Patients with low VWF–QL have significant bleeding. (A) The ISTH-BAT bleeding scores (n = 214) for patients with low VWF–QL (qualitative low VWF) and those with low VWF–QT (quantitative low VWF). The P value was determined using an independent t test. (B) Bleeding scores for the individual ISTH-BAT domains in patient with low VWF–QL (red bars) and those with low VWF–QT (blue bars). The P value for each ISTH-BAT domain was determined using an independent t test. (C-D) Patients from the LVEMC study (40 of 96 diagnosed based on an isolated VWF:Act level in the 30 to 50 IU/dL range; low VWF–QL) were followed for 6.6 ± 3.4 years after diagnosis. (C) Patients with low VWF–QL had a higher incidence of bleeding after diagnosis. (D) Similar types of bleeding were observed during follow-up in patients with low VWF–QL and those with low VWF–QT. (E) Patients with low VWF–QL also had a significantly higher incidence of bleeding that required treatment after diagnosis. The P values were determined using log-rank tests. CNS, central nervous system; GI, gastrointestinal; HMB, heavy menstrual bleeding; n.s., not significant; PPH, postpartum hemorrhage.