Primary Non-adherence to Treatment with New Oral Anticoagulants: The Results of a Prospective Observational Study «ANTEY»

To assess the main characteristics of patients with non-valvular Atrial Fibrillation (AF) who are initially non-adherent to New Oral Anticoagulants (NOAC), and to identify factors associated with this version of non-adherence.

The ANTEY study included 201 patients with non-valvular AF, who had indications and without contraindications for NOAC treatment. The patients had previously been advised to take oral anticoagulants but they did not comply with all medical recommendations. The observation period was 1 year, during which 2 in-person visits were performed: an inclusion visit (V0) and a visit (V1), as well as 1 telephone contact/follow up (FU); the interval between contacts was 6 months. All patients were recommended to take the NOAC by decision of the physician. During the V0, V1 and FU visits, the “National Society for Evidence-Based Pharmacotherapy (NSEPh) Adherence Scale” questionnaire was used to assess overall adherence and associated factors. 15 (7.5%) patients had not started NOAC therapy by the end of the study (primary non-adherent patients). Their characteristics are analysed in this work.

The main reasons for primary non-adherence to NOAC were high cost (33.3%), fears of adverse effects (AE) (33.3%), doubts about the need for treatment (13.3%) and the complex therapy regimen (13.3%). In the group of primary non-adherent patients in comparison with the rest of the patients there were significantly more patients with 1 point according to CHADS₂VASc (20% and 2.2%, respectively, p = 0.029) and patients with 3 points according to HAS-BLED (33.3% and 9.1%, respectively, p = 0.006); they took antiplatelet drugs more often 73.3% versus 21.5%, respectively (p = 0.001). Full employment at work (OR = 5.2; CI95% [1.5; 18.1], p = 0.009), history of quitting smoking (OR = 5.1; CI95% [1.5; 17.0], p = 0,008), the presence of any pharmacotherapy AE (OR = 4.0; CI95% [1.01; 16.0], p = 0.048) increased the chance of primary non-adherence to NOAC by 4-5 times.

The most vulnerable in relation to initiation of NOAC therapy for the prevention of thromboembolic complications in AF are those patients who continue to work or have any pharmacotherapy AE. The leading factors preventing the initiation of NOAC administration are their high cost, fear of the development of AE from the therapy, and patients’ doubts about the need for treatment with these drugs. The clinical trial registration number is NCT 03790917.