Metabolic acidosis is associated with increased risk for graft failure and premature death in stable renal transplant recipients

A.W. Gomes Neto, M.C.J. Osté, E. van den Berg, A. Post, J.S.F. Sanders, S. P. Berger, J.J. Carrero, G.J. Navis, S.J.L. Bakker

Wednesday 4 march 2020

17:00 - 17:10h at Theaterzaal

Parallel session: Parallel sessie VI – Klinische abstracts

Background: Metabolic acidosis is a risk factor of end-stage renal disease and death in patients with chronic kidney disease (CKD). Correction of metabolic acidosis has shown to help preserve kidney function and reduce mortality in CKD. It remains unclear, however, whether metabolic acidosis is associated with worse outcome in stable renal transplant recipients (RTR).

Methods: For this study we used data from the TransplantLines Food & Nutrition Cohort Study (NCT02811835), collected between 2008-2011. Venous bicarbonate (HCO₃^-) was assessed on a Radiometer 800 blood gas analyzer, and metabolic acidosis was defined as HCO₃^- 3^- levels and metabolic acidosis with graft failure and mortality. Additionally, separate analyses were performed in RTR to investigate the association of HCO₃^- in RTR without metabolic acidosis.

Results: We included 651 RTR (56% men, 53±13 years old, eGFR 52 ± 20 ml/min/1.73 m²) at a median of 5 years after transplantation. Mean HCO₃^- was 24.6±3.1 mmol/L and 203 RTR had metabolic acidosis. During follow-up of 5.4 years, 77 RTR developed graft failure and 142 died. HCO₃^- was inversely associated with graft failure (HR 0.75; 95%CI 0.70-0.80) and death (HR 0.93; 95%CI 0.88-0.98). Adjustment for potential confounders including age, sex, eGFR, time after transplantation and proteinuria did not materially affect these results. RTR with metabolic acidosis had higher risk of graft failure (adjusted HR 2.41; 95%CI 1.42-4.09) and mortality (HR 1.71; 95%CI 1.18-2.47). We observed a similar inverse association of HCO₃^- in RTR without metabolic acidosis with graft failure (adjusted HR 0.75; 95%CI 0.56-0.99) but the association of HCO₃^- with mortality was not significant (adjusted HR 0.97; 95%CI 0.87-1.09).

Conclusions: Higher HCO₃^- levels are associated with lower risk of graft failure and mortality in RTR. Moreover, in RTR with HCO_3- within normal range, HCO₃^- levels were associated with lower risk of graft failure.