1. From the Immuno-Hematology Unit and Department of Biostatistics, Hôpital Saint Louis; Epidemiology Unit, Hôpital Bichat; Rheumatology Unit, Hôpital Lariboisière; Hôpital Kremlin-Bicêtre; Hematology Unit, Hôpital Pitié; Hematology Unit, Hôpital Necker; Hematology Unit, Hôpital Cochin, Paris; Hematology Unit, Hôpital Henri Mondor, Créteil; Hematology Unit, Centre R. Huguenin, Saint Cloud; Hematology Unit, Centre Hospitalier, Amiens; and Hematology Unit, Centre Hospitalier, Caen, France