know the coverage and the remaining 135 (56%) reported a mean population coverage of 78% (standard deviation 31%). For 2004–05, 65 (27%) did not answer the question, 45 (19%) stated that they did not know the coverage and the remaining 130 (54%) reported a mean population coverage of 79% (standard deviation 30%). Eighteen (8%) PCTs claimed 100% population coverage for both years.

Issues raised
Most PCTs took advantage of the free text response, which enquired about ‘other periods’ where measurements were taken, and any ‘special measuring’. The most common reasons given for non-routine measurement were ‘failure of the child to thrive’, ‘child protection issues’, ‘parental or professional request’ and ‘chronically ill children’.

Eleven of eighty-five (13%) PCTs making free text comments expressed frustration over the difficulty in getting information out of their child health information systems.


   Discussion
TOP
 Introduction
 Participants and methods
 Results
 Discussion
Conflicts of interest
 Acknowledgements
 References
 
Main findings of this study
We have shown that around the time of the UK government issuing guidance on BMI surveillance in children, four-fifths of PCTs were collecting the data required at infant school entry (~5 years), whereas only a fifth were collecting the data from older children at transfer to senior school (~11 years). The data were collated using various information systems without national standards relevant to public health uses. Despite this, most English PCTs had access to child health surveillance data relevant to monitoring obesity, whilst few (6%) of them used these data for public health purposes until recently.

What is already known on this topic
BMI (weight for height as kg/m2) is the easiest and arguably least intrusive measure of adiposity. Skin fold thicknesses and/or body circumferences allow intra-abdominal or visceral fat mass to be differentiated from total fat mass, which gives more accurate measures for predicting known risks of adverse outcomes from obesity at the individual level.14 At the population level, however, BMI is adequate for monitoring adiposity in pre-pubertal children, provided it is standardized for the growth proxies of age and sex.11,15,16

Child height and weight data exist in child health information systems, but the quality of these data has been called into question.17 Poor data quality, however, does not negate the usefulness of these data unless there has been systematic over or under measurement, and that this error is different between time periods or groups being compared. In 2001, we reported the value of such data for signalling an ‘obesity epidemic’—the large population coverage of the data outweighed random error inflation because of the routine nature of the data.18 Why then have PCTs not used these data for surveillance? Figure 2 shows the signal of the obesity epidemic in 3-year olds from Wirral that is discernable from health visiting data: a statistically highly significant rise in BMI was apparent in the mid-1990s; however, it was a further 5 years before national concerns were raised.19


Figure 2
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  		Fig. 2 Three-monthly rolling average body mass index (BMI) of Wirral 3-year olds from 1988 to 2004. BMI SDS, BMI Standard Deviation Score (based on 1990 British Growth Reference).

 

Current guidance on measuring children to monitor obesity neglects the pre-school period.20 Yet, there is mounting evidence that the risk of overweight and obesity starts early in life—as early as infancy.3,21,22 We have previously reported substantial findings in obesity epidemiology using data collected routinely by health visitors in the pre-school period; however, little mention of this important role has been made in government guidance thus far.18,21

What this study adds
The UK government has issued both (i) guidance on monitoring child BMI20,23 and (ii) consultation on public health information and intelligence.24 In addition, there has been a multi-billion pound investment in NHS information systems, and the Department of Health has recently set up a separate database to collate summary statistics from the measurement of children in schools.25 We found a fragmented picture of child health information systems: there appears to be a need for policy analysis to identify ways to incorporate the public health functions of these systems into the NHS ‘care record’. Given that obesity is the most prominent rising threat to public health, we recommend that new investments in NHS IT and public health intelligence give high priority to the monitoring of population adiposity.

In the case of children, where measurements are taken in schools, the sharing of data between education and health sectors might prove difficult, as two sets of information governance are involved. The sharing of relatively non-sensitive data such as height and weight might be impeded by rules that treat all health-related data as equally sensitive. The Academy of Medical Sciences recently reported on the current net loss of public good because of the lack of consideration given to the benefits of sharing data as opposed to the risks.26 The benefits of sharing data to monitor population adiposity, in our opinion, vastly outweigh the risks. If authorities, such as the Patient Information Advisory Group, demand that explicit consent be sought for such data, then the cost of achieving sufficiently large numbers for robust epidemiological use is likely to be prohibitive. The monitoring of most conceivable public health problems, including childhood adiposity, does not require identifiable data—depending on the situation the data can be pseudonymous or anonymous and linked or unlinked. Therefore, explicit consent should not be required. Health agencies need to separate the issue of consent to use identifiable data from that of permission to use non-identifiable data for public health purposes—perhaps through explicit procedures. Furthermore, it is unhelpful to refer to such activities as ‘secondary uses’27 of health e-records, because the public health rationale for electronic linkage of health records is arguably stronger, in terms of public good, than the financial or clinical cases.

Auditors and regulators in the United Kingdom have been critical of the progress made in tackling child obesity in the United Kingdom: a lack of timely and coherent action underpinned by information and intelligence is cited.28,29 We have shown that data that could be used for obesity intelligence are collected but have not been used in this way. We suggest that the most important missing factor is focus—the focus of leadership, resource and co-ordination to work effectively across government departments and professions to establish a system for obesity intelligence that is proportionate to the gravity of the public health problem.

Limitations of this study
The main strength of this study is the high response rate to the two surveys. The main weakness is the limited detail of the surveys. In addition, some of the detail might be inaccurate, notably the claim of 100% coverage of measurement by 8% of PCTs responding.


   Conflicts of interest
TOP
 Introduction
 Participants and methods
 Results
 Discussion
 Conflicts of interest
Acknowledgements
 References
 
The authors have no direct conflicts of interest. Iain Buchan is an unpaid, independent member of two relevant groups for the Department of Health: the Taskforce on Public Health Information and Intelligence and the Expert Advisory Group on Child Obesity.


   Acknowledgements
TOP
 Introduction
 Participants and methods
 Results
 Discussion
 Conflicts of interest
 Acknowledgements
References
 
This work was supported by a grant from the Child Growth Foundation.


   References
TOP
 Introduction
 Participants and methods
 Results
 Discussion
 Conflicts of interest
 Acknowledgements
 References
 

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This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow All Versions of this Article:
28/4/330    most recent
fdl070v1
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