Diagnostic Performance of Vibration-Controlled Transient Elastography in Liver Transplant Recipients

A Clinical Review of Noninvasive Tests for Hepatic Fibrosis

Identifying hepatic fibrosis is paramount in managing patients with chronic liver disease. The etiology of liver disease can be owing to many factors, including chronic viral hepatitis, steatotic liver diseases such as alcohol-associated liver disease or metabolic dysfunction-associated steatotic liver disease, autoimmune hepatitis, and cholestatic liver diseases. Currently, invasive liver biopsy with histopathologic evaluation is the gold standard; however, noninvasive tests are becoming more prevalent, especially because they do not carry the risks of invasive procedures such as biopsy. This article reviews noninvasive tests for fibrosis, separating them into blood-based and imaging-based tests.

Vibration-Controlled Transient Elastography-Based Parameters Predict Clinical Outcomes in Liver Transplant Recipients

BACKGROUND AND AIMS

Vibration-controlled transient elastography (VCTE) is used in clinical practice to risk-stratify liver transplant (LT) recipients; however, there are currently little data demonstrating the relationship between VCTE and clinical outcomes.

METHODS

A total of 362 adult LT recipients with successful VCTE examination between 2015 and 2022 were included. Presence of advanced fibrosis was defined as liver stiffness measurement (LSM) ≥10.5 kPa and hepatic steatosis as controlled attenuation parameter (CAP) ≥270 dB/m. The outcomes of interest included all-cause mortality, myocardial infarction (MI), and graft cirrhosis using cumulative incidence analysis that accounted for the competing risks of these outcomes.

RESULTS

The LSM was elevated in 64 (18%) and CAP in 163 (45%) LT recipients. The baseline LSM values were similar in patients with elevated vs normal CAP values. After a median follow-up of 65 (interquartile range, 20-140) months from LT to baseline VCTE, 66 (18%) patients died, 12 (3%) developed graft cirrhosis, and 18 (5%) experienced an MI. Baseline high LSM was independently associated with all-cause mortality (hazard ratio [HR], 1.97; 95% confidence interval [CI], 1.11-3.50; P = .02) and new onset cirrhosis (HR, 6.74; 95% CI, 2.08-21.79; P < .01). A higher CAP value was significantly and independently associated with increased risk of experiencing a MI over study follow-up (HR, 4.14; 95% CI, 1.29-13.27; P = .017).

CONCLUSIONS

The VCTE-based parameters are associated with clinical outcomes and offer the potential to be incorporated into clinical risk-stratification strategies to improve outcomes among LT recipients.

Metabolic-Dysfunction-Associated Steatotic Liver Disease (MASLD) after Liver Transplantation: A Narrative Review of an Emerging Issue

The development of steatotic liver disease after liver transplant (LT) is widely described, and epidemiological data have revealed an increased incidence in recent times. Its evolution runs from simple steatosis to steatohepatitis and, in a small proportion of patients, to significant fibrosis and cirrhosis. Apparently, post-LT steatotic disease has no impact on the recipient's overall survival; however, a higher cardiovascular and malignancy burden has been reported. Many donors' and recipients' risk factors have been associated with this occurrence, although the recipient-related ones seem of greater impact. Particularly, pre- and post-LT metabolic alterations are strictly associated with steatotic graft disease, sharing common pathophysiologic mechanisms that converge on insulin resistance. Other relevant risk factors include genetic variants, sex, age, baseline liver diseases, and immunosuppressive drugs. Diagnostic evaluation relies on liver biopsy, although non-invasive methods are being increasingly used to detect and monitor both steatosis and fibrosis stages. Management requires a multifaceted approach focusing on lifestyle modifications, the optimization of immunosuppressive therapy, and the management of metabolic complications. This review aims to synthesize the current knowledge of post-LT steatotic liver disease, focusing on the recent definition of metabolic-dysfunction-associated steatotic liver disease (MASLD) and its metabolic and multisystemic concerns.

Recurrence of autoimmune liver diseases after liver transplantation: Review and expert opinion statement

Autoimmune liver diseases (AILDs) constitute the fourth most common indication for liver transplantation (LT) across the world. In general, the outcomes after LT are acceptable; however, disease recurrence after LT is common for all AILD, which can negatively affect graft and overall survival. Several questions persist, including the risk factors associated with recurrent disease, optimal antirejection medications, strategies to reduce the risk of recurrence, and how to best incorporate these strategies into clinical practice. For that reason, we assembled an international group of experts to review evidence to address these outstanding questions regarding LT for AILD. Survival rates after LT are ~90% and 70% at 1 and 5 years, and recurrent disease occurs in 10%-50% of patients with AILD. In patients with disease recurrence, graft survival decreased by 18% and 28% and overall survival by 8% and 12% at 5 and 10 years after LT, respectively. Recurrent autoimmune hepatitis is associated with high aminotransferases and immunoglobulin G (IgG) before LT, lymphoplasmacytic infiltrates in the explants, and may be associated with the absence of steroids after LT. However, the efficiency and safety of triple immunosuppressive maintenance therapy is still debatable. Younger age at diagnosis with primary biliary cholangitis or LT is associated with primary biliary cholangitis recurrence. Preventive use of ursodeoxycholic acid reduces the risk of recurrence and has a benefit in graft and patient survival. Episodes of systemic inflammation, including T-cell-mediated rejection, active ulcerative colitis, and episodes of cholangitis, are associated with recurrent PSC. Recurrent disease for AILD is associated with worse graft and patient survival. Patients with autoimmune hepatitis could be considered for long-term low-dose predniso(lo)ne, whereas patients with primary biliary cholangitis should be placed on preventive ursodeoxycholic acid after LT. There are no specific treatments for PSC recurrence; however, adequate control of inflammatory bowel disease and optimal immunosuppression to avoid T-cell-mediated rejection should be encouraged.

Banff 2022 Liver Group Meeting report: Monitoring long-term allograft health

The Banff Working Group on Liver Allograft Pathology met in September 2022. Participants included hepatologists, surgeons, pathologists, immunologists, and histocompatibility specialists. Presentations and discussions focused on the evaluation of long-term allograft health, including noninvasive and tissue monitoring, immunosuppression optimization, and long-term structural changes. Potential revision of the rejection classification scheme to better accommodate and communicate late T cell-mediated rejection patterns and related structural changes, such as nodular regenerative hyperplasia, were discussed. Improved stratification of long-term maintenance immunosuppression to match the heterogeneity of patient settings will be central to improving long-term patient survival. Such personalized therapeutics are in turn contingent on a better understanding and monitoring of allograft status within a rational decision-making approach, likely to be facilitated in implementation with emerging decision-support tools. Proposed revisions to rejection classification emerging from the meeting include the incorporation of interface hepatitis and fibrosis staging. These will be opened to online testing, modified accordingly, and subject to consensus discussion leading up to the next Banff conference.

Development of Clinical Algorithm Utilizing Vibration-Controlled Transient Elastography to Detect Advanced Hepatic Fibrosis in Liver Transplant Recipients

INTRODUCTION

Vibration-controlled transient elastography (VCTE) based liver stiffness measurement (LSM) is an excellent 'rule-out' test for advanced hepatic fibrosis in liver transplant (LT) recipients, however, its ability to 'rule-in' the disease is suboptimal. The study aimed to improve diagnostic performance of LSM in LT recipients.

METHODS

Adult LT recipients with a liver biopsy and VCTE were included (N = 150). Sequential covering analysis was performed to create rules to identify patients at low or high risk for advanced fibrosis (stage 3-4).

RESULTS

Advanced hepatic fibrosis was excluded in patients with either LSM < 7.45 kPa (n = 72) or 7.45 ≤ LSM < 12.1 kPa and time from LT < 5.6 years (n = 25). Conversely, likelihood of advanced fibrosis was 95% if patients had LSM > 14.1 and controlled attenuation parameter > 279 dB/m (n = 21). Thus, 118 (79%) were correctly identified and 32 (21%) would have required a biopsy to establish the diagnosis. Compared to previously established LSM based cutoff values of 10.5 kPa (Youden index) and 13.3 kPa (maximized specificity), the false positive rates of sequential covering analysis was 1% compared to 16.5% with LSM ≥ 10.5 kPa and 8.3% with LSM ≥ 13.3 kPa. The true positive rates were comparable at 87% for sequential covering analysis, 93% for LSM ≥ 10.5 kPa and 83% for LSM ≥ 13.3 kPa.

CONCLUSION

The proposed clinical sequential covering analysis allows for better risk stratification when evaluating for advanced fibrosis in LT recipients compared to LSM alone. Additional efforts are necessary to further reduce the number of patients with indeterminate results in whom a liver biopsy may be required.

Clinical value of [18F]AlF-NOTA-FAPI-04 PET/CT for assessing early-stage liver fibrosis in adult liver transplantation recipients compared with chronic HBV patients

AIMS

To investigate the clinical value and performance of [18F]AlF-NOTA-FAPI-04 PET/CT in assessing early-stage liver fibrosis in liver transplantation (LT) recipients.

METHODS

A prospective study including 17 LT recipients and 12 chronic Hepatitis B (CHB) patients was conducted. All patients received liver biopsy, transient elastography (TE), and [18F]AlF-NOTA-FAPI-04 PET/CT. On [18F]AlF-NOTA-FAPI-04 PET/CT scans, the liver parenchyma's maximum standardized uptake values (SUVmax) were measured. The receiver operating characteristic (ROC) curve analysis was applied to determine the diagnostic efficacy of [18F]AlF-NOTA-FAPI-04 PET/CT in early-stage liver fibrosis (S1-S2) compared with the diagnostic performance of TE.

RESULTS

Among those 29 patients enrolled in this study, 15(51.7%) had fibrosis S0, 10(34.5%) had S1, and 4(13.8%) had S2, respectively. The SUVmax of patients with early-stage liver fibrosis was significantly higher than those without liver fibrosis in LT recipients and CHB patients (P = 0.004, P = 0.02). In LT recipients, a SUVmax cut-off value of 2.0 detected early-stage liver fibrosis with an AUROC of 0.92 (P = 0.006), and a liver stiffness measurements (LSM) score cut-off value of 8.2 kPa diagnosed early-stage liver fibrosis with an AUROC of 0.80 (P = 0.012). In CHB patients, a SUVmax cut-off value of 2.7 detected early-stage liver fibrosis with an AUROC of 0.94 (P < 0.001) and an LSM scores cut-off value of 8.4 kPa diagnosed early-stage liver fibrosis with an AUROC of 0.91 (P < 0.001).

CONCLUSION

[18F]AlF-NOTA-FAPI-04 PET/CT could be applied to evaluate early-stage liver fibrosis in LT recipients and CHB patients properly, with the potential additional advantages in monitoring and predicting complications after LT.

Noninvasive assessment of liver fibrosis and portal hypertension

PURPOSE OF REVIEW

The result of ongoing liver injury - and disease, regardless of cause - is fibrosis, and fibrosis appears to be a critically important result of ongoing injury. Further, in a number of different liver diseases, the presence of fibrosis has prognostic value. Therefore, the assessment of fibrosis is of critical clinical importance. Given the importance of fibrosis, there has been a rapid evolution in the use of noninvasive liver tests. This review highlights a number of the core principles surrounding.

RECENT FINDINGS

The use of noninvasive test has progressed rapidly over the last decade and data are rapidly accumulating. New terminology has been adapted by the American Association for the Study of Liver Disease (AASLD) for noninvasive assessment of liver disease and termed 'NILDA' (Non-Invasive Liver Disease Assessment). Blood based such as APRI and or FIB-4 and imaging tests such as liver stiffness measurement (LSM) have moderate to high degrees of accuracy for detection of advanced liver fibrosis (≥ F2) and even higher accuracy for detection of severe fibrosis (F4 or cirrhosis). NILDA are particularly effective at the ends of the liver disease spectrum. For example, a very low LSM (less than 7 kPa) essentially excludes significant fibrosis or portal hypertension, and a very high LSM (> 25 kPa) makes significant fibrosis with portal hypertension (cirrhosis) highly likely.

SUMMARY

NILDA are currently front and center in terms of assessment of the severity of liver disease. In all patients with known or suspected liver disease, noninvasive blood tests, including APRI and or FIB-4, should be the initial choice to assess the severity of liver fibrosis and/or portal hypertension. In most patients, these tests should be followed with imaging evaluation. The most commonly available imaging is LSM, which appears to be more accurate in predicting fibrosis severity, and is superior to blood tests in the assessment of portal hypertension. In situations in which there is diagnostic uncertainly, liver biopsy with or without HVPG remains an important consideration.

A Comprehensive Review of Liver Allograft Fibrosis and Steatosis: From Cause to Diagnosis

Despite advances in posttransplant care, long-term outcomes for liver transplant recipients remain unchanged. Approximately 25% of recipients will advance to graft cirrhosis and require retransplantation. Graft fibrosis progresses in the context of de novo or recurrent disease. Recurrent hepatitis C virus infection was previously the most important cause of graft failure but is now curable in the majority of patients. However, with an increasing prevalence of obesity and diabetes and nonalcoholic fatty liver disease as the most rapidly increasing indication for liver transplantation, metabolic dysfunction-associated liver injury is anticipated to become an important cause of graft fibrosis alongside alloimmune hepatitis and alcoholic liver disease. To better understand the landscape of the graft fibrosis literature, we summarize the associated epidemiology, cause, potential mechanisms, diagnosis, and complications. We additionally highlight the need for better noninvasive methods to ameliorate the management of graft fibrosis. Some examples include leveraging the microbiome, genetic, and machine learning methods to address these limitations. Overall, graft fibrosis is routinely seen by transplant clinicians, but it requires a better understanding of its underlying biology and contributors that can help inform diagnostic and therapeutic practices.

Clinical practice guidelines of the Catalan Society of Gastroenterology about hepatic elastography 2022

INTRODUCTION

After almost 20 years using transient elastography (TE) for the non-invasive diagnosis of liver fibrosis, its use has been extended to population screening, evaluation of steatosis and complications of cirrhosis. For this reason, the «Catalan Society of Gastroenterology» commissioned a group of experts to update the first document carried out in 2011.

MATERIAL AND METHODS

The working group (8 doctors and 4 nurses) prepared a panel of questions based on the online survey «Hepatic Elastography in Catalonia 2022» following the PICO structure and the Delphi method.

RESULTS

The answers are presented with the level of evidence, the degree of recommendation and the final consensus after being evaluated by two external reviewers.

CONCLUSION

Transient elastography uses the simplest and most reliable elastographic method to quantify liver fibrosis, assess steatosis, and determine the risk of complications in patients with cirrhosis. The document has been endorsed by the "Catalan Society of Gastroenterology" and the "Col·legi Oficial d'Infermeres i Infermers de Barcelona".

Fibrosis and steatosis of the liver graft: Are non-invasive tests useful? A short review

As life expectancy of liver transplanted patients improves, new questions are arising to avoid progressive graft loss. The spectrum of chronic inflammation and fibrosis are known to be important triggers in the alteration of graft function. Liver biopsy remains the gold standard to better understand progressive, normal, and abnormal histological modifications of the graft. In parallel, the interest for metabolic steatosis development in post-transplantation is also growing. Long-term survival of these patients involves the management of comorbidities including metabolic syndrome and cardiovascular diseases. Early detection of altered graft parenchyma, and monitoring of its evolution are undoubtedly essential. Non-invasive methods including transient elastography and fibrosis biomarkers are attractive tools to avoid drawbacks and complications of liver biopsy. Accuracy of these methods are well-known in a pre-transplantation setting, but evidence is lacking in post-transplantation setting. We review current knowledge of progressive liver fibrosis and steatosis development after transplantation and non-invasive methods of their assessment.

Prevalence and predictors of metabolic-associated fatty liver disease in liver transplant recipients: A cross-sectional prospective study

Background and Aim

Metabolic-associated fatty liver disease (MAFLD) has emerged as a significant global health concern. However, the prevalence and predictors of MAFLD in post-liver transplantation (LT) patients remain uncertain. This study aimed to determine the prevalence and predictors of MAFLD in LT recipients and to assess the effectiveness of controlled attenuation parameter (CAP) values in diagnosing post-transplant MAFLD.

Materials and Methods

A cross-sectional prospective study was conducted involving 128 adult patients who had undergone LT, and had received liver imaging, and vibration-controlled transient elastography (VCTE). MAFLD was diagnosed on the basis of the presence of liver steatosis detected through imaging and specific metabolic risk abnormalities.

Results

The prevalence of MAFLD after LT was 34.4%, with 22.1% categorized as de novo MAFLD, and 12.3% as recurrent MAFLD. Posttransplant diabetes (OR: 4.88; 95% CI 1.30-18.34; p=0.019) and higher CAP values (OR: 1.04; 95% CI 1.02-1.06; p=0000) were identified as independent predictors of post-LT MAFLD. A CAP cutoff value of 270 dB/m exhibited an area under the receiver operating curve of 0.84 in detecting MAFLD.

Conclusion

These findings underscore the notable prevalence of MAFLD in liver transplant recipients and suggest the potential utility of VCTE as a non-invasive tool for its detection.

Saroglitazar improves nonalcoholic fatty liver disease and metabolic health in liver transplant recipients

NAFLD is common after liver transplantation (LT) and is associated with an increased metabolic burden. Currently, there is a paucity of investigations into the treatment of post-LT NAFLD. In the present study, we evaluated the safety and efficacy of saroglitazar, a novel dual peroxisome proliferator-associated receptor α/γ agonist, on the treatment of post-LT NAFLD and metabolic burden. This is a phase 2A, single-center, open-label, single-arm study in which patients with post-LT NAFLD received saroglitazar magnesium 4 mg daily for 24 weeks. NAFLD was defined by a controlled attenuation parameter ≥264 dB/m. The primary endpoint was the reduction in liver fat as measured by MRI proton density fat fraction (MRI-PDFF). Secondary MRI-based metabolic endpoints included visceral adipose tissue, abdominal subcutaneous adipose tissue volumes, muscle fat infiltration, and fat-free muscle volume. Saroglitazar treatment led to a reduction in MRI-PDFF from 10.3±10.5% at baseline to 8.1±7.6%. A relative 30% reduction from baseline MRI-PDFF value was noted in 47% of all patients and 63% of patients with baseline MRI-PDFF >5%. Reduction in serum alkaline phosphatase was an independent predictor of MRI-PDFF response. Saroglitazar did not decrease fat-free muscle volume nor increase muscle fat infiltration, but did lead to a mild increase in visceral adipose tissue and abdominal subcutaneous adipose tissue. The study drug was well tolerated and a mild nonsignificant increase in serum creatinine was noted. Saroglitazar did not affect the weight. The study provides preliminary data demonstrating the safety and metabolic benefits of saroglitazar in LT recipients and underscores the importance of future studies to establish its efficacy after LT.

Development of a Radiomics-Based Model to Predict Graft Fibrosis in Liver Transplant Recipients: A Pilot Study

Liver Transplantation is complicated by recurrent fibrosis in 40% of recipients. We evaluated the ability of clinical and radiomic features to flag patients at risk of developing future graft fibrosis. CT scans of 254 patients at 3-6 months post-liver transplant were retrospectively analyzed. Volumetric radiomic features were extracted from the portal phase using an Artificial Intelligence-based tool (PyRadiomics). The primary endpoint was clinically significant (≥F2) graft fibrosis. A 10-fold cross-validated LASSO model using clinical and radiomic features was developed. In total, 75 patients (29.5%) developed ≥F2 fibrosis by a median of 19 (4.3-121.8) months. The maximum liver attenuation at the venous phase (a radiomic feature reflecting venous perfusion), primary etiology, donor/recipient age, recurrence of disease, brain-dead donor, tacrolimus use at 3 months, and APRI score at 3 months were predictive of ≥F2 fibrosis. The combination of radiomics and the clinical features increased the AUC to 0.811 from 0.793 for the clinical-only model (p = 0.008) and from 0.664 for the radiomics-only model (p < 0.001) to predict future ≥F2 fibrosis. This pilot study exploring the role of radiomics demonstrates that the addition of radiomic features in a clinical model increased the model's performance. Further studies are required to investigate the generalizability of this experimental tool.

Non-Invasive Measurement of Hepatic Fibrosis by Transient Elastography: A Narrative Review

Transient elastography by FibroScan® (Echosens, Paris, France) is a non-invasive method that can provide a reliable measurement of liver fibrosis through the evaluation of liver stiffness. Despite its limitations and risks, liver biopsy has thus far been the only procedure able to provide data to quantify fibrosis. Scientific evidence and clinical practice have made it possible to use FibroScan® in the diagnostic work-up of several liver diseases to monitor patients' long-term treatment response and for complication prevention. For these reasons, this procedure is widely used in clinical practice and is still being investigated for further applications. The aim of this narrative review is to provide a comprehensive overview of the main applications of transient elastography in the current clinical practice.

A deep learning framework for personalised dynamic diagnosis of graft fibrosis after liver transplantation: a retrospective, single Canadian centre, longitudinal study

BACKGROUND

Recurrent graft fibrosis after liver transplantation can threaten both graft and patient survival. Therefore, early detection of fibrosis is essential to avoid disease progression and the need for retransplantation. Non-invasive blood-based biomarkers of fibrosis are limited by moderate accuracy and high cost. We aimed to evaluate the accuracy of machine learning algorithms in detecting graft fibrosis using longitudinal clinical and laboratory data.

METHODS

In this retrospective, longitudinal study, we trained machine learning algorithms, including our novel weighted long short-term memory (LSTM) model, to predict the risk of significant fibrosis using follow-up data from 1893 adults who had a liver transplantation between Feb 1, 1987, and Dec 30, 2019, with at least one liver biopsy post transplantation. Liver biopsy samples with indefinitive fibrosis stage and those from patients with multiple transplantations were excluded. Longitudinal clinical variables were collected from transplantation to the date of last available liver biopsy. Deep learning models were trained on 70% of the patients as the training set and 30% of the patients as the test set. The algorithms were also separately tested on longitudinal data from patients in a subgroup of patients (n=149) who had transient elastography within 1 year before or after the date of liver biopsy. Weighted LSTM model performance for diagnosing significant fibrosis was compared against LSTM, other deep learning models (recurrent neural network and temporal convolutional network), and machine learning models (Random Forest, Support vector machines, Logistic regression, Lasso regression, and Ridge regression) and aspartate aminotransferase-to-platelet ratio index (APRI), fibrosis-4 index (FIB-4), and transient elastography.

FINDINGS

1893 people who had a liver transplantation (1261 [67%] men and 632 [33%] women) with at least one liver biopsy between Jan 1, 1992, and June 30, 2020, were included in the study (591 [31%] cases and 1302 [69%] controls). The median age at liver transplantation was 53·7 years (IQR 47·3-59·0) for cases and 55·3 years (48·0 to 61·2) for controls. The median time interval between transplant and liver biopsy was 21 months (5 to 71). The weighted LSTM model (area under the curve 0·798 [95% CI 0·790 to 0·810]) consistently outperformed other methods, including unweighted LSTM (0·761 [0·750 to 0·769]; p=0·031) Recurrent Neural Network (0·736 [0·721 to 0·744]), Temporal Convolutional Networks (0·700 [0·662 to 0·747], and Random Forest 0·679 [0·652 to 0·707]), FIB-4 (0·650 [0·636 to 0·663]) and APRI (0·682 [0·671 to 0·694]) when diagnosing F2 or worse stage fibrosis. In a subgroup of patients with transient elastography results, weighted LSTM was not significantly better at detecting fibrosis (≥F2; 0·705 [0·687 to 0·724]) than transient elastography (0·685 [0·662 to 0·704]). The top ten variables predictive for significant fibrosis were recipient age, primary indication for transplantation, donor age, and longitudinal data for creatinine, alanine aminotransferase, aspartate aminotransferase, total bilirubin, platelets, white blood cell count, and weight.

INTERPRETATION

Deep learning algorithms, particularly weighted LSTM, outperform other routinely used non-invasive modalities and could help with the earlier diagnosis of graft fibrosis using longitudinal clinical and laboratory variables. The list of most important predictive variables for the development of fibrosis will enable clinicians to modify their management accordingly to prevent onset of graft cirrhosis.

FUNDING

Canadian Institute of Health Research, American Society of Transplantation, Toronto General and Western Hospital Foundation, and Paladin Labs.

Performance of Vibration-Controlled Transient Elastography and Clinical Prediction Models In Liver Transplant Recipients

Hepatic fibrosis is a strong predictor of clinical outcomes following liver transplantation (LT).1 Despite the centrality of hepatic fibrosis in clinical outcomes, the published literature with noninvasive fibrosis assessment in LT recipients is limited and liver biopsy, despite its invasive nature, remains the reference standard. Vibration-controlled transient elastography (VCTE) and clinical prediction models (CPM) are point-of-care tests that can provide noninvasive assessment of hepatic fibrosis2-4; however, the data comparing the diagnostic performance of VCTE and CPM in LT recipients are lacking. The current study evaluated the diagnostic performance of VCTE and CPM in LT recipients using best practices in regulatory sciences for biomarker development.

Main factors influencing long-term outcomes of liver transplantation in 2022

Liver transplant (LT) outcomes have markedly improved in the recent decades, even if long-term morbidity and mortality are still considerable. Most of late deaths are independent from graft function and different comorbidities, including complications of metabolic syndrome and de novo neoplasms, seem to play a key role in determining long-term outcomes in LT recipients. This review discusses the main factors associated with late mortality and suggests possible strategies to improve long-term management and follow-up after liver transplantation. In particular, the reduction of drug toxicity, the use of tools to identify high-risk patients, and setting up a multidisciplinary team also for long-term management of LT recipients may further improve survival after liver transplantation.

Evaluation of liver stiffness measurement-based scores in liver transplantation recipients

Combining bioclinical parameters with liver stiffness measurement (LSM) has improved the diagnostic performance of vibration-controlled transient elastography (VCTE) for detection of advanced fibrosis in patients with chronic liver disease. However, this approach has not yet been tested in liver transplantation (LT) recipients. Thus, the aim of this study was to evaluate the diagnostic performance of combining LSM-based scores with LSM alone for the detection of advanced fibrosis in LT recipients. Adult LT recipients with a liver biopsy, VCTE, and clinical data necessary to construct LSM-based fibrosis models (FibroScan-AST [FAST], AGILE-3+, and AGILE-4) were included ( n = 132). The diagnostic statistics for advanced fibrosis (fibrosis stage 0-2 vs. 3-4) were determined by optimal cut-off using the Youden index. The area under the receiver operating characteristic curve (AUROC) for LSM was 0.94 (95% confidence interval [95% CI], 0.89-0.99), FAST was 0.65 (95% CI, 0.50-0.79), AGILE-3+ was 0.90 (95% CI, 0.83-0.97), and AGILE-4 was 0.90 (95% CI, 0.83-0.97). No statistically significant differences were noted between the AUROC of LSM versus LSM-based scores. The false-positive rates for AGILE-3+ and AGILE-4 were 14.5% and 11.8% compared with 8.3% for LSM alone. The false-positive rates in LSM-based scores were higher among patients with diabetes mellitus, higher AST levels, and lower platelet counts. The LSM-based scores did not improve the diagnostic performance of LSM alone in LT recipients for the detection of advanced fibrosis. This lack of improvement in diagnostic performance results from the impact of immunosuppression on bioclinical profile and underscores the importance of developing LSM-based scores that are specific to LT patients.

Accuracy of Noninvasive Diagnostic Tests for the Detection of Significant and Advanced Fibrosis Stages in Nonalcoholic Fatty Liver Disease: A Systematic Literature Review of the US Studies

BACKGROUND

The purpose of this systematic literature review (SLR) was to evaluate the accuracy of noninvasive diagnostic tools in detecting significant or advanced (F2/F3) fibrosis among patients with nonalcoholic fatty liver (NAFL) in the US healthcare context.

METHODS

The SLR was conducted in PubMed and Web of Science, with an additional hand search of public domains and citations, in line with the PRISMA statement. The study included US-based original research on diagnostic test sensitivity, specificity and accuracy.

RESULTS

Twenty studies were included in qualitative evidence synthesis. Imaging techniques with the highest diagnostic accuracy in F2/F3 detection and differentiation were magnetic resonance elastography and vibration-controlled transient elastography. The most promising standard blood biomarkers were NAFLD fibrosis score and FIB-4. The novel diagnostic tools showed good overall accuracy, particularly a score composed of body mass index, GGT, 25-OH-vitamin D, and platelet count. The novel approaches in liver fibrosis detection successfully combine imaging techniques and blood biomarkers.

CONCLUSIONS

While noninvasive techniques could overcome some limitations of liver biopsy, a tool that would provide a sufficiently sensitive and reliable estimate of changes in fibrosis development and regression is still missing.

Metabolic syndrome, hepatic fibrosis, and steatosis diagnosed by liver stiffness measurement and controlled attenuation parameter after liver transplantation: the impact on long-term survival

BACKGROUND

Liver stiffness measurement (LSM) and controlled attenuation parameter (CAP) are used for diagnosis of liver fibrosis and steatosis. This study aimed to noninvasively evaluate hepatic steatosis and fibrosis in liver transplant recipients using CAP and LSM and the impact on survival of patients.

METHODS

In a prospective study, adult liver transplant recipients were included. CAP and LSM obtained during transient elastography (TE) were used for assessment of hepatic steatosis and fibrosis. Patients were followed during 4 years for mortality as the main outcome after liver transplantation.

RESULTS

From 296 patients, 24.7% and 25% of liver transplant recipients had liver steatosis and fibrosis in CAP and LSM, respectively. In multivariable Cox regression analysis, etiology of liver disease (NASH versus non-NASH) (HR: 3.125; 95% CI: 1.594-6.134; p = 0.001), and post-transplant diabetes mellitus (PTDM) (HR: 2.617; 95% CI: 1.396-4.926; p = 0.003) were associated with hepatic steatosis after liver transplantation.  In multivariable Cox regression analysis, liver fibrosis was an independent predictor of mortality after liver transplantation (HR: 4.926; 95%CI: 1.779-13.513; p = 0.002).

CONCLUSION

CAP and LS measurement during TE are useful methods for diagnosis of hepatic steatosis and fibrosis in liver transplant recipients. LS measurement might predict long-term survival of patients.

The prevalence of alcoholic and nonalcoholic fatty liver disease in adolescents and young adults in the United States: analysis of the NHANES database

BACKGROUND

The prevalence of fatty liver disease is potentially increasing in adolescents and young adults (AYAs) due to the obesity and alcohol pandemics. The aim of this study was to assess the prevalence of alcohol-associated fatty liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD) in a representative U.S. cohort utilizing transient elastography to directly measure hepatic steatosis and suspected fibrosis.

METHODS

AYAs (age 15-39 years) with valid FibroScan® measurements in the National Health and Nutrition Examination Survey (NHANES) database (2017-2018) were included in the analyses. Those with viral hepatitis, pregnancy, or ALT/AST > 500 U/L were excluded. The population was divided into those with excessive alcohol consumption (ALQ130) and those without. Controlled attenuation parameter (CAP) score ≥ 248 dB/m was used to identify suspected ALD and NAFLD. In those with evidence of ALD, the following cutoffs of liver stiffness measurement (LSM) were used for suspected fibrosis: F ≥ F2 at LSM ≥ 7.5 kPa and F ≥ F3 at ≥ 9.5 kPa, respectively. In those with suspected NAFLD, the following LSM cutoffs were used: F ≥ F2 at 6.1 and F ≥ F3 at ≥ 7.1, respectively. Cutoffs were chosen based on published literature to maximize sensitivity.

RESULTS

Comparing to those without, subjects with excessive alcohol consumption tended to be older (29.8 vs 28.5 years), have a higher BMI (29.3 vs 28.9 kg/m2), and be from a White ethnicity (65.3% vs. 55.4%). In subjects with excessive alcohol consumption, suspected ALD was present in 56.59% (95% CI 41.57-70.49). In those with suspected ALD, suspected significant fibrosis (F ≥ F2) was present in 12.3% (95% CI 4.74-28.34) and advanced fibrosis (F ≥ F3) was present in 6.31% (95% CI 0.69-39.55). Similarly, in subjects without excessive alcohol consumption, suspected NAFLD was present in 40.04% (36.64-43.54). In those with suspected NAFLD, suspected significant fibrosis (F ≥ F2) was present in 31.07% (27.25-35.16) and suspected advanced fibrosis (F ≥ F3) was present in 20.15% (16.05-24.99).

CONCLUSION

A significant percentage of AYAs are at risk for ALD and NAFLD and a subset of these subjects is at risk for significant fibrosis. Efforts should focus on increasing awareness of the prevalence of ALD and NAFLD in this population and to mitigate modifiable risk factors.

Differential fuel utilization in liver transplant recipients and its relationship with non-alcoholic fatty liver disease

Metabolic flexibility is the ability to match biofuel availability to utilization. Reduced metabolic flexibility, or lower fatty acid (FA) oxidation in the fasted state, is associated with obesity. The present study evaluated metabolic flexibility after liver transplantation (LT).

METHODS

Patients receiving LT for non-alcoholic steatohepatitis (NASH) (n = 35) and non-NASH (n = 10) were enrolled. NASH was chosen as these patients are at the highest risk of metabolic complications. Metabolic flexibility was measured using whole-body calorimetry and expressed as respiratory quotient (RQ), which ranges from 0.7 (pure FA oxidation) to 1.0 is (carbohydrate oxidation).

RESULTS

The two cohorts were similar except for a higher prevalence of obesity and diabetes in the NASH cohort. Post-prandially, RQ increased in both cohorts (i.e. greater carbohydrate utilization) but peak RQ and time at peak RQ was higher in the NASH cohort. Fasting RQ in NASH was significantly higher (0.845 vs. 0.772, p < .001), indicative of impaired FA utilization. In subgroup analysis of the NASH cohort, body mass index but not liver fat content (MRI-PDFF) was an independent predictor of fasting RQ. In NASH, fasting RQ inversely correlated with fat-free muscle volume and directly with visceral adipose tissue.

CONCLUSION

Reduced metabolic flexibility in patients transplanted for NASH cirrhosis may precede the development of non-alcoholic fatty liver disease after LT.

Vibration-controlled Transient Elastography for Assessment of Liver Fibrosis at a USA Academic Medical Center

Background and Aims

Vibration-controlled transient elastography (VCTE) is a noninvasive tool that uses liver stiffness measurement (LSM) to assess fibrosis. Since real-life data during everyday clinical practice in the USA are lacking, we describe the patterns of use and diagnostic performance of VCTE in patients at an academic medical center in New York City.

Methods

Patients who received VCTE scans were included if liver biopsy was performed within 1 year. Diagnostic performance of VCTE in differentiating dichotomized fibrosis stages was assessed via area under the receiver operating characteristics (AUROC). Fibrosis stage determined from VCTE LSM was compared to liver biopsy.

Results

Of 109 patients, 49 had nonalcoholic fatty liver disease, 16 chronic hepatitis C, 15 congestive hepatopathy, and 22 at least two etiologies. AUROC was 0.90 for differentiating cirrhosis (stage 4) with a positive predictive value (PPV) range of 0.28 to 0.45 and negative predictive value range of 0.96 to 0.98. For 31 (32%) patients, VCTE fibrosis stage was at least two stages higher than liver biopsy fibrosis stage. Thirteen of thirty-five patients considered to have cirrhosis by VCTE had stage 0 to 2 and 12 stage 3 fibrosis on liver biopsy.

Conclusions

VCTE has reasonable diagnostic accuracy and is reliable at ruling out cirrhosis. However, because of its low PPV, caution must be exercised when used to diagnose cirrhosis, as misdiagnosis can lead to unnecessary health care interventions. In routine practice, VTCE is also sometimes performed for disease etiologies for which it has not been robustly validated.

The use of transient elastography in identifying sub-clinical chronic ductopenic rejection in adult liver transplant recipients: A case series

BACKGROUND

Transient elastography has become a standard tool for the accurate non-invasive assessment of liver stiffness and fat content. Liver transplant recipients can develop allograft fibrosis during long-term follow-up despite normal or mildly abnormal liver chemistries. Tapering of immunosuppression in long-term liver transplant survivors is performed relying solely on liver chemistries. It is important to know if underlying liver histology would be abnormal or if rejection was present as this would alter the desire to decrease stable maintenance doses of immunosuppression.

METHODS

We present our experience of five liver transplant recipients who had transient elastography performed prior to consideration of weaning of their immunosuppression.

RESULTS

All five patients showed signs of elevated liver stiffness on transient elastography in the setting of normal to slightly abnormal liver tests with very stable immunosuppressant doses. This prompted the performance of liver biopsies which demonstrated immune-mediated liver injury and thus negated the immunosuppression withdrawal.

CONCLUSION

Transient elastography has utility as a non-invasive method to evaluate allograft health in long-term liver transplant survivors and can be useful in the decision-making process for immunosuppression weaning.

A Diagnostic Test Meta-Analysis Evaluating Imaging-Based and Blood Biomarker-Based Assessment Tools for Fibrosis After Liver Transplantation

Early detection of liver graft fibrosis is crucial for risk stratification to identify patients for liver biopsy and timely treatment. However, diagnostic accuracy of noninvasive tests (NITs) remains unclear. Thus, this study sought to evaluate diagnostic accuracy of NITs in assessing liver allograft fibrosis and compare the differences in specificities and sensitivities among NITs. Medline and Embase databases were searched to include articles on diagnostic tests in liver transplantation (LT) patients with fibrosis. A meta-analysis on diagnostic test accuracy was conducted in a random-effects model. Sensitivities and specificities among the diagnostic tests were compared, and threshold values were calculated where applicable. A total of 25 articles were included. Vibration-controlled transient elastography (VCTE) met the minimum diagnostic accuracy requirements, yielding sensitivity, specificity, and diagnostic odds ratios of 0.9 (CI, 0.8-1.0), 0.9 (CI, 0.8-1.0), and 379.6 (CI, 45.8-1728.7), respectively. In the threshold assessment, the optimal cutoff was 9.30 kPa with a sensitivity, specificity, and area under the curve of 0.7 (CI, 0.5-0.9), 0.9 (CI, 0.8-0.9), and 0.9 (CI, 0.8-0.9), respectively. For significant fibrosis, acoustic radiation force impulse (ARFI) was superior to FibroTest (LabCorp [Burlington, NC]) and magnetic resonance elastography (MRE) in sensitivity. VCTE was superior to FibroTest in specificity. For advanced fibrosis, ARFI was superior to the Fibrosis-4 Index (FIB-4) in sensitivity. VCTE was superior to the AST to Platelet Ratio Index (APRI), MRE, and FIB-4 in specificity. In cirrhosis, VCTE was superior to APRI in specificity (P = 0.004) with comparable sensitivity. This study demonstrates the potential of VCTE and ARFI as diagnostic tools for fibrosis in LT recipients compared with blood-based NITs, which were shown to be less optimal.

Associations of Uric Acid With Liver Steatosis and Fibrosis Applying Vibration Controlled Transient Elastography in the United States: A Nationwide Cross-Section Study

BACKGROUND AND OBJECTIVE

Serum uric acid (UA) is related to many metabolic diseases. However, the association of UA with liver diseases was not very clear. The objective of this study is to clarify the relationship of UA with liver steatosis and fibrosis.

METHODS

This is a cross-sectional study of 4364 people of National Health and Nutrition Examination Survey (NHANES) 2017-2018. Liver steatosis and fibrosis were assessed by controlled attenuation parameter (CAP) and liver stiffness measurements (LSM) using Vibration-controlled transient elastography (VCTE). Linear and logistic regressions were performed.

RESULTS

After adjusting for potential confounders, UA levels were associated with the prevalence of liver steatosis [OR=2.097 (95%CI: 1.245, 3.534)] and liver fibrosis [OR=2.983 (95%CI: 1.797, 4.952)]. Furthermore, the results were consistent in the subgroup analyses of males and females.

CONCLUSIONS

UA levels were positively associated with the prevalence of liver steatosis and fibrosis.

Non-alcoholic steatohepatitis in liver transplant recipients diagnosed by serum cytokeratin 18 and transient elastography: A prospective study

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) seem common after liver transplantation.

AIM

To investigate incidence and predictors of NAFLD and NASH by employing noninvasive testing in liver transplant recipients, namely controlled attenuation parameter (CAP) and the serum biomarker cytokeratin 18 (CK-18). We also evaluated the diagnostic accuracy of CK-18 and CAP compared to liver histology.

METHODS

We prospectively recruited consecutive adult patients who received liver transplant at the McGill University Health Centre between 2015-2018. Serial measurements of CK-18 and CAP were recorded. NAFLD and NASH were diagnosed by CAP ≥ 270 dB/m, and a combination of CAP ≥ 270 dB/m with CK-18 > 130.5 U/L, respectively. Incidences and predictors of NAFLD and NASH were investigated using survival analysis and Cox proportional hazards.

RESULTS

Overall, 40 liver transplant recipients (mean age 57 years; 70% males) were included. During a median follow-up of 16.8 mo (interquartile range 15.6-18.0), 63.0% and 48.5% of patients developed NAFLD and NASH, respectively. On multivariable analysis, after adjusting for sex and alanine aminotransferase, body mass index was an independent predictor of development of NAFLD [adjusted hazard ratio (aHR): 1.21, 95% confidence interval (CI): 1.04-1.41; P = 0.01] and NASH (aHR: 1.26, 95%CI: 1.06-1.49; P < 0.01). Compared to liver histology, CAP had a 76% accuracy to diagnose NAFLD, while the accuracy of CAP plus CK-18 to diagnose NASH was 82%.

CONCLUSION

NAFLD and NASH diagnosed non-invasively are frequent in liver transplant recipients within the first 18 mo. Close follow-up and nutritional counselling should be planned in overweight patients.

Metabolic Complications in Liver Transplantation Recipients: How We Can Optimize Long-Term Survival

Liver transplantation (LT) recipients have experienced a significant improvement in short-term survival during the past 3 decades attributed to advancements in surgical techniques, perioperative management, and effective immunosuppressive regimens. However, long-term survival is affected by a high incidence of metabolic disorders and their consequences, including cardiovascular disease (CVD) and malignancies. Pretransplant metabolic impairments especially in those with nonalcoholic steatohepatitis cirrhosis are aggravated by the addition of posttransplant weight gain, physical inactivity, and reversal from catabolic to anabolic state. Moreover, although immunosuppressants are vital to avoid graft rejection, long-term exposure to these medications is implicated in metabolic impairments after LT. In this review, we summarize the molecular pathogenesis of different metabolic disorders after LT, including diabetes mellitus, dyslipidemia, and nonalcoholic fatty liver disease. Furthermore, CVD, malignancies, and graft rejections were provided as significant complications of post-LT metabolic conditions threatening both the patient and graft survival. Ultimately, emerging preventive and treatment strategies for posttransplant diabetes mellitus are summarized. This review highlights the significant need for more clinical trials of antihyperglycemic agents in LT recipients. Also, translational studies will help us to better understand the molecular and genetic factors underlying these metabolic complications and could lead to more personalized management in this high-risk population.

The Use of Transient Elastography Technology in the Bariatric Patient: a Review of the Literature

Transient elastography (TE) is a non-invasive technology that demonstrates promise in assessing liver steatosis and fibrosis without the risks of traditional percutaneous liver biopsy. Many studies have examined its reliability in respect to liver biopsy, but fewer have examined using TE in obese and bariatric surgery patients. With evidence showing that bariatric surgery can lead to improvement of liver steatosis and fibrosis, TE has the potential to provide a simple avenue of hepatic assessment in patients before and after procedures. This review article investigates what is known about the reliability of TE and its implementation in obese and bariatric surgery patients.