Context: Colorectal cancer is a major cause of mortality in the United States, with 52,857 deaths estimated in 2012. To explore further the social inequalities in colorectal cancer mortality, we used fundamental cause theory to consider the role of societal diffusion of information and socioeconomic status.
Methods:We used the number of deaths from colorectal cancer in U.S. counties between 1968 and 2008. Through geographical mapping, we examined disparities in colorectal cancer mortality as a function of socioeconomic status and the rate of diffusion of information. In addition to providing year-specific trends in colorectal cancer mortality rates, we analyzed these data using negative binomial regression.
Findings:The impact of socioeconomic status (SES) on colorectal cancer mortality is substantial, and its protective impact increases over time. Equally important is the impact of informational diffusion on colorectal cancer mortality over time. However, while the impact of SES remains significant when concurrently considering the role of diffusion of information, the propensity for faster diffusion moderates its effect on colorectal cancer mortality.
Conclusions:The faster diffusion of information reduces both colorectal cancer mortality and inequalities in colorectal cancer mortality, although it was not sufficient to eliminate SES inequalities. These findings have important Address correspondence to: Andrew Wang, Mailman School of Public Health, Columbia University, New York, NY 10032 (email: acw2148@columbia.edu).The Milbank Quarterly, Vol. 90, No. 3, 2012 (pp. 592-618) D espite great medical advances in the prevention and treatment of the major chronic diseases causing the most deaths during the latter half of the twentieth century, socioeconomic disparities in mortality attributable to these conditions have substantially widened over time. One underlying cause of death that exemplifies this longitudinal patterning of death is colorectal cancer. In an effort to deepen our understanding of this perplexing epidemiologic trend, we elaborated on the so-called fundamental cause theory (FCT) (Link and Phelan 1995), including a novel focus on the diffusion of innovations. Specifically, we drew on FCT to suggest that our relatively new capacity to prevent colorectal cancer mortality has not been distributed equally throughout the U.S. population but instead has spread more rapidly to wealthier areas of the country. In addition, we used the observation that some areas tend to adopt innovations more rapidly than others, in order to investigate (1) whether this tendency helps explain how innovations diffuse to wealthier areas of the country; (2) how diffusion exerts its own independent influence on the distribution of mortality; and (3) the extent to which more rapid diffusion modifies the influence of socioeconomic status (SES) on aggregate death rates over time.