In medicine, a chronic disease is a disease that is long-lasting or recurrent. The term chronic describes the course of the disease, or its rate of onset and development. A chronic course is distinguished from a recurrent course; recurrent diseases relapse repeatedly, with periods of remission in between. As an adjective, chronic can refer to a persistent and lasting medical condition. Chronicity is usually applied to a condition that lasts more than three months. The opposite to chronic is acute.
The definition of a disease or causative condition may depend on the disease being chronic, and the term chronic will often, but not always appear in the description:
Many chronic diseases require chronic care management for effective long-term treatment.
Nearly one in two Americans (133 million) has a chronic medical condition of one kind or another, and chronic illnesses cause about 70% of deaths in the United States and take up about 75% of the costs each year. However, most of these people are not actually disabled, as their medical conditions do not impair normal activities. According to this report, the most common chronic conditions are high blood pressure, arthritis, respiratory diseases like emphysema, and high cholesterol. That number is projected to increase by more than one percent per year by 2030, resulting in an estimated chronically ill population of 171 million.