[1] Childrens Hosp, Div Hematol Oncol, Thrombosis Program, Boston, MA 02115 USA
[2] Childrens Hosp, Anticoagulat Serv, Boston, MA 02115 USA
[3] Childrens Hosp, Med Patient Serv, Boston, MA 02115 USA
[4] Childrens Hosp, Clin Res Program, Boston, MA 02115 USA
[5] Childrens Hosp, Div Hematol, Boston, MA 02115 USA