“Fundamental Causes” of Social Inequalities in Mortality: A Test of the Theory

Abstract

Medicine and epidemiology currently dominate the study of the strong association between socioeconomic status and mortality. Socioeconomic status typically is viewed as a causally irrelevant "confounding variable" or as a less critical variable marking only the beginning of a causal chain in which intervening risk factors are given prominence. Yet the association between socioeconomic status and mortality has persisted despite radical changes in the diseases and risk factors that are presumed to explain it. This suggests that the effect of socioeconomic status on mortality essentially cannot be understood by reductive explanations that focus on current mechanisms. Accordingly, Link and Phelan (1995) proposed that socioeconomic status is a "fundamental cause" of mortality disparities-that socioeconomic disparities endure despite changing mechanisms because socioeconomic status embodies an array of resources, such as money, knowledge, prestige, power, and beneficial social connections, that protect health no matter what mechanisms are relevant at any given time. We identified a situation in which resources should be less helpful in prolonging life, and derived the following prediction from the theory: For less preventable causes of death (for which we know little about prevention or treatment), socioeconomic status will be less strongly associated with mortality than for more preventable causes. We tested this hypothesis with the National Longitudinal Mortality Study, which followed Current Population Survey respondents (N = 370,930) for mortality for nine years. Our hypothesis was supported, lending support to the theory of fundamental causes and more generally to the importance of a sociological approach to the study of socioeconomic disparities in mortality.

The social side of accidental death

“…Though not a focus of their analyses, the preventability rankings produced by Phelan and colleagues (see Appendix A of Phelan et al 2004) show that accidental deaths display variability in their preventability; a claim supported in the injury prevention literature (Barss et al 1998).…”

“…Systematic investigations of the fundamental role of social factors on mortality risk have primarily focused on SES (Phelan and Link 2005;Phelan et al 2004). However, a similar set of arguments follows for those who maintain solid social relationships, such as those found in family settings, which hold substantial potential for social support.…”

“…Accidental deaths by poisoning and fire represent the most preventable, air and water transport accidents represent the least preventable, 1 and motor vehicle deaths, falls, and drowning lie in between the least and most preventable forms of accidental death (Phelan et al 2004). …”

“…Second, we provide an empirical test of the fundamental cause perspective by examining relationships between marital status and SES on more and less preventable forms of accidental death. The theory predicts that marital status and SES should be more relevant for more preventable than for less preventable unintentional injuries leading to death (Link and Phelan 1995;Phelan et al 2004). …”

“…2 Some causes, such as air and water, drownings, and fire or smoke related include fewer than 200 deaths. However, including these causes separately rather than combining them is justified because of their distinctiveness and because their preventability varies (Phelan et al 2004). …”