The Scottish Health Survey 2011: Volume 1 - Adults

INTRODUCTION

Lisa Rutherford and Catherine Bromley

OVERVIEW OF THE ADULTS' VOLUME

Policy context

This report provides an overview of some of the key information collected about adult health in the recent surveys in the Scottish Health Survey (SHeS) series.

Health features strongly within the Scottish Government's National Performance Framework (NPF).^1,2 One of the Government's five strategic objectives for a healthier Scotland focuses on Scotland's considerable need for health improvement particularly in disadvantaged communities. Of the 16 national outcomes allied to the Government's strategic objectives, those of greatest relevance to health are:

We live longer, healthier lives.

We have tackled the significant inequalities in Scottish society.

Several of the 50 national indicators that track progress towards these outcomes relate to health and the addition, in the revised NPF published in December 2011,² of new health related indicators highlight the ongoing commitment to improving health: Progress towards the following national indicators is monitored via SHeS:

Improve mental wellbeing

Increase physical activity

Improve self-assessed general health

As a study of public health, SHeS plays an important role in assessing health outcomes and the extent of health inequalities in Scotland and how these have changed over time. Each of the chapters in this report addresses an aspect of health that relates either directly or indirectly to the Government's objective of improving health in Scotland. Chapters begin with a brief introduction to the relevant policy initiatives in that area. These should be considered alongside the higher level policies noted above and related policy initiatives covered in other chapters.

The Scottish Health Survey

The 2008-2011 Scottish Health Surveys were commissioned by the Scottish Government Health Directorates. It is the continuation of a series of surveys aimed at monitoring health in Scotland. During 2005 and 2006 a comprehensive review of the survey was carried out by the then Scottish Executive.³ One of the key recommendations to emerge from the review was that the survey should be carried out on a more frequent basis. This recommendation was adopted and the survey began running continuously in 2008 with a contract awarded for the 2008-2011 surveys. A further contract has now been awarded for the 2012 -2015 surveys, by the end of which there will health survey data spanning two decades, and eight continuous years of data from 2008 onwards. This report is based on data collected in the fourth year of its new format, 2011.

Prior to 2008, the previous three surveys took place in 1995,⁴ 1998,⁵ and 2003⁶ and were conducted by the Joint Health Surveys Unit (JHSU) of the National Centre for Social Research (NatCen) and the Department of Epidemiology and Public Health at University College London (UCL). In 2003, the JHSU collaborated with the MRC/CSO Social and Public Health Sciences Unit based in Glasgow (MRC/CSO SPHSU). The 2008-2011 surveys were conducted by a collaboration between ScotCen Social Research, the MRC/CSO SPHSU and UCL.

Topics

Each survey in the series consists of main questions and measurements (for example, anthropometric and, if applicable, blood pressure measurements and analysis of blood and saliva samples), plus modules of questions on specific health conditions. The principal focus of the 2008-2011 surveys was cardiovascular disease (CVD) and related risk factors. The main components of CVD are coronary heart disease (CHD) and stroke. As noted in Chapter 8, CHD is Scotland's second biggest cause of death and is the focus of a significant number of health policies, many of which have a specific emphasis on reducing the significant health inequalities associated with CVD in Scotland. The SHeS series means that there are now trend data going back for over a decade, and providing the time series is an important function of the survey.

Many of the key behavioural risk factors for CVD are in themselves of particular interest to health policy makers and the NHS. For example, smoking, poor diet, lack of physical activity, obesity and alcohol misuse are all the subject of specific strategies targeted at improving the nation's health. SHeS includes detailed measures of all these factors and these are reported on separately in Chapters 3-7.

Sample design

The sample covering the four year period 2008-2011 was designed to provide data, at both national and Health Board level, about the population living in private households in Scotland. Each single year of the survey has been designed to provide estimates at the national level. The survey used a multi-stage stratified probability sampling design, with data zones (or groups of data zones) selected at the first stage and addresses (delivery points) at the second.

Prior to 2008 the samples were designed to ensure that the sample size was sufficiently large within seven regions based on aggregations of Health Boards for the purpose of regional analysis. When the survey moved to an annual basis in 2008, it was designed to produce a large enough sample to allow NHS Board analysis every four years. The publication of the 2011 data provides the first opportunity since 2003, to publish results for all fourteen NHS Boards in Scotland.

Two samples were selected for the survey: a general population (main) sample in which all adults and up to two children were eligible to be interviewed in each household; and a child boost sample in which up to two children were eligible to be interviewed but adults were not.

The sample of addresses was selected from the small user Postcode Address File (PAF). This is a list of nearly all the residential addresses in Scotland and is maintained by The Royal Mail. The population surveyed was therefore people living in private households in Scotland. People living in institutions, who are likely to be older and, on average, in poorer health than those in private households, were not covered. This should be considered when interpreting the survey estimates. The very small proportion of households living at addresses not on PAF (less than 1%) was not covered.

Data collection

Interviewing was conducted using Computer Assisted Personal Interviewing (CAPI). Children aged 13-15 were interviewed in the presence of a parent or guardian. Parents answered on behalf of younger children, who were nevertheless required to be present.

In addition, those aged 13 and over were asked to complete a short paper questionnaire on more sensitive topics. There were four such booklets: one for adults aged 18 and over, one for young adults aged 16-17 (with the option of using it for those aged 18-19 at the interviewer's discretion), and one for teenagers aged 13-15. Parents of children aged 4-12 years, included in the sample, were also asked to fill in a self completion booklet about the child's strengths and difficulties designed to detect behavioural, emotional and relationship difficulties in children.

Interviewers were also responsible for measuring the height and weight of participants aged 2 and over. For adults, these measurements are reported in Chapter 7, while child measurements are presented in Volume 2 Chapter 5.

Finally, in a sub-sample of households, interviewers sought permission from adults (aged 16 and over) for a follow-up visit by a specially trained survey nurse. At the nurse interview, participants were asked about their use of prescribed medication and recent experiences of food poisoning and stress, anxiety and depression. The nurse then took the blood pressure and waist and hip measurements for all aged 16 and over, and measured the arm length (demi-span) for those aged 65 and over. Lung function was measured via a spirometer. With written agreement, a small sample of blood was taken by venepuncture. The blood sample was analysed for: total and HDL-cholesterol, c-reactive protein, fibrinogen, glycated haemoglobin and vitamin D.⁷ Nurses also sought agreement for the storage of a small sample of blood for possible future analysis. Samples of saliva and urine were also collected. Further details of these samples and measurements are available in the Glossary.

Survey response and sample sizes

The following table sets out the numbers of participating households and adults in the four most recent survey years. It also presents response rates for each year. Further details of all the 2011 figures are presented in Volume 3 of this report, information about the 2008, 2009 and 2010 surveys can be found in the technical reports accompanying the annual reports.^8,9,10

	2008	2009	2010	2011
Numbers participating:
Participating households (main & health board boost sample)	4,139	4,872	4,776	5,010
Adult interviews	6,465	7,531	7,245	7,544
Adults eligible for nurse sample	1,878	2,205	2,199	2,224
Adults who saw a nurse	1,123	1,115	1,063	972
Adults who gave a blood sample	903	885	843	725
Response rates:
% of all eligible households (main & health board boost sample)	61%	64%	63%	66%
% of all eligible adults	54%	56%	55%	56%

Data

Since addresses and individuals did not all have equal chances of selection, the data have to be weighted for analysis. SHeS comprises of a general population (main sample) and a boost sample of children screened from additional addresses. Therefore slightly different weighting strategies were required for the adult sample (aged 16 or older) and the child main and boost samples (aged 0-15). Different weights were also created for the various combined datasets (described below). These are described in full in Volume 3.

The 2011 SHeS data will be deposited at the Data Archive at the University of Essex, from where earlier years' datasets and combined years datasets can also be obtained.

This report

This report is based on data collected in all the survey years to date (1995, 1998, 2003, and 2008 to 2011). It takes advantage of the continuous sample design since 2008 to include analysis based on a number of pooled datasets:

• The 2008, 2009, 2010 and 2011 surveys combined - this enables more detailed analysis of sub-groups to be conducted, for example by age group or socio-economic groups.
• The 2008/2009 and 2010/2011 surveys combined - these enable short-term trends to be examined, while still providing greater precision for the estimates than is the case with the single years' figures.
• The 2009 and 2011 surveys combined - some topics, such as accidents, were only included in the 2009 and 2011 survey years. The combined sample allows more detailed reporting of sub-group differences.

The 2011 SHeS report consists of three volumes, published as a set as 'The Scottish Health Survey 2011.' Volume 1 presents results for adults and covers the topics listed below; Volume 2 presents results for children and Volume 3 provides methodological information and survey documentation. These three volumes are available on the Scottish Government's SHeS website along with a short summary report of the key findings from Volumes 1 and 2. A set of web tables and an interactive mapping tool breaking down the key results by NHS Board are also available on the survey website. (www.scotland.gov.uk/scottishhealthsurvey).

Volume 1 contents: Adults

1. General health and mental wellbeing
2. Dental health
3. Alcohol consumption
4. Smoking
5. Diet
6. Physical activity
7. Obesity
8. Cardiovascular disease, diabetes and hypertension

While preparing the SHeS chapter on lung function some anomalous results were apparent and, as a consequence, the decision was taken to withdraw the chapter from this report to allow a full investigation of these anomalies to be carried out. A separate topic report on lung function will be published in winter 2012.

As in all previous SHeS reports, data for men and women are presented separately. Many of the measures are also reported for the whole adult population. Survey variables are tabulated by age groups and, usually, Scottish Index of Multiple Deprivation (SIMD), National Statistics Socio-Economic Classification (NS-SEC), and equivalised household income. Trend data are presented, where possible, from the seven surveys in the SHeS series (1995, 1998, 2003, 2008, 2009, 2010 and 2011). In some cases trend data are restricted to those aged 16-64 (the age range common to all seven surveys), for some measures trends are available for the 16-74 age range (common to the 1998 survey onwards). Trends based on the surveys from 2003 onwards can be presented for all adults aged 16+.