Choice of endpoint in kidney outcome trials: considerations from the EMPA-REG OUTCOME® trial

Nephrol Dial Transplant. 2020 Dec 4;35(12):2103-2111. doi: 10.1093/ndt/gfz179.


Background: Doubling of serum creatinine [equivalent to 57% reduction in estimated glomerular filtration rate (eGFR)] is an established surrogate for end-stage kidney disease (ESKD); however, this endpoint necessitates lengthy follow-up and large sample sizes in clinical trials. We explored whether alternative eGFR decline thresholds provide more feasible surrogate kidney endpoints.

Methods: The study involved post hoc analysis of the EMPA-REG OUTCOME® trial. Adults with type 2 diabetes, high cardiovascular risk and eGFR ≥30 mL/min/1.73 m2 were assigned empagliflozin 10 mg or 25 mg (n = 4687) or placebo (n = 2333), on top of standard of care. We assessed composite endpoints incorporating different eGFR decline thresholds (≥30, ≥40, ≥50 or ≥57%) combined with initiation of renal replacement therapy (RRT) or renal death. This trial is registered with (NCT01131676).

Results: Empagliflozin versus placebo significantly lowered the risk of decline in eGFR for each threshold listed above, combined with initiation of RRT or renal death, ranging from a hazard ratio (HR) of 0.81 [95% confidence interval (CI) 0.72-0.91] for endpoints based on 30% eGFR decline to an HR of 0.37 (0.23-0.61) for endpoints based on 57% eGFR decline. Lower thresholds (e.g. 30%) were associated with higher event rates but weaker treatment effects. The time to the 95% CI of the HR falling to <1.0 decreased with increasing eGFR threshold.

Conclusions: The composite of 40% decline in eGFR, ESKD or renal death appears to provide reliable results similar to the traditional 57% decline in eGFR.

Keywords: CKD; ESKD; GFR; clinical trial; type 2 diabetes.

Publication types

  • Clinical Trial, Phase III
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Benzhydryl Compounds / therapeutic use*
  • Creatinine / blood
  • Diabetes Mellitus, Type 2 / drug therapy
  • Diabetes Mellitus, Type 2 / mortality*
  • Diabetes Mellitus, Type 2 / pathology
  • Double-Blind Method
  • Female
  • Glomerular Filtration Rate
  • Glucosides / therapeutic use*
  • Humans
  • Kidney Failure, Chronic / drug therapy
  • Kidney Failure, Chronic / epidemiology
  • Kidney Failure, Chronic / mortality*
  • Kidney Failure, Chronic / pathology
  • Male
  • Middle Aged
  • Prognosis
  • Sodium-Glucose Transporter 2 Inhibitors / therapeutic use*
  • Survival Rate


  • Benzhydryl Compounds
  • Glucosides
  • Sodium-Glucose Transporter 2 Inhibitors
  • Creatinine
  • empagliflozin

Associated data