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. Link and Phelan have developed and presented the theory based on the relationship between SES and health outcomes, but have noted that many combinations between an independent variable and sets of dependent variables are possible as long as the required components are fulfilled.

Key components

According to Link and Phelan, a fundamental social cause of health inequalities has four key components:

The cause influences multiple disease outcomes

The cause affects disease outcomes through multiple risk factors.

The cause involves access to resources that can assist in avoiding health risks or to minimize the sequelae of disease once it occurs.

"The association between a fundamental cause and health is reproduced over time via the replacement of intervening mechanisms"

By these criteria, SES is a fundamental cause for healthcare disparities.

Previous school of thought on health disparities

Health has been linked to social class dating back to the early 19th century, when the French tracked mortality in connection with areas of poverty. Similarly, the English began documenting mortality by occupation in the mid-1800s. In the United States, more attention was paid to racial connections to health disparities up until 1973, when Evelyn M. Kitagawa and Philip Hauser published a report connecting SES to increased morbidity and mortality.