Chronic pain as a disease entity.
D001519:Behavior; D002908:Chronic Disease; D003469:Culture; D003863:Depression / Q000209:etiology; D006801:Humans; D010146:Pain / Q000175:diagnosis / Q000503:physiopathology / Q000523:psychology*; D012803:Sick Role; D012959:Socioeconomic Factors; D013001:Somatoform Disorders