Clinical usefulness of international normalized ratio calibration of prothrombin time in patients with chronic liver disease

Abstract

The international normalized ratio (INR) may not be directly applicable to patients with liver disease. We aimed to establish an alternative INR calibration system for patients with liver disease and to evaluate the effect of their use in chronic liver disease patients. Eighty-two patients with liver cirrhosis (LC) were included, and their prothrombin times (PTs) were measured by using 5 commercial thromboplastins. Each of the thromboplastins was also assigned an international sensitivity index (ISIliver) by the plasmas from LC patients. INRvka, INRliver, model for end-stage liver disease (MELD)vka, MELDliver, Child-Pugh (Child)vka, and Childliver scores were calculated. The coefficient of variance of INRvka was significantly larger than that of INRliver (P<0.01). The mean difference in INRvka between the thromboplastins was also significantly larger than that in INRliver (P<0.01). The total mean MELDliver score was higher than the total mean MELDvka score. The mean difference between the MELDvka and MELDliver scores (MELD score≥15) was 3.2%. We reconfirmed that the use of the alternative calibration system described herein for patients with liver disease may resolve the variability of INR measurement. Our data suggest that we would need to reevaluate the correlation between Child-Pugh class, MELD score, and clinical prognosis by using INRliver for patients with LC.