The risks of stroke and systemic thromboembolism and the effects of antithrombotic treatment have not been well studied in patients with both Afib and CKD because patients with renal disease have typically been excluded from the large Afib trials.
To explore the issue, Olesen and colleagues turned to Danish national registries to identify all patients discharged with a diagnosis of nonvalvular atrial fibrillation from 1997 through 2008. Of the 132,372 patients discharged over that time period, 2.7 percent had non-end-stage CKD and 0.7 percent had ESRD.
After adjustment for congestive heart failure, hypertension, age greater than 75 years, diabetes, history of stroke or thromboembolism, vascular disease, age 65 to 74 years, female sex, antithrombotic treatment, and year of inclusion, the risk of stroke or systemic embolism was significantly higher in the patients with non-end-stage renal disease (HR 1.49, 95% CI 1.38 to 1.59) and end-stage renal disease (HR 1.83, 95% CI 1.57 to 2.14) than in those with normal kidney function.
The risks of bleeding, myocardial infarction, and all-cause death also were higher among those with any degree of renal disease.
Whereas warfarin was associated with a decreased risk of stroke or systemic thromboembolism in patients with and without renal disease, aspirin was associated with a greater risk both in the overall cohort (HR 1.10, 95% CI 1.06 to 1.14) and among patients who had any renal disease (HR 1.17, 95% CI 1.01 to 1.35).
Warfarin, aspirin, or both raised bleeding risk across patient groups, regardless of kidney function.
The authors acknowledged that their study was limited by the observational design, which left open the possibility of residual confounding. In addition, rates of various risk factors and aspirin use may have been underestimated.