Anticoagulation Control in Different Ethnic Groups Receiving Vitamin K Antagonist for Stroke Prevention in Atrial Fibrillation

Abstract

Vitamin K antagonist such as warfarin reduces the risk of stroke in atrial fibrillation (AF) patients. Since warfarin has a narrow therapeutic index, its administration needs to be regularly monitored to avoid any adverse clinical outcomes such as stroke and bleeding. The quality of anticoagulation control with warfarin therapy can be measured by using time in therapeutic range (TTR). This review focuses on the prevalence of AF, quality of anticoagulation control (TTR) and adverse clinical outcome in AF patients within different ethnic groups receiving warfarin therapy for stroke prevention. A literature search was conducted in Embase and PubMed using keywords of “prevalence,” “atrial fibrillation,” “stroke prevention,” “oral anticoagulants,” “warfarin,” “ethnicities,” “race” “time in therapeutic range,” “adverse clinical outcome,” “stroke, bleeding.” Articles published by 1st February 2020 were included. Forty-one studies were included in the final review consisting of AF prevalence (n = 14 studies), time in therapeutic range (n = 18 studies), adverse clinical outcome (n = 9 studies) within different ethnic groups. Findings indicate that higher prevalence of AF but better anticoagulation control among the Whites as compared to other ethnicities. Of note, non-whites had higher risk of strokes and bleeding outcomes while on warfarin therapy. Addressing disparities in prevention and healthcare resource allocation could potentially improve AF-related outcomes in minorities.

A Novel Nomogram for Predicting Warfarin-Related Bleeding: A Retrospective Cohort Study

“…The narrow therapeutic window for warfarin, and the obvious individual variability in its effects make regular coagulation monitoring and dose adjustments essential. 34 TTR represents the percentage of time that the INR remains within the target range of 2.0 to 3.0 across time, 21 and is one measure of quality of anticoagulation dose management. 35 …”

Selection of Non-vitamin K Antagonist Oral Anticoagulant for Stroke Prevention in Atrial Fibrillation Based on Patient Profile: Perspectives from Vietnamese Experts. Part 1

“…Furthermore, Asian patients using VKAs face an elevated risk of major bleeding and intracranial haemorrhage (ICH) than their White counterparts. [ 34 ] This can be explained by the observation that Asian populations exhibit specific polymorphisms in genes involved in the metabolism of and response to VKAs. In Asian patients, the prevalence of certain polymorphisms in the vitamin K epoxide reductase complex subunit 1 ( VKORC1 ) gene, which is associated with lower VKA dose requirements, is considerably higher compared with that in other ethnic groups.…”

“…[ 35 ] In addition, Asian patients may be less likely to have cytochrome P450 family 2 subfamily C member 9 ( CYP2C9 ) polymorphisms that result in poor VKA metabolism and lower dose requirements. [ 34 , 35 ] As a result, Asians may be more susceptible to major bleeding events and ICH due to increased VKA dose variations.…”