ASSESSMENT OF THE VALIDITY OF THE INR SYSTEM FOR PATIENTS WITH LIVER IMPAIRMENT

The INR system was developed to standardize PT reporting in patients o n oral anticoagulants. We prospectively collected blood samples from 2 9 patients with liver impairment (INR 1.5-3.5). Control patients were on warfarin (n = 31). PT's were measured on an ACL-300 with three thro mboplastin reagents, INR's were calculated using instrument specific I SI's. Other tests performed were FDP's: fibrinogen, aPTT, factors II, V, VII and X. The INR's for each patient in the study population using the three thromboplastin reagents were significantly different (p = 0 .0001). Those for the control population were not (p = 0.0658), Fibrin ogen, factors V, II and X were different at the 5% level of significan ce between the populations. FDP's were detected in 17 study subjects. The INR system is not valid for comparison of patients with liver impa irment because different reagents do not give the same INR for the sam e sample. It is, however, no less valid than the use of PT with differ ent thromboplastin reagents. Further study is recommended.