Scottish Health Survey 2015 - volume 1: main report

Introduction

Stephen Hinchliffe and Diarmid Campbell-Jack

Policy Context
Health features prominently in the Scottish Government's National Performance Framework ( NPF) ^[1,2] . The Government's core purpose, to create a more successful Scotland, is underpinned by five strategic objectives, one of which is to create a healthier Scotland. The objective is driven, in part, by the recognition of the considerable need to help people to sustain and improve health, 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.

Many of the National Indicators that track progress towards the national outcomes have relevance to health ^[2] . The Scottish Health Survey ( SHeS) is used to monitor progress towards the following National Indicators:

Improve mental wellbeing

Increase physical activity

Improve self-assessed general health

Increase the proportion of healthy weight children

Reduce the percentage of adults who smoke.

In addition, the purpose target to improve healthy life expectancy over the 2007 to 2017 period uses SHeS data for children (aged 0-15) in the calculations used to measure progress.

As a study of public health, the Scottish Health Survey 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 included in this volume addresses an aspect of health that relates either directly or indirectly to the Government's objective of improving the health of the people living in Scotland.

The Scottish Health Survey Series

The survey has been carried out annually since 2008 and prior to this was carried out in 1995 ^[3] , 1998 ^[4] , and 2003 ^[5] . The 2015 survey was the eleventh in the series.

Commissioned by the Scottish Government Health Directorates, the series provides regular information on aspects of the public's health and factors related to health which cannot be obtained from other sources. The SHeS series was designed to:

• estimate the prevalence of particular health conditions in Scotland
• estimate the prevalence of certain risk factors associated with these health conditions and to document the pattern of related health behaviours
• look at differences between regions and between subgroups of the population in the extent of their having these particular health conditions or risk factors, and to make comparisons with other national statistics for Scotland and England
• monitor trends in the population's health over time
• make a major contribution to monitoring progress towards health targets.

Each survey in the series includes a set of core questions and measurements (height and weight and, if applicable, blood pressure, waist circumference, urine and saliva samples), plus modules of questions on specific health conditions that vary from year to year. Each year the core sample has also been augmented by an additional boosted sample for children. Since 2008 NHS Health Boards have also had the opportunity to boost the number of adult interviews carried out in their area.

The 2012-2015 surveys were carried out by ScotCen Social Research, the MRC/ CSO Social and Public Health Sciences Unit ( MRC/ CSO SPHSU) based in Glasgow, The Centre for Population Health Sciences at the University of Edinburgh and The Public Health Nutrition Research Group at Aberdeen University.

The 2015 Survey

Topics

Cardiovascular disease ( CVD) and related risk factors remains the principal focus of the survey. The main components of CVD are ischaemic heart disease ( IHD) (or coronary heart disease) and stroke, both of which have been identified as clinical priorities for the NHS in Scotland ^[6,7,8] . Diseases of the circulatory system are the second most common causes of death in Scotland after cancer, accounting for 27% of deaths in 2015. This includes 12% of deaths which are caused by IHD, with a further 7% caused by cerebrovascular disease (e.g. stroke) ^[9] . Early mortality from heart disease and stroke have also both improved in recent years (surpassing targets in both cases), but concern remains about continuing inequalities in relation to morbidity and mortality linked to these conditions ^[6] . The SHeS series now has trend data going back two decades, and providing time series data remains 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, which are reported on separately in Chapters 4-8. Chapter 9 covers CVD and diabetes. The other chapters report on measures of mental health and wellbeing ( Chapter 1), general health and multiple conditions ( Chapter 2), dental health ( Chapter 3) and injuries / accidents ( Chapter 10).

Sample

The 2012-2015 surveys were designed to yield a representative sample of the general population living in private households in Scotland every year. Estimates at NHS Health Board level are published at the same time as this report for the four-year period.

Those living in institutions, who are likely to be older and, on average, in poorer health than those in private households, were outwith the scope of the survey. This should be borne in mind when interpreting the survey findings.

A random sample of 4,437 addresses was selected from the Postcode Address File ( PAF), using a multi-stage stratified design. Where an address was found to have multiple dwelling units, one was selected at random. Where there were multiple households at a dwelling unit, a single household was selected at random. Each individual within a selected household was eligible for inclusion. Where there were more than two children in a household, two were randomly selected for inclusion, to limit the burden on households.

Three further samples were selected for the survey in 2015: a child boost sample (4,146 addresses) in which up to two children in a household were eligible to be interviewed but adults were not, a Health Board boost sample (1,026 addresses) for those Health Boards which opted to boost the number of adults interviewed in their area, and an additional sample designed to address the shortfall of adult interviews in specific Health Boards (916 addresses).

Fieldwork

A letter stating the purpose of the visit was sent to each sampled address in advance of the interviewer visit. Interviewers sought the permission of each eligible adult in the household to be interviewed, and both parents' and children's consent to interview up to two children aged 0-15.

Interviewing was conducted using Computer Assisted Interviewing ( CAI). The content of the interview and full documentation are provided in Volume 2 of this report.

Adults (aged 16 and over) and children aged 13-15 were interviewed themselves. Parents of children aged 0-12 completed the interview on behalf of their child.

Those aged 13 and over were also asked to complete a short paper self-completion questionnaire on more sensitive topics during the interview. Parents of children aged 4-12 years selected for interview 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.

Towards the end of the interview height and weight measurements were taken from those aged 2 and over.

In a sub-sample of households, interviewers sought permission from adults (aged 16 and over) to take part in an additional 'biological module'. The biological module was administered by specially trained interviewers. In the module, participants were asked questions about prescribed medication and anxiety, depression, self-harm and suicide attempts. In addition, the interviewer also took participants' blood pressure readings and waist measurement as well as samples of saliva and urine. Further details of these samples and measurements are available both in the Glossary and in Volume 2.

Survey response

In 2015, across all sample types, interviews were held in 3,782 households with 5,000 adults (aged 16 and over), and 1,421 children (aged 0-15). 910 adults also completed the biological module. The number of participating households and adults in 2015 is listed in the table below. Further details on survey response in 2015 are presented in Chapter 1, Volume 2.

Main and Health Board boost samples
Participating households	3,301
Eligible households responding	59%
Adult interviews	5,000
Eligible adults responding	52%
Adults eligible for biological module	1,179
Adults who completed biological module	910
Child boost sample
Participating households	481
Eligible households responding	65%
Child interviews (child boost sample only)	738
Child interviews (main and child boost sample combined	1,421

Ethical Approval

Ethical approval for the 2015 survey was obtained from the REC for Wales committee (reference number 12/WA/0261).

Data Analysis

Weighting

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). Additional weights have been created for the biological module and for use on combined datasets (described below). A detailed description of the weights is available in Volume 2, Chapter 1.

Weighted and unweighted data and bases in report tables

All data in the report are weighted. For each table in the report both weighted and unweighted bases are presented. Unweighted bases indicate the number of participants involved. Weighted bases indicate the relative sizes of sample elements after weighting has been applied.

Standard analysis variables

As in all previous SHeS reports, data for men, women, boys and girls are presented separately where possible. Many of the measures are also reported for the whole adult or child population. Survey variables are tabulated by age groups and in some cases also by Scottish Index of Multiple Deprivation ( SIMD) and equivalised household income.

Statistical information

The SHeS 2015 used a clustered, stratified multi-stage sample design. In addition, weights were applied when obtaining survey estimates. One of the effects of using the complex design and weighting is the standard errors for the survey estimates are generally higher than the standard errors that would be derived from an unweighted simple random sample of the sample size. The calculations of standard errors shown in tables, and comment on statistical significance throughout the report, have taken the clustering, stratifications and weighting into account. Full details of the sample design and weighting are given in Volume 2, Chapter 1.

Presentation of trend data

Trend data are presented, where possible, for the eleven surveys in the series to-date (1995, 1998, 2003, 2008-2015). In some cases trend data are restricted to those aged 16-64 (the age range common to all eleven surveys in the series to-date) and for some other measures trends are available for the 16-74 age range (common to the 1998 survey onwards). Trends based on the surveys from 2003 onwards are presented for all adults aged 16 and over. Trends for children are based on the 2-15 years age group from 1998 onwards, and 0-15 years from 2003 onwards.

Presentation of results

Commentary in the report highlights differences that are statistically significant at the 95% confidence level. Statistical significance is not intended to imply substantive importance. A summary of findings is presented at the beginning of each chapter. Each chapter then includes a brief overview of the relevant policy area. These overviews should be considered alongside the higher level policies noted above and related policy initiatives covered in other chapters. A description of the methods and key definitions are also outlined in detail in each chapter. Tables showing the results discussed in the text are presented at the end of each chapter.

Availability of further data and analysis

As with surveys from previous years, a copy of the SHeS 2015 data will be deposited at the UK Data Archive along with copies of the combined datasets for 2013/2015, 2014/2015 and 2012/2013/2014/2015. In addition, trend tables showing data for key variables are available on the Scottish Government SHeS website along with a detailed set of web tables for 2015, providing analysis by age, area deprivation, socioeconomic classification, equivalised income and long-term condition for a large range of measures.

Comparability with other UK statistics

The National Statistician commissioned a piece of work to examine comparability and coherency between official statistics published by the four nations of the UK with the aim of ensuring there was clarity on the suitability of comparability across the UK. The review was carried out by a Government Statistical Service ( GSS) Task and Finish Group on Comparability ( TFG). The findings, published in a Government Statistical Service publication ^[11] , include guidance on comparing statistics on three of the topics included in this report: alcohol consumption ( chapter two), smoking ( chapter three) and obesity ( chapter six). Further guidance on the comparability of statistics across the UK on these topics is included in the introductory section of each of the relevant chapters.

Content of This Report

This volume contains chapters with substantive results from the SHeS 2015, and is one of two volumes based on the survey, published as a set as 'The Scottish Health Survey 2015':

Volume 1: Main Report

1. Mental health and wellbeing
2. General health and multiple conditions
3. Dental health
4. Alcohol
5. Smoking
6. Diet
7. Physical activity
8. Obesity
9. Cardiovascular conditions and diabetes
10. Injuries / Accidents

Volume 2: Technical Report

Volume 2 includes a detailed description of the survey methods including: survey design and response; sampling and weighting procedures; and, information on laboratory analysis of urine and saliva samples.

Both volumes are available from the Scottish Government's SHeS website. A summary report of the key findings from the 2015 report and a set of web tables are also available on the survey website: www.gov.scot/scottishhealthsurvey.