New pain complaints account for 40 million visits annually. Nearly 64 million people suffer from trauma-related pain each year.
Pain complicating acute and chronic disease or medical procedures is also common.
Approximately 35 million people experience chronic headache, and another 16 million people have chronic back pain. Burns cause chronic painful sequelae in as many as two million people annually. Nearly all patients with advanced cancer report severe pain. Acute and chronic pain can be viewed as a public health problem. Fortunately, much has been learned about fundamental pain mechanisms.