The 31 providers, which have been asked to respond in depth to Grassley’s letter “by no later than Feb. 16, 2010,” are:

• Banner Health
• Brigham & Women's Hospital
• Case Western Reserve University Hospital Health System
• Catholic Healthcare West
• Cedars Sinai
• Children’s National Medical Center
• Geisinger Medical Center
• Hackensack Hospital
• HCA TriStar
• Intermountain Healthcare
• Indiana University Hospital
• Jefferson Regional Medical Center
• Kaiser Permanente System
• Marshfield Clinic
• Massachusetts General Hospital
• Mayo Clinics
• Memorial Hermann Healthcare System
• Methodist Hospital of Indiana
• North Shore-Long Island Jewish Health System
• Palo Alto Medical Foundation
• Rainbow Babies and Children’s Hospital
• Saint Mary Mercy Hospital
• Seattle Children’s Hospital
• Stony Brook University Medical Center
• Trinity Hospital System
• Tufts Medical Center
• University of California San Francisco Medical Center
• University of Pennsylvania Health System
• University of Pittsburgh Medical Center
• University of Virginia Medical Center
• Vanderbilt University Hospital