Comparison of anti-Xa and activated partial thromboplastin time monitoring for heparin dosing in patients with cirrhosis.

BACKGROUND

Cirrhosis of the liver results in complex hemostatic changes that place patients at risk for both bleeding and thrombotic events. This study evaluates the adverse effects of anticoagulation with unfractionated heparin among patients with cirrhosis and analyzes the discrepancy between anti-Xa and activated partial thromboplastin time (aPTT) values for heparin monitoring among cirrhotics.

METHODS

Patients with cirrhosis receiving unfractionated heparin were matched 2:1 to patients without evidence of cirrhosis anticoagulated with unfractioned heparin. Markers of bleeding events including blood product administration and use of heparin reversal were analyzed between groups. Patients from both groups with aPTT and anti-Xa values obtained at the same time were also analyzed.

RESULTS

A higher incidence of blood product administration or use of heparin reversal was observed among patients with cirrhosis [35/105 (33.3%) versus 37/210 (17.6%), P = 0.002]. This finding was consistent among those receiving anticoagulation through an established anti-Xa-based heparin dosing protocol [23/62 (37.1%) versus 25/124 (20.2%), P = 0.013]. A decrease in hemoglobin greater than 2 g/dL or a platelet decrease 50% or greater from baseline was also more frequently identified among cirrhotics when receiving heparin therapy [20/105 (19%) versus 23/210 (11%), P = 0.049 and 21/105 (20%) versus 12/210 (6%), P < 0.001, respectively]. A total of 88 correlated anti-Xa and aPTT values from 35 patients with cirrhosis demonstrated supratherapeutic aPTT values for anti-Xa levels within the therapeutic range (P < 0.001). This discrepancy was not observed among controls.

CONCLUSIONS

A greater use of blood products among the cirrhotic population may indicate potential bleeding events on therapy. A discrepancy in correlated anti-Xa and aPTT values among patients with cirrhosis may explain the propensity for adverse effects. Further study is required to identify effective heparin anticoagulation monitoring strategies in liver disease.