Correcting the Concentration Index

Abstract

In recent years attention has been drawn to several shortcomings of the Concentration Index, a frequently used indicator of the socioeconomic inequality of health. Some modifications have been suggested, but these are only partial remedies. This paper proposes a corrected version of the Concentration Index which is superior to the original Concentration Index and its variants, in the sense that it is a rank-dependent indicator which satisfies four key requirements (transfer, level independence, cardinal invariance, and mirror). The paper also shows how the corrected Concentration Index can be decomposed and generalized.

Decomposing socio-economic inequality in colorectal cancer screening uptake in England

“…Making use of rich individual level data, our analyses showed the existence of pro-rich inequalities (CCI: 0.16) in screening uptake with respect to wealth, health literacy region and partner screening status. Despite the scarcity of directly comparable studies using this measure in the UK, our figure appears similar to those of other European countries for uptake of colonoscopy or stool examination, such as Belgium (CCI 0.04), Germany (CCI: 0.126), France 0.135 (but not Denmark, CCI:-0.074) (Carrieri & Wuebker, 2013) and Ireland (CI: 0.069) (Walsh, Silles, & O'Neill, 2012), although the latter estimate did not employ the Erreygers correction (Erreygers, 2009). …”

“…inequalities in ill-health do not 'mirror' those of good health) (Costa-Font, Hernández-Quevedo, & Jiménez-Rubio, 2014). Wagstaff (2005) and Erreygers (2009) have proposed different correction mechanisms to deal with these problems, the former measuring relative inequalities, the latter quasi-absolute inequalities. Given its focus on quasi-absolute inequalities we use the Erreygers (2009) correction, which has also been used in other studies (Costa-Font et al, 2014;VallejoTorres & Morris, 2010), and is given by:…”

Inequity in Dental Care Utilization in the Indonesian Population with a Self-Assessed Need for Dental Treatment

“…This study employed the concentration index for several reasons: (1) it reflects the socioeconomic dimension to inequalities in health; (2) it reflects the experiences of the entire population; (3) it is sensitive to changes in the distribution of the population across socioeconomic groups; (4) its visual representation by means of the concentration curve; (5) and the ease with which it can be decomposed (Wagstaff et al 1991;Erreygers 2009a). Nonetheless, there is still some controversy in the literature regarding which disparity indices meet the most ideal properties (Clarke et al 2002;Erreygers 2009a, b;Wagstaff 2009).…”

Socioeconomic Variations in Induced Abortion in Turkey

“…Concentration indices (Wagstaff et al, 1991;Wagstaff, 2005;Erreygers, 2009a) can be used to measure levels of inequality; however they are unable to highlight the individual factors leading to the inequalities (Wagstaff et al, 2003;O'Donnell et al, 2006). Instead, decomposition methods provide the opportunity of unpacking the individual contributions of socioeconomic factors to the outcome of interest (Wagstaff et al, 2001(Wagstaff et al, , 2003Wildman, 2003;O'Donnell & van Doorslaer, 2006).…”