Comparison of modes of prothrombin time reporting in patients with advanced liver disease associated with viral hepatitis

Background Prothrombin time is widely utilized for evaluation of liver disease severity. However, its standardization of modes of reporting is not established for universal purpose. Variability in thromboplastin reagents leads to large intralaboratory and interlaboratory differences in PT results. Objective The aim of this study was to establish standardization of modes of PT reporting by the interchangeability analysis of prothrombin time in patients with advanced liver disease associated with viral hepatitis measured with different thromboplastin reagents by the use of various methods of expression, i.e. prothrombin time (PTs), prothrombin activity percentage (PTp), prothrombin time ratio (PTr) and International Normalized Ratio (INR). Methods we prospectively collected blood samples from 61 patients with advanced liver disease associated with viral hepatitis, control patients were on warfarin ( n = 20). PT was measured on a STA-R with six thromboplastin reagents. PT was expressed in PTs, PTr, PTp, and INR. Neoplastin was selected as reference reagent for comparison of methods of reporting. Results The study revealed the closest agreement of the results in study population between Neoplastin and the other five reagents, and the regression lines of these reagents were close to each other, when the results were expressed in PTp while INR, PTs and PTr is not valid for comparison of patients with liver disease. In patients on oral anticoagulant therapy, only INR standardize PT results. Conclusion we conclude that, in patients with liver disease, only activity percentage expression may provide a common international scale of PT reporting.