Renal decline in patients with non-valvular atrial fibrillation treated with rivaroxaban or warfarin: A population-based study from the United Kingdom

Background: Reports suggest that renal decline is greater among patients with non-valvular atrial fibrillation (NVAF) treated chronically with warfarin vs. some non-vitamin K antagonist oral anticoagulants. Methods and results: Using primary care electronic health records from the United Kingdom we followed adults with NVAF and who started rivaroxaban (20 mg/day, N = 5338) or warfarin (N = 6314), excluding those with estimated glomerular filtration rate (eGFR) <50 ml/min/1.73m2, end-stage renal disease (ESRD) or no eGFR or serum creatinine (SCr) values recorded in the previous year. Outcomes were: doubling SCr levels, >30% decline in eGFR and progression to ESRD. We calculated adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) for each outcome. Average eGFR slope was estimated using mixed model regression. After a mean follow-up 2.5 years, the number of incident cases of adverse renal events within the two cohorts was: doubling SCr (n = 322), >30% decline in eGFR (n = 1179), and progression to ESRD (n = 22). Adjusted HRs (95% CIs) for the renal outcomes among rivaroxaban vs. warfarin users were: doubling SCr, 0.63 (0.49-0.81); >30% decline in eGFR, 0.76 (0.67-0.86); ESRD, 0.77 (0.29-2.04). Similar results were observed among patients with diabetes or heart failure. Estimated mean decline in renal function over the study period was 2.03 ml/min/1.73 m2/year among warfarin users and 1.65 ml/min/1.73 m2/year among rivaroxaban users (p = 0.03). Conclusions: We found clear evidence that patients with NVAF, preserved renal function at baseline and treated with rivaroxaban had a markedly reduced risk and rate of renal decline compared with those treated with warfarin.