180 likes | 262 Views
The National Surveys Linkage Project. Dr Roger Harrison, Bolton PCT & EPHU Prof. Heller, EPHU Prof. Baker & Mr Barrow, IPHRP. Linking Data: Understanding the past and looking into the future. May 7 th 2004. National Survey of Surveys.
E N D
The National Surveys Linkage Project Dr Roger Harrison, Bolton PCT & EPHU Prof. Heller, EPHU Prof. Baker & Mr Barrow, IPHRP Linking Data: Understanding the past and looking into the future. May 7th 2004
National Survey of Surveys • To find out how many population based health/lifestyle surveys carried out • Limited to n>3,000 & post 1989 • Area-based limitation to LA Borough/PCT or Region • Postal questionnaire to all DPH & Information Analysts in PCTs & PH Observatories • Conducted in November 2003
National Survey of Surveys • @ 300 organisations were sent a questionnaire • 62 returned (20%) • 53 individual surveys identified • Sample size in each survey 3,000 to 25,000 • Individual response rates from 30% to 70%
National Survey of Surveys • Coverage: extremes of North & South • Providing a total sample size of @250,000 adultsat the level of the general population
Where is the data? • Information remains isolated within each locality • Data/information restricted to ‘internal’ access • Often not published in scientific/academic literature • Until now, no previous attempt to merge individual survey data sets • ?? Huge loss of information potential
Survey similarities? • Most surveys used an in-house questionnaire • Questions often based on national surveys • Some developed by the same academic unit • Some begged/borrowed/stealed from previous localities
Survey similarities FHSA/GP Register Postal Questionnaire Social class Social capital Neighbourhood aspects Physical activity Diet Smoking Use of health/social services Age Sex Ethnicity General health Specific health Mental health
Detailed survey-content Detailed analysis of 20 survey instruments obtained confirmed similarities • For example, the surveys had information on: • Sex (19 of 20) • BMI (17 of 20) • Smoking (18 of 20) Alcohol intake p.w (19 of 20) Fruit/veg intake p.w. (17 of 20) Physical activity (19 of 20)
Missed opportunities with individual surveys • No storage of postcodes • Analysis by social deprivation may not be possible • No storage of person-identifiers such as NHS number • Not possible to link with morbidity/mortality datasets (eg. NHS Mortality Flagging) • No previous or future linkage with same subjects in repeat surveys • Failure to gain benefits from longitudinal analyses
Lost opportunities from non-comparative analyses • Larger n = power + precision • Particular benefit for minority groups/specific issues not powered in relatively smaller surveys • Possibilities for benchmarking • To influence/improve local service provision • Exploration of differences/similarities in health & lifestyle associations • To increase understanding of factors influencing health/well-being • Examining the impact of ‘natural experiments’ • To inform the effectiveness of interventions in the ‘real world’
“that’s another fine mess we’re in!” ? Feasibility
Area level data National/local policies Type & extent of service provision Service use Additional demographics Individual surveys Outcomes Morbidity Mortality Service use Repeated/longitudinal analysis
Service/investigator support World Wide Web Guides on Methodology Sample size Question selection Analysis Outputs Automated analysis Cross-survey comparisons Question Bank UK Data Archive Data entry interface