An overview of methods for monitoring social disparities in cancer with an example using trends in lung cancer incidence by area-socioeconomic position and race-ethnicity, 1992-2004

Abstract

The authors provide an overview of methods for summarizing social disparities in health using the example of lung cancer. They apply four measures of relative disparity and three measures of absolute disparity to trends in US lung cancer incidence by area-socioeconomic position and race-ethnicity from 1992 to 2004. Among females, measures of absolute and relative disparity suggested that area-socioeconomic and race-ethnic disparities increased over these 12 years but differed widely with respect to the magnitude of the change. Among males, the authors found substantial disagreement among summary measures of relative disparity with respect to the magnitude and the direction of change in disparities. Among area-socioeconomic groups, the index of disparity increased by 47% and the relative concentration index decreased by 116%, while for race-ethnicity the index of disparity increased by 36% and the Theil index increased by 13%. The choice of a summary measure of disparity may affect the interpretation of changes in health disparities. Important issues to consider are the reference point from which differences are measured, whether to measure disparity on the absolute or relative scale, and whether to weight disparity measures by population size. A suite of indicators is needed to provide a clear picture of health disparity change.

FIGURE 1

Age-adjusted (year 2000 standard) incidence of lung cancer in those aged 45 years or more among socioeconomic (left) and race-ethnic (right) groups, by gender, United States, 1992–2004. Top panels, females; bottom panels, males. NH, non-Hispanic; AI/AN, American Indian/Alaska Native; API, Asian/Pacific Islander.

FIGURE 2

Percent change since 1992 in the US absolute concentration index (ACI), between-group variance (BGV), and rate difference (RD) as measures of absolute area-socioeconomic disparity (left), as well as the index of disparity (IDisp), relative concentration index (RCI), rate ratio (RR), and mean log deviation (MLD) as measures of relative area-socioeconomic disparity (right) in lung cancer incidence. Top panels, females; bottom panels, males.

FIGURE 3

Percent change since 1992 in the US between-group variance (BGV) and rate difference (RD) as measures of absolute race-ethnic disparity (left), as well as the index of disparity (IDisp), mean log deviation (MLD), Theil index (TI), and rate ratio (RR) as measures of relative race-ethnic disparity (right) in lung cancer incidence. Top panels, females; bottom panels, males.