title: Comparison of Warfarin and Non-vitamin K Oral Anti-Coagulants in Non-Valvular Atrial Fibrillation in South-East Queensland
Creators: name: Rathinam, Iniya
Publisher: name: Griffith University
Year: 2020
Subjects: subject: Atrial Fibrillation
subject: warfarin
subject: Non-Vitamin K Oral Anticoagulants
subject: Non-Valvular Atrial Fibrillation

description: Background: Atrial Fibrillation (AF) is a cardiac rhythm disorder that can result in stroke and heart failure. Treatment to prevent the incidence of ischemic stroke involves initiating patients on an Oral Anticoagulant (OAC.). Warfarin which is a vitamin K antagonist has long been the only OAC available, but now other options include dabigatran which is a direct thrombin inhibitor, and rivaroxaban and apixaban which are factor Xa inhibitors. These OACs can cause adverse drug reactions, including bleeding complications which cause fears associated with prescribing of OAC. When the OAC options became available in Australia, a government review of anticoagulant usage highlighted key points such as the underuse of anticoagulants in patients with a high risk of stroke and the concerns regarding the safety of anticoagulants. Therefore, investigating the introduction of Non-Vitamin K Oral Anticoagulants (NOAC) and the use of warfarin will assist in addressing the concerns raised by the government-commissioned review of anticoagulant therapy in AF. Aim: This study aims to compare the prescribing of warfarin and the introduction of NOACs in patients with Non-Valvular Atrial Fibrillation (NVAF) in Southeast Queensland. Method: This retrospective cohort study was conducted in a hospital located in Southeast Queensland, Australia, using hospital records from patients admitted from 2012 to 2015. Data was extracted for all adult patients (aged ≥18 years) with an admission of AF and prescribed an OAC from 1 July 2012 to 10 June 2015. Data collection included patient details such as age, gender, comorbidities, and primary diagnosis together with admission details such as length of stay in hospital and discharge status. Data analysis included calculating CHA2DS2 (Congestive heart failure, Hypertension, Age&gt;75, Diabetes, prior Stroke/transient ischaemic attack) and CHA2DS2VA (Congestive heart failure, Hypertension, Age&gt;75, Diabetes, prior Stroke/transient ischaemic attack, Vascular disease, Age 65-74 years, Sex category of female) scores to find the risk of stroke and HASBLED (Hypertension, Abnormal renal/liver function, Stroke, Bleeding history, Labile INR, Elderly&gt;65years, Drugs/alcohol) scores to show the risk of bleeds, comparison of OAC usage from 2012 to 2015, logistic regression analysis for further data analysis. Results: Data extraction found 10636 admissions for AF. These admissions were further screened according to the inclusion and exclusion criteria, leaving 3396 admissions by 1911 patients for further analysis. There were 834 (54.4%) patients on nil OAC therapy during the first admission with a CHA₂DS₂-VA score of ≥2, which significantly decreased (p &lt; 0.001) to 285 (18.6%) patients discharged on nil OAC therapy. There were 745 patients on nil OAC during the first admission and 450 (42.1%) patients were discharged on NOAC therapy, while 295 (27.6%) patients were discharged on warfarin therapy. A total of 68 patients admitted on an OAC were ceased from OAC therapy upon discharge for various reasons. This study found 27 patients had changed therapies from warfarin to NOAC or NOAC to warfarin due to numerous reasons. Furthermore, this study found the risk of bleeding, stroke episode, and ischaemic heart disease to significantly affect the prescribing of OACs. In addition, age regarding the high risk of falls and kidney function influenced the prescribing of OAC. Conclusion: The findings from this study highlighted the under prescribing of OAC upon patient admission. However, upon discharge and subsequent patient admissions, there was an increased prescribing of OAC, especially for patients with a high risk of stroke. Therefore, this study established that the total prescribing and initiation of OAC had increased overall after the introduction of NOACs, with rivaroxaban being more commonly prescribed than warfarin. Further investigations into the usage of OAC highlighted the fears associated with prescribing of OAC especially the risk of bleeding, which significantly affected the prescribing of OAC in regards to ceasing and changing OAC therapies. In addition, the outcomes of OAC therapy investigated, found admissions to hospital due to bleeding, stroke, and death for patients initiated and established on OACs.