Initiation of oral anticoagulation in patients with new-onset atrial fibrillation diagnosed between 2002 and 2014: Trends from a registry-based study in Flanders, Belgium

Abstract

Introduction Atrial fibrillation is an arrhythmia that puts patients at risk of developing thromboembolic events, including stroke, heart failure, hospitalisation and death, and decreases quality of life. In order to prevent thromboembolic events oral anticoagulants must be initiated in high-risk patients, as defined by a CHA2DS2-VASc score score ≥ 2, should be considered in medium-risk patients (CHA2DS2-VASc score of 1) and is not recommended in low-risk patients with a CHA2DS2-VASc score of 0. For more than 50 years, vitamin K antagonists (VKA) have been the only oral anticoagulant (OAC) available on the market. In August 2012, the first direct oral anticoagulant (DOAC) was available in Belgium, offering new potential perspectives in the area of anticoagulation. The aim of the present study was to provide trends on oral anticoagulation initiation in patients with new-onset AF in general practice and diagnosed between 2002 and 2014, and particularly the change since the introduction of DOACs into the Belgian market. Methods Data were obtained from Intego, a Flemish general practice-based morbidity registration network in Belgium, including GPs from 79 practices. GPs prospectively and routinely registered all new diagnoses and new drug prescriptions. Diagnoses were classified according to the International Classification of Primary Care (ICPC-2). Drugs were classified according to the WHO's Anatomical Therapeutic Chemical (ATC) classification system. All people who had at least one contact with their GP between 2002 and 2015 and a new diagnosis of AF (ICPC-2 code K78) recorded between 2002 and 2014 were selected. Among these 3784 incident cases of AF, 3280 people had a follow-up of ≥ 1 year after the diagnosis of AF and were included in the analyses to allow a minimum period of time to start oral anticoagulation after the diagnosis of AF. In the present study, VKAs and DOACs were considered as oral anticoagulation. By the end of 2015, three different DOACs were available and reimbursable for patients with AF in Belgium: dabigatran etexilate, rivaroxaban and apixaban. A chronic prescription of OAC was considered if a patient had ≥ 2 prescriptions of OAC with at least 6 months between 2 prescriptions. The CHA2DS2-VASc score was calculated for each patient at the time of diagnosis of AF, based on ICPC-2 codes, gender and age. Joinpoint regression models were performed to investigate pattern of crude rate of oral anticoagulant initiation over years, and by thromboembolic risk categories. All P-values Results The proportion of patients with new-onset AF who received ≥ 1 OAC prescription within the year after the AF diagnosis varied between 32.4% in 2002 and 73.5% in 2014. This proportion increased significantly among medium-risk and high-risk patients. The proportion of patients who received a chronic OAC prescription within the year after the AF diagnosis varied between 21.8% in 2002 and 50.4% in 2013. This proportion was 49.5% in 2014. A significant increase was observed in high-risk patients with an average annual percent change (95% CI) of 6.7% (5.4; 7.9%) per year. A non-significant increase was observed in medium-risk patients whereas a non-significant decrease was observed in low-risk patients. The proportion of anticoagulated patients that received a DOAC overcame 50% in those diagnosed in 2013 and reached three-quarter of chronic OAC prescriptions in 2014. The most prescribed DOAC was rivaroxaban in 2012 and 2013, and apixaban in 2014. Conclusions The proportion of patients with a new diagnosis of AF who received a chronic OAC prescription within the year after the AF diagnosis increased significantly between 2002 and 2014, to reach 50% in 2014. A significant increase was observed in high-risk patients, whereas a non-significant decrease was observed in low-risk patients. In patients diagnosed in 2013 and 2014, the prescriptions of DOACs overcame the prescriptions of VKAs.