Kidney Week

Abstract: TH-PO157

Serum Bicarbonate Levels Are Associated with Graft Survival and Mortality in Swiss Kidney Transplant Recipients

Session Information

• Transplantation: Cardiovascular and Metabolic Diseases
  October 25, 2018 | Location: Exhibit Hall, San Diego Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Transplantation

• 1802 Transplantation: Clinical

Authors

• Wiegand, Anna, University Hospital Zürich, Zürich, Switzerland

Anna Wiegand,

• Lim, Sandar Felicity, University of Zurich, Zurich, Switzerland

Sandar Felicity Lim,

• Wuthrich, Rudolf P., University Hospital Zürich, Zürich, Switzerland

Rudolf P. Wuthrich,

• Held, Leonhard, University of Zurich, Zurich, Switzerland

Leonhard Held,

• Mohebbi, Nilufar, University Hospital Zürich, Zürich, Switzerland

Nilufar Mohebbi,

Background

Metabolic acidosis (MA) is a frequent complication of chronic kidney disease (CKD) and an independent risk factor for kidney disease progression. MA is also highly prevalent after kidney transplantation (12%-58%). A recent study has shown that MA after kidney transplantation was associated with increased risk of graft loss and death indicating an impact of MA on long-term graft function. However, the cohort had a fairly low prevalence of MA. Also a cut-off value for bicarbonate of 22 mEq/L, as commonly used for the definition of MA, may be questionable since kidney outcome and mortality have been shown to correlate best with TCO₂ values of 24-28 mEq/L. Thus, we wanted to investigate if serum bicarbonate is associated with graft outcome and mortality in Swiss kidney transplant recipients (KTRs).

Methods

We performed a single-center retrospective study including adult (≥ 18 years) patients that have been subjected to de novo kidney transplantation between 1999 and 2015. Cox proportional hazard model was used to analyze a possible association between time-dependent serum bicarbonate measurements and graft loss (defined as re-entry to dialysis or second kidney transplantation) or death

Results

430 KTRs were included in the analysis with a mean age of 50.9±13.4 years. Mean observation time was 4.7±2.8 years. 284 (66%) were male and 318 (74%) had received a deceased donor kidney transplant. Mean bicarbonate and eGFR levels one year post-transplant were 22.7±3.1 mmol/L and 61±26 ml/min, respectively. Prevalence of MA (defined as bicarbonate <22 mmol/L) was 51.2% after transplantation and decreased to 30.8% one year post-transplant. 14 (3%) patients died and 31 (7%) suffered from graft failure. Higher bicarbonate levels were associated with significantly lower hazards for graft failure (HR=0.88; 95% CI, 0.79-0.98; p=0.022) and mortality (HR=0.79; 95% CI, 0.66-0.93; p=0.006) after adjusting for potential confounders such as age, type of donor and time-varying eGFR.

Conclusion

Our analysis showed that higher serum bicarbonate levels are associated with long-term graft and patient survival in Swiss KTRs. Thus, serum bicarbonate may serve as a predictor for graft and patient outcome after kidney transplantation as has been previously shown for patients with CKD.