Frequency of monitoring, non-adherence, and other topics dear to an anticoagulation clinic provider

Abstract

Historically, there has been limited data informing practical matters encountered in day-to-day warfarin management. Several studies have recently explored topics that address several of these gaps in the literature. Extending INR recheck intervals to 12 weeks is feasible with comparable time-in-therapeutic range compared to traditional 4 week intervals. Patients more likely to maintain stable anticoagulation are older, have an INR target of 2-3 (versus higher targets), and do not have heart failure. Unsurprisingly, non-adherence with reliably taking warfarin is associated with poor anticoagulation control. In addition, non-adherence with INR monitoring is associated with an increased risk of thromboembolism. Evidence-based interventions to improve adherence are lacking. When managing a modestly out of range INR value in previously stable warfarin patients, providers have a few options: 1) change the maintenance warfarin dose, 2) give a one-time dose adjustment, followed by resumption of the previous warfarin dose, or 3) continue the same warfarin dose with no adjustment. Each of these options can be successful, particularly when paired with increased INR monitoring. Bridging with low-molecular-weight heparin for a single subtherapeutic INR is not warranted for most patients. The 9th edition of the American College of Chest Physicians Evidence-Based Clinical Practice Guidelines for Antithrombotic Therapy and Prevention of Thrombosis chapter "Evidence-Based Management of Anticoagulant Therapy" reviews these and many new and practical recommendations for anticoagulation clinic providers.