Significance of early aminotransferase elevation after liver transplantation

Liver glutathione depletion after preservation and reperfusion in human liver transplantation

PURPOSE: The oxidative stress is an important mechanism responsible for dysfunction after orthotopic liver transplantation (OLT). Glutathione (GSH) low levels after cold storage render the grafts vulnerable to reperfusion injury. Aim of this study was to evaluate GSH and oxidized glutathione (GSSG) liver concentrations, the hepatocellular injury and function in optimal and suboptimal grafts after human OLT. METHODS: Liver biopsies were taken in 33 patients before the implant and two hours after reperfusion, allowing determination of GSH, GSSG and oxidative stress ratio (GSH/GSSG). Serum transaminases, prothrombin activity (PT) and factor V were measured to evaluate injury and function respectively. Histopathological injury was analyzed by an index of five parameters. RESULTS: There was a decrease in GSH (p<0.01) after reperfusion (0.323 ± 0.062 ìmol/g to 0.095 ± 0.01 ìmol/g and 0.371 ± 0.052 ìmol/g to 0.183 ± 0.046 ìmol/g) in suboptimal and optimal groups, respectively. An increase of GSSG (p<0.05) occurred after reperfusion (0.172 ± 0.038 ìmol/g to 0.278 ± 0.077 ìmol/g and 0.229 ± 0.048 ìmol/g to 0.356 ± 0.105 ìmol/g) in suboptimal and optimal groups, respectively. A decrease (p<0.01) occurred in the GSH/GSSG ratio after reperfusion (2.23 ± 0.31 to 0.482 ± 0.042 and 2.47 ± 0.32 to 0.593 ± 0.068) in suboptimal and optimal groups, respectively. Histopathological injury scores were higher (p<0.05) in the suboptimal group than in optimal (6.46 ± 0.4 vs. 5.39 ± 1.1) and showed correlation with PT and factor V in the optimal group (p<0.05). Multivariate analysis pointed steatosis as an independent risk factor to histopathological injury (p<0.05). CONCLUSION: There was a significant GSH depletion and GSSG formation after cold storage and reperfusion due to a similar oxidative stress in optimal and suboptimal grafts, but these levels were not related to graft viability.

Diagnosis and management of allograft failure

The article focuses on diagnosis and management of allograft failure in four main categories: (1) ischemic-reperfusion injury (primary nonfunction), (2) technical complications (hepatic artery and portal vein thrombosis), (3) chronic rejection, and (4) recurrent disease. It also discusses the complex problems involved in retransplantation for allograft failure.

Ischaemic preconditioning in transplantation and major resection of the liver

BACKGROUND

Ischaemia-reperfusion injury (IRI) contributes significantly to the morbidity and mortality of transplantation and major resection of the liver. Its severity is reduced by ischaemic preconditioning (IP), the precise mechanisms of which are not completely understood. This review discusses the pathophysiology and role of IP in this clinical setting.

METHODS

A Medline search was performed using the keywords 'ischaemic preconditioning', 'ischaemia-reperfusion injury', 'transplantation' and 'hepatic resection'. Additional articles were obtained from references within the papers identified by the Medline search.

RESULTS AND CONCLUSION

The mechanisms underlying hepatic IRI are complex, but IP reduces the severity of such injury in several animal models and in recent human trials. Increased understanding of the cellular processes involved in IP is of importance in the development of treatment strategies aimed at improving outcome after liver transplantation and major hepatic resection.

Initial hepatic microcirculation correlates with early graft function in human orthotopic liver transplantation

Microcirculatory disturbances are an initial causative determinant in hepatic ischemia/reperfusion injury. The aim of this study was to assess sinusoidal perfusion during human liver transplantation using orthogonal polarization spectral imaging and to evaluate the significance of intraoperative microcirculation for early postoperative graft function. Hepatic microcirculation was measured in 27 recipients undergoing full-size liver transplantation and compared to a group of 32 healthy living-related liver donors. The microvascular parameters were correlated with postoperative aspartate aminotransferase and bilirubin levels. Hepatic perfusion following liver transplantation was found to be significantly decreased when compared with the control group. Volumetric blood flow within the individual sinusoids increased due to sinusoidal dilatation and enhanced flow velocity. Regression analysis of postoperative aspartate aminotransferase and bilirubin with microvascular parameters revealed significant correlations. The extent of volumetric blood flow increased within the first 30 minutes after reperfusion and showed a significant correlation with postoperative aspartate aminotransferase release and bilirubin elimination. In conclusion, postischemic hepatic microvascular perfusion was analyzed in vivo, demonstrating significant microvascular impairment during liver transplantation. Sinusoidal hyperperfusion appears to confer protection against postischemic liver injury, as given by the correlation with aspartate aminotransferase and bilirubin levels. Thus, these findings may have therapeutic importance with respect to mechanisms mediating postischemic reactive hyperemia.

Surgical advances in liver and bowel transplantation

Liver and intestinal transplantation are currently the treatments of choice for life-threatening hepatic and gastrointestinal failure. These technologies have evolved through contributions from the fields of immunology, anatomy, physiology, surgery, anesthesiology, critical care, ethics, epidemiology, and public health. Transplantation now accounts for the treatment of over 5,000 recipients per year who are in a state of organ failure. The available donor population, however, is not increasing to meet the demands of the faster growing recipient population. This discrepancy has led to the rapid development of novel strategies that require critical evaluation to build on the success rates in recent years. This article presents the most salient advances in liver and intestinal transplantation in the last 15 years.

Can the use of marginal liver donors change recipient survival rate?

Liver transplantation as a therapeutic method for the treatment of end-stage liver disease is beclouded by a scarcity of organs. The aim of this study was to retrospectively analyze the relation between the classification of donors as marginal versus ideal and recipients survival after 148 of 197 orthotopic liver transplantations (OLT) performed from 1991 to 2001. Donors were classified as marginal if they showed the major criteria of: age over 55 years, aspartate aminotransferase greater than 150 UI/L; serum bilirubin greater than 2 mg/dL, serum sodium greater 150 mEq/L, high-dose dopamine or any other vasoactive amine, cardiac arrest, intensive care unit (ICU) stay over 5 days, and moderate severe macrosteatosis. The minor criteria for a marginal donor were: use of dopamine below 10 microg/kg/min, history of alcoholism, drug abuse, ICU stays less than 4 days, microsteatosis of any degree, and mild macrosteatosis. Statistical analysis was performed using Cox regression analyzing and the Kaplan-Meier survival method. The rate of marginal donors was 61.5%. The 180 postoperative day survival was 77.0%. Survival rates were 81.1% for recipients of marginal donor organs, and 70.7% for ideal donor recipients (P >.05). In conclusion, the use of marginal liver donors is viable and safely expands the numbers of liver transplants, thereby diminishing the number of waiting list deaths.

Vasopressor agents without volume expansion as a safe alternative to venovenous bypass during cavaplasty liver transplantation

BACKGROUND

Cavaplasty orthotopic liver transplantation (OLT) offers advantages for hepatectomy and implantation and eliminates the risk of outflow obstruction. However, it does require clamping of the cava. This study describes the use of a vasopressor without fluid expansion or venovenous bypass (VB) for hemodynamic control during the anhepatic phase.

METHODS

The cavaplasty OLT technique was used routinely. A vasopressor was administered if the mean arterial blood pressure (MAP) was less than 60 mm Hg after clamping of the cava. If the MAP did not reach 60 mm Hg after adjusting the dosage of the vasopressor, femoro-axillary VB would be used. VB was also indicated for preexisting cardiac disease or for massive hemorrhage from severe portal hypertension and extensive adhesions.

RESULTS

Among all the 121 adult cavaplasty OLTs, 33 were supported with VB and 50 received a vasopressor. The remaining 38 were excluded. However, baseline variables were well matched, except that preexisting cardiac disease was more frequent in the VB group. The median dosage of epinephrine was 0.07 microg/kg/min (range 0.01-0.6). The VB and vasopressor groups were similar in the reduction in mean MAP and the accumulation in arterial lactate upon clamping as well as in the central venous pressure upon unclamping. Postreperfusion hypotension was more frequent in the VB than in the vasopressor group (27.3% vs. 4.0%, P=0.006). There was no primary graft nonfunction or intraoperative right heart failure. One patient in the vasopressor group required postoperative temporary dialysis. Ninety-day patient and graft survival for the VB and vasopressor groups were 97.0% vs. 98.0% and 97.0% vs. 94.0%, respectively.

CONCLUSION

Modest doses of vasopressor without volume expansion or VB can maintain hemodynamic stability during the anhepatic phase of cavaplasty OLT.

Endoscopic Management of Biliary Complications After Orthotopic Liver Transplantation

After orthotopic liver transplantation (OLT), biliary duct complications can occur in as many as 10% to 35% of patients. In the early medical and surgical literature, surgical therapy was the primary mode of management of biliary tract complications and was the eventual course of operative intervention in up to 70% of cases. However, with recent advances in therapeutic biliary endoscopy, the current endoscopic and transplantation literature suggests that endoscopic management with techniques such as endoscopic retrograde cholangiopancreatography (ERCP) with endoscopic sphincterotomy, biliary stenting, and stone removal techniques can be successfully applied for the majority of post-OLT biliary complications. The most common biliary complications after OLT include biliary strictures (anastomotic and nonanastomotic); bile duct leaks, common bile duct stones, and biliary casts; sphincter of Oddi/ampullary muscle dysfunction/spasm; and disease recurrence (eg, primary sclerosing cholangitis). Predisposing factors for biliary complications after OLT include hepatic artery thrombosis, impaired perfusion of the biliary tree, portal vein thrombosis, and preservation or harvesting injuries, which can increase the incidence of complications as much as 40%. Use of immunosuppressive agents such as cyclosporine can lead to cholesterol/bile stasis and stone formation. Outside of endoscopic therapy, there is little medical or dietary management that can be applied for post-OLT biliary complications. Ursodiol (ursodeoxycholic acid) has often been used as a neoadjuvant to ERCP therapy in the setting of common bile duct stones/casts, and low-fat diets may be recommended in this setting, but no large, randomized trials have advocated medical or conservative management alone.

Graft failure from severe recurrent primary sclerosing cholangitis following orthotopic liver transplantation

Speculation that primary sclerosing cholangitis (PSC) may recur in the transplanted liver is based on the relative increase in frequency of biliary abnormalities and histologic evidence of periportal fibrosis without other causes. A recent study demonstrated almost 9% of patients undergoing liver transplantation (OLT) for primary sclerosing cholangitis (PSC) develop recurrent sclerosing cholangitis although the patient and graft survival is not different from those in whom recurrence does not develop. Most reports of PSC recurrence post-OLT estimate rates of 1% to 14%, but to date, no center has reported rapidly progressive fibro-obliterative cholangitis leading to graft failure.

CASE REPORT

DV was a 39-year-old white man with ulcerative colitis, since age 21, who developed jaundice and pruritus in 1992. ERCP and liver biopsy were consistent with PSC, and he developed thrombocytopenia and bleeding esophageal varices. He underwent an uneventful OLT in May 1994 with an ABO-compatible organ and normal ischemic times. There was no evidence of postoperative cytomegalovirus infection, hepatic artery thrombosis, or rejection. In October 1994, mild abnormalities of liver function tests (LFTs) led to liver biopsy that revealed inflammatory infiltrate in triad with spillover into lobules and mild periportal fibrosis. LFTs normalized without any treatment, but in February 1995 repeat liver biopsy for increased LFTs revealed moderate periportal fibrosis with inflammatory cells in triads and lobules. Viral shell and CMV titers were negative. No evidence of infectious etiology or rejection was noted. The patient was started on ursodeoxycholic acid at that time and percutaneous transhepatic cholangiogram (PTC) revealed marked narrowing of the intrahepatic ducts. Esophagogastroduodenoscopy (EGD) revealed esophageal varices. Hepatic arteriogram and Doppler ultrasound were negative. He developed progressive graft failure, and died at home while awaiting re-transplant.

CONCLUSIONS

Although most series report mild recurrence of PSC following OLT, this case illustrates that early, severe recurrence of PSC may occur, leading to graft failure and need for re-transplantation.

Syngeneic living-donor liver transplantation without the use of immunosuppression

Transplantation between monozygotic twins has been successfully performed using the kidney, small intestine, and pancreas. Identical HLA matching has enabled these individuals to be transplanted without the need for immunosuppressive medication. Liver transplantation without immunosuppression would lessen the risk of recurrent viral hepatitis and eliminate much of the morbidity associated with long-term use of immunosuppressive medication. Living-donor liver transplantation (LDLT) has been performed with increasing success in recent years without an opportunity arising to use a monozygotic twin as a donor. We report 2 cases of LDLT between identical twins wherein perfect haploidentity has allowed these recipients to be transplanted without the need for immunosuppression. Although HLA matched genotypically, there may be differences in anatomy between donor and recipient. Mild liver chemistry test abnormalities may occur after transplant despite the absence of immunosuppression.

Centrilobular fibrosis in long-term follow-up of pediatric liver transplant recipients

BACKGROUND

Centrilobular fibrosis after liver transplant in adults is caused mainly by viral hepatitis, chronic rejection, and azathioprine toxicity. The aim of this study was to investigate possible etiologies and the long-term outcome of this lesion in children.

METHODS

We identified centrilobular fibrosis in 12 of 117 pediatric liver transplant recipients who were investigated for persistent elevations in aminotransferases. Etiologic factors, histologic features on serial biopsies, and clinical and biochemical changes over time were noted for 8 recipients in whom a readily identifiable cause was not apparent.

RESULTS

Centrilobular fibrosis developed a mean of 1.7 years (range: 30 days-3.6 years) posttransplantation in patients receiving cyclosporine, azathioprine, and prednisone. Centrilobular fibrosis was always associated with portal fibrosis and, in six recipients, with persistent, low-grade, cellular rejection. None demonstrated chronic cholestasis, ductopenia, or identifiable vasculopathy. Ischemic, viral, and autoimmune etiologies were excluded. Discontinuing azathioprine did not lead to biochemical or histological improvement. After changing to tacrolimus, aminotransferases normalized in three recipients and repeat biopsies in six were unchanged during a further 2 years of follow-up.

CONCLUSIONS

Centrilobular fibrosis may develop in a small number of pediatric liver transplant recipients, resulting in considerable difficulties in biopsy interpretation. It is not associated with viral hepatitis nor with classical features of chronic rejection. The prognostic significance of centrilobular fibrosis is uncertain, although no child has required retransplantation in up to 12 years of follow-up. A role for a low-grade, chronic form of cellular rejection heralded by persistent, variable, and otherwise unexplained elevations in aminotransferases is suggested.

Retransplantation for hepatic allograft failure: prognostic modeling and ethical considerations

Retransplantation already accounts for 10% of all liver transplants performed, and this percentage is likely to increase as patients live long enough to develop graft failure from recurrent disease. Overall, retransplantation is associated with significantly diminished survival and increased costs. This review summarizes the current causes of graft failure after primary liver transplant, prognostic models that can identify the subset of patients for retransplantation with outcomes comparable to primary transplantation, and ethical considerations in this setting, i.e., outcomes-based versus urgency-based approaches.

Copper metabolism and biliary secretion in patients receiving orthotopic liver transplantation

BACKGROUND

The quantitative aspects of biliary copper excretion in health and disease have not been fully defined yet. The aim of the study was to evaluate copper metabolism and biliary excretion of patients who have received an orthotopic liver transplant (OLT) during the immediate postoperative period.

METHODS

We have studied retrospectively 16 patients undergoing primary OLT and eight undergoing cholecystectomy, and measured serum concentration of copper and its secretion in bile and urine by flame atomic absorption spectrometry (FAAS).

RESULTS

We found a progressive increase of biliary copper secretion rates and a corresponding lowering of urinary copper during the postoperative period. Thus, in OLT patients, the mean of biliary copper secretion on day 1 is 0.7+/-0.2 micromol/day compared with 2.3+/-1.1 micromol/day on day 7 (p<0.01) and 6.1+/-2.5 micromol/day on day 15 (p<0.0001). The rate of copper output on day 5 after surgery is about one sixth of the value reported for patients who had undergone cholecystectomy. In patients suffering an acute rejection episode, there was an abrupt fall in bile flow (<15 ml/day) and excretion of biliary copper (<1 micromol/day), accompanied by an increase of urine copper excretion (>3 micromol/day), and both were recovered when the rejection episode was solved. We found an inverse relationship between the serum bilirubin (Bt), alkaline phosphatase (ALP) and the biliary copper excretion (p<0.01), and a direct relationship with urinary copper excretion (p<0.01).

CONCLUSIONS

The copper measurements in urine and bile are non-invasive techniques, of low cost, rapid and easy to accomplish, and available in hospitals accredited for hepatic transplantation. These characteristics make these methods helpful in the monitoring of patients submitted to OLT for assessment of graft quality and subsequent outcome.

Prognostic model for early acute rejection after liver transplantation

Hepatic graft rejection is a common complication after liver transplantation (LT), with a maximum incidence within the first weeks. The identification of high-risk patients for early acute rejection (EAR) might be useful for clinicians. A series of 133 liver graft recipients treated with calcineurin inhibitors was retrospectively assessed to identify predisposing factors for EAR and develop a mathematical model to predict the individual risk of each patient. The incidence of EAR (< or =45 days after LT) was 35.3%. Multivariate analysis showed that recipient age, underlying liver disease, and Child's class before LT were independently associated with the development of EAR. Combining these 3 variables, the following risk score for the development of EAR was obtained: EAR score [F(x)] = 2.44 + (1.14 x hepatitis C virus cirrhosis) + (2.78 x immunologic cirrhosis) + (2.51 x metabolic cirrhosis)--(0.08 x recipient age in years) + (1.65 x Child's class A) [corrected]. Risk for rejection = e(F(x))/1 + e(F(x)). The combination of age, cause of liver disease, and Child's class may allow us to predict the risk for EAR.

Pathophysiological mechanisms of postrevascularization hyperkalemia in orthotopic liver transplantation

The underlying mechanisms of hyperkalemia occurring immediately after revascularization in orthotopic liver transplantation (OLT) are unknown. We investigated the possible pathophysiological mechanisms of hyperkalemia in relation to the donor and recipient. The study included 64 consecutive patients undergoing OLT. Recipients were divided into two groups: Group 1 consisted of 47 patients with serum K(+) concentration <5.5 mmol/L at 1-min postrevascularization, and Group 2 consisted of 17 patients with serum K(+) exceeding 5.5 mmol/L. Increased serum K(+) concentration, more progressive metabolic acidosis, and decreased mean arterial blood pressure and cardiac index during the anhepatic phase were recognized in Group 2. Multiple regression analysis showed that cardiac index, serum lactate, and serum K(+) concentration during the anhepatic phase were independent and significant factors that could predict serum K(+) concentration 1-min postrevascularization. Hyperkalemia at 1-min postrevascularization did not correlate with the extent of preservation injury of the graft liver (represented by the peak value of aspartate aminotransferase measured within the first 72 h after OLT) or the duration of cold ischemia. We conclude that hyperkalemia occurring immediately after revascularization in OLT is mainly caused by metabolic acidosis as a result of insufficient cardiac output during the anhepatic phase.

Pharmacologic graft protection without donor pretreatment in liver transplantation from non-heart-beating donors

BACKGROUND

Non-heart-beating donors (NHBDs) are considered potential sources of transplant organs in an effort to alleviate the problem of donor shortage in clinical liver transplantation. We investigated the possibility of pharmacologic protection of hepatic allograft function from NHBDs without donor pretreatment.

METHODS

Orthotopic liver transplantation was performed using pigs. In donors, cardiac arrest was induced by stopping the respirator. Forty-five minutes after cessation of the respirator, the liver was flushed with cold lactated Ringer's solution including heparin and with the University of Wisconsin (UW) solution, and then preserved for 8 hr at 4 degrees C in the UW solution. The pigs were divided into two groups: a control group and a treated group. In the treated group, an endothelin antagonist TAK-044 was added to the UW solutions (10 mg/L), and TAK-044 (10 mg/kg body weight) and a platelet activating factor antagonist E5880 (0.3 mg/kg body weight) were also administered to the recipients.

RESULTS

TAK-044 and E5880 treatment significantly increased the 7-day survival rate of the recipients (100% vs. 17%, P<0.05). In the treated group, portal venous pressure immediately after reperfusion of the graft was significantly lower than in the control group, and postoperative increase in serum concentrations of glutamic oxaloacetic transaminase and total bilirubin was attenuated. Moreover, the energy charge and adenosine triphosphate concentration of the liver were rapidly restored after reperfusion.

CONCLUSIONS

Pharmacologic modulation with TAK-044 and E5880 avoiding donor pretreatment can improve the viability of hepatic allografts procured from NHBDs.

The utility of noninvasive serologic markers in the management of early allograft rejection in liver transplantation recipients

BACKGROUND

Early allograft rejection after orthotopic liver transplantation (OLT) currently requires a biopsy for diagnosis. Alpha-glutathione S-transferase (alpha-GST) and Pi-glutathione S-transferase (Pi-GST) are potential noninvasive markers of hepatocyte and biliary epithelial cell injury. Our aim was to determine the utility of noninvasive serologic markers in the management of early hepatic allograft rejection.

METHODS

Forty-four of 52 consecutive adult patients undergoing primary OLT at the University of Florida were included in the study. All had protocol liver biopsies between days 6 and 8 after OLT. Serum alpha-GST and plasma Pi-GST were determined using a sandwich enzyme immunoassay (Biotrin International, Dublin, Ireland). All biopsy specimens were retrospectively reviewed and scored for rejection and cholestasis.

RESULTS

The biopsy specimens were scored for rejection as moderate to severe in 14 patients (group 1) or none to mild in 30 patients (group 2). Group 1 had statistically higher mean levels than group 2 for alpha-GST on days 6, 7, and 9; alanine aminotransferase on days 6 and 9; aspartate aminotransferase (AST) on days 6 and 7; alkaline phosphate (AP) on days 3 through 7, 9, and 10; and gamma-glutamyl transferase on day 3. No differences between groups were seen with Pi-GST or total bilirubin. Between days 6 and 8, the following values were found more frequently in group 1 than group 2: alpha-GST level >15 ng/ml (11/14 vs. 14/30; P<0.01); AST >100 U/L (8/14 vs. 2/30; P=0.002); and AP >120 U/L (14/14 vs. 17/30). Combining AP with either alpha-GST or AST led to improved detection of rejection over any single marker alone. In the first week after the initiation of rejection treatment, alpha-GST was the only marker that accurately predicted response.

CONCLUSION

Serum alpha-GST may be useful in the management of early hepatic allograft rejection. A combination of noninvasive markers may be beneficial to diagnose early hepatic allograft rejection.

An endothelin receptor antagonist ameliorates injuries of sinusoid lining cells in porcine liver transplantation

BACKGROUND

TAK-044 is an endothelin receptor antagonist. Whether the agent has protective effects on liver graft injuries from non-heart-beating donors is unknown.

METHODS

In donor pigs, cardiac arrest was induced by stopping the respirator. Forty-five minutes after cessation of the respirator, the liver was flushed with University of Wisconsin (UW) solution, preserved for 8 hours at 4 degrees C, and transplanted orthotopically. The pigs were divided into two groups: a control group and a drug-treated group in which TAK-044 was given in the UW solutions (10 mg/L) and was administered to recipients (10 mg/kg body weight).

RESULTS

TAK-044 treatment significantly increased recipient survival rate. After reperfusion of the graft, portal venous pressure and 15-minute retention rate of indocyanine green were significantly reduced in the drug-treated group. Electron microscopic findings indicated that TAK-044 attenuated endothelial cell injuries.

CONCLUSION

TAK-044 treatment improves the viability of livers harvested from non-heart-beating donors. The main effect of the agent is protection of endothelial cells from ischemia/reperfusion injuries.

Liver transplantation

The growing disparity between available organs for liver transplantation and the number of waiting recipients has prompted significant debate over organ allocation and distribution. In light of this debate, recipient selection and prediction of factors relating to outcome have become increasingly important. Current immunosuppressive regimens provide excellent short-and long-term survival for patients and grafts. Increasingly, efforts are being made to decrease or withdraw immunosuppression late after transplantation to minimize long-term side effects. Viral disease, particularly cytomegalovirus infection, results in significant morbidity and mortality in patients. However, strategies for targeting high-risk patients with prophylactic antiviral therapy have been successful in reducing the incidence of cytomegalovirus disease. Recurrent viral hepatitis following liver transplantation may limit long-term graft success. Lamivudine appears to limit recurrent infection with hepatitis B virus in a significant number of patients who develop this condition following liver transplantation and may represent a cost savings over hepatitis B immunoglobulin. Although the overall survival of patients with chronic hepatitis C virus infection after orthotopic liver transplantation is excellent, significant morbidity and mortality occur in the subset of patients with severe recurrent disease. Interferon may delay the onset of disease in patients infected with hepatitis C virus following orthotopic liver transplantation, and investigation continues into antiviral therapy in this group of patients.

A model to predict survival following liver retransplantation

In the current era of critical-organ shortage, one of the most controversial questions facing transplantation teams is whether hepatic retransplantation, which has historically been associated with increased resource utilization and diminished survival, should be offered to a patient whose first allograft is failing. Retransplantation effectively denies access to orthotopic liver transplantation (OLT) to another candidate and further depletes an already-limited organ supply. The study group was comprised of 1,356 adults undergoing hepatic retransplantation in the United States between 1990 and 1996 as reported to the United Network for Organ Sharing (UNOS). We analyzed numerous donor and recipient variables and created Cox proportional-hazards models on 900 randomly chosen patients, validating the results on the remaining cohort. Five variables consistently provided significant predictive power and made up the final model: age, bilirubin, creatinine, UNOS status, and cause of graft failure. Although both hepatitis C seropositivity and donor age were significant by univariate and multivariate analyses, neither contributed independently to the estimation of prognosis when added to the final model. The final model was highly predictive of survival (whole model chi2 = 139.63). The risk scores for individual patients were calculated, and patients were assigned into low-, medium-, and high-risk groups (P <.00001). The low degree of uncertainty in the probability estimates as reflected by confidence intervals, even in our high-risk patients, underscores the applicability of our model as an adjunct to clinical judgment. We have developed and validated a model that uses five readily accessible "bedside" variables to accurately predict survival in patients undergoing liver retransplantation.