(A) Relationship between the presence of inhibitors and the clinical manifestation of bleeding tendency. There was a close relationship between the presence of inhibitor to vWF and bleeding tendency. Six patients out of the 8 patients with inhibitors (75 %) had bleeding tendency, as well as one of the 15 patients without inhibitors (6%). The sensitivity of the presence of the inhibitor as a predictor of bleeding was 86%, and the specificity was 88%, with a positive predictive value of 75% and a negative predictive value of 93%. (B) Relationship between the absence of inhibitors and the efficacy of the treatment of underlying diseases and/or DDAVP therapy. Four patients of the 8 patients with inhibitors (50%) had poor response to treatment of the underlying disease and/or DDAVP therapy, as well as one of the 16 patients without inhibitors (6%) . The sensitivity of the absence of inhibitor as a predictor of response to these therapy was 79%, and the specificity was 80%, with positive predictive value of 94% and a negative predictive value of 50%.