Glomerular filtration rate in patients with atrial fibrillation on warfarin treatment: a subgroup analysis from the AURICULA registry in Sweden.

INTRODUCTION: Numerous associations between chronic kidney disease (CKD) and atrial fibrillation (AF) have been reported and patients with CKD on anticoagulation therapy have an increased risk of bleeding. Currently, new anticoagulant agents are emerging in clinical practice, some of which are excreted by the kidneys. The proportion of AF patients on anticoagulant treatment with reduced renal function is, however, unknown.
MATERIALS AND METHODS: Using AURICULA, a Swedish registry for anticoagulation, estimated glomerular filtration rate (eGFR) was investigated in AF patients on warfarin treatment (n = 2,603). The study group was compared with a healthy sample from the population (n = 2,261). Two different creatinine prediction equations were used for calculating eGFR: the Lund-Malmö (LM) and MDRD Study equation.
RESULTS: The fraction of AF patients with eGFR <30 and <45 ml/min/1.73 m(2) were 8.1% and 22.9% with the LM and 4.3% and 16.3% with the MDRD equation, respectively, and significantly higher than corresponding values in the reference population. GFR decreased with increasing age, where 11.4% and 5.6% of AF patients aged ≥ 75 years had eGFR <30 ml/min/1.73 m(2) according to the LM and MDRD equations, respectively.
CONCLUSIONS: Severe renal impairment is common among AF patients on anticoagulant treatment with warfarin, especially at higher ages. Monitoring of renal function should be implemented in clinical practice for AF patients treated with new anticoagulants eliminated by the kidneys.