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Switching from vitamin K antagonist to dabigatran in atrial fibrillation: differences according to dose
Naja Emborg Vinding1, Laila Staerk2, Gunnar Hilmar Gislason2,3,4
1Department of Cardiology, Copenhagen University Hospital, Rigshospitalet, Blegdamsvej 3, København 2100, Denmark.
Insights
In atrial fibrillation (AF) patients switching from warfarin, one in four received an inappropriate dabigatran dose. Guidelines for reduced dabigatran dosing were not consistently followed, impacting patient outcomes.
Area of Science:
- Cardiology
- Pharmacology
- Public Health
Background:
- Atrial fibrillation (AF) patients typically receive 150 mg of dabigatran twice daily.
- Guidelines recommend a lower 110 mg dose for patients with high bleeding risk.
- Current adherence to these dosing recommendations in patients switching from warfarin is not well understood.
Purpose of the Study:
- To investigate the appropriateness of dabigatran dosing in AF patients transitioning from vitamin K antagonist (VKA) therapy.
- To determine the extent to which European guidelines for dabigatran dosing are followed in this patient population.
Main Methods:
- A nationwide registry study identified VKA-experienced AF patients who switched to dabigatran between August 2011 and December 2012.
- Dabigatran dosing (110 mg or 150 mg twice daily) was assessed against 2012 European guideline criteria for dose reduction (age ≥80, HAS-BLED ≥3, eGFR <50 mL/min/1.73 m², or interacting drugs).
Main Results:
- Of 1626 patients, 26% were inappropriately dosed. 14% received the lower 110 mg dose when the higher dose was indicated.
- 39% of patients on the 150 mg dose met criteria for the 110 mg dose, primarily due to high HAS-BLED scores.
- Patients switched to 110 mg were older, more likely female, had higher comorbidity, and a greater risk of mortality compared to those on 150 mg.
Conclusions:
- One in four VKA-experienced AF patients were switched to a dabigatran dose inconsistent with guideline recommendations.
- Inappropriate dosing was common, with significant proportions receiving either too low or too high a dose based on guideline criteria.
- Factors such as female sex, advanced age, reduced kidney function, and prior bleeding influenced the switch to the lower dabigatran dose.
Aims:
In atrial fibrillation (AF) patients 150 mg b.i.d. dabigatran is the standard dose, yet guidelines recommend 110 mg b.i.d. when bleeding risk is high. It is unknown to which extend these recommendations are followed in patients switching from vitamin K antagonist (VKA) to dabigatran. The aim of this study was to investigate if AF patients are switched from VKA to the appropriate dose of dabigatran.
Methods And Results:
Using nationwide registries (22 August 2011 to 31 December 2012), we identified VKA-experienced AF patients with available creatinine values who switched to dabigatran. European guidelines criteria 2012 on dabigatran dosing were examined: age ≥80 years, HAS-BLED ≥3, estimated glomerular filtration rate (eGFR)<50 mL/min/1.73 m2, or use of interacting drugs. We identified 1626 VKA-experienced AF patients who switched to dabigatran 110 mg (820 patients) or 150 mg (806 patients). Patients who switched to 110 mg compared with 150 mg were older [median age 82 years (Q1-Q3: 77-86) vs. 68 years (Q1-Q3: 64-74)], more often females (54% vs. 35%), had a higher comorbidity burden, higher proportion with CHA2DS2-VASc score ≥2 (98% vs. 80%), and more with a HAS-BLED score ≥3 (46% vs. 28%). Patients switched to 110 mg had a higher absolute risk of mortality compared with patients switched to 150 mg. Overall, 26% were inappropriately dosed and 14% were switched to 110 mg although the higher dose was indicated. Furthermore, 39% of patients switched to 150 mg fulfilled one or more criteria for 110 mg, this mostly driven by high HAS-BLED scores (28.2% of patients on 150 mg). Female sex, age ≥80 years, eGFR < 50 mL/min/1.73 m2, drugs interacting with dabigatran, and prior bleeding were associated with switch to 110 mg. Patients inappropriately dosed had similar risk of mortality as patients appropriately dosed.
Conclusion:
Among VKA-experienced AF patients one in four were switched to a dabigatran dose contrary to guideline recommendations.
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