No abstract

Patients require different warfarin dosages to achieve the target therapeutic anticoagulation. The variability is largely genetically determined, and it can be only partly explained by genetic variability in the cytochrome CYP2C9 locus. In 147 patients followed from the start of anticoagulation with warfarin, we have investigated whether VKORC1 gene mutations have affected doses of drug prescribed to acquire the target anticoagulation intensity. Two synonymous mutations, 129C>T at Cys43 and 3462C>T at Leu120, and 2 missense mutations, Asp38Tyr and Arg151Gln, were identified. None of these mutations was found to affect the interindividual variability of warfarin prescribed. Finally, 2 common polymorphisms were found, 1173C>T in the intron 1 and 3730G>A transition in the 3 untranslated region (UTR). Regardless of the presence of confounding variables, the mean adjusted dose required of warfarin was higher (6.2 mg) among patients with the VKORC1 1173CC genotype than those of patients carrying the CT (4.8 mg; P ‫؍‬ .002) or the TT genotype (3.5 mg; P < .001). In the present setting, VKORC1 and CYP2C9 genetic variants investigated accounted for about a third (r 2 , 0.353)

Summary.  Background: The optimal intensity of oral anticoagulation for the prevention of recurrent thrombosis in patients with antiphospholipid antibody syndrome is uncertain. Retrospective studies show that only high‐intensity oral anticoagulation [target international normalized ratio (INR) >3.0] is effective but a recent randomized clinical trial comparing high (INR range 3.0–4.0) vs. moderate (INR 2.0–3.0) intensities of anticoagulation failed to confirm this assumption. Methods: We conducted a randomized trial in which 109 patients with antiphospholipid syndrome (APS) and previous thrombosis were given either high‐intensity warfarin (INR range 3.0–4.5, 54 patients) or standard antithrombotic therapy (warfarin, INR range 2.0–3.0 in 52 patients or aspirin alone, 100 mg day−1 in three patients) to determine whether intensive anticoagulation is superior to standard treatment in preventing symptomatic thromboembolism without increasing the bleeding risk. Results: The 109 patients enrolled in the trial were followed up for a median time of 3.6 years. Mean INR during follow‐up was 3.2 (SD 0.6) in the high‐intensity warfarin group and 2.5 (SD 0.3) (P < 0.0001) in the conventional treatment patients given warfarin. Recurrent thrombosis was observed in six of 54 patients (11.1%) assigned to receive high‐intensity warfarin and in three of 55 patients (5.5%) assigned to receive conventional treatment [hazard ratio for the high intensity group, 1.97; 95% confidence interval (CI) 0.49–7.89]. Major and minor bleeding occurred in 15 patients (two major) (27.8%) assigned to receive high‐intensity warfarin and eight (three major) (14.6%) assigned to receive conventional treatment (hazard ratio 2.18; 95% CI 0.92–5.15). Conclusions: High‐intensity warfarin was not superior to standard treatment in preventing recurrent thrombosis in patients with APS and was associated with an increased rate of minor hemorrhagic complications.

The liver plays a central role in the clotting process, and acute and chronic liver diseases are invariably associated with coagulation disorders due to multiple causes: decreased synthesis of clotting and inhibitor factors, decreased clearance of activated factors, quantitative and qualitative platelet defects, hyperfibrinolysis, and accelerated intravascular coagulation. The bleeding tendency accounts for increased risk of morbidity and mortality in patients with liver disease undergoing diagnostic or therapeutic invasive procedures. Peculiar coagulation disorders are prevalent in patients with acute fatty liver of pregnancy or undergoing liver transplantation. Emerging evidence shows that sepsis further impairs hemostasis in patients with liver cirrhosis bleeding from esophageal varices. Thrombotic events, even if rare in cirrhotic patients, occur mainly in the portal and mesenteric veins. The therapeutic approach to coagulative disorders is also discussed.