Most patients on dialysis not prescribed anticoagulant after atrial fibrillation diagnosis
A study assessing anticoagulant use in patients on hemodialysis who were diagnosed with atrial fibrillation revealed 81.5% did not initiate treatment with any anticoagulant within 30 days of being diagnosed.
Further findings indicated off-label underdosing of apixaban was common which, according to study investigators, “might reflect the uncertainty regarding the available data on dosing.”
The results were published in the American Journal of Kidney Diseases.
In a letter to the editor, Min Zhuo, MD, MPH, of the division of pharmacoepidemiology and pharmacoeconomics in the division of renal medicine in department of medicine at Brigham and Women's Hospital, and colleagues addressed the impact of atrial fibrillation (AF) on this patient population, noting 21% of patients with end-stage kidney disease are affected by the condition.
Management of atrial fibrillation
“AF is associated with twofold higher adjusted risk of ischemic stroke and nine times higher adjusted mortality risk during the first 30 days after AF diagnosis in the hemodialysis population,” Zhuo and colleagues wrote. “In 2012 the [FDA] approved apixaban for AF in patients with creatinine clearance [of at least] 25 mL/min. This label was subsequently amended to include patients with ESKD with a dose reduction indicated by age [of at least] 80 years or weight [of at least] 60 kg. The overall prescribing patterns of anticoagulants for incident nonvalvular AF in hemodialysis patients and dose selection for apixaban in routine practice remain unknown.”
To illuminate how atrial fibrillation is managed in patients on hemodialysis, the researchers linked data from the U.S. Renal Data System to Medicare part A (related to inpatients), Medicare part B (related to outpatient) and Medicare part D (related to prescription medications).
After excluding patients based on several criteria – including a preexisting diagnosis of AF or the prior use of anticoagulation – 43,111 patients with new-onset AF were identified.
Of these, 81.51% did not initiate any anticoagulant within 30 days. For those who did begin anticoagulation, 82% were prescribed warfarin and 16.84% were prescribed apixaban, with researchers observing “a steady increase in new-onset AF patients treated with apixaban ... over the study years accompanied by a compensatory decrease in non-initiators.”
After comparing patients who initiated treatment with an anticoagulant with those who did not, Zhuo and colleagues determined that the latter group had a higher prevalence of comorbidities that were associated with an increased risk of bleeding, as well as markers of frailty; apixaban initiations were more likely to have received IV iron and erythropoiesis-stimulating therapy than warfarin initiators.
Appropriate dosing of apixaban
An analysis of dosing appropriateness in patients taking apixaban showed 3.69% of those who started the medication on a standard dose were eligible for a reduced dose and 58.91% of patients who started on a reduced dose did not fulfill the FDA recommended criteria for dose reduction.
According to Zhuo and colleagues, “the risk benefit trade-offs of initiating anticoagulant therapy or not” should be re-evaluated as newer agents with improved safety profiles (compared with warfarin) emerge.
“Currently, randomized studies on apixaban dosing are lacking,” the researchers wrote. “A cohort study observed superiority of the standard-dose apixaban compared with reduced-dose in protecting against stroke and reducing mortality in the ESKD population. Given the increased prescription of apixaban in hemodialysis patients, robust research evaluating the appropriate apixaban dosing is urgently needed.”