BACKGROUND: Patients being managed on warfarin make frequent or regular visits to anticoagulation monitoring appointments. International studies have evaluated transportation cost and associated time related to anticoagulation clinic visits. To our knowledge, no studies have evaluated the cost of transportation to such clinic visits in the United States.
Long-term anticoagulation with a vitamin K antagonist (VKA) or the new agent dabigatran is recommended to decrease stroke risk in patients with atrial fibrillation. When patients with atrial fibrillation undergo initiation or interruption of VKA therapy, or experience an isolated subtherapeutic international normalized ratio (INR), bridge therapy with a parenteral anticoagulant may be considered. To describe the literature for anticoagulation bridge therapy in patients with atrial fibrillation, we conducted a MEDLINE search (1966-February 2011) of the English-language literature to identify related studies. Ongoing clinical trials were identified through a search of the ClinicalTrials.gov registry. Major national and international guidelines were gathered and evaluated. Additional literature was obtained through review of relevant references of the identified articles. Bridging is not supported by guidelines or clinical trials for patients starting VKA therapy for atrial fibrillation. A subtherapeutic INR value during long-term VKA therapy may be associated with increased thromboembolic events, but the benefit of bridging has not been demonstrated. When VKA therapy is interrupted for procedures, retrospective and cohort data suggest that the decision to bridge should be based on a patient's thromboembolic and bleeding risks associated with the procedure. Typically, it is recommended to use bridge therapy in patients with atrial fibrillation at high risk for thromboembolism, but the benefit of bridging is less clear in patients at low risk. Not all procedures necessitate anticoagulation interruption. Recent trials suggest that VKAs can be continued when patients are undergoing cardiac device procedures and some types of radiofrequency ablation. Several clinical trials are ongoing that will provide more definitive guidance for perioperative anticoagulation management of patients with atrial fibrillation. Patients taking dabigatran are unlikely to require bridge therapy because of a predictable anticoagulant effect and rapid onset of action. However, evidence for optimal perioperative management of dabigatran is needed.
No formal recommendations support bridging patients taking warfarin for a subtherapeutic international normalized ratio (INR). This study aimed to: (1) characterize practices at one anticoagulation clinic, (2) evaluate adverse events, and (3) compare cost of bridging versus withholding bridging for subtherapeutic INR. A retrospective chart review of 320 patients having 546 isolated subtherapeutic INR episodes included patients with an INR below their therapeutic range, preceded by two INRs within or above range. Bridged episodes required more frequent follow-up visits to achieve therapeutic INR (2.5 ± 1.0 vs. 2.2 ± 0.6; P = 0.097), but fewer days until the INR returned to therapeutic range (6.8 ± 5.0 vs. 18.9 ± 16.0; P < 0.0001). The strongest predictor of bridging was the magnitude the INR fell below the therapeutic range, where those with a severely-low INR were 30-fold more likely to be bridged (P < 0.0001), and moderately-low INR episodes were 6-fold more likely to be bridged compared with mildly-low INR (P < 0.0001). Those at high thromboembolic risk were more likely to be bridged than at low-risk (OR 3.39 [1.50-7.68]; P = 0.0034). Increasing age reduced the likelihood of being bridged (OR 0.97 [0.95-0.99]; P = 0.0118). Adverse events were infrequent in both the bridged and non-bridged; thrombosis (2.0 vs. 0.7%), major bleeding (2.0 vs. 1.3%), minor bleeding (4.1 vs. 3.1%) and bruising (18.4 vs. 3.6%). Incremental cost difference of bridging was significantly greater for total cost ($967.13) and its components, direct medical ($951.32), transportation ($2.73) and productivity cost ($13.08). It is unclear if bridging for an isolated subtherapeutic INR reduces thrombosis risk, but it is associated with higher costs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.