Fundamental causes of colorectal cancer mortality in the United States: Understanding the importance of socioeconomic status in creating inequality in mortality

Objectives. We used the fundamental cause hypothesis as a framework for understanding the creation of health disparities in colorectal cancer mortality in the United States from 1968 to 2005. Methods. We used negative binomial regression to analyze trends in countylevel gender-, race-, and age-adjusted colorectal cancer mortality rates among individuals aged 35 years or older. Results. Prior to 1980, there was a stable gradient in colorectal cancer mortality, with people living in counties of higher socioeconomic status (SES) being at greater risk than people living in lower SES counties. Beginning in 1980, this gradient began to narrow and then reversed as people living in higher SES counties experienced greater reductions in colorectal cancer mortality than those in lower SES counties. Conclusions. Our findings support the fundamental cause hypothesis: once knowledge about prevention and treatment of colorectal cancer became available, social and economic resources became increasingly important in influencing mortality rates.