Kidney Function and Mortality in Octogenarians: Cardiovascular Health Study All Stars

Abstract

Objectives:

To examine the association between kidney function and all-cause mortality in octogenarians. Design

Retrospective analysis of prospectively collected data. Setting:

Community. Participants:

Serum creatinine and cystatin C were measured in 1,053 Cardiovascular Health Study (CHS) All Stars participants. Measurements:

Estimated glomerular filtration rate (eGFR) was determined using the Chronic Kidney Disease Epidemiology Collaboration creatinine (eGFR[subscript CR]) and cystatin C one-variable (eGFR[subscript CYS]) equations. The association between quintiles of kidney function and all-cause mortality was analyzed using unadjusted and adjusted Cox proportional hazards models. Results:

Mean age of the participants was 85, 64% were female, 66% had hypertension, 14% had diabetes mellitus, and 39% had prevalent cardiovascular disease. There were 154 deaths over a median follow-up of 2.6 years. The association between eGFR[subscript CR] and all-cause mortality was U-shaped. In comparison with the reference quintile (64–75 mL/min per 1.73 m²), the highest (≥75 mL/min per 1.73 m²) and lowest (≤43 mL/min per 1.73 m²) quintiles of eGFR[subscript CR] were independently associated with mortality (hazard ratio (HR) = 2.49, 95% confidence interval (CI) = 1.36–4.55; HR = 2.28, 95% CI = 1.26–4.10, respectively). The association between eGFR[subscript CYS] and all-cause mortality was linear in those with eGFR[subscript CYS] of less than 60 mL/min per 1.73 m², and in the multivariate analyses, the lowest quintile of eGFR[subscript CYS] (<52 mL/min per 1.73 m²) was significantly associated with mortality (HR = 2.04, 95% CI = 1.12–3.71) compared with the highest quintile (>0.88 mL/min per 1.73 m²). Conclusion:

Moderate reduction in kidney function is a risk factor for all-cause mortality in octogenarians. The association between eGFR[subscript CR] and all-cause mortality differed from that observed with eGFR[subscript CYS]; the relationship was U-shaped for eGFR[subscript CR], whereas the risk was primarily present in the lowest quintile for eGFR[subscript CYS].