use of an extended inr follow-up interval for veteran patients in an anticoagulation clinic

A prospective, single-arm study of 50 participants evaluated an extended inr follow-up interval to determine the implementation feasibility and safety of an extended interval in veterans on a stable dose of warfarin. a protocol was designed to allow for a rigorous, yet pragmatic evaluation of a 12-week inr follow-up interval. feasibility was determined by study enrollment, retention, and participant achievement rates for the extended inr interval. safety was determined by bleeding and thromboembolism rates. participants were monitored for 6 months. despite the long-term stability of participants prior to enrollment, only 56% achieved a 12-week follow-up interval and only 34% of enrolled participants maintained a 12-week interval. sixteen percent of participants were never eligible for an extension of their inr follow-up interval despite meeting initial enrollment criteria. there were two major bleeding events and one participant who experienced a thromboembolic event. implementation of an extended interval of inr follow-up appears feasible as participant enrollment goals were met and pharmacists were able to follow the study protocol. however, a lower than expected proportion of participants were able to achieve and maintain an extended inr follow-up interval. future evaluations are needed to confirm the safety of an extended inr interval.