Evaluation of indications for reduced-dose non-vitamin K antagonist oral anticoagulants in hospitalised patients with atrial fibrillation

Background: Prevention of thromboembolic complications is a priority in patients with atrial fibrillation (AF). The use of non-vitamin K antagonist oral anticoagulants (NOACs) is more common and some patients have indications for a reduced dose. Aim: We sought to evaluate the frequency of NOACs being prescribed to AF patients and to compare the groups of AF patients receiving standard and reduced doses. Methods: The study included 1327 patients diagnosed with AF and hospitalised at an institution of the highest referral level in cardiology in the years 2015-2016. Final analysis encompassed 713 patients with nonvalvular AF, who were prescribed NOACs upon discharge. Results: In the group of patients receiving NOACs, standard doses were used in 383 (53.7%) patients, while 330 (46.3%) patients received reduced doses. Among patients treated with reduced doses, dabigatran was prescribed to 186 (56.4%) patients, rivaroxaban to 124 (37.5%) patients, and apixaban to 20 (6.1%) patients. Absence of indications tor dose reduction was identified in 54 out of 330 (16.4%) patients receiving reduced-dose NOACs, including six out of 20 patients receiving reduced dose apixaban (30%), 21 out of 186 patients receiving reduced-dose dabigatran (11.3%), and 24 out of 124 patients receiving reduced-dose rivaroxaban (19.3%). Among patients treated with reduced dose of dabigatran (n = 186), one indication for dose reduction was observed in 75 patients, and at least two indications were observed in 90 patients. One indication was observed in 71 patients, and at least two indications were observed in 30 patients treated with a reduced dose of rivaroxaban (n = 124). Conclusions: Standard closes of NOACs were prescribed to most hospitalised AF patients. Apixaban was prescribed more frequently in the reduced dose regimen, while the frequencies of standard and reduced doses prescribed were similar for dabigatran and rivaroxaban. Absence of indications for dose reduction as defined in relevant guidelines and Summaries of Product Characteristics was identified in 15.5% of patients receiving reduced doses of NOACs. More than one indication for dose reduction was identified in most patients receiving reduced-dose dabigatran, while one indication was identified in most patients receiving reduced-dose rivaroxaban.