Results of a study published in the 17 March, 2009 issue of Circulation showed that chronic kidney disease increases the risk of thromboembolism in atrial fibrillation independently of other risk factors.
“Knowing the level of kidney function and the presence of proteinuria may improve risk stratification for decision making about the use of antithrombotic therapy for stroke prevention in atrial fibrillation,” the authors wrote.
The researchers of the ATRIA (Anticoagulation and risk factors in atrial fibrillation) study, led by Dr Alan S Go, Kaiser Permanent of North California, Oakland, and University of California at San Francisco, USA, examined how chronic kidney disease (reduced glomerular filtration rate or proteinuria) affects the risk of thromboembolism off anticoagulation in patients with atrial fibrillation. The group estimated glomerular filtration rate using the Modification of Diet in Renal Disease equation and proteinuria from urine dipstick results found in laboratory databases. Patient characteristics, warfarin use, and thromboembolic events were ascertained from clinical databases, with validation of thromboembolism by chart review.
During 33,165 person-years off anticoagulation among 10,908 patients with atrial fibrillation, we observed 676 incident thromboembolic events. After adjustment for known risk factors for stroke and other confounders, proteinuria increased the risk of thromboembolism by 54% (relative risk, 1.54; 95% CI, 1.29 to 1.85), and there was a graded, increased risk of stroke associated with a progressively lower level of estimated glomerular filtration rate compared with a rate 60mL, min-1, 1.73 m-2: relative risk of 1.16 (95% CI, 0.95 to 1.40) for estimated glomerular filtration rate of 45 to 59mL, min-1, 1.73 m-2 and 1.39 (95% CI, 1.13 to 1.71) for estimated glomerular filtration rate <45mL, min-1, 1.73 m-2 (p=.0082 for trend).