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

ABSTRACT

In a normal population, VWF plasma levels (VWFAg) and VWF activity (VWFRCo) 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 VWFAg, VWFRCo and factor VIII levels ( FVIII 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 VWFAg, VWFRCo and FVIII 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 VWFAg, VWFRCo and FVIII 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 VWFAg, VWFRCo and FVIII C levels that increased into the normal range. The rate of change in VWFAg, VWFRCo 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 VWFAg and VWFRCo which can result in normalization of VWF levels. Further studies are required to determine if the bleeding phenotype resolves with the increases in VWFAg and VWFRCo levels.