Metabolic Acidosis and Long-Term Clinical Outcomes in Kidney Transplant Recipients

J Am Soc Nephrol. 2017 Jun;28(6):1886-1897. doi: 10.1681/ASN.2016070793. Epub 2016 Dec 28.


Metabolic acidosis (MA), indicated by low serum total CO2 (TCO2) concentration, is a risk factor for mortality and progressive renal dysfunction in CKD. However, the long-term effects of MA on kidney transplant recipients (KTRs) are unclear. We conducted a multicenter retrospective cohort study of 2318 adult KTRs, from January 1, 1997 to March 31, 2015, to evaluate the prevalence of MA and the relationships between TCO2 concentration and clinical outcomes. The prevalence of low TCO2 concentration (<22 mmol/L) began to increase in KTRs with eGFR<60 ml/min per 1.73 m2 and ranged from approximately 30% to 70% in KTRs with eGFR<30 ml/min per 1.73 m2 Multivariable Cox proportional hazards models revealed that low TCO2 concentration 3 months after transplant associated with increased risk of graft loss (hazard ratio [HR], 1.74%; 95% confidence interval [95% CI], 1.26 to 2.42) and death-censored graft failure (DCGF) (HR, 1.66; 95% CI, 1.14 to 2.42). Cox regression models using time-varying TCO2 concentration additionally demonstrated significant associations between low TCO2 concentration and graft loss (HR, 3.48; 95% CI, 2.47 to 4.90), mortality (HR, 3.16; 95% CI, 1.77 to 5.62), and DCGF (HR, 3.17; 95% CI, 2.12 to 4.73). Marginal structural Cox models adjusted for time-varying eGFR further verified significant hazards of low TCO2 concentration for graft loss, mortality, and DCGF. In conclusion, MA was frequent in KTRs despite relatively preserved renal function and may be a significant risk factor for graft failure and patient mortality, even after adjusting for eGFR.

Keywords: acidosis; chronic graft deterioration; glomerular filtration rate; kidney transplantation; mortality; transplant recipients.

Publication types

  • Multicenter Study

MeSH terms

  • Acidosis / epidemiology*
  • Adult
  • Cohort Studies
  • Female
  • Humans
  • Kidney Transplantation*
  • Male
  • Middle Aged
  • Postoperative Complications / epidemiology*
  • Prevalence
  • Proportional Hazards Models
  • Retrospective Studies
  • Risk Factors
  • Time Factors
  • Treatment Outcome