Score may help determine safe anticoagulation with warfarin in patients with liver disease

A 4-point score may help clinicians determine which patients with chronic liver disease can safely receive warfarin, a new study reports.

Researchers used the Veterans Affairs Study to Improve Anticoagulation database to identify 1,763 patients with liver disease who were receiving oral anticoagulation with warfarin from Oct. 1, 2006, to Sept. 30, 2008. When compared with the 102,134 patients who were treated with warfarin and did not have liver disease, those with liver disease spent less mean time in the therapeutic range (61.7% vs. 53.5%; P<0.001) and had more hemorrhages (hazard ratio, 2.02; P<0.001). The researchers found that liver disease patients with lower albumin levels and higher creatinine levels were most likely to experience these 2 outcomes.

Accordingly, the researchers developed a 4-point risk score in which patients received 1 point each for an albumin level of 2.5 to 3.49 g/dL and a creatinine concentration of 1.01 to 1.99 mg/dL and 2 points each for an albumin level below 2.5 g/dL and a creatinine concentration of 2 mg/dL or greater. Patients who had a 0 score on this scale spent 56.7% of time in the therapeutic range, slightly better than patients with liver disease overall. In addition, their hemorrhage risk was not higher than that of patients without liver disease (hazard ratio, 1.16; P=0.59). In contrast, patients with liver disease and a score of 4 spent only 29.4% of time in the therapeutic range and had a high risk for hemorrhage (hazard ratio, 8.53; P<0.001).

The authors noted that most of the study patients were men and that most were receiving anticoagulation for reasons unrelated to liver disease. Therefore, they said, their findings might not apply to the general population of patients with this disorder. They also noted that patients with valvular heart disease were not included, that major hemorrhagic events were determined through automated data instead of chart review, and that they were not able to control for several bleeding risk factors, among other limitations.

However, they concluded that although anticoagulation control and hemorrhage risk were worse in patients with liver disease than in those without, some liver disease patients appeared to be at lower risk for these outcomes. The 4-point risk score they developed based on albumin and creatinine was able to better stratify liver disease patients according to risk for hemorrhage. “This finding may have considerable clinical use, by offering a simple, readily available indicator of a patient's likelihood to succeed on traditional vitamin K antagonist treatment,” the authors wrote. The study was published online May 13 by Circulation: Cardiovascular Quality and Outcomes.