Joint modeling of liver transplant candidates outperforms the model for end-stage liver disease: The effect of disease development over time on patient outcome

Liver function is measured regularly in liver transplantation (LT) candidates. Currently, these previous disease development data are not used for survival prediction. By constructing and validating joint models (JMs), we aimed to predict the outcome based on all available data, using both disease severity and its rate of change over time. Adult LT candidates listed in Eurotransplant between 2007 and 2018 (n = 16 283) and UNOS between 2016 and 2019 (n = 30 533) were included. Patients with acute liver failure, exception points, or priority status were excluded. Longitudinal MELD(-Na) data were modeled using spline-based mixed effects. Waiting list survival was modeled with Cox proportional hazards models. The JMs combined the longitudinal and survival analysis. JM 90-day mortality prediction performance was compared to MELD(-Na) in the validation cohorts. MELD(-Na) score and its rate of change over time significantly influenced patient survival. The JMs significantly outperformed the MELD(-Na) score at baseline and during follow-up. At baseline, MELD-JM AUC and MELD AUC were 0.94 (0.92-0.95) and 0.87 (0.85-0.89), respectively. MELDNa-JM AUC was 0.91 (0.89-0.93) and MELD-Na AUC was 0.84 (0.81-0.87). The JMs were significantly (p < .001) more accurate than MELD(-Na). After 90 days, we ranked patients for LT based on their MELD-Na and MELDNa-JM survival rates, showing that MELDNa-JM-prioritized patients had three times higher waiting list mortality.

De novo hepatocellular carcinoma in a non-cirrhotic allograft 27 years after liver transplantation: A case report

Hepatocellular carcinoma recurrence after liver transplantation is a well-known complication but the development of de novo hepatocellular carcinoma in non-cirrhotic allograft with no previous history of hepatic malignancy either in the donor or the recipient is extremely rare. A 33-year-old man underwent deceased donor liver transplantation due to HBV-HDV cirrhosis in 1991. The donor was healthy, with negative viral serology. Pretransplant assessment and explant liver pathology revealed no tumor. He developed an 8 cm mediastinal thymus cancer in 2014, a chronic myeloid leukemia in 2015 and a 16 mm renal cell carcinoma in 2017. After 27 years, in 2018, his routine follow-up sonography showed incidentally a 37 mm hepatic nodule in segment VII which revealed after percutaneous liver guided biopsy a hepatocellular carcinoma. As no extra hepatic metastasis was noted, segmentectomy was done. The pathological report confirmed a moderately differentiated hepatocellular carcinoma nodule of 50 mm diameter with absence of microvascular invasion and the non-tumoral liver showed histological features of NASH (SAF score: S1A2F3, NAS score: A3F3 and LAFSc:5) with absence of HBsAg and HBcAg. This case emphasizes the importance of long-term close surveillance by imaging of the graft even in the absence of viral recurrence and graft cirrhosis.

Heterotopic segmental liver transplantation on splenic vessels after splenectomy with delayed native hepatectomy after graft regeneration: A new technique to enhance liver transplantation

We describe a patient with liver metastases from colorectal cancer treated with chemotherapy and hepatic resection, who developed unresectable multifocal liver recurrence and who received liver transplantation using a novel planned technique: heterotopic transplantation of segment 2-3 in the splenic fossa with splenectomy and delayed hepatectomy after regeneration of the transplanted graft. We transplanted a segmental liver graft after in-situ splitting without any impact on the waiting list, as it was previously rejected for pediatric and adult transplantation. The volume of the graft was insufficient to provide liver function to the recipient, so we performed this novel operation. The graft was anastomosed to the splenic vessels after splenectomy, and the native liver portal flow was modulated to enhance graft regeneration, leaving the native recipient liver intact. The volume of the graft doubled during the next 2 weeks and the native liver was removed. After 8 months, the patient lives with a functioning liver in the splenic fossa and without abdominal tumor recurrence. This is the first case reported of a segmental graft transplanted replacing the spleen and modulating the portal flow to favor graft growth, with delayed native hepatectomy.

Validation of the Model for End-stage Liver Disease sodium (MELD-Na) score in the Eurotransplant region

The MELD score is used in the Eurotransplant (ET) region to allocate liver grafts. Hyponatremia in cirrhotic patients is an important predictor of death but is not incorporated in MELD. This study investigated the performance of the MELD-Na score for the ET region. All adult patients with chronic liver disease on the ET liver transplantation waiting list (WL) allocated through lab MELD scores were included. The MELD-corrected effect of serum sodium (Na) concentration at listing on the 90-day WL mortality was calculated using Cox regression. The MELD-Na performance was assessed with c-indices, calibration per decile and Brier scores. The reclassification from MELD to MELD-Na score was calculated to estimate the impact of MELD-Na-based allocation in the ET region. For the 5223 included patients, the risk of 90-day WL death was 2.9 times higher for hyponatremic patients. The MELD-Na had a significantly higher c-index of 0.847 (SE 0.007) and more accurate 90-day mortality prediction compared to MELD (Brier score of 0.059 vs 0.061). It was estimated that using MELD-Na would reduce WL mortality by 4.9%. The MELD-Na score yielded improved prediction of 90-day WL mortality in the ET region and using MELD-Na for liver allocation will very likely reduce WL mortality.

Application of Prescription Drug Monitoring Program to detect underreported controlled substance use in patients evaluated for liver transplant

Presurgical controlled substance use predicts postoperative complications, increased readmissions, and mortality. We aimed to examine if a Prescription Drug Monitoring Program (PDMP) would detect underreported controlled substance use in patients undergoing liver transplant evaluation. We performed a retrospective cohort study at a tertiary referral center of patients undergoing liver transplant evaluation in 2017. PDMP reviews were performed on all 360 patients and urine drug screen (UDS) results were reviewed when available to evaluate dispensed controlled substances. These results were compared to the patient's self-reported medication list at evaluation to identify any underreporting. The primary outcome was the number of self-reported controlled substance discrepancies on the medication list identified by PDMP and UDS at the time of evaluation. Among the 360 patients, 87 (24%) had a discrepancy where PDMP revealed a controlled substance prescription that the patient did not report on their medication list. Seventy-seven (67/87) of these discrepancies involved opiates. Of the 360 patients, 219 (61%) had a negative UDS, but 70 (32%) of these patients had at least one controlled substance listed on PDMP. PDMP is a promising screening tool when used in conjunction with the UDS for detecting underreported controlled substance use in liver transplant candidates.

Development and validation of an optimized prediction of mortality for candidates awaiting liver transplantation

Since 2002, the Model for End-Stage Liver Disease (MELD) has been used to rank liver transplant candidates. However, despite numerous revisions, MELD allocation still does not allow for equitable access to all waitlisted candidates. An optimized prediction of mortality (OPOM) was developed (http://www.opom.online) utilizing machine-learning optimal classification tree models trained to predict a candidate's 3-month waitlist mortality or removal utilizing the Standard Transplant Analysis and Research (STAR) dataset. The Liver Simulated Allocation Model (LSAM) was then used to compare OPOM to MELD-based allocation. Out-of-sample area under the curve (AUC) was also calculated for candidate groups of increasing disease severity. OPOM allocation, when compared to MELD, reduced mortality on average by 417.96 (406.8-428.4) deaths every year in LSAM analysis. Improved survival was noted across all candidate demographics, diagnoses, and geographic regions. OPOM delivered a substantially higher AUC across all disease severity groups. OPOM more accurately and objectively prioritizes candidates for liver transplantation based on disease severity, allowing for more equitable allocation of livers with a resultant significant number of additional lives saved every year. These data demonstrate the potential of machine learning technology to help guide clinical practice, and potentially guide national policy.

Case report of high-dose hydroxocobalamin in the treatment of vasoplegic syndrome during liver transplantation

A 66-year-old man with cryptogenic cirrhosis secondary to nonalcoholic steatohepatitis presented for orthotopic liver transplantation. Following organ reperfusion, the patient developed vasoplegic syndrome, with arterial blood pressures of approximately 60-70/30-40 mm Hg (mean arterial pressure [MAP] <45 mm Hg) for >90 minutes. He required high-dose norepinephrine and vasopressin infusions, as well as i.v. bolus doses of norepinephrine and vasopressin to reach a goal MAP> 60 mm Hg. There was minimal response to a 2 mg/kg i.v. bolus of methylene blue. Following the administration of 5 g of i.v.hydroxocobalamin, the patient had a profound improvement in arterial blood pressure, with subsequent discontinuation of the vasopressin infusion and rapid reduction of norepinephrine infusion from 20 to 2 μg/min. While there have been several reports of the efficacy of hydroxocobalamin for vasoplegia after cardiopulmonary bypass, there have been only limited cases of hydroxocobalamin used in liver transplantation, and none with high-dose administration. We present a case of vasoplegic syndrome during liver transplantation that was refractory to high-dose vasopressors and methylene blue but responsive to high-dose i.v. hydroxocobalamin.

Geographic Disparities in Liver Availability: Accidents of Geography, or Consequences of Poor Social Policy?

Recently, a redistricting proposal intended to equalize Model for End-stage Liver Disease score at transplant recommended expanding liver sharing to mitigate geographic variation in liver transplantation. Yet, it is unclear whether variation in liver availability is arbitrary and a disparity requiring rectification or reflects differences in access to care. We evaluate the proposal's claim that organ supply is an "accident of geography" by examining the relationship between local organ supply and the uneven landscape of social determinants and policies that contribute to differential death rates across the United States. We show that higher mortality leading to greater availability of organs may in part result from disproportionate risks incurred at the local level. Disparities in public safety laws, health care infrastructure, and public funding may influence the risk of death and subsequent availability of deceased donors. These risk factors are disproportionately prevalent in regions with high organ supply. Policies calling for organ redistribution from high-supply to low-supply regions may exacerbate existing social and health inequalities by redistributing the single benefit (greater organ availability) of greater exposure to environmental and contextual risks (e.g. violent death, healthcare scarcity). Variation in liver availability may not be an "accident of geography" but rather a byproduct of disadvantage.

Left Lobe Auxiliary Liver Transplantation for End-stage Hepatitis B Liver Cirrhosis

Auxiliary liver transplantation (ALT) for hepatitis B virus (HBV)-related liver cirrhosis previously showed poor results, because the native liver was a significant source of HBV recurrence and the graft could be rapidly destroyed by HBV infection in an immunosuppressive condition. Four patients with HBV-related liver cirrhosis were unable to undergo orthotopic liver transplantation because the only available grafts of left lobe were too small. Under entecavir-based anti-HBV treatment, they underwent ALT in which the recipient left liver was removed and the small left lobe graft was implanted in the corresponding space. The mean graft weight/recipient weight was 0.49% (range, 0.38%-0.55%). One year after transplantation, the graft sizes were increased to 273% and the remnant livers were decreased to 44%. Serum HBV DNA was persistently undetectable. Periodic graft biopsy showed no signs of tissue injury and negative immunostaining for hepatitis B surface antigen and hepatitis B core antigen. After a mean follow-up period of 21 months, all patients live well with normal graft function. Our study suggests that ALT for HBV-related liver cirrhosis is feasible under entecavir-based anti-HBV treatment. Successful application of small left livers in end-stage liver cirrhosis may significantly increase the pool of left liver grafts for adult patients.

Improving the Diagnostic Criteria for Primary Liver Graft Nonfunction in Adults Utilizing Standard and Transportable Laboratory Parameters: An Outcome-Based Analysis

Current diagnostic criteria for primary nonfunction (PNF) of liver grafts are based on clinical experience rather than statistical methods. A retrospective, single-center study was conducted of all adults (n = 1286) who underwent primary liver transplant (LT) 2000-2008 in our center. Laboratory variables during the first post LT week were analyzed. Forty-two patients (3.7%) had 2-week graft failure. Transplant albumin, day-1 aspartate aminotransferase (AST), day-1 lactate, day-3 bilirubin, day-3 international normalized ratio (INR), and day-7 AST were independently associated with PNF on multivariate logistic regression. PNF score =(0.000280*D1AST)+ (0.361*D1 Lactate)+(0.00884*D3 Bilirubin)+(0.940*D3 INR)+(0.00153*D7 AST)-(0.0972*TxAlbumin)-4.5503. Receiver operating curve analysis showed the model area under receiver operating curve (AUROC) of 0.912 (0.889-0.932) was superior to the current United Kingdom (UK) PNF criteria of 0.669 (0.634-0.704, p < 0.0001). When applied to a validation cohort (n = 386, 34.4% patients), the model had AUROC of 0.831 (0.789-0.867) compared to the UK early graft dysfunction criteria of 0.674 (0.624-0.721). The new model performed well after exclusion of patients with marginal grafts and when modified to include variables from the first three post-LT days only (AUROC of 0.818, 0.776-0.856, p = 0.001). This model is superior to the current UK PNF criteria and is based on statistical methods. The model is also applicable to recipients of all types of grafts (marginal and nonmarginal).

Cost-Effectiveness of New Direct-Acting Antivirals to Prevent Post-Liver Transplant Recurrent Hepatitis

Preliminary studies on HCV-cirrhotics listed for transplant suggest that sofosbuvir in combination with ribavirin is very effective in promoting viral clearance and preventing disease recurrence. Unfortunately, the high cost of such treatment (€46 500 per 12 weeks of treatment) makes its cost-effectiveness questionable. A semi-Markov model was developed to assess the cost-effectiveness of sofosbuvir/ribavirin treatment in cirrhotic patients without HCC (HCV-CIRRH) and with HCC (HCV-HCC) listed for transplant. In the base-case analysis, the incremental cost-effectiveness ratio for 24 weeks of sofosbuvir/ribavirin was €44 875 per quality-adjusted life-year gained in HCV-CIRRH and €60 380 in HCV-HCC patients. Both results were above the willingness to pay threshold of €37 000 per quality-adjusted life-year. Our data also show that in order to remain cost-effective (with a 24-week treatment), any novel interferon-free treatment endowed with ideal efficacy should cost less than €67 224 or €95 712 in HCV-cirrhotics with and without HCC, respectively. The results shows that sofosbuvir/ribavirin therapy, given to patients listed for transplant, is not cost-effective at current prices despite being very effective, and new, more effective treatments will have little economic margins to remain cost-effective. New interferon-free combinations have the potential to revolutionize the treatment and prognosis of HCV-positive patients listed for transplant; however, without sustainable prices, this revolution is unlikely to happen.

Tacrolimus and the risk of solid cancers after liver transplant: a dose effect relationship

Although increased rates of solid organ cancers have been reported following liver transplantation (LT), the impact of quantitative exposure to calcineurin inhibitors (CNI) remains unclear. We have therefore probed the relationship between the development of solid organ cancers following LT and the level of CNI exposure. This prospective single-center study was conducted between 1995 and 2008 and is based on 247 tacrolimus-treated liver transplant recipients who survived at least 1 year following surgery. The incidence of cancer was recorded, and the mean blood concentration of tacrolimus (TC) was determined at 1 and 3 years following LT. The study results indicate that 43 (17.4%) patients developed de novo solid cancers. Mean TC during the first year after LT was significantly higher in patients who developed solid organ tumors (10.3 ± 2.1 vs. 7.9 ± 1.9 ng/mL, p < 0.0001). Independent risks factors in multivariate analysis were tobacco consumption before LT (OR = 5.42; 95% CI [1.93-15.2], p = 0.0014) and mean annual TC during the first year after LT (p < 0.0001; OR = 2.01; 95% CI [1.57-2.59], p < 0.0001). Similar effects were observed in 216 patients who received tacrolimus continuously for ≥3 years. It appears therefore that CNI should be used with caution after LT, and that new immunosuppressive therapies could deliver significant clinical benefits in this regard.

What's hot, what's new at WTC--clinical science

More than 3000 abstracts of innovative and exciting findings, covering the whole field of organ transplantation, were presented at the World Transplant Congress 2014. Key areas of presentations across all organs and tissues included HLA antibodies, antibody-mediated rejection, living donation, immunosuppression, organ perfusion and surgical procedures. In addition, cutting edge science and future perspectives were presented in state-of-the-art lectures. This review will present highlights of this meeting and demonstrate strength and success of clinical sciences in transplantation.