부산대학교 도서관

Background: Non-vitamin K oral anticoagulants (NOAC) are commonly prescribed to prevent stroke for at-risk atrial fibrillation (AF) patients. Dosing reduction of these agents is recommended by Health Canada when certain clinical criteria are met. Adherence to these recommendations may be incomplete. We examined the rates and patterns of inappropriate dosing for rivaroxaban and apixaban.Methods/Results: We enrolled 2,498 AF patients from 132 community-based sites in Canada (Nov 2013 to Mar 2016) in a prospective observational registry. Patients treated with rivaroxaban or apixaban at the baseline visit were identified. Creatinine clearance (CrCl) was estimated by the Cockcroft-Gault formula. For rivaroxaban-treated patients, inappropriate dosing was present if the 20 mg dose was prescribed when the CrCl was <50 ml/min or if the 15 mg dose was prescribed when the CrCL was ≥50 ml/min. For apixaban-treated patients, inappropriate dosing was present if the 2.5 mg dose was prescribed when 0/3 or 1/3 criteria needed for dose reduction was met (age≥80 years, creatinine ≥133 umoL, weight ≤60 kg) or if the 5 mg dose was prescribed when ≥2/3 criteria were present.There were 898 patients included in this analysis and inappropriate dosing was observed for 178 (19.8%) patients; 19.0% for rivaroxaban and 21.5% for apixaban, respectively (p=0.42). The majority of these patients were under-dosed (n=144, 80.9%). Patients who received inappropriate NOAC dosing were older (79.8±7.6 vs. 72.5±9.5 years, p<0.01), more likely to be female (47.8% vs. 36.7%, p<0.01), had higher CHA2DS2-VASc scores (4.1±1.5 vs. 3.2±1.6, p<0.01), and had lower weight (79.7±18.1 vs. 88.5±21.4 kg, p<0.01) when compared to those who received appropriate dosing. The rates of concomitant antiplatelet use were similar in both groups.Conclusions: Inappropriate dosing was observed in 1 out of 5 patients who were treated with rivaroxaban or apixaban in this Canadian registry. This could have been purposely done by clinicians to mitigate bleeding risk in certain patient subsets even though their stroke risk was high. Further work is needed to examine the motivations behind for inappropriate NOAC dosing and whether this decision is associated with adverse thromboembolic or bleeding risks.