Evaluation of a warfarin initiation protocol for older people

A protocol for initiation of warfarin therapy, targeted specifically for older people and based on individual responses to initial warfarin doses, was evaluated in a case-control study. People within the protocol group: (i) received higher initial doses of warfarin, (ii) reached an international normalized ratio (INR) of 2 more quickly, (iii) spent more time with INR of 2-3 in the first week and (iv) were less likely to be over-anticoagulated. However, the proportion of people who reached an INR of 2 too quickly (in <4 days) was no greater. The protocol correctly predicted the maintenance dose range of warfarin in over 70% of cases.