 This trial was conducted in the Department of Rehabilitation, Hospital das Clinicas, University, of Sao Paulo Medical School, one of the largest rehabilitation centers in Brazil. The trial was initiated in January of 2007 and close to enrollment in January of 2013. Investigators included patients with a diagnosis of chronic nonspecific low back pain who were referred from various clinics in São Paulo that were linked to this rehabilitation center. Thus, patients were referred primarily by physiatrists, general practitioners, neurologists, orthopedic surgeons, and physiotherapists. 