Abstract Number: PB1082
Meeting: ISTH 2021 Congress
Background: Atrial fibrillation (AF) is the most prevalent arrhythmia worldwide, being the main cause of anticoagulation. DOACS are used often for the stroke prevention in these patients. Each DOAC has two presentations, the standard dose and the reduced dose.
Aims: To assess the frequency, effectiveness and safety of inappropriate DOAC dosing in patients with AF.
Methods: Retrospective study that included patients with AF who started a DOAC (Rivaroxaban, Apixaban, Dabigatran or Edoxaban) from January 1, 2013 to December 31, 2016, in three Spanish hospitals (Hospital Clínico Universitario Virgen de la Arrixaca, Hospital Comarcal del Noroeste and Hospital Vega Baja). Inappropriate dosing was analysed according to labeling recommendations. Thromboembolic, hemorrhagic complications and mortality were recorded. Mean follow-up was 1,6 years. Statistical analysis was performed using SPSS® Statistics program v25 (SPSS Inc., Chicago, Illinois, USA).
Results: A total of 2218 patients were included, of which, 506 patients (23 %) were receiving an inappropriate dose. Among these patients, inappropriate reduced dose (underdosing) predominated (87 %). Table 1 shows the main characteristics of the cohort. Rivaroxaban was the drug incorrectly prescribed most often.
|Table 1. Cohort characteristics
N = 2218
|Age (years)||76 ± 9|
|Sex (female)||1116 (53 %)|
|Smoking||142 (6 %)|
|Alcoholism||49 (2 %)|
|CrCl (ml/min)||74 ± 35|
|Hypertension||1943 (88 %)|
|Diabetes mellitus||734 (33 %)|
|Heart failure||416 (19 %)|
|CHA2DS2-VASc||4,0 ± 1,6|
|HAS-BLED||2,4 ± 0,9|
Compared to the correctly dosing group, a higher rate of mortality was observed in the underdosing group (13,6 vs 8,5 %, p<0,001). However, regarding ischemic stroke and major bleeding, we could not find differences between groups (table 2).
|Table 2. Events according to appropriate dosing of DOAC|
N = 506
N = 1712
|Mortality||69 (13,6 %)||5 (8,6 %)||145 (8,5 %)||<0,001||0,974|
|Ischemic stroke/TIA||16 (3,6 %)||2 (3,4 %)||51 (3,0 %)||0,532||0,840|
|Sistemic embolism||0||1 (1,7 %)||3 (0,2 %)||0,743||0,015|
|Intracraneal bleeding||3 (0,6 %)||0||10 (0,6 %)||0,841||0,559|
|Major bleeding||25 (5,5 %)||3 (6,7 %)||88 (5,1 %)||0,727||0,995|
|Minor bleeding||73 (14,4 %)||7 (12,0 %)||226 (13,12%)||0,100||0,796|
pa: underdosing vs appropriate dosing. pb :underusing vs appropriate dosing
Multivariate analysis revealed that underdosing was associated to elderly, prior major bleeding and the drug rivaroxaban, while overdosing was associated to elderly, higher CHA2DS2-VASc score and the drug dabigatran.
Conclusions: Almost a quarter of the population was receiving an off-label dose. This is traduced in a higher rate of mortality in patients undersing. A higher rate of ischemic events in the underdosing group or a higher rate of bleeding events in the overdosing group were not shown.
To cite this abstract in AMA style:Navarro Almenzar B, Cerezo Manchado JJ, García Candel F. Inappropriate Direct Oral Anticoagulant Dosing in a Spanish Cohort with Atrial Fibrillation [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 1). https://abstracts.isth.org/abstract/inappropriate-direct-oral-anticoagulant-dosing-in-a-spanish-cohort-with-atrial-fibrillation/. Accessed September 16, 2021.
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