Abstract Number: OC 71.1
Meeting: ISTH 2022 Congress
Background: While non-vitamin K antagonist oral anticoagulants (NOACs) are increasingly prescribed, concerns have emerged about patients receiving a lower dose against guideline recommendations, i.e. off-label dose reduction. The clinical impact of off-label dose reduction remains unclear.
Aims: To investigate the effects of off-label NOAC dose reduction compared to on-label standard dosing in atrial fibrillation (AF) patients in routine care.
Methods: Population-based cohort study using data from the United Kingdom Clinical Practice Research Datalink, comparing adults with non-valvular AF receiving an off-label reduced NOAC dose to patients receiving an on-label standard dose. Outcomes were ischaemic stroke, major bleeding, non-major bleeding and mortality. Inverse probability of treatment weighting (IPTW) on the propensity score was applied to adjust for confounding.
Results: Off-label dose reduction occurred in 2,466 patients (8.0%), compared to 18,108 (58.5%) on-label standard dose users. Median age was 80 years (interquartile range (IQR) 73.0-86.0) versus 72 years (IQR 66-78), respectively. Incidence rates were higher in the off-label dose reduction group compared to the on-label standard dose group, for ischaemic stroke (0.94 vs. 0.70 per 100 person years), major bleeding (1.48 vs. 0.83), non-major bleeding (6.78 vs. 6.16) and mortality (10.12 vs 3.72). IPTW resulted in an adjusted hazard ratio of 1.07 (95%CI 0.65-1.74) for ischaemic stroke; 0.98 (95%CI 0.65-1.48) for major bleeding; 0.89 (95%CI 0.74-1.08) for non-major bleeding; and 1.48 (95%CI 1.25-1.76) for mortality.
Conclusion(s): In this large population-based study, the risk of ischaemic stroke, non-major bleeding and major bleeding was similar in AF patients receiving an off-label reduced NOAC dose compared to on-label standard dose users, while mortality risk appeared to be higher. Therefore, altogether, off-label dose reduction seems unlikely to be a fruitful strategy when aiming to reduce bleeding risk in (high-risk) AF patients.
To cite this abstract in AMA style:Van Den Dries C, Pajouheshnia R, van den Ham R, Souverein P, Moons C, Hoes A, Geersing G, van Doorn S. Safety of off-label dose reduction of non-vitamin K antagonist oral anticoagulants in patients with atrial fibrillation [abstract]. https://abstracts.isth.org/abstract/safety-of-off-label-dose-reduction-of-non-vitamin-k-antagonist-oral-anticoagulants-in-patients-with-atrial-fibrillation/. Accessed September 22, 2023.
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