The Health of Children and Young People

 

Introduction    
 

The Health Survey for England

The Health Survey for England (HSE) comprises a series of annual surveys, of which the 2002 survey is the twelfth. All surveys have covered the adult population aged 16 and over living in private households in England. Since 1995, the surveys have also covered children aged 2 to 15 living in households selected for the survey, and in 2001 the age range was extended to include children aged under 2.

The HSE series is part of an overall programme of surveys commissioned by the Department of Health and designed to provide regular information on various aspects of the nation's health. Each survey in the series consists of core questions and measurements (for example, anthropometric and blood pressure measurements and analysis of blood and saliva samples) which are included each year, plus modules of questions on specific health conditions that are repeated at regular intervals.

Since 1994, the Health Survey for England has been carried out by the Joint Health Surveys Unit of the National Centre for Social Research and the Department of Epidemiology and Public Health, Royal Free and University College Medical School, London.

This report

This report is one of three reports using data from the HSE 2002, published in a set as The Health Survey for England 2002. This report (Volume 1) presents the main findings on children and young people.¹ The information on infants and mothers is presented, separately, in Volume 2, Maternal and Infant Health.² A description of the methods, and the survey documents, are presented in Volume 3, Methodology and Documentation.³

Although the sample of children was boosted in 2002 (see below), the aggregation of data for children from the 2001 and 2002 surveys permits more detailed analysis of sub-groups. This report therefore uses a data set combining these two survey years. The analysis is occasionally limited to one survey year, because of topic coverage, but this is always made clear in reporting.

Comparisons are made throughout this report with the previous published report on the health of children and young people which used data from the HSE 1997.⁴ The majority of the analysis for that report used an aggregated dataset for children from the 1995, 1996 and 1997 surveys. When making comparisons with results from the earlier report, it is always stated in the text or table which years' data form the basis for the comparison.

Overview of HSE 2002

The HSE 2002 was designed to provide data about the population living in private households in England. As well as providing a sample designed to give a cross-section of the population of England, the HSE 2002 also focussed on the health of a number of specific groups, namely: infants and children (aged 0-15), young adults (aged 16-24), and mothers with infants aged under 1.

For children, the coverage of the HSE 2002 was similar to several earlier years of the HSE, including 2001 and 1997. The special topics included in these years were respiratory conditions (asthma and asthma-related symptoms), lung function, non-fatal accidents, physical activity and the Strengths and Difficulties Questionnaire (which is completed by parents of children aged 4-15 to describe the behaviour of each child). In HSE 2002, these same topics were included for young adults aged 16-24 (except the Strength and Difficulties Questionnaire).

'Core' topics, repeated every year for both adults and children, include general health, blood pressure, anthropometry, fruit and vegetable consumption, prescribed medicines, cigarette smoking and alcohol consumption. Adults are also asked questions on social support and social capital. The General Health Questionnaire (GHQ12) was administered to those aged 13 and over. Saliva samples were obtained from those aged 4 and over and blood samples from those aged 11-24.

A new module of questions on maternal health was introduced in the HSE 2002. This was asked of all women who were the natural mothers of an infant aged under 1. The module provided a wide range of information about the infant and the mother, the pregnancy, the delivery, pregnancy related illness, post-natal service use, and other relevant factors. The results are included in the second report Health Survey for England 2002: Maternal and infant health.

A brief outline of survey methodology is given in the remainder of this chapter. Full details are given in the third report Health Survey for England 2002: Methodology and documentation.

Ethical clearance

Ethical approval for the 2002 HSE was obtained from the London Multi-centre Research Ethics Committee (MREC).

Boosting the sample of children and young adults

While the HSE includes children and adults of all ages, children and young people aged 0-24 are normally included in the proportion they occur in the population and thus comprise about one-fifth of the sample. In order to increase the number of children and young people available for analysis, the design of HSE 2002 was modified to boost the number of informants in this age range. The sample was divided in two parts. In one part, the procedure was the same as in most other years of the HSE: all adults in the selected households were surveyed, as were all children if there were no more than two. If there were more than two, then two children were randomly selected for the survey.

In the second part of the sample, only children (aged 0-15), young adults (aged 16-24) and mothers with infants aged under 1 were selected and interviewed. In these households, no data was collected from adults aged 25 and over (unless they were mothers of infants under 1), except for a short household questionnaire which collected key information about the household and its members. The proportion of interviews with children and young people was thus much higher than in previous survey years (except for 1997 when there was a similar boost of children), and child and young adult interviews comprised nearly two-thirds of the total. Interviews were obtained with 8,067 children aged 0-15 and 3,625 young adults aged 16-24.

Sample design

The HSE 2002 was designed to provide a representative sample of adults and children living in private households in England. The survey also included a boosted sample of children and young adults as described above. Although people living in institutions were excluded from the survey, this is likely to make little difference to the boosted sample of the 0-24 age range.

A random sample of 27,360 addresses was selected from the Postcode Address File, using a stratified multi-stage sample design. 720 postcode sectors were selected from the Postcode Address File, with the sectors being selected with probability proportionate to size (number of addresses). Within each sector, 38 addresses were selected, and 29 were assigned to Sample type I and 9 to Sample type II. Thus, Sample I consisted of 20,880 addresses and Sample II of 6,480 addresses. Sample I addresses were screened for children and young adults aged 0-24 and for mothers of infants under 1. In Sample I, only individuals meeting these criteria were eligible for inclusion in the survey.

In Sample II, at each contacted address, a brief household interview was carried out, in which all household members were listed and some demographic data was obtained. All adults and children were eligible for the survey, unless there were more than two children (aged 0-15) in which case two were randomly selected.

In Sample I, the same household interview was carried out, but only children, young people (aged 16-24) and mothers with infants under 1 were eligible for the survey. As in Sample II, if there were more than two children (aged 0-15), two were randomly selected for interview.

Full details of the sample design can be found in the third report Health Survey for England 2002: Methodology and documentation.

Fieldwork design

Each sampled address was sent an advance letter explaining the purpose of the survey before the interviewer visit. In Sample I addresses, the letter explained that the survey was looking at the health of young people so the interviewer would be asking about children in the household. In Sample I, the interviewer sought agreement to interview children and young people aged 0-24, as well as mothers with young infants, and in Sample II the interviewer sought to interview all adults and children.

The content of the interview is outlined above and complete listings of the interviewer and nurse questionnaires are included in the third report Health Survey for England 2002: Methodology and documentation. At the end of the interview, the interviewer measured the informant's height and weight, and then sought agreement for a visit by a nurse. At all stages of the survey, informants were given the opportunity to opt out.

The nurse collected information on current medication, took blood pressure, waist ­hip and lung function measurements, obtained a sample of saliva from those aged 4 and over and, with written agreement, a small sample of blood was taken by venepuncture from those aged 11-24. The saliva sample was analysed for cotinine. The blood sample was analysed for haemoglobin, ferritin, total IgE and house dust mite specific IgE.

Interviewing children

Children aged 13-15 were interviewed in person, with the permission of a parent or guardian. For children aged under 13, one of the child's parents or guardians answered the questions on the child's behalf, with the child present during the interview. Because of children's potential need for privacy for answering some of the questions, self-completion booklets were provided to children aged 8-15 covering topics such as smoking and drinking. Permission for a nurse to carry out any measurements or take any samples was obtained from a parent or guardian.

Response

Interviews were held in 9,445 households with 18,129 individuals: 8,067 interviews were with children aged 0-15, 3,625 were with young adults aged 16-24 and 6,437 were with adults aged 25 and over. Among the adults (aged 16+), 475 were mothers with infants aged under 1; 449 of the infants under 1 were included in the sample. 6,881 of the children saw a nurse, as did 2,673 of the young adults and 388 of the mothers with infants.

Response to the survey can be calculated in two ways: at a household and at an individual level. A summary of responses to the different components of the survey is shown in the table below.

Interviews were carried out at 76% of eligible Sample I households and 74% of eligible Sample II households. Interviews were obtained with 99% of (sampled) children and 89% of young adults in co-operating Sample I and II households, and with 90% of adults in co-operating Sample II households.

Assuming that households where the number of adults and children was not known contained, on average, the same number as in households where it was known, the individual response rate was 79% among children and 62% among young adults, in Sample I and II combined. In Sample II only, the individual response rate was 67% among all adults aged 16 and over. The response rate among mothers with infants was 72% (in Sample I and II).

The table below shows response rates to the different stages of the survey. Columns 1 and 2 give the proportion of children and young adults, in both Sample I and II, who responded to each stage of the survey, based on the estimated total number of eligible adults and children in the sample. Column 3 shows the proportion of adults in Sample II households who responded to each survey stage (also based on an estimated total). Where a stage is age-specific, the base for the percentage is the estimated total number of adults or (sampled) children in that age group in the sample. A full response analysis is provided in Section 6 in the third report Health Survey for England 2002: Methodology and documentation.

		Children	Young	All adults
		(aged 0-15)	adults	(aged 16+)
		in Sample	(aged 16-24)	in Sample II
		I and II	in Sample	households
		households	I and II
			households
		%	%	%
	Interviewed	79	67	67
	Height measured	73	63	62
	Weight measured	72	61	60
	Saw nurse	68	49	54
Waist-hip measured
	(aged 16 and over)	na	48	52
Blood pressure measured
	(aged 5 and over)	66	48	52
Lung function measured
	(aged 7-24)*	63	45	46
Blood sample obtained
	(aged 11-24)*	33	31	na
Saliva sample obtained
	(aged 4 and over)*	69	47	52

*Based on the estimated number of informants in the relevant age range.

Weighting the data

None of the Health Surveys have involved weighting the adult sample, as the achieved samples have been judged to reflect the shape of the general population sufficiently closely to make this unnecessary. However, since children were introduced into the Health Survey in 1995, it has been necessary to apply an inverse probability 'child weight' to the child sample to compensate for limiting the number of children interviewed in the household to two. Full details of the weighting strategy can be found in the third report Health Survey for England 2002: Methodology and documentation.

Age as an analysis variable

Age is a continuous variable. The presentation of tabular data involves classifying the sample into year bands. This can be done in two ways, age at last birthday and 'rounded age', that is, rounded to the nearest integer. In the present report, age always refers to age at last birthday.

Availability of unpublished data

As for previous surveys, a copy of the HSE 2002 data will be deposited at the UK Data Archive at the University of Essex. Copies of anonymised data files can be made available for specific research projects through the Archive (www.data-archive.ac.uk).

In addition, trend tables showing data for adults and children are available on the Department of Health's website at www.doh.gov.uk/public/summary.htm

References and notes

1 Sproston K and Primatesta P (eds). Health Survey for England 2002. Volume 1: The health of children and young people. The Stationery Office, London, 2003.

2 Sproston K and Primatesta P (eds). Health Survey for England 2002. Volume 2: Maternal and infant health. The Stationery Office, London, 2003.

3 Sproston K and Primatesta P (eds). Health Survey for England 2002: Volume: 1 Methodology and documentation. The Stationery Office, London, 2002.

4 Prescott-Clarke P and Primatesta P (eds). Health Survey for England: The health of young people 1995-1997. The Stationery Office, London, 1998.