Impact of Chronic Kidney Disease on Risk of Incident Atrial Fibrillation and Subsequent Survival in Medicare Patients

Abstract

Background Atrial fibrillation ( AF ) and chronic kidney disease ( CKD ) are prevalent in the elderly and are independently associated with increased risk of death. We evaluated risk of incident AF with advancing CKD and examined the mortality rate associated with CKD after incident AF in elderly patients. Methods and Results This retrospective cohort study used the M edicare 5% database. Point‐prevalent M edicare enrollees on December 31, 2006, without preexistent AF or end‐stage renal disease were followed up for incident AF through 2008. CKD and AF were identified from International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis codes. Associations between CKD stage and incident AF and subsequent risk of death were examined in a Cox proportional‐hazards model. Unadjusted survival after incident AF was estimated by the K aplan‐ M eier method. CKD was present in 55 962 patients (5.1% of the cohort). Of these, 4952 (8.8%) had CKD stages 1 and 2; 19 795 (35.3%), stages 3 to 5; and 31 215 (55.7%), unknown stage. The hazard ratio for incident AF in CKD stages 3 to 5 was 1.13 (95% confidence interval 1.09 to 1.18). Other stages were not independently associated with incident AF . Survival after incident AF decreased progressively as CKD stage increased ( P <0.0001). The 1‐year mortality rate for CKD stages 3 to 5 with incident AF was 35.6%. Adjusted hazard ratios for death after incident AF were 1.14 (95% confidence interval 1.00 to 1.30) for CKD stages 1 and 2, 1.27 (95% confidence interval 1.20 to 1.35) for CKD stages 3 to 5, and 1.29 (95% confidence interval 1.23 to 1.36) for unknown stage. Conclusions Advanced CKD is associated with increased risk of incident AF . In Medicare patients with incident AF, mortality rates are higher for those with advanced CKD than for those without CKD.