Kidney Week

Abstract: FR-PO1107

Association of Urine-to-Plasma Urea Ratio with the Incidence of Kidney Failure in Patients with CKD

Session Information

• CKD: Epidemiology, Risk Factors, and Prevention - 2
  October 25, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: CKD (Non-Dialysis)

• 2301 CKD (Non-Dialysis): Epidemiology, Risk Factors, and Prevention

Authors

• Kumari, Usha, The University of Tennessee Health Science Center, Memphis, Tennessee, United States

Usha Kumari, MD

• Elkhodary, Mohamed Tarek, The University of Tennessee Health Science Center, Memphis, Tennessee, United States

Mohamed Tarek Elkhodary, MD

• Sumida, Keiichi, The University of Tennessee Health Science Center, Memphis, Tennessee, United States

Keiichi Sumida, MD, PhD, MPH, FASN

• Wall, Barry M., The University of Tennessee Health Science Center, Memphis, Tennessee, United States

Barry M. Wall, MD

• Kovesdy, Csaba P., The University of Tennessee Health Science Center, Memphis, Tennessee, United States

Csaba P. Kovesdy, MD, FASN

Background

Estimated glomerular filtration rate (eGFR) and proteinuria are traditional markers used to assess the risk of kidney outcomes. Measures of tubular function such as the ratio of urine to plasma urea (U/P urea) can offer additional insight on the kidneys’ functional capacity, but its association with long term kidney outcomes is unclear.

Methods

In a retrospective cohort of 638 patients with eGFR <60 ml/min/1.73m² from a single institution, we measured U/P urea from single spot urine specimens. We examined the association of U/P urea with end-stage kidney disease (ESKD, defined as the initiation of kidney replacement therapy) using the Kaplan Meier method and multivariable adjusted Cox models with adjustment for demographic characteristics, smoking status, comorbidities, eGFR and proteinuria. U/P urea was analyzed both as a natural log-transformed continuous variable and as a categorical variable divided in tertiles.

Results

The mean±SD age was 67±10 years old, 96% were male, 58% were African-American and the mean±SD eGFR was 21±11 mL/min/1.73 m². There were 188 ESKD events (event rate, 65.9/1000PY; 95% CI: 57.1-76.1) over a median follow-up of 4.5 years. Lower U/P urea was associated with higher risk of ESKD in unadjusted (hazard ratio and 95%CI for 1 log-unit lower U/P urea: 2.39 [1.95-2.92], p<0.001) and after multivariable adjustment (1.40 [1.06-1.85], p=0.018, Figure).

Conclusion

Lower U/P urea ratio, a marker of impaired renal concentration ability, is associated with higher risk of ESKD independent of known risk factors such as eGFR and proteinuria. U/P urea obtained from spot urine specimens could provide additional information for risk stratification in patients with chronic kidney disease.