Association Between Deceased Donor Acute Kidney Injury Assessed Using Baseline Serum Creatinine Back-Estimation and Graft Survival: Results From the French National CRISTAL Registry

Abstract

Rationale & objective: Deceased donor acute kidney injury (AKI) frequently leads to kidney discards, but its impact on long-term graft survival in kidney transplant recipients remains unclear. We investigated the association between deceased donor AKI assessed using back-estimation of baseline serum creatinine (Scr) and graft survival.

Study design: Observational cohort study.

Setting & participants: Adult patients represented within the French CRISTAL registry who received a single kidney allograft from brain-dead deceased donors between January 2006 and December 2017.

Exposure: A back-estimated Scr baseline value was derived for an assumed glomerular filtration rate at 75mL/min/1.73m², using the MDRD Study equation. A refined classification system for donor AKI was implemented as follows: no AKI, undetermined AKI/chronic kidney disease (CKD), recovery from AKI, and ongoing AKI.

Outcome: Death-censored graft survival.

Analytical approach: Multivariable Cox models using a robust variance estimator for paired kidneys from the same donor.

Results: We classified 26,786 recipients as follows: no AKI (n=19,276); undetermined AKI/CKD (n=1,745); recovery from AKI (n=2,392); and ongoing AKI (n=3,373). We observed 4,458 kidney graft losses during a median follow-up period of 5.7 years. Compared with no AKI, ongoing AKI was associated with an increased risk of graft failure (hazard ratio [HR], 1.24 [95% CI, 1.13-1.35]). The HRs for graft failure in the undetermined AKI/CKD and recovery from AKI groups (1.22 [95% CI, 1.07-1.38] and 1.18 [95% CI, 1.06-1.31], respectively) were similar to those observed in the ongoing AKI group. The adverse effect of deceased donor AKI was no longer evident when relying either on the admission or the lowest Scr throughout the procurement procedure as baseline Scr.

Limitations: No measurement of urine output in donors.

Conclusions: Deceased donor ongoing AKI, undetermined AKI/CKD, and recovery from AKI according to back-estimated baseline Scr are associated with decreased graft survival. The definition of baseline Scr as the first value measured on admission would have led to a misclassification bias and erroneous estimates.

Keywords: Acute kidney failure; acute kidney injury (AKI); clinical epidemiology; graft survival; kidney failure; kidney transplantation; organ discard; renal function; serum creatinine (Scr).