#430 Risk factors for major bleeding in patients with non-valvular atrial fibrillation and CKD G3-G5D on oral anticoagulants
Authors: Welander Frida , Renlund Henrik , Själander Anders 
Published: May 2024

Abstract

Background and Aims
We previously published a register-based cohort study comparing direct oral anticoagulants (DOAC) and warfarin in patients with atrial fibrillation (AF) and chronic kidney disease (CKD) GFR category 3-5 (G3-G5) including patients on dialysis (G5D) (1). This study showed that DOAC was associated with lower risk of major bleeding but similar risk of ischemic stroke compared to warfarin. Bleedings were however more common than strokes, especially in advanced CKD (G5-G5D) where the risk of major bleeding was up to 10 times higher than the risk of stroke. Subsequently, the stroke- and bleeding risk in patients with AF and advanced CKD must be carefully evaluated when deciding on whether to prescribe oral anticoagulants (OAC) or not. Available stroke- and bleeding scoring systems do not perform well in CKD (2, 3). This study aims to present risk factors associated with major bleeding in a Swedish cohort of OAC-treated patients with CKD G3-G5D.

Method
Data was collected from high quality Swedish healthcare registers including Swedish Renal Registry and Auricula, a register for atrial fibrillation and oral anticoagulants and the National Patient Register. Patients with eGFR&lt;60 ml/min/1.73m2 and non-valvular atrial fibrillation and either DOAC (apixaban, rivaroxaban, edoxaban and dabigatran) or warfarin treatment between 2009-2018 where included. DOAC treatment periods were collected from the Swedish Prescribed Drug Register (PDR), starting from dispense date covering assumed standard pill use and an additional 30 days grace period. Warfarin treatment periods were collected directly from Auricula. An undefined treatment was a period of no OAC or a period of warfarin from PDR not matching a treatment period in Auricula. All periods of OAC treatment with either DOAC or warfarin were evaluated in a multivariate Cox regression model regarding the risk of major bleeding requiring inpatient care. Time-dependent covariates adjusted for in the model were age, sex, years from study start, GFR category, congestive heart failure, diabetes mellitus, hypertension, excessive alcohol use, liver disease, vascular disease, previous gastrointestinal bleeding, intracranial bleeding, other bleeding, ischemic stroke/ transient ischemic attack (TIA), myocardial infarction, PCI and exposures (DOAC, warfarin and periods of undefined treatment).

Results
Of 2453 included patients, 59% had warfarin (time in therapeutic range, TTR, 67%) and 41% DOAC at inclusion, predominantly apixaban (81% of DOAC users). The mean age was 77 years, 28.3% had G3, 45.4% G4, 9.1% G5 and 17.3% G5D (Table 1). Mean follow up was 2.2 years. During follow up 424 major bleedings occurred yielding 8.9 (95% confidence interval 8.1-9.8) bleedings per 100 patient-years.
Table 2 shows effect estimates of each covariate on the outcome major bleeding. Covariates, besides warfarin, associated with increased risk of major bleeding were GFR category, G5/5D versus G3, hazard ratio 1.92 (95% CI 1.43-2.56), previous GI bleeding, 1.77 (1.39-2.25) and previous other bleeding 1.33 (1.09-1.62). Other factors associated with major bleeding were congestive heart failure 1.36 (1.11-1.68), male sex 1.28 (1.03-1.60) and vascular disease, 1.35 (1.01-1.79).

Conclusion
Patients with non-valvular atrial fibrillation and CKD G3-G5D on OAC are at high risk of major bleeding. Previous major bleeding and kidney failure are strongly associated with major bleeding, this reiterates the results of many previous studies. The present study also shows an association between OAC-associated major bleeding in CKD and male sex, congestive heart failure and vascular disease. Similar associations have been showed in non-CKD cohorts previously but is inadequately studied in CKD. Knowledge about risk factors for major bleeding on OAC in advanced CKD is essential when deciding on when to anticoagulate or not.