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Kidney Week

Abstract: PO0446

Urinary Retinol-Binding Protein Is Associated with the Risk of Kidney Replacement Therapy in CKD

Session Information

Category: CKD (Non-Dialysis)

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

Authors

  • Domingos, Maria Alice Muniz, University of Sao Paulo, Universidade de Sao Paulo, Sao Paulo, Sao Paulo, Brazil
  • Lotufo, Paulo, University of Sao Paulo, Universidade de Sao Paulo, Sao Paulo, Sao Paulo, Brazil
  • Bensenor, Isabela M., University of Sao Paulo, Universidade de Sao Paulo, Sao Paulo, Sao Paulo, Brazil
  • Titan, Silvia M., University of Sao Paulo, Universidade de Sao Paulo, Sao Paulo, Sao Paulo, Brazil
Background

Urinary Retinol-Binding Protein (uRBP), a biomarker of proximal tubular injury, is used in clinical practice as a risk factor for CKD in tubular diseases, such as Dent's disease and cystinosis, and in renal transplantation. However, its role as a biomarker of CKD progression outside these conditions is less clear. The aim of our study was to evaluate the association of uRBP with the risk of mortality and kidney replacement therapy (KRT) in CKD of multiple etiologies.

Methods

The Progredir Cohort is composed of 454 older adults with CKD (predominantly G3 and G4) recruited from the outpatient services of a tertiary hospital in Sao Paulo, Brazil. Baseline uRBP was measured using an immunoenzymatic assay with monoclonal antibody and expressed as mg/g urinary creatinine, and those with missing values were excluded (n=22). Events of death (n=184) and KRT (n=60) were ascertained (median follow-up of 6 years, with 5 participants lost to follow-up). Uni and multivariable Cox and Competitive Risk models (R package “cmprsk”) were computed.

Results

Mean age was 67(12)y, mean eGFR was 38(15) mL/min/1.73m2, 64% were male and 58% were diabetic. Median (P25, P75) for uRBP were: 0.29 (0.08, 1.47) in all; 0.24 (0.06, 0.84) vs. 0.46 (0.10, 2.87) in those who remained alive vs. those who died (p=0.001); and 0.26 (0.08, 0.90) vs. 2.98 (0.21, 17.5) in those without and with KRT, respectively (p<0.0001). In Cox models, RBP was not related to mortality. However, competitive models showed that uRBP was related to the risk of KRT, even after adjustments (Table). This association was also present when only normoalbuminuric participants (CKD A1) were included.

Conclusion

URBP is significantly associated with the risk of KRT in the setting of CKD, and may be particularly useful as a biomarker in CKD patients with normoalbuminuria (CKD A1).

Competing risk models for the risk of KRT.
 SHR (95%CI)p-value
uRBP (mg/g creatinine) - unadjusted1.03 (1.01 to 1.04)<0.0001
uRBP (mg/g creatinine) - adj. 11.01 (1.00 to 1.02)0.015
uRBP (mg/g creatinine) - adj. 21.01 (1.00 to 1.02)0.03

Adj.1= age, sex, eGFR; adj.2 = same as 1 + SBP, DM, MI, ACR, smoking. Models for KRT were computed considering the competing risk of death. SHR, subdistribution hazard ratio.

Funding

  • Government Support - Non-U.S.