Theory of fundamental causes

In 1995, Jo C. Phelan and Bruce G. Link developed the theory of fundamental causes. This theory seeks to outline why the association between socioeconomic status (SES) and health disparities has persisted over time, particularly when diseases and conditions previously thought to cause morbidity and mortality among low SES individuals have resolved. The theory states that an ongoing association exists between SES and health status because SES '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.' In other words, despite advances in screening techniques, vaccinations, or any other piece of health technology or knowledge, the underlying fact is that those from low SES communities lack resources to protect and/or improve their health.According to Link and Phelan, a fundamental social cause of health inequalities has four key components:In the 19th century, the major causes of mortality were typically infectious diseases, as well as diseases that resulted from poor sanitation and crowded living conditions. In 1900, the top three causes of death were pneumonia, tuberculosis, and diarrhea. These conditions have been largely eradicated thanks to the development of antibiotics, vaccinations, sewage management systems, and improved education regarding sanitation and food handling. Because lower SES individuals were more likely to live in crowded, unsanitary conditions, it was thought that the improvement of these conditions would lead to an improvement in health. However, disparities in healthcare and health outcomes have persisted.Link and Phelan state that the key resources that lower SES individuals lack include knowledge, money, power, prestige, and beneficial social connections. At a given SES level, this lack of resources persists despite what other factors, beneficial or not so, are at play.A final key part of the theory is the persistence of resource disparities that perpetuate unequal health outcomes, despite intervening mechanisms that may otherwise appear to improve health status. An example of this is the Pap smear for cervical cancer screening. Since the development of the Pap smear in the 1940s, a disparity has existed in utilization of this screening test given differences in resources mentioned above. Another example is the polio vaccine. Prior to the vaccine, polio could afflict people of all socioeconomic classes. Once the vaccine became available, it was primarily accessible by those who possessed the resources to obtain it. We also see an example of this in colorectal cancer, in which the variable diffusion has role in the theory; in which diffusion has reduced mortality, but not enough to eliminiate SES inequalities as seen in Wang et al. 2012.