Kidney Function May Interact with Oral Anticoagulants

For patients with atrial fibrillation (AF), baseline renal function may influence the risks and benefits of oral anticoagulation with dabigatran versus warfarin, according to a research letter in the Journal of the American College of Cardiology.

The retrospective analysis included propensity-matched groups of adults with AF who were taking warfarin (11,546 patients) or dabigatran (5469 patients). Baseline eGFR showed normal kidney function in about 20% of patients, mild kidney disease in 50%, and moderate kidney disease in 30%. Only 2% had severe kidney disease (eGFR of 30 mL/min per 1.73 m2 or lower). Interactions between treatment and baseline eGFR for thromboembolic events and major bleeding were assessed.

For patients with normal kidney function, dabigatran was associated with a higher risk of thromboembolism (incidence rate ratio [IRR], 3.14) but a lower risk of major bleeding (IRR, 0.28). For those with mild kidney disease, thromboembolism risk was similar between treatment groups, but major bleeding risk remained lower with dabigatran (IRR, 0.39).

Among patients with severe kidney disease, there were no thromboembolic events in the dabigatran group versus 2.95 events per 100 person-years in the warfarin group. However, major bleeding risk was higher with dabigatran (IRR, 3.58). The interaction between kidney function and treatment was significant for gastrointestinal but not intracranial bleeding.

Studies have found dabigatran to be superior to warfarin in reducing AF-associated thromboembolism, with similar rates of major bleeding. Kidney disease increases the risk of both thromboembolism and bleeding, whereas dabigatran has significant renal clearance.

This cohort study suggests that dabigatran has a more favorable risk-to-benefit ratio for AF patients with mild to moderate kidney disease but may be associated with a higher risk of thromboembolism in those with normal renal function. The study is limited by the small number of patients with severe kidney disease [Del-Carpio Munoz F, et al. Dabigatran versus warfarin in relation to renal function in patients with atrial fibrillation. J Am Coll Cardiol 2016; 68:129–131].