CATCH Registry Members: The following CATCH (Complications After Thrombocytopenia Caused by Heparin) Registry investigators, study coordinators, and institutions participated (listed in order of the number of patients): Duke University Medical Center, Durham, North Carolina: K. Mahaffey and C. Martz. Rapid City Regional Hospital, Rapid City, South Dakota: S. Durr and D. Gadd. Central Arkansas Veterans Healthcare System, Little Rock: J. Joseph and S. Shuler. Mercy General Health Partners/Trinity Healthcare, Muskegon, Michigan: M. Meengs and C. Opalek. Wellmont Holston Valley Medical Center, Kingsport, Tennesee: R. Santos and A. Armstrong. Spectrum Health Hospital, Grand Rapids, Michigan: J. Bishop and L. Viewing. Sinai Hospital of Baltimore, Maryland: P. Gurbel and K. Bliden. University Hospital, Augusta, Georgia: B. Chandler and P. Easler. Methodist Hospital, Houston, Texas: N. Kleiman and L. Felker. Baystate Medical Center, Springfield, Massachusetts: M. Schweiger and L. Eaton. Pittsburgh Healthcare System, Pennsylvania: A. Sonel and L. Wall. Glendale Memorial Hospital and Health Center, Glendale, California: D. Lee and L. Brown. University of Arkansas, Little Rock: J. Joseph and S. Shuler. Cleveland Clinic, Cleveland, Ohio: D. Moliterno and R. Bartow. Deborah Heart and Lung Center, Brown Mills, New Jersey: M. Cotto and L. Dewey. Brookhaven Memorial Hospital Medical Center, Patchogue, New York: M. Zema and S. Veltri. Latter Day Saints Hospital, Salt Lake City, Utah: B. Muhlestein and K. Robinson. Lakeland Regional Medical Center, Lakeland, Flordia: C. Simek and P. Matheny. Beth Israel Deaconess Medical Center, Boston, Massachusetts: J. Carrozza and P. Rooney. University of North Carolina Hospital, Chapel Hill: V. Menon and L. Davis. University of Massachusetts, Worchester: F. Spencer and C. Emery. Tallahassee Memorial Regional Medical Center, Tallahassee, Florida: D. Tedrick and P. Knap. Alamance Regional Medical Center, Burlington, North Carolina: K. Fath and D. Isley. Moses H. Cone Memorial Hospital, Greensboro, North Carolina: N. Gupta and J. Knapp. Western Pennsylvania Hospital, Pittsburgh: R. Kaplan and D. Blackwell. Trinity Medical Center–West Campus, Rock Island, Illinois: F. Munoz and C. Antonio. University of Missouri Hospital and Clinics, Columbia: R. Webel and A. Lau-Sieckman. Houston V.A. Medical Center, Houston, Texas: G. Levine and T. Ferrando. William Beaumont Hospital–Troy, Troy, Michigan: D. Cragg and A. Murawka. Presbyterian Medical Center–University of Pennsylvania, Philadelphia: W. Matthai and S. Donovan. Sentara Virginia Beach General Hospital, Virginia Beach: J. Griffin and T. Mellinger. Ben Taub General Hospital, Houston: N. Lakkis and J. Bobek. Lakeland Medical Center, St Joseph, Michigan: D. Arora and J. Hoseth. Good Samaritan Hospital of Maryland, Baltimore: J. Insel and J. Swartengruber. Christus Saint Frances Cobrini Hospital, Alexandria, Louisiana: D. Shaw and D. Fleck. Pennsylvania State University–Hershey Medical Center, Hershey: I. Gilchrist and H. Zimmerman. Maricopa Medical Center, Phoenix, Arizona: E. Zavala and P. Graham. Durham Veterans Administration, Durham: M. Krucoff and F. Anderson. High Point Regional Hospital, High Point, North Carolina: B. Cheek and T. Hedrick. Saint Johns Riverside Hospital, Yonkers, New York: S. Chaudhry and J. Strauss. Torrance Memorial Medical Center, Torrance, California: M. Luire and D. Switzer. Michael Reese Hospital, Chicago, Illinois: C. Gidea and W. Dahdal. Morton Plant Hospital, Clearwater, Florida: D. Spriggs and J. Maugeri. Saint Marks Hospital, Salt Lake City: R. Callihan and R. Neuharth. The Johns Hopkins Hospital, Baltimore: J. Miller and N. Fredde. Medical Center of Louisiana–University Hospital, New Orleans: S. Jain and L. Wicks. William W. Backus Hospital, Norwich, Connecticut: J. Foley and P. Provost. Riverside General Hospital, Houston: T. Otey and N. Hinton.