The Scottish Health Survey-Scottish Morbidity Record Linked Datasets:Introduction to a new resource

Peter Craig

Chief Scientist Office

Outline

• The Scottish Health Surveys

• The Scottish Morbidity Record Linked Datasets

• The SHS-SMR Linked Datasets

• Examples

• Further information and access to the data

The Scottish Health Surveys

• Aims: to measure the health of the Scottish population, and to monitor changes in health, with a particular emphasis on cardiovascular disease and its risk factors

• Three surveys carried out so far, in 1995-6, 1998-9 and 2003-4, and a fourth in progress

SHS - Design

• Repeated cross-sectional survey, using a stratified, clustered random probability sample of individuals living in private households

• Covers the whole of mainland Scotland plus the larger inhabited islands

• Two-stage data-gathering: interview followed by a nurse visit

SHS - contentHealth: self-assessed general health, limiting longstanding illness, acute sickness; CVD and use of health services; respiratory health; asthma; accidents; food poisoning; use of dental services; psychosocial health (GHQ, SDQ*), health-related quality of life (SF-12)*

Health behaviours: physical activity; eating habits; smoking; drinking; use of prescribed drugs, contraceptive pill, vitamin supplements and NRT; immunisations*; breastfeeding*; exposure to environmental tobacco smoke

Measurements: height (length, demispan), weight; blood pressure; waist, hip, mid-upper arm circumference; salivary cotinine; blood analytes (total and HDL cholesterol, C-reactive protein, total and house dust mite specific IgE, etc.); urinary sodium*†, ECG*†

*2003 only †subsample only

SHS - Content

Household characteristics: size, composition, relationships; tenure, car ownership; receipt of state benefits; income*; economic status/occupation of household reference person*; Carstairs score; SIMD*

Individual characteristics: age, sex; economic status, occupation; education (age left FTE, highest qualification); ethnic background, religion*; parental social class*; parental history of CVD

*2003 only

SHS - changes

• Content extended: household income; parental social class; fruit and vegetable consumption; HRQoL; SDQ; urinary sodium; ECG

• Age range extended from 16-64 (1995) to 2-74 (1998) to all ages (2003)

• Design modified– 1995, 1998 one adult per household interviewed– 2003 interviews attempted with all adults

SHS – non-response and weighting

1995 1998 2003

Household - - 67

Individual interview

81 76 60

Nurse visit 71 63 40

SHS – non-response and weighting

Weights• 1995, 1998 – single interview weight to take account of

– disproportionate sampling within health regions– differing probabilities of selection within households of different

sizes and within multi-occupied addresses– differential non-response

• 2003 – interview, nurse visit and blood weights to take account of– disproportionate sampling within health regions– differing probabilities of selection within multi-occupied

addresses– differential non-response at each stage of data-gathering

The SMR Linked Datasets

• Records of hospital episodes (date of admission and discharge, diagnosis, etc.) linked to provide individual patient-based records

• Contains information on acute and psychiatric hospital episodes, cancer registrations and deaths in Scotland from 1981-present

SHS-SMR Linked Datasets

SHS Survey data + encrypted serial number

Names, postcodes, DoBs + encrypted serial number

National Centre for Social Research

SMR01 data + encrypted serial number

SHS Survey data + SMR01 data

SHS-SMR Linked Datasets

• Currently include hospital episodes and deaths up to Sept 2006 and cancer registrations to December 2004– Minimum datasets contain all survey data plus

summary of SMR data – freely available– Full datasets contain survey data plus

specified fields from the SMR01 catalogue – available subject to PAC approval

The ‘minimum datasets’

• All survey data for respondents who consent to linkage

• Summary of SMR data– Death: date, cause– Psychiatric admissions: total number; date and

diagnosis of 1st admission– Cancer registrations: total number; date and diagnosis

of 1st registration for a range of sites– Cardiovascular disease: total numbers of AMI, CHD,

stroke, angiography, PCTA, and CABG admissions; date of 1st admission for each cause

• Emigration status

SHS-SMR Linked Datasets

1995 1998 2003

Cases 7363 8305 10470

Cancer registrations 560 755 500

Cancer registrations post survey 389 455 70

CHD admissions 367 531 441

CHD admissions post survey 291 330 121

Psych hospital admissions 260 300 167

Psych hosp. admissions post survey 147 140 35

Deaths 442 618 208

Deprivation quintile

Hazard ratio

Lower CI

Upper CI

P value

Highest 1.00

2 1.33 0.99 1.79 0.058

3 1.48 1.11 1.96 0.007

4 1.73 1.29 2.32 0.000

Lowest 1.93 1.45 2.56 0.000

Self-assessed health

Hazard ratio

Lower CI

Upper CI

P value

Very good 1.00

Good 1.44 1.11 1.87 0.006

Fair 3.10 2.41 3.98 0.000

Poor 4.98 3.75 6.62 0.000

Very poor 5.80 3.62 9.28 0.000

SHS-SMR Linked Datasets

• Strengths– Large, nationally representative samples– Numbers of events continually increasing– Easily accessible

• Weaknesses– Non response and missing data– Exposure data not updated– Outcomes restricted to ‘major events’

SHS-SMR linked datasets

• Examples of current uses– Modelling impact of public health interventions on

health inequalities– Self-reported alcohol consumption and alcohol-related

hospital admission– Social, biological and behavioural risk factors for

hospital admission and death– Psychological distress as a predictor of

cardiovascular disease and mortality– Developing models of cardiovascular risk and benefit

to improving prescribing decisions

Further information

To find out about the Scottish Health Surveywww.scotland.gov.uk/Topics/Statistics/Browse/Health/scottish-health-survey

To access the survey datawww.data_archive.ac.uk

To access the linked datasets, contactCatherine.storey@isd.csa.scot.nhs.ukDavid.clark@isd.csa.scot.nhs.uk