Pretransplant predictors of recovery of renal function after ...
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Pretransplant predictors of recovery of renal function after liver
Liver Transplantation Volume 16, Issue 4, 2010. Pages: 440-446
Patrick G. Northup, Curtis K. Argo, Mihir R. Bakhru, Timothy M. Schmitt, Carl L.
Berg, Mitchell H. Rosner
This study aims to identify risk factors for persistent renal failure after liver
transplantation in patients who required renal replacement therapy (RRT) prior to
Being able to determine which patients are likely going to require chronic RRT
after liver transplantation would substantially facilitate the allocation of combined
liver-kidney transplants. If we were able to identify patients who will not recover
renal function after liver transplantation with sufficient sensitivity and specificity
we could rationally allocate combined liver–kidney transplants (CLKT) without
neither wasting organ nor exposing patients to the increased mortality and
morbidity associated with chronic RRT. Current guidelines for the indication for
CLKT are controversial, not uniformly accepted and often based on expert
opinion only and we therefore need more objective data.
Approach/Methods/ Analysis (Study Design)
This is a retrospective observational study. From the UNOS database patients
were identified who required RRT prior to undergoing liver transplantation
between February 2002 and January 2007. The authors excluded re-transplants
(“to exclude calcineurin inhibitor toxicity as a confounder”), multi-visceral
transplant, CLKT and transplants for acute liver failure.
Postoperative renal data was obtained from the US Renal Data System that
collects data on all patients who require RRT for more than 30 days in the US
and no spontaneous recovery of renal function was assumed if the patient did
require RRT 30 days after transplant or underwent a kidney transplant after the
1041 patients were identified from the UNOS database who underwent liver
transplantation and required RRT prior to transplantation. 334 of these did not
recover renal function after liver transplantation and 26 of these eventually
underwent kidney transplantation.
Patients who did not recover renal function were older, had higher preoperative
MELD scores, serum creatinine and a longer duration of RRT and were more
likely diabetic. They were longer on the waiting list prior to transplantation, had a
longer length of stay after transplant and a higher total bilirubin when finally
discharged. Donors for these patients were also older and had a higher donor
risk index. Patients who did not recover had a 1-year survival of 38% compared
to 99% in patients who did not require RRT postoperatively. Patients who
underwent subsequent kidney transplantation had comparable 1-year survival
rate compared to patients without RRT.
The authors then created 4 groups depending on how long patients required
RRT preoperatively (<30, 31-60, 61-90 and > 90 days) and found that the longer
the patient required RRT preoperatively the more likely he/she would need
chronic RRT postoperatively.
In a multivariate model, duration of preoperative RRT was the strongest predictor
for the requirement of postoperative RRT. Patients who required more than 90
days of preoperative RRRT had a 16.7 times higher risk for chronic postoperative
RRT when compared to patients with preoperative RRT less than 30 days.
This is a retrospective study that relies on two different databases. Combining
data from different databases is problematic. Reporting to these database may
be not as reliable as ones hopes (lack sufficient quality control) and the results
may therefore may have selection bias. The etiology of renal failure is not
reported and may affect the results and the duration of RRT. The number of
variables that were included in the uni- and multivariate models is limited;
important variables such as immunosuppression after transplant, postoperative
complications or donor organ function were not reported. However this study is
generously powered and as a multicenter study more relevant than comparable
single center studies with few patients.
Despite its shortcomings this is an important study that confirms our intuition that
the duration of preoperative RRT is one of the most important predictors for renal
recovery after liver transplantation. It seems prudent to consider combined liver-
kidney transplants for patients who required more than 90 days of RRT prior to
liver transplantation to avoid the increased mortality and morbidity associated
with postoperative chronic RRT. Patients with preoperative RRT of less than 30
days however have reasons be optimistic that their renal function will recover
without a kidney transplant if additonal insults are avoided.