The International Association for the Study of Pain has developed a new classification system for chronic pain. A fundamental distinction is made between chronic primary pain and chronic secondary pain. Chronic primary pain is defined as pain in one or more anatomical regions that persists for longer than three months, is associated with disability or emotional distress, not better accounted for by another diagnosis of chronic pain. Chronic primary pain is subdivided into five categories. Chronic secondary pain is pain secondary to an underlying disease.