Abstract
Rationale and Objectives: Apart from the differences in factor VIII:C levels, it is difficult to explain the significant variation in bleeding events observed among individual patients with similar levels of FVIII:C and standard laboratory profiles. We hypothesize that additional dispositional (genetic) and expositional (non-genetic) factors of hemostasis may augment or attenuate the likelihood of bleeding symptoms in hemophiliacs.
Patients and Methods: To test this hypothesis, we studied 61 patients diagnosed with hemophilia A. The following laboratory parameters were examined in multivariate analysis using a case-only analysis: genotyping for a2C807T, HPA-1 of aIIbb3, factor V G1691A, prothrombin G20210A; coagulation factor activity/antigen of fibrinogen, factor II, V, VII, VIII, IX, X, XI, XII, XIII, vWF; in-vitro bleeding time (PFA-100 closure times), and plasminogen.
Results: After adjustment for age, low levels of factor VIII (p=0.0296) and increased levels of plasminogen (p=0.0415), and collagen/ADP closure times (PFA-100) (p=0.04) could be identified as independent predictors of mucosal bleeding. 10% higher activity of plasminogen increased the bleeding risk 10.4 fold. For joint bleeding low levels of fibrinogen (p=0.003) and longer collagen/epinephrine closure times (PFA-100) could be identified as bleeding predictors.
Conclusion: Apart from low levels of factor VIII, increased activity of plasminogen is an independent predictor of mucosal bleeding in hemophiliacs. In consequence, it will be of importance to examine whether the critical subgroup of patients with increased plasminogen levels and mucosal bleeding can benefit from prevention with specific antifibrinolytic agents.
