A 78-year-old woman with end-stage renal disease (ESRD) is hospitalized with cellulitis and is incidentally found to be in atrial fibrillation. She does not have a history of mitral stenosis, nor does she have a prosthetic valve. She does have a history of hypertension, diabetes, and prior stroke without residual deficits.
After counseling her about the risk of stroke associated with atrial fibrillation (AFib) she makes it clear she is interested in pharmacologic therapy to minimize her risk of stroke and asks what medication you would recommend for anticoagulation.
Brief overview of the issue
Anticoagulation for AFib is indicated for stroke prophylaxis in patients with an elevated risk of stroke. The CHA2DS2-VASc score is useful in calculating an individual patient’s risk of stroke and as a decision tool to determine who would benefit from anticoagulation, and it is recommended in the American Heart Association guidelines.1
Low-risk patients (CHA2DS2-VASc score of 0 in men or 1 in women) should not be started on anticoagulation for stroke prophylaxis. For anyone with a risk factor, other than being female, anticoagulation is indicated and should be considered.
The guideline recommends anticoagulant therapy, not antiplatelet agents. For most of the recent past, this has meant a vitamin K antagonist (warfarin) or sometimes a low-molecular-weight heparin injected subcutaneously. Over the past decade, however, with the approval of multiple direct oral anticoagulants (DOACs), nonwarfarin oral anticoagulation has grown in popularity as the prophylactic medication of choice.2
While the data for patients with preserved renal function is robust, there is far less data to guide decision making for patients with end-stage renal disease.
Overview of the data
Until the introduction of DOACs, warfarin was the main agent used for stroke prophylaxis in patients with end-stage kidney disease and AFib. Professional guidelines favored warfarin for these patients who were mostly excluded from DOAC trials. Specialized conferences also looked at this issue.
The Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference, which reviewed chronic kidney disease and arrhythmias, noted that there were no randomized controlled trials that examined the efficacy and safety of anticoagulation in chronic kidney disease patients with estimated creatinine clearance less than 30 mL/min. They remarked that there was insufficient high-quality evidence to recommend warfarin for the prevention of stroke in patients with AFib and dialysis-dependent chronic kidney disease.
Since, according to other trials, DOACs had better safety profiles in other populations, the conference noted that lower-dose apixaban (2.5 mg orally twice daily) or rivaroxaban (15 mg daily) may be considered in this population until clinical safety data were available. Furthermore, the conference recommended that these patients be treated with a multidisciplinary approach in regards to anticoagulation and have an annual reevaluation of treatment goals, along with a risk-benefit assessment.3
Since the publication of the 2018 AHA guidelines and the guidance document that resulted from the KDIGO conference, additional research has been published comparing anticoagulation with a DOAC versus warfarin for AFib in patients with ESRD.
“Outcomes associated with apixaban use in patients with end-stage kidney disease and atrial fibrillation in the United States” was an observational, retrospective, cohort study that compared outcomes in dialysis patients who took warfarin for AFib with those who took apixaban.4 Patients’ data was taken from the U.S. Renal Data System database and were included in the final analysis if they had ESRD, a recent diagnosis of AFib or atrial flutter, and a new prescription for either warfarin or apixaban. Outcome measures were stroke or systemic embolism, major bleeding (critical site, transfusion, or death), gastrointestinal bleeding, intracranial bleeding, or death. Drug usage and compliance were assessed using Medicare Part D prescription information.
A total of 25,523 patients met the inclusion/exclusion criteria and had taken either warfarin (n = 23,172) or apixaban (n = 2,351). To account for selection bias in these cohorts, a subset of the warfarin patients was selected based on prognostic score matching. The prognostic score was calculated from the baseline characteristics (which included age, stroke history, diabetes, smoking, antiplatelet medication, liver disease, prior bleeding, and CHA2DS2-VASc score). Kaplan-Meier and Cox regression analysis were used to give hazard ratios and 95% confidence intervals for each outcome measure. Prespecified subgroup analyses were conducted to compare apixaban doses, where 44% were prescribed 5 mg b.i.d. and 56% were prescribed 2.5 mg b.i.d..
In the study, patients in the apixaban group had a significantly lower risk of major bleeding as compared with the warfarin group (HR, 0.72; 95% CI, 0.59-0.87; P less than .001) with overall high rates of major bleeding in both groups at 19.7 and 22.9 per 100 patient-years in the apixaban group and warfarin group, respectively. There was no difference in the rate of stroke/systemic embolism between patients receiving apixaban and warfarin (HR, 0.88; 95% CI, 0.69-1.12; P = .29). There was a nonsignificant trend toward decreased risk of GI bleeding in the apixaban group and no significant differences between the groups in the rates of intracranial bleeding. Apixaban was also associated with a nonsignificant trend toward lower risk of mortality (HR, 0.85; 95% CI, 0.71-1.01; P = .06).
Notably, censoring rates because of expired prescriptions or a 1-month gap between prescriptions were high in both groups and the majority of censoring occurred within the first 12 months. Additionally, in dose specific analyses, patients receiving the 5-mg, twice-daily dose were found to have statistically significant decreases in risk of stroke/systemic embolism (P = .035) and mortality (P = .005) as compared with the 2.5-mg, twice-daily dose without significant differences in GI or intracranial bleeding.
There are three ongoing, open-label, randomized, controlled trials examining anticoagulation for nonvalvular AFib in patients with ESRD on hemodialysis with two comparing apixaban to warfarin (or derivative) and the other warfarin versus no anticoagulation.5 All trials are in adult patients with documented AFib and CHA2DS2-VASc score of at least 2. AKADIA (Germany based) plans to enroll 222 patients and compares a vitamin K antagonist (INR goal, 2-3) with 2.5-mg b.i.d. apixaban patients with ESRD on hemodialysis for at least 3 months with primary outcome of major and clinically relevant nonmajor bleeding and secondary outcome of thromboembolic events, as well as apixaban levels pre- and post hemodialysis.
RENAL-AF (U.S. based) plans to enrolled 762 patients and compares 5-mg b.i.d. apixaban (with 2.5 mg for selected patients) with warfarin in people of chronic hemodialysis with primary outcome of days to first major or clinically relevant nonmajor bleeding event and secondary outcome of stroke, systemic embolism, mortality, adherence and plasma apixaban levels. AVKDIAL (France based) plans to enroll 855 patients and compares no anticoagulation with vitamin K antagonists in patients on hemodialysis for at least 1 month, with primary outcome of cumulative incidence of severe bleeding and thrombosis.