Prognostic significance of von Willebrand factor (VWF) level in patients with Waldenström macroglobulinemia (WM). (A) Overall survival in 72 patients with WM and (B) survival after first-line therapy in 55 patients with WM, according to VWF antigen (VWF:Ag) level. The line of alternating dashes and dots indicates VWF:Ag < 110 U/dL, the dotted line indicates VWF:Ag level between 110 and 250 U/dL, and the solid line indicates VWF:Ag more than 250 U/dL.