A chronic illness usually develops slowly, lasts for an indefinite period of time, can deteriorate overall health and usually requires intervention to resolve. Many chronic diseases are uncertain in prognosis. Cure is problematic or impossible, so treatment concentrates in making the patient comfortable or relieving pain. Sometimes patients suffer from multiple diseases; and the side effects of medical treatments can lead to additional chronicity. Long-time use of drugs, routine monitoring and crisis requiring hospitalization make chronic diseases expensive. The extent to which patients succumb to the various effects of chronic disease depends upon numerous factors, in particular their psycho-social support, financial status, childhood experiences, sense of humour and determination to push on.
In the 19th and early 20th centuries, infectious diseases like polio, tuberculosis and smallpox were put down to one common cause: germs. The germ theory led to improvements in public health, hygiene and ultimately the discovery of antibiotics. As these infectious diseases became less common, chronic diseases sprang up from the 1960s to take their place. But health specialists had no equivalent of a “germ” theory for chronic diseases. This lack of a unifying theory has contributed to the fact scientists who study chronic diseases tend to work (and research) in silos. Some focus on heart disease, kidney problems, respiratory disorders, cancers, diabetes and obesity. The “lifestyle” tag for the causes of chronic disease is one way of overcoming this. But its glib misuse has led to a search for a better alternative cause: "anthropogens", defined as man-made environments, their by-products and/or lifestyles encouraged by these, some of which are detrimental to human health. These include: nutrition, (in)activity,
technopathology, environmental imbalance (external and internal), pollution and degradation, meaningless, alienation and loss of culture and identity, occupational influences, drug dependence, lack of supportive relationships and social inequality.
There is an epidemic of allergic (60 million people), asthmatic (30 million people), and autoimmune disorders (24 million people). Globally, chronic diseases kill about 24 million people a year, and are responsible for half the deaths on the planet. As populations age, the proportion of deaths due to chronic disease will rise.
In 2016, around 60-70% of all deaths and disability in countries like Australia is from heart disease, cancer, respiratory disease and other non-communicable chronic diseases.
In 2001, chronic diseases such as cancer, asthma, Parkinson's, birth defects and diabetes were responsible for 7 out of 10 deaths in the USA. More than a third of the population, over 100 million men, women and children, suffered from one or more chronic illness, such as heart conditions, arthritis, rheumatism, autism, multiple sclerosis, leukaemia and impairments of back and spine. By 2020, studies estimate that chronic disease will afflict 134 million Americans and cost $1 million million a year. The Centers for Disease Control and Prevention estimates that 70% are preventable.