Association between renal function and clinical outcomes in elderly patients with nonvalvular atrial fibrillation: sub-analysis of the ANAFIE Registry
Authors: Shimizu W ,   ANAFIE Registry Group
Published: October 2021

Abstract

Background
With the advance of age, the prevalence of non-valvular atrial fibrillation (NVAF) increases and renal function decreases. Decreased renal function is associated with a higher risk of both thrombotic and bleeding events. In clinical practice, warfarin (WF) is often administered to patients with decreased renal function rather than direct oral anticoagulants (DOAC) due to the lack of evidence for DOAC. Therefore, it is important to clarify the clinical features and optimal management of anticoagulants for elderly AF patients.

Purpose
The All Nippon Atrial Fibrillation In the Elderly (ANAFIE) Registry is a prospective, multicenter, observational study designed to collect real-world data on clinical status and prognosis for more than 30,000 Japanese patients (age ≥75 years) with NVAF. This sub-analysis of the ANAFIE Registry assessed 2-year outcomes and anticoagulant treatment in elderly NVAF patients, stratified by renal function.

Methods
A total of 32,275 patients from the ANAFIE registry were divided into 5 groups by creatinine clearance (CrCL), estimated using the Cockcroft–Gault equation modified for Japanese (CrCL: &lt;15, 15 to &lt;30, 30 to &lt;50, 50 to &lt;80, ≥80 mL/min). Kaplan-Meier analysis was used to evaluate the annualized incidence rates of clinical outcomes. Hazard ratios (HR) for clinical outcomes were analyzed using the Cox proportional-hazards model.

Results
In the total population, the mean age was 81.5 years; men accounted for 57.3%; the mean CHA2DS2-VASc score was 4.5; the mean HAS-BLED score was 1.9; the prevalence of paroxysmal AF was 42.1%; the mean follow-up period was 1.88 years; and oral anticoagulants were used by 92.4% of patients (WF, 25.5%; DOAC, 66.9%). The percentages of patients with CrCL &lt;15, 15 to &lt;30, 30 to &lt;50, 50 to &lt;80, and ≥80 mL/min were 1.3%, 10.7%, 33.4%, 32.4%, and 3.4%, respectively. As renal function decreased, the mean age was higher, the CHA2DS2-VASc and HAS-BLED scores were higher, the proportion of patients receiving anticoagulants was lower, the administration rate of WF was higher, and that of DOAC was lower. The overall incidence rates of clinical outcomes were 3.01% for stroke or systemic embolic events (SEE), 2.00% for major bleeding, 2.03% for CV death, and 6.95% for all-cause mortality. Compared with the reference group (CrCL ≥50 mL/min), the HRs for these clinical outcomes except major bleeding increased significantly as renal function decreased (p-value for trend &lt;0.05 for all) (Table). In patients with CrCL15 to &lt;30 mL/min, compared to patients receiving WF, those receiving DOAC had no significant difference in the HRs for stroke/SEE, major bleeding, CV death, and all-cause death.

Conclusions
Elderly NVAF patients with decreased CrCL were less likely to use oral anticoagulants and more likely to experience clinical events than those with normal renal function. Among patients with CrCL15 to &lt;30 mL/min, the incidences of clinical events were similar between WF and DOAC.

Funding Acknowledgement
Type of funding sources: Private company. Main funding source(s): Daiichi Sankyo Co., Ltd.