There are somewhere between 60 and 80 million people in the United States with persistent pain of over 100 days per year, including 35 million with arthritic pain, 30 million with back pain, 10 million with migraine pain, 3 million with cancer related pain and 2 million with neuropathic pain. The National Pain foundation considers this number to be between 40 to 50 million Americans. Regardless it is a largely underserved population with fewer than 8,000 pain specialists. Most care is done by primary care physicians accounting for 80% of physician visits.