Educational differences in chronic conditions and their role in the educational differences in overall mortality

Abstract Demographers use different models to decompose the prevalence of given health conditions. This article discusses how these models can help us understand the ways in which these conditions affect overall mortality. In particular, this framework can be used to understand the role that any given condition plays in producing differences in overall mortality across populations. The empirical analysis in this study focuses on chronic conditions as factors behind elderly US citizens' differences in overall mortality across educational levels. The analysis of differences by education level shows that while the prevalence differences of chronic conditions is mostly the outcome of incidence differences, regarding overall mortality differences, the role of chronic conditions is equally channelled through incidence and excess mortality differences. (ProQuest: ... denotes formulae omitted.) 1. Introduction Existing research on the relationship between education and mortality presents robust evidence that death rates are higher among individuals with lower levels of education.2 This phenomenon is observable during an individual's whole life span3 and increases over time.4 Furthermore, the correlation exists at all income distribution levels (Smith 2005.) Although part of the mortality and health gradient has not been attributed to any specific factor,5 there is an extensive body of research dealing with the wide range of conditions that allegedly underlie the education-mortality relationship. In fact, the vast majority of conditions that influence mortality are also linked to education, in terms of their incidence rates and their associated excess mortality rates. Several studies focus on decomposing differentials in the prevalence of a given condition across population groups, which are seen as the outcome of differentials on the condition's incidence and excess mortality. This study emphasises that this analysis can be extended to the differentials of overall mortality, with the aim of better understanding the impact of any given condition in overall mortality across gender, location, race or educational level. Demographers and epidemiologists make use of multi-state life tables6 to simulate prevalence dynamics. These enable the differences in the prevalence of any condition across populations to be simulated as the outcome of differences in underlying incidence and mortality rates. Examples of this are Leveille et al. (2000) and Melzer et al. (2001) for gender and educational differences in the prevalence of disability, and Lipscombe and Hux (2007) for time differences in the prevalence of diabetes in Canada. The idea behind this analysis has been extended even further, for example, to the study of car accidents (where the "states" are defined by the action of driving in Dellinger et al. 2002); the study of the existence of disability given a chronic condition (Freedman et al. 2007) or to better portray the dynamics of entry and exit from states of depression through life (Patten and Lee 2005). Another extension is to simulate the dynamics of overall mortality, which arises from the same model as that of prevalence, as discussed in Section 2.1, 2.2, and 2.3. In other words, the demographic rates behind the prevalence of any given condition are also the components behind the condition's influence on the overall mortality rate. One important lesson is that while one component may have the greatest influence on prevalence, it may not be the most important way in which the condition affects overall mortality. The empirical contribution of this study focuses on the role of chronic conditions in US educational differences in mortality. The most common causes of death in the developed world are associated with chronic diseases. The U.S. Centers for Disease Control and Prevention states that, according to Kung et al. (2008): "7 out of 10 deaths among Americans each year are from chronic diseases and heart disease, cancer and strokes account for more than 50% of all deaths each year". …