The Association of Kidney Function and Albuminuria With the Risk and Outcomes of Syncope: A Population-Based Cohort Study

Background: The risks and subsequent outcomes of syncope among seniors with chronic kidney disease (CKD) are unclear. Methods: We conducted a population-based retrospective cohort study of 272,146 patients >= 66 years old, in Ontario, Canada, from April 1, 2006, to March 31, 2016. Using administrative health care databases, we examined the association of estimated glomerular filtration rate (eGFR) and urine albumin to creatinine ratio (ACR) with incident syncope and the association of incident syncope with the composite outcome of myocardial infarction, stroke, and death by levels of eGFR/ACR, using adjusted Cox proportional hazards models. Results: A total of 15,074 incident syncopal events occurred during the study period. The adjusted risk for syncope was higher with a lower eGFR and higher ACR in a stepwise manner (eGFR 60 to < 90: HR 1.17 [1.09-1.26] vs eGFR < 30: HR 1.67 (1.50-1.87) with eGFR >= 90 referent; ACR > 30: HR 1.15 [1.07-1.24] with ACR < 3 referent). Among the 12,710 patients with a first syncope event and 1 year of follow-up, the adjusted risk for the composite outcome was higher with a lower eGFR and higher ACR in a stepwise manner (eGFR 60 to < 90: HR 1.05 [0.90-1.22] vs eGFR < 30: HR 1.62 [1.34-1.96] with eGFR >= 90 referent; ACR > 30: HR 1.77 [1.60-1.96], ACR < 3 referent). Conclusions: A lower eGFR and higher ACR are associated with a higher risk of a hospital encounter for syncope and of related complications among persons of advanced age.