BACKGROUND: Warfarin is one of the most widely used anticoagulation medications. It requires frequent monitoring due to its chemical and physiological nature. A majority of patients need to maintain an INR between 2.0 and 3.0. Previous research has shown that patients who can maintain a higher time in therapeutic range (TTR) have improved outcomes. For some patients, this can be difficult to achieve. Clinicians utilize numerous strategies to improve TTR in their patients. The diversity of methods, disparate outcomes, and varying levels of evidence means that researchers and clinicians are often overwhelmed by the comparisons.
OBJECTIVE: Our objective is to gather all known strategies used to optimize TTR in warfarin patients and provide a resource that clinicians can use to improve patient outcomes. We also hope to identify any potential gaps in the literature so other studies may be done.
METHODS: We performed a scoping review, searching for articles in Medline, Embase, and Cochrane library databases including CENTRAL and International Pharmaceutical Abstracts. We searched for all articles that contained a combination of keywords and database subject terms for the drug “warfarin” and “time in therapeutic range” concepts.
RESULTS: An initial search result of 7,628 articles was reduced to 236 articles which underwent data extraction. Of the different strategies to improve TTR, a majority of the articles focused on clinical management (n=84, 69.4%), such as pharmacist managed anticoagulation. Other groups that contained a large number of strategies include strategies involving nomograms/protocols (n=27, 22.3%), pharmacogenetics (n=13, 10.7%, dietary factors (n=5, 4.1%), a combination of the groups previously mentioned (n=19, 15.7%), or others (n=10, 8.3%). These strategies offered varying degrees of improvement in TTR, with n=65, (53.7%) being statistically significant.
CONCLUSIONS: Our search provided numerous modalities in improving TTR in patients taking warfarin. Clinicians can use the results from our search to improve therapies for patients by applying strategies that show benefit in patients struggling to maintain within therapeutic range. Each patient’s situation is unique and may require a combination of strategies offered. By utilizing this resource, it is our hope that clinicians will be able to improve patient outcomes overall.