Autoimmune diseases are a group of disorders in which the immune system attacks the body and destroys or alters tissues. There are more than 80 serious chronic illnesses in this category, including lupus, multiple sclerosis, and type 1 diabetes. According to the American Autoimmune Related Diseases Association (AARDA), about 75% of autoimmune diseases occur in women. By themselves, each disease appears to be uncommon except for diabetes, thyroid disease, and lupus but as a group, the disorders make up the fourth-largest cause of disability among American women.
The meaning of health has evolved over time. In keeping with the biomedical perspective, early definitions of health focused on the theme of the body's ability to function; health was seen as a state of normal function that could be disrupted from time to time by disease. An example of such a definition of health is: "a state characterized by anatomic, physiologic, and psychological integrity; ability to perform personally valued family, work, and community roles; ability to deal with physical, biological, psychological, and social stress". Then in 1948, in a radical departure from previous definitions, the World Health Organization (WHO) proposed a definition that aimed higher: linking health to well-being, in terms of "physical, mental, and social well-being, and not merely the absence of disease and infirmity". Although this definition was welcomed by some as being innovative, it was also criticized as being vague, excessively broad and was not construed as measurable. For a long time, it was set aside as an impractical ideal and most discussions of health returned to the practicality of the biomedical model.