Choice of indicator is important

EDITOR—The paper by Sacker et al,1 and the associated editorial by Vågerö,2 discuss differences in health inequality between men and women measured with two alternative schemes. We have been investigating a similar problem—the indicators that are most sensitive for measuring health inequalities in an older population.

Sacker et al included only those people in paid work in 1981. The 1981 census shows that 20% of men and 49% of women in the age groups they consider were not working, so this restriction will have resulted in many people in the sample being excluded. Such exclusions are known to result in bias.3 In the older population the use of classifications based on current occupation is problematic. Other common indicators of socioeconomic status, such as income and education, also present difficulties. This is because of the strong association between income and employment status and because most of today's older …