The future of anticoagulation clinics: a journey to thrombosis centers?

Coumarins were discovered in the late 1930s as a result of decades of research spent identifying the cause of a hemorrhagic disease in cattle. At first they were used as rat poison, but from the mid 1950s they began to have some clinical impact.1 Since their efficacy was proved in several clinical studies,2 the use of coumarins, in particular warfarin, has increased progressively in many countries. Concomitantly with their clinical use, there was a need for more precise laboratory control, since bleeding can at times be fatal. Over the years the prothrombin time, as a monitoring test to tailor the dosage of oral anticoagulants in the single patient, underwent a process of standardization, which was started in 1962 by Leon Poller.3 In 1983 Kirkwood4 proposed the international normalized ratio (INR) system, approved by the World Health Organisation. Despite a few limitations, the INR, recently reviewed by Poller,5 is currently the standard way to express the result of a prothrombin time test, and has served to validate the efficacy of oral anticoagulants in a number of clinical studies