BACKGROUND: Renal function may decline over time, and the efficacy and safety of dabigatran in atrial fibrillation (AF) in relation to renal function changes are unknown.
METHODS: The RE-LY trial randomized 18,113 patients with AF to 2 doses of dabigatran or warfarin for stroke prevention. Serial creatinine measurements were available in 16,988 patients. The relations between treatment, outcomes, and renal function (Cockcroft-Gault) were investigated using Cox-regression (1) with renal function as a time-dependent covariate and (2) according to worsening renal function (WRF) during follow-up, predefined as a decline in estimated glomerular filtration rate >20% from baseline.
RESULTS: During a median follow-up of 1.8 years, 4,106 (24.2%) participants were observed to have WRF, and 12,882 (75.8%) had stable renal function. The risks of all-cause mortality and major bleeding were higher in patients with WRF versus those with stable renal function (hazard ratio [95% CI]: 2.17 [1.81-2.59] and 1.43 [1.19-1.71], respectively; both P < .0005). The efficacy and safety of dabigatran versus warfarin were similar irrespective of renal function changes over time (interaction P values ≥ .13 in both models). Dabigatran 110 mg showed a greater relative risk reduction of major bleeding in patients with normal renal function (estimated glomerular filtration rate >80 mL/min) during follow-up (interaction P = .026).
CONCLUSIONS: In AF, WRF was associated with a higher risk of death and major bleeding. The efficacy and safety profile of dabigatran compared with warfarin was similar irrespective of renal function changes over time. Dabigatran 110 mg showed a greater relative risk reduction of major bleeding in patients with normal renal function during follow-up.