Scottish Longitudinal Study
Development & Support Unit
Area-based versus Individual measures of socioeconomic background – How do they compare in predicting cancer incidence?
Katharine Sharpe (NHS Information Services Division)
David Conway (University of Glasgow)
David Brewster (Scottish Cancer Registry)
Alex McMahon (University of Glasgow)
Approved on 13-10-2009
Socioeconomic differences in cancer risk exist as evidenced by ISD cancer statistics and measured by area-based indicators such as the Scottish Index of Multiple Deprivation (SIMD) and Carstairs. Site specific age standardised incidence rates by SIMD 2006 quintiles show that there are positive, negative and neutral socioeconomic (SE) gradients depending on the site.
As noted in several reviews on SE gradients and health, consistency and strength of associations between SE status and morbidity and mortality within and across countries attest to the validity of the indicators and the degree the relatively crude indicators must be tapping some underlying construct that powerfully influences health. However, the relation of cancer risk and various components of SE status are not well understood and are most frequently studied at area level.
This may suggest area-based measures are not sensitive enough. Individual indicators of SE status may prove to be better indicators of deprivation and better predictors of observed health status; the relative role of area-based and individual indicators in explaining observed health status is debated.
Geographic area based SE indices result in all people living in a particular area being allocated the same SE score. Individual indicators of deprivation may prove to be better indicators of deprivation and better predictors of cancer incidence or provide insight additional to that provided by area-based deprivation indices.
The long, variable lag time between exposure and carcinogenesis suggests that to understand cancer risk, it is relevant to compare trends over time. Different approaches (closest to diagnosis or earliest point) and which indicator (area-based v. individual) can be evaluated to establish best predictor of cancer risk.
To date, little work has been done in Scotland exploring differences between area-based and individual SE measures in their ability to predict and inform the aetiology of cancer incidence.
The over arching aim of this study is to identify which socioeconomic factors (area and individual) are the most important determinants of cancer risk and are there interactions between the factors. Two related aims are:
- How area-based measures (Carstairs and SIMD) compare to individual level socioeconomic factors in predicting cancer incidence rates.
- If and how the relationship between socio-economic background and cancer incidence changes over time and if the time reference of socio-economic background affects ability to predict cancer incidence rates.
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