Changes in von Willebrand factor level and von Willebrand activity with age in type 1 von Willebrand disease

In a normal population, VWF plasma levels (VWF:Ag) and VWF activity (VWF:RCo) increase by approximately 0.17 and 0.15 IU mL(-1) per decade, but the influence of age is unknown in patients with type 1 von Willebrand disease (VWD). In a retrospective cohort study, the medical records of 31 type 1 VWD patients over the age of 30, who had been followed for ≥5 years, were reviewed for baseline clinical data and previously performed VWF:Ag, VWF:RCo and factor VIII levels (

C). VWF multimer analysis was normal in 28/31 cases performed. Mean age at diagnosis was 33 (range 16-60 years), and duration of follow-up ranged from 5 to 26 years (mean 11 years). Patients had 2-10 time points of VWD testing (mean of 5.2). The mean VWF:Ag, VWF:RCo and

C at time of diagnosis were 0.44 IU mL(-1) 0.34 IU mL(-1) and 0.75 IU mL(-1) . At last follow-up, the mean VWF:Ag, VWF:RCo and

C were significantly increased to 0.71 IU L(-1) , 0.56 IU mL(-1) and 0.90 IU mL(-1) (P ≤ 0.001, <0.001, and 0.0081 respectively). Here 18/31 patients had VWF:Ag, VWF:RCo and

C levels that increased into the normal range. The rate of change in VWF:Ag, VWF:RCo and FVIII was 0.30 IU mL(-1) (0.21-0.39, CI 95%, P < 0.0001), 0.20 IU mL(-1) per decade (0.13-0.27, CI 95%, P = 0.0001) and 0.20 IU mL(-1) (0.11-0.29, CI 95%, P = 0.0011). Patients with type 1 VWD experience age-related increases to VWF:Ag and VWF:RCo which can result in normalization of VWF levels. Further studies are required to determine if the bleeding phenotype resolves with the increases in VWF:Ag and VWF:RCo levels.