Predictors and Rate of Anticoagulant Therapy Discontinuation in Patients with Atrial Fibrillation

Global Prevalence of Atrial Fibrillation 

Atrial fibrillation is the most common persistent arrhythmia and is associated with significant morbidity, mortality, and treatment costs. In 2019, an estimated 60 million people worldwide had AF, with a global age-adjusted prevalence of 744/100,000 persons. 

In most regions of the world, the prevalence of AF is increasing, indicating the need to improve its prevention and treatment and limit risk factors such as hypertension, diabetes, and obesity. Australia is one of the countries with a high prevalence of AF – in 2019, it was documented in more than half a million of its inhabitants (out of a total of approximately 26 million). 

Oral Anticoagulant Therapy 

Oral anticoagulants (OACs) reduce the risk of iCMP in patients with AF. The use of OACs should be continuous, but in clinical practice, discontinuation of this therapy is relatively common. Each interruption predisposes to the occurrence of thrombotic complications. The aim of the cited Australian study was to investigate the rate of OACs discontinuation in patients with AF using data from local general practitioners. 

Study Methodology 

The analyzed data were obtained from the MedicineInsight dataset of the non-profit organization NPS MedicineWise under the Australian Department of Health. The entry criteria were age ≥ 18 years, diagnosis of AF, and initiation of OACs therapy between January 1, 2013 and December 31, 2017. Patients with venous thromboembolism (VTE) were excluded. Persistence was defined as OAC prescription without interruption longer than 60 days. The follow-up period was 12 months. Multivariable models were used to analyze predictors. 

Assessed Patient Population

Of the total of 16,075 monitored patients, 52.7% were men, and the average age was 74.6 years (standard deviation [SD] 10.2). Their most common comorbidities were hypertension (70.9%) and arthritis (60.8%).

Most (91.2%) patients had a CHA₂DS₂-VASc score ≥ 2, with an average value of 3.9 (SD 1.9). The initial bleeding risk was low in 66.3% of patients, with an average ORBIT score of 1.9 (SD 1.4).

In the analyzed cohort, patients used 4 OACs: warfarin (n = 4490), apixaban (n = 4761), dabigatran (n = 1651), rivaroxaban (n = 5173). 

Results

The overall rate of OACs discontinuation during 12 months was 13.2% (95% confidence interval [CI] 12.6–13.7%). The majority of discontinuations (69.3%) occurred within the first 6 months of starting therapy. 

The rate of therapy discontinuation was highest for warfarin (18.3%; n = 823; 95% CI 17.2–19.5) and statistically significantly lower for rivaroxaban (12.2%; n = 633; 95% CI 11.4–13.2), dabigatran (10.9%; n = 180; 95% CI 9.4–12.2), and apixaban (10.1%; n = 480; 95% CI 9.2–11.0). Better persistence was observed in patients with factors associated with increased risk of iCMP (higher age, diabetes, hypertension). 

Discussion and Conclusion

This study indicates that a relatively high proportion of patients with AF continue to use OACs 12 months after initiating this therapy. The rate of its discontinuation was highest for warfarin. Lower dosing frequency of DOACs (rivaroxaban 1× daily vs. apixaban or dabigatran 2× daily) was not a predictor of treatment persistence. The encouraging finding is that patients with the highest risk of iCMP showed the highest persistence on anticoagulant therapy.  

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Source: Kefale A., Bezabhe W., Peterson G. Oral anticoagulant discontinuation and its predictors in patients with atrial fibrillation. J Clin Med 2022 Oct 12; 11 (20): 6022, doi: 10.3390/jcm11206022.