A comparison of individual and area-based socio-economic data for monitoring social inequalities in health.

Background: Area-based indicators are commonly used to measure and track health outcomes by socioeconomic group. This is largely because of the absence of socio-economic information about individuals in health administrative databases. The literature shows that the magnitude of differences in health outcomes varies depending on whether the socio-economic indicators are at the individual level or are area-based. This study compares the two types of indicators.

Data And Methods: The data are from a file linking the results of the 1991 Census with deaths that occurred from 1991 to 2000--a 15% sample of the Canadian population aged 25 or older. The socio-economic indicator used for comparison is a material and social deprivation index, in individual and area-based versions. The health indicators are life expectancy and disability-free life expectancy, and risks of mortality and disability.

Results: The individual version of the deprivation index yields wider gaps in life expectancy and disability-free life expectancy than does the area-based version. These gaps vary by sex and geographic setting. However, both versions are associated with inequalities in mortality and disability, independent of each other.

Interpretation: Despite some limitations, area-based socioeconomic indicators are useful in assessing inequalities in health. The inequalities that they identify are significant, consistent and reliable and can be tracked through time and for different geographic settings.