The mismatch choice in liver transplantation: a suggestion for the selection of the recipient in relation to the characteristics of the donor

Machine Perfusion for Extended Criteria Donor Livers: What Challenges Remain?

Based on the renaissance of dynamic preservation techniques, extended criteria donor (ECD) livers reclaimed a valuable eligibility in the transplantable organ pool. Being more vulnerable to ischemia, ECD livers carry an increased risk of early allograft dysfunction, primary non-function and biliary complications and, hence, unveiled the limitations of static cold storage (SCS). There is growing evidence that dynamic preservation techniques—dissimilar to SCS—mitigate reperfusion injury by reconditioning organs prior transplantation and therefore represent a useful platform to assess viability. Yet, a debate is ongoing about the advantages and disadvantages of different perfusion strategies and their best possible applications for specific categories of marginal livers, including organs from donors after circulatory death (DCD) and brain death (DBD) with extended criteria, split livers and steatotic grafts. This review critically discusses the current clinical spectrum of livers from ECD donors together with the various challenges and posttransplant outcomes in the context of standard cold storage preservation. Based on this, the potential role of machine perfusion techniques is highlighted next. Finally, future perspectives focusing on how to achieve higher utilization rates of the available donor pool are highlighted.

Using old liver grafts for liver transplantation: Where are the limits?

The scarcity of ideal liver grafts for orthotopic liver transplantation (OLT) has led transplant teams to investigate other sources of grafts in order to augment the donor liver pool. One way to get more liver grafts is to use marginal donors, a not well-defined group which includes mainly donors > 60 years, donors with hypernatremia or macrosteatosis > 30%, donors with hepatitis C virus or hepatitis B virus positive serologies, cold ischemia time > 12 h, non-heart-beating donors, and grafts from split-livers or living-related donations. Perhaps the most practical and frequent measure to increase the liver pool, and thus to reduce waiting list mortality, is to use older livers. In the past years the results of OLT with old livers have improved, mainly due to better selection and maintenance of donors, improvements in surgical techniques in donors and recipients, and intra- and post-OLT management. At the present time, sexagenarian livers are generally accepted, but there still exists some controversy regarding the use of septuagenarian and octogenarian liver grafts. The aim of this paper is to briefly review the aging process of the liver and reported experiences using old livers for OLT. Fundamentally, the series of septuagenarian and octogenarian livers will be addressed to see if there is a limit to using these aged grafts.

Beyond survival: how well do transplanted livers work? A preliminary comparison of standard-risk, high-risk, and living donor recipients

To help decrease mortality on the liver transplant waitlist, transplant centers are using living donors (LD) and high-risk donors (HRD) in addition to standard-risk donors (SRD). HRD is defined as having a donor risk index score higher than 1.6, which suggests a great risk of graft failure. Recent studies have examined survival rates between HRD and SRD recipients; however, little is known about outcomes other than survival, specifically psychosocial outcomes. The purpose of this preliminary, prospective study was to compare post-transplant psychosocial and recovery outcomes between SRD and LD and HRD liver recipients. These outcomes include cognitive functioning, psychological distress, quality of life, and self-reported and objective measures of recovery. Eighty-four patients provided baseline and six-month post-transplant data. There were generally no statistically significant differences at baseline or the six-month follow-up, suggesting that patients receiving HRD livers have similar outcomes to those who receive SRD livers. However, some effect sizes suggest potential advantages for LD recipients compared to SRD recipients. Transplant centers may be more willing to encourage patients to accept HRD or LD livers knowing that they may have comparable outcomes to SRD recipients, which also has implications for the transplant waitlist.

Influence of larger graft weight to recipient weight on the post-liver transplantation course

Size matching between recipient and donor livers is an important factor in organ allocation in the context of liver transplantation (LT). The aim of this study was to determine whether a large graft for recipient size influenced the post-transplant course. One hundred and sixty-two successive LT recipients were included and retrospectively divided into two groups: 25 (15%) had a graft-to-recipient weight ratio (GWRW) ≥ 2.5% and 137 (85%) had a GWRW <2.5%. Postoperative complications and outcomes were recorded. In the GWRW >2.5% group, more end-to-end caval replacement (72% vs. 38%, p = 0.003) and veno-venous bypass (48% vs. 23%, p = 0.01) were used. Peak AST/ALT values were higher in the GWRW >2.5% group (AST: 596 [70-5876] vs. 453 [29-5132] IU/l, p = 0.03; ALT: 773 [101-5025] vs. 383 [36-4921] IU/l, p = 0.02). Among postoperative complications, the rate of respiratory failure was higher in the GWRW >2.5% group (32% vs. 14%, p = 0.04). The rates of other complications did not differ between the two groups. Both groups had similar graft and patient survival rates at one yr. Using large grafts for recipient size did not impair liver function and did not modify graft and patient outcomes at one yr. However, a GWRW >2.5% appeared to be a determining factor for respiratory morbidity following LT.

Model for end-stage liver disease dynamic stratification of survival benefit

Only patients with Model for End-stage Liver Disease (MELD) scores ≥18 or ≥17 experience a survival benefit (SB) at 12 and 36 months after liver transplantation (OLT). The SB calculation estimates the difference after stratification for risk categories between the survival rate of transplanted versus waiting list patients. The aim of this study was to perform a short- and long-term (60 months) SB analyses of a Italian OLT program. One-hundred seventy-one patients were stratified into four MELD classes (6-14, 15-18, 19-25, 26-40), and two groups: namely, waiting list (WL) and transplanted groups (TX). The median waiting time for transplanted patients was 4.4 months (range, 0-35). SB was expressed as mortality hazard ratio (MHR) as obtained through a Cox regression analysis using as a covariate the status of each patient in the waiting list (WL = 0, reference group) or the TX group (TX = 1). Values over 1 indicated the MHR in favor of the WL with the values below 1 indicating MHR in favor of Tx. In the MELD class 6 to 14, the MHR was above 1 at 3 and 6 months, indicating an SB in favor of WL; subsequently, the MHR dropped below 1, indicating an SB in favor of TX (P < .05). In the MELD class 15 to 18 the MHR was above 1 at 3 months, but below 1 subsequently (P < .05). For MELD classes 19 to 25 and 26 to 40, the MHR was always below 1 (P < .01). According to the SB approach, patients in the MELD class 6 to 14 could safely wait for at least 36 months; patients in the MELD class 15 to 18 should likely remain no longer than 12 months on the waiting list, and all the remaining patients with MELD > 18 should be transplanted as soon as possible. OLT should not be precluded but only postponed for MELD < 19 patients.

Balancing donor and recipient risk factors in liver transplantation: the value of D-MELD with particular reference to HCV recipients

Donor-recipient match is a matter of debate in liver transplantation. D-MELD (donor age × recipient biochemical model for end-stage liver disease [MELD]) and other factors were analyzed on a national Italian database recording 5946 liver transplants. Primary endpoint was to determine factors predictive of 3-year patient survival. D-MELD cutoff predictive of 5-year patient survival <50% (5yrsPS<50%) was investigated. A prognosis calculator was implemented (http://www.D-MELD.com). Differences among D-MELD deciles allowed their regrouping into three D-MELD classes (A < 338, B 338-1628, C >1628). At 3 years, the odds ratio (OR) for death was 2.03 (95% confidence interval [CI], 1.44-2.85) in D-MELD class C versus B. The OR was 0.40 (95% CI, 0.24-0.66) in class A versus class B. Other predictors were hepatitis C virus (HCV; OR = 1.42; 95% CI, 1.11-1.81), hepatitis B virus (HBV; OR = 0.69; 95% CI, 0.51-0.93), retransplant (OR = 1.82; 95% CI, 1.16-2.87) and low-volume center (OR = 1.48; 95% CI, 1.11-1.99). Cox regressions up to 90 months confirmed results. The hazard ratio was 1.97 (95% CI, 1.59-2.43) for D-MELD class C versus class B and 0.42 (95% CI, 0.29-0.60) for D-MELD class A versus class B. Recipient age, HCV, HBV and retransplant were also significant. The 5yrsPS<50% cutoff was identified only in HCV patients (D-MELD ≥ 1750). The innovative approach offered by D-MELD and covariates is helpful in predicting outcome after liver transplantation, especially in HCV recipients.

Outcome of liver transplantation based on donor graft quality and recipient status

BACKGROUND

Availability of suitable donor organs has always limited the number of liver transplantations performed. Use of marginal donor organs is an alternative to overcome organ shortage.

OBJECTIVE

To analyze the effect of various combinations of donor organ quality and recipient status on the outcome of liver transplantation.

MATERIALS AND METHODS

Data from 260 whole-liver transplantations performed between January 2003 and September 2009 were analyzed retrospectively. Study groups were established according to donor organ quality (marginal score 0-1 vs 2-5) and recipient status (Model for End-Stage Liver Disease [MELD] score <17 or >17). In patients at low risk, 102 received optimal grafts (good-to-good group [G/G], and 75 received marginal grafts (bad-to-good group [B/G]. In patients at high risk, 46 received optimal grafts (good-to-bad group [G/B], and 37 received marginal grafts (bad-to-bad group [B/B].

RESULTS

No differences were observed in cumulative patient and graft survival rates; however, total survival differed in the early period after transplantation, that is, within 1 year. There was a higher rate of overall postoperative complications including initial poor graft function, bleeding, infection, and kidney failure in group B/B compared with group G/B (25 of 37 patients [67.5%] vs 27 of 46 patients [59.0%]), group B/G (25 of 37 patients [68%] vs 39 of 75 patients [52%], and group G/G (25 of 37 patients [68%] vs 43 of 102 patients [42%]) (P = .04). Patients with a high MELD score (G/B and B/B) demonstrated increased risk of postoperative complications. Use of donor organs with marginal score of 2 or higher in patients with high MELD scores increased early patient mortality.

CONCLUSION

In summary, patients with a high MELD score (G/B and B/B) are at an increased risk of post-OLT complications. In contrast, use of marginal grafts (B/G and B/B) increased the rate of hepatitis C virus recurrence and decreased the response rate to antiviral therapy. The combination of impaired donor grafts and recipients at high risk should be avoided.

Prediction of graft dysfunction based on extended criteria donors in the model for end-stage liver disease score era

BACKGROUND

To explain the influence of recipient status combined with the accumulation of extended criteria donor (ECD) variables on the appearance of severe ischemia-reperfusion injury and graft survival in a model for end-stage liver disease (MELD)-based system, we analyzed our most recent consecutive liver transplantations (LTs), dividing them into two periods: 400 LTs (1992-2002; pre-MELD era) and 275 LTs (2002-2007; post-MELD era).

METHODS

Primary dysfunction (PD) was defined as primary graft failure that required emergency retransplantation or as initial poor function. Donor variables were included in a regression model to assess the probability of PD.

RESULTS

Donor age, macrovesicular steatosis more than 30%, and cold ischemia time were associated with allograft dysfunction. Mean probability of PD was 14.8%, 19.2%, 27.5%, and 37.4% for ECD 0, 1, 2, and more than or equal to 3, respectively (P=0.003). Distribution of no-mild, moderate, and severe ischemia-reperfusion injuries among MELD categories was 72.53%, 24.17%, and 3.30% (MELD group=12-19); 56.52%, 36.96%, and 6.5% (MELD group=20-28); and 23.91%, 54.35%, and 21.74% (MELD group >or=29), respectively (P=0.043). The development of PD according to ECD variables was 18.8%, 18.1%, 28.0%, and 35.3% for ECD 0, 1, 2, and more than or equal to 3, respectively (P=0.047). These variables were independent predictors of PD (Cox proportional regression model): ECD 2 (relative risk [RR]=1.59; 95% confidence interval [CI]=1.25-1.62), ECD 3 (RR=2.74; 95% CI=2.38-3.13), MELD 21 to 30 (RR=1.89; 95% CI=1.32-2.06), and MELD more than or equal to 30 (RR=3.38; 95% CI=2.43-3.86). Graft survival decreased, whereas MELD and the number of ECD variables increased.

CONCLUSION

The combination of three or more ECD variables and an MELD more than or equal to 29 is the worst scenario for graft success after LT.

Successful use of extended criteria donor grafts with low to moderate steatosis in patients with model for end-stage liver disease scores below 27

Liver transplantation may be performed using extended criteria donor grafts (ECDg). The characteristics of ECDg include age >60 years, long intensive care unit (ICU) stay, history of malignancy or steatosis. Grafts are often discarded due to steatosis, which can be macrovesicular (MaS) or microvesicular (MiS). MaS is the variety most frequently involved with unfavorable outcomes due to primary nonfunction (PNF) or primary dysfunction (PDF). As of January 2000, all livers referred to our institution were considered potentially transplantable. Steatosis was defined as the presence of fat droplets in more than 5% of hepatocytes. We observed 35 steatotic grafts. Grafts were stratified according to MaS and MiS as follows: low steatosis (5%-15%), mild steatosis (16%-30%), moderate steatosis (31%-60%), or severe steatosis (>60%). Fifteen grafts with moderate (n = 2) or severe (n = 13) MaS were discarded. Twenty grafts were harvested: 18 of them were transplanted at our institution, the remaining 2, discarded by our donor team, were transplanted by other Italian centers. Low MaS was detected in 10 grafts (50%), mild MaS in 4 (20%), and moderate MaS in 2 (10%). Low MiS was detected in 8 grafts (40%), mild MiS in 5 (25%), and moderate MiS in 1 (5%). Steatotic grafts were transplanted only into recipients with model for end-stage liver disease (MELD) scores <27. The 6-month graft survival was 80%; the PNF rate was 10%; and the PDF rate was 15%. The careful use of ECDg with low to moderate steatosis is possible if particular care is taken to avoid additional risk factors related to the recipient.

Donor risk index and organ patient index as predictors of graft survival after liver transplantation

In liver transplantation the identification of risk factors and the risk quantification for each single case represent a field of great interest. There are donor-related and recipient-related risk factors. Donor risk index (DRI) was retrospectively calculated in 223 liver transplant cases. We did not include patients with preoperative diagnosis of hepatocarcinoma and retransplants. The cases were stratified into two classes according to the DRI (low risk, DRI<1.7, and high risk, DRI >or= 1.7). A new index, namely the organ patient index (OPI) was calculated adding the Model for End-stage Liver Disease (MELD) score to the DRI. Patients were stratified into two classes according to the OPI (low risk, OPI <or= 2.85, and high risk, OPI>2.85). The cases with low DRI (n=144) showed better survival than the cases with high DRI (n=82; P< .02). The cases with low OPI (n=173) showed better survival than cases with high OPI (n=50; P< .01). The OPI predicted outcomes better than DRI, increasing the gap in the long-term graft survival between the low- and the high-risk class. The inclusion of the MELD in the new index allowed better prediction of graft survival.

The marginal liver donor--an update

The number of patients awaiting liver transplantation keeps steadily rising with no corresponding rise in suitable grafts for transplantation. There also is an increasing trend of patients dying or being taken off waiting lists because of deterioration while waiting for a transplant. Over the preceding years the use of marginal grafts in liver transplantation has been driven by the critical shortage of donor organs and by emerging data that their use has resulted in a favourable outcome. This review revisits the factors defining marginality of a graft, and the issues faced by transplant units in making the decision to use such a graft. It also looks at the innovations in transplantation geared towards increasing the donor pool and the resulting issues of matching marginal grafts to suitable recipients.

Allocation of nonstandard livers to transplant candidates with high MELD scores: Should this practice be continued?

MELD and PELD scores of 255 consecutive grafts were calculated (236 adult cases and 19 pediatric cases). No correction for the etiology of liver disease was performed. Retransplants were excluded. Three categories of patients were identified: low MELD (scores <12, n = 61); intermediate MELD (scores between 12-24, n = 159); high MELD (scores > or =25, n = 35). Grafts were categorized according to donor quality: standard livers (n = 199), vs nonstandard livers (n = 56). Nonstandard livers were identified by age > or =60, or at least by two of the following conditions: severe hemodynamic instability, ultrasound evidence of steatosis, natriemia > or =155 mEq/L, ICU stay >7 days, liver trauma, protracted anoxia as cause of brain death, transaminases levels x 4. In standard livers, the 12-month graft survival (GS) for low, intermediate, and high MELD classes were 88%, 74%, and 77%, respectively. In nonstandard livers, the 12-month GS for the low, intermediate, and high MELD classes were 84%, 55%, and 44%, respectively; differences between low MELD class and both intermediate and high MELD classes were significant (P < .05). Cox regression analysis of all cases identified the following parameters as independent predictors of GS: donor status; donor age; and recipient creatinine. The highest correlation with GS was found using donor age and recipient creatinine as covariates. In standard livers no variable was able to predict GS. In nonstandard livers the MELD-PELD score was the unique variable able to predict GS. We suggest avoiding the use of nonstandard livers for patients with high MELD scores.

Prognostic value of MELD score and donor quality in liver transplantation: implications for the donor recipient match

The model for End-stage Liver Disease (MELD) has been adopted by the Organ Procurement and Transplantation Network (OPTN) in 2002 as the standard priority rule for the liver transplantation waiting list. We retrospectively calculated the pretransplant MELD scores of 226 consecutive adult grafts. We did not correct for hepatocellular carcinoma comorbidity or for the etiology of liver disease. Cases were categorized according to the MELD score: class I, MELD scores between 6 and 14 (low MELD, n = 116); class II, MELD score between 15 and 24 (intermediate MELD, n = 78); class III, MELD score between 25 and 42 (high MELD, n = 32). All patients were transplanted using deceased donors. Grafts were categorized also according to donor quality (standard donor vs nonstandard donor). Sorting into categories was performed before transplant by officers of the Central-South Italian Transplant Organization overregional organ procurement agencies, namely OCST. Differences in Kaplan-Meier graft survivals (GS) between low MELD class and high MELD class were statistically significant (P < .01). Among standard donors, the 6-month GS were 83%, 94%, and 63% for the low, intermediate, and high MELD subset, respectively, differences that did not reach statistical significance. Among nonstandard donors, the 6-month GS were 77%, 71%, and 38% for the low, intermediate, and high MELD classes, respectively. Differences between low MELD class and intermediate MELD class and between low MELD class and high MELD class were statistically significant (P < .01). We strongly suggest that the utilization of nonstandard organs should be avoided for patients with high MELD scores.

The Nonstandard Liver, a Hidden Resource That Cannot Be Overlooked: Implications for the Identification of the Best Recipient

We described the characteristics of livers already labeled as marginal, nonstandard, or selected with extended criteria: donors of elderly age, steatosis, hemodynamic instability, long cold ischemia time, high serum Na, HbcAb-positive status, HCVAb-positive status. Recipients characteristics (gender, UNOS status, MELD score, indication for transplantation) and their best possible match to nonstandard donors were evaluated with a report of the recent guidelines and the specific algorithms to optimize recipient identification.