Kidney Week

Abstract: TH-OR68

The Effect of Age on Performance of the Kidney Failure Risk Equation in Advanced CKD

Session Information

• Preventing Progression and Reassessing Race in GFR Estimation
  November 04, 2021 | Location: Simulive, Virtual Only
  Abstract Time: 04:30 PM - 06:00 PM

Category: CKD (Non-Dialysis)

• 2101 CKD (Non-Dialysis): Epidemiology, Risk Factors, and Prevention

Authors

• Hundemer, Gregory L., Ottawa Hospital Research Institute, Ottawa, Ontario, Canada

Gregory L. Hundemer, MD, MPH

• Tangri, Navdeep, University of Manitoba, Winnipeg, Manitoba, Canada

Navdeep Tangri,

• Sood, Manish M., Ottawa Hospital Research Institute, Ottawa, Ontario, Canada

Manish M. Sood,

• Akbari, Ayub, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada

Ayub Akbari,

Background

The Kidney Failure Risk Equation (KFRE) is a validated clinical tool used to predict progression from CKD to kidney failure. Concerns over risk overestimation have been raised with prediction models, such as the KFRE, where death is not treated as a competing event. Herein, we evaluated the effect of age (with which the competing risk of death would be anticipated to increase) on KFRE performance in advanced CKD.

Methods

All patients referred to the advanced CKD clinic at the Ottawa Hospital from 2010-2018 were divided into age quartiles: <58, 58-67, 68-77, and ≥78 years. Predicted vs observed rates of kidney failure were compared over 2- and 5-years. Predictive performance of the KFRE was determined by ROC curves (discrimination) and calibration plots. Cumulative incidence of kidney failure was compared between models that accounted for the competing risk of death and those that did not.

Results

The mean (SD) age and eGFR were 66 (15) years and 17 (6) mL/min/1.73m². The median (IQR) 2- and 5-year KFRE scores were 41% (22-64%) and 81% (55-96%), respectively. The KFRE overestimated the risk of kidney failure among the oldest age quartile (≥78 years) with absolute differences of 5.8% (P=0.01) and 21.6% (P<0.001) between predicted and observed risks over 2- and 5-years, respectively. The 2-year KFRE discrimination was reduced among patients ≥78 years compared with patients 58-67 years (P=0.03) and 68-77 years (P=0.03) though the difference was non-significant when compared with patients <58 years (P=0.06). The KFRE displayed adequate calibration across all age quartiles. The cumulative incidence of kidney failure was overestimated in models that did not account for the competing risk of death and this overestimation was more prominent with older age.

Conclusion

In older patients with advanced CKD at high risk of kidney failure, the KFRE overestimates risk and this overestimation relates to the increasing competing risk of death with older age.