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Volume: 15 Issue: 1 February 2017 - Supplement - 1

FULL TEXT

Incidence and Patient Outcomes in Renal Replacement Therapy After Orthotopic Liver Transplant

Objectives: Our objective was to evaluate the incidence of renal replacement therapy after orthotopic liver transplant and to evaluate and analyze patient outcomes.

Materials and Methods: We performed a retrospective analysis of 177 consecutive patients at a tertiary care unit who underwent orthotopic liver transplant between January 2010 and June 2016. Patients who were admitted to the intensive care unit after orthotopic liver transplant and who required renal replacement therapy were included.

Results: A total of 177 (79 adult, 98 pediatric) orthotopic liver transplants were performed during the study period. Of these, 35 patients (19%) required renal replacement therapy during the early posttrans­plantation period. After excluding 5 patients with previous chronic renal failure, 30 patients (17%; 20 adult [25%], 10 pediatric [10%]) with acute kidney injury required renal replacement therapy. The mean patient age was 31.1 ± 20.0 years, with a mean Model for End-stage Liver Disease score of 16.7 ± 12.3. Of the patients with acute kidney injury who underwent renal replacement therapy, in-hospital mortality was 23.3% (7 of 30 patients), and 40% remained on dialysis. No significant difference was seen in mortality between early versus delayed initiation of renal replacement therapy in patients with stage 3 acute kidney injury (P = .17).

Conclusions: Of liver transplant recipients who present with acute kidney injury, 19% require renal replace­ment therapy, and in-hospital mortality is 20% in the early postoperative period.


Key words : Acute kidney injury, Liver transplant, Orthotopic, Renal replacement therapy

Introduction

Acute kidney injury (AKI) is among the most frequent complication in the early period after orthotopic liver transplant (OLT) and has been associated with significant morbidity and mortality.1,2 The prevalence of AKI after OLT varies from 12% to 70%, according to the definition used for AKI.3 Renal replacement therapy (RRT) is the main treatment for severe AKI and is required in 5% to 35% of liver transplant recipients who develop AKI in the early postoperative period.4 Early initiation of RRT could confer a survival benefit by avoiding hypervolemia, eliminating toxins, establishing acid-base homeostasis, and preventing other complications attributable to AKI.5

The aim of this single-center retrospective study is to evaluate and analyze the incidence and outcomes of patients requiring early or delayed RRT after OLT.

Materials and Methods

We conducted a retrospective analysis of 177 consecutive liver transplant recipients who received their graft at Baskent University Transplantation Center between January 2010 and June 2016. We included in our analysis all patients who were admitted to the intensive care unit (ICU) after OLT, diagnosed with AKI, and required RRT. Five patients who were previously diagnosed with chronic renal failure were excluded.

We evaluated patient demographics and clinical and laboratory data. The Kidney Disease: Improving Global Outcomes (KDIGO) classification was used for staging patients with AKI6 (Table 1). The initiation of RRT was designated as early (during the first 24 hours) or delayed. We recorded the modality of RRT (intermittent hemodialysis or continuous hemo­diafiltration), intraoperative and postoperative complications, the use of immunosuppressive therapy, the length of stay in the ICU and in the hospital, and the duration of mechanical ventilation. In-hospital mortality was also calculated.

Statistical analyses were performed using software (SPSS version 20.0, SPSS Inc., Armonk, NY, USA). The groups were compared using either chi-squared or Mann–Whitney U tests as appropriate. A P value of < .05 was considered significant. Data were expressed as the mean and standard deviation for continuous variables and as the percentage for categorical variables.

Results

A total of 177 (98 pediatric [55%], 79 adult [45%]) OLTs were performed during the study period. A total of 54 patients (30.5%) experienced AKI after transplant. Of these, 35 recipients (19%) required RRT during the early posttransplant period. After excluding 5 patients with previous chronic renal failure, 30 patients (17%; 10 pediatric [10%], 20 adult [25%]) with AKI required RRT (Table 2). Stage 1 AKI occurred in 26% of patients, stage 2 in 37%, and stage 3 in 37%. The mean patient age was 31.1 ± 20.0 years (63% male), with a mean Model for End-stage Liver Disease (MELD) score of 16.7 ± 12.3. In 63% of patients, RRT was initiated for metabolic acidosis; 83% of these patients received mechanical ventilation. The modality of RRT was intermittent hemodialysis in 17% and continuous hemodiafiltration in 83%. In 50% of recipients, RRT was initiated within 24 hours. There was a significant difference between early and delayed RRT in the incidence of hepatorenal syndrome, MELD score, and the preoperative creatinine values (P < .05 for all). None of the other examined parameters exhibited statistically significant differences (Table 2).

Of the AKI patients who underwent RRT, in-hospital mortality was 23.3% (7 of 30 patients), and 40% of patients remained on dialysis. No significant difference in mortality was seen between early and delayed RRT initiation in patients with stage 3 AKI (P = .17).

Discussion

Our aim was to analyze the incidence of RRT and the associated outcomes in liver graft recipients requiring either early or delayed RRT after OLT. The incidence of AKI, using the KDIGO definition, was 30.5%, and 19% of patients required RRT, with an in-hospital mortality of 23% in the early postoperative period. No significant difference in mortality was seen between early and delayed initiation of RRT in patients with stage 3 AKI.

Acute kidney injury is a frequent and well-known complication of OLT. As a result of the varying definitions previously used for AKI, a wide range of prevalence is reported: from 11% to 95%, according to previous publications.7,8 Our assessment is based on the most recent classification system; we found that the incidence of AKI in patients with KDIGO stage 1, 2, and 3 was 26%, 37%, and 37%, with an overall value of 17%. After OLT, reported dialysis requirements ranged from 8% to 47% of patients, with hemodialysis rates up to 51.5%,7,9,10 the corresponding values in our series vere 17% and 40%.

The MELD score is reportedly a useful qualitative variable for evaluating patients with liver disease for AKI. However, different cutoff scores are reported in the literature (22 by Barreto et al7 and 13 by Narciso et al11) to predict which patients are at high risk of developing severe renal dysfunction; the mean MELD score was 16.7 in our series, which reflects the intermediate liver function in our patients. When we compared the MELD scores of early and delayed RRT patients, we found higher MELD scores in patients whose RRT is initiated early. We also found a statistical difference in the presence of preoperative hepa­torenal syndrome and higher preoperative creatinine values in early RRT patients. Taken together, these findings may indicate that the presence of preo­perative hepatorenal syndrome and higher serum creatinine and MELD scores may be considered important risk factors, and RRT should be initiated early in these patients.

A search of the literature suggests that AKI patients have longer ICU and hospital stays; AKI may be the only independent risk factor for in-hospital mortality after OLT.7 Although we did not compare AKI and non-AKI patients, our overall in-hospital mortality was 23.3%, which is similar to that reported in other studies.7,12 Furthermore, our results demonstrated no significant difference in mortality between early and delayed initiation of RRT in patients with stage 3 AKI. Aside from mortality, the length of stay in the ICU and the length of stay in the hospital, which are surrogate (alternate) markers of outcome, were also statistically similar between early and delayed RRT patients with stage 3 AKI. Another important finding of our study was the higher incidence of metabolic acidosis and the increased necessity for mechanical ventilation in AKI patients after OLT. It is well known that RRT is generally initiated for metabolic acidosis.

This study has several limitations. Its retro­spective design and its single-center nature may have both positive and negative effects: a small number of patients may affect the overall results. Our study focused on the incidence of AKI in patients requiring RRT after OLT and the effect of early versus delayed RRT, instead of the risk factors for AKI after OLT. We have not compared non-AKI and AKI patients, and we did not evaluate AKI patients who did not undergo RRT. While it may be useful to evaluate the risk factors for AKI after OLT, this is not the focus of our study, and this topic has recently been evaluated and published elsewhere.7,8,13

In conclusion, the present study demonstrated that 19% of liver-graft recipients who present with AKI (30.5% of all OLT patients) require RRT. The in-hospital mortality for these patients was 20% in the early postoperative period, and there was no statistically significant difference between early and delayed RRT in patients with AKI.


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Volume : 15
Issue : 1
Pages : 258 - 260
DOI : 10.6002/ect.mesot2016.P126


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From the 1Department of Anaesthesiology and Reanimation, 2Department of General Surgery, Baskent University School of Medicine, Ankara, Turkey
Acknowledgements: The authors have no financial disclosures and have no conflicts of interest to disclose.
Corresponding author: Asude Ayhan, Department of Anaesthesiology and Reanimation, Baskent University School of Medicine, Maresal Fevzi Cakmak Caddesi No:45, 06490, Cankaya, Ankara, Turkey
Phone/Fax: +90 312 203 6868
E-mail: aayhan@baskent.edu.tr, drasu@mynet.com