Effect of Sodium Bicarbonate in Kidney Transplant Recipients With Chronic Metabolic Acidosis

Background. Metabolic acidosis (MA) is a common complication after kidney transplantation and regarded to increase mortality, graft failure, and bone fractures. Here, we conducted a retrospective cohort study to analyze the effect of sodium bicarbonate on those events. Methods. All kidney transplant recipients of the German health insurance Allgemeine Ortskrankenkasse (AOK) were selected, who received their transplantation between 2007 and 2015. Three groups were formed: (1) control group (no acidosis, n = 3602), (2) acidosis group (encoded acidosis, n = 370), and (3) treatment group (encoded therapy, n = 769). The study endpoints were mortality, death-censored graft failure, and bone fractures. Results. The prevalence of MA in the first year after transplantation was 46.2%. The 5-year patient and graft survival were 89.8% and 89.3% in the control group, 90% and 90.8% in the acidosis group, and 87.5% and 81.6% in the treatment group, respectively. The rate of bone fractures did not differ between the groups. Neither log-rank tests nor multivariable Cox regression analyses could detect a negative impact of MA on mortality (hazard ratio [HR] 0.94; confidence interval [CI] 0.67-1.30), graft failure (HR1.18; CI 0.82-1.72), or the incidence of bone fractures (HR1.19; CI 0.92-1.55). Treatment with sodium bicarbonate was associated with an increased risk of graft failure (HR1.52; CI 1.03-2.25), whereas mortality (HR0.86; CI 0.59-1.26) and the incidence of bone fractures (HR1.16; CI 0.86-1.56) were not altered. Conclusions. MA is common after kidney transplantation but not associated with an increased frequency of death, graft failure, or bone fractures. Conversely, sodium bicarbonate therapy increased the incidence of graft failure.