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Acute kidney injury common, reduces survival among liver transplant recipients

Acute kidney injury occurs frequently and significantly impacts survival rates among liver transplant recipients, particularly with delayed initiation of renal replacement therapy, according to recent results.

Researchers evaluated 315 patients (mean age 51 years) who underwent liver transplantation (LT) between January 2002 and November 2006 at a medical facility in Brazil. Incidence of acute kidney injury (AKI), renal replacement therapy (RRT) and mortality were observed.

AKI occurred in 93% of the cohort, with a cumulative incidence rate of 32% within 48 hours of the procedure and 81% within the first post-transplant week. RRT was required in 48 cases, including 31 within the first week (median 3 days) and 17 afterward (median 15 days).

After a mean follow-up of 4.1 years, overall mortality was 24%. Among patients who required RRT after LT, the mortality rate was 58%, compared with 17% among those who did not (OR=6.7; 95% CI, 3.49-12.96).

Multivariate analysis indicated an association between reduced overall survival and the time between diagnosis of AKI and initiation of RRT or reaching peak serum creatinine levels (adjusted HR=1.03; 95% CI, 1.01-1.05). Investigators calculated an optimal cut-off value of 7 days between diagnosis and RRT, with an AUROC of 0.607, sensitivity of 44% and specificity of 77%.

AKI lasting 1 week or longer before replacement therapy was associated with increased mortality risk (HR=3.02; 95% CI, 2.04-4.46). Among patients with stage 2 or stage 3 AKI, risk for death doubled within 4 days (HR=1.19; 95% CI, 3-7; HR=1.18; 95% CI, 3-9, respectively).

“Acute kidney injury after liver transplantation is remarkably frequent and has a substantial impact on patient survival,” the researchers concluded. “Our findings suggest a higher mortality in LT recipients with longer exposure period to AKI, especially for those reaching AKI stage 2 or 3 with AKI episodes lasting longer than four days. In such [a] group, lack of recovery of kidney function or initiation of RRT seems to double the risk of death. … Delaying RRT initiation seems to be unjustifiable, especially in this population, where absolute RRT indications may take longer to occur.”