Dynamics in Liver Stiffness Measurements Predict Outcomes in Advanced Chronic Liver Disease

Background &amp; Aims:Liver stiffness measurements (LSMs) provide an opportunity to monitor liver disease progression and regression noninvasively. We aimed to determine the prognostic relevance of LSM dynamics over time for liver-related events and death in patients with chronic liver disease. Methods:Patients with chronic liver disease undergoing 2 or more reliable LSMs at least 180 days apart were included in this retrospective cohort study and stratified at baseline (BL) as nonadvanced chronic liver disease (non-ACLD, BL-LSM &lt; 10 kPa), compensated ACLD (cACLD; BL-LSM ≥ 10 kPa), and decompensated ACLD. Data on all consecutive LSMs and clinical outcomes were collected. Results: There were 2508 patients with 8561 reliable LSMs (3 per patient; interquartile range, 2–4) included: 1647 (65.7%) with non-ACLD, 757 (30.2%) with cACLD, and 104 (4.1%) with decompensated ACLD. Seven non-ACLD patients (0.4%) and 83 patients with cACLD (10.9%) developed hepatic decompensation (median follow-up, 71 months). A 20% increase in LSM at any time was associated with an approximately 50% increased risk of hepatic decompensation (hazard ratio, 1.58; 95% CI, 1.41–1.79; P &lt;.001) and liver-related death (hazard ratio, 1.45; 95% CI, 1.28–1.68; P &lt;.001) in patients with cACLD. LSM dynamics yielded a high accuracy to predict hepatic decompensation in the following 12 months (area under the receiver operating characteristics curve = 0.933). The performance of LSM dynamics was numerically better than dynamics in Fibrosis-4 score (0.873), Model for End-Stage Liver Disease (0.835), and single time-point LSM (BL-LSM: 0.846; second LSM: 0.880). Any LSM decrease to &lt;20 kPa identified patients with cACLD with a substantially lower risk of hepatic decompensation (hazard ratio, 0.13; 95% CI, 0.07–0.24). If reliable, LSM also confers prognostic information in decompensated ACLD. Conclusions: Repeating LSM enables an individual and updated risk assessment for decompensation and liver-related mortality in ACLD.</p

Modellierung, Analysis und numerische Diskretisierung von Maxwell-Stefan-Kreuzdiffusionssystemen

Abweichender Titel nach Übersetzung der Verfasserin/des VerfassersDie Maxwell-Stefan Gleichungen sind ein wichtiges Modell mit zahlreichen Anwendungen in Industrie und Technik, welche rein diffusive Prozesse zwischen zwei und mehr Gasen beschreiben können. Als einige Anwendungen der Maxwell-Stefan-Gleichungen (je nach Anwendungen mit leichten Modifikationen) seien unter anderem Polymere, Plasmen, Ultrafiltration, Elektrolyse und sogar die Beschreibung diffusiver Phänomene in der menschlichen Lunge zu nennen. In dieser Arbeit wird zunächst zum besseren Verständnisses des Modells eine Herleitung der Maxwell-Stefan Gleichungen aus den Boltzmann-Gleichungen anhand eines jüngeren Resultats von Boudin unternommen, um den physikalischen Anwendungsbereich und die Verbindung zwischen mikroskopischer und makroskopischer Beschreibung deutlich zu machen. Weiters wird ein kurzer Überblick auf aktuelle Forschungsfragen gegeben, wonach möglicherweise einige Simplifizierungen des Modells fallen gelassen werden können. Weiters wird ein wichtiges Resultat zur Existenz schwacher Lösungen der Maxwell-Stefan Gleichung von Jüngel und Stelzer ausgearbeitet, wobei die Einordnung des Beweises in den verallgemeinerten Rahmen der "Boundedness-By-Entropy''-Methode für Kreuz-Diffusionssysteme von Jüngel besprochen wird. Im praktischen Teil der Arbeit wird anhand der in dem Existenzbeweis verwendeten Methode, welche sogenannte Entropievariablen verwendet, eine neuartige numerische Diskretisierung vorgestellt, welche die Maxwell-Stefan-Gleichungen löst. Die Ortsdiskretisierung wird hierbei mit einer Finite Elemente-Diskretisierung niedrigster Ordnung vorgenommen, während für die Zeitschritte ein semi-implizites Euler-Verfahren verwendet wird. Zur Untersuchung der Methode wurde Code in Python geschrieben, welcher in 1D und 2D auch auf komplexen polygonalen Gebieten die Maxwell-Stefan Gleichungen lösen kann. Mittels der "Method of Manufactured Solutions'', welche ein Problem mit einer bekannten analytischen Lösung erzeugt und im Fall der Maxwell-Stefan Gleichungen erstmals angewendet wurde, wird hierbei die Performance des Codes genauer untersucht und diskutiert.Whenever describing purely diffusive behavior in multicomponent mixtures, the Maxwell-Stefan equations pose an important framework for various engineering applications, which include polymers, plasmas, ultrafiltration, electrolysis and even diffusion processes in the human lung. In this thesis, the link between molecular diffusion and the continuum-mechanical description in the Maxwell-Stefan equation is made plausible by following the recent exposition by Boudin, which illustrates the physical assumptions under which the Maxwell-Stefan equations pose a valid model for describing multi-component diffusion on a macroscopic scale. In addition, several current efforts of generalizing some of the simplifications made in the model are stated. Furthermore, an important result for the existence of weak solutions to the Maxwell-Stefan equations (as presented by Jüngel and Stelzer) is discussed in detail, by hinting links to the more general framework of the "Boundedness-By-Entropy'' method developed by Jüngel. Finally, a new conforming lowest-order Finite Element discretization in space and a semi-implicit Euler discretization in time is discussed, which employs an "entropy-variable'' formulation of the Maxwell-Stefan equations using techniques from Jüngel. For this purpose, Python code employing this method has been written to solve 1D and 2D problems even on complex polygonal geometries. The performance of the code is then investigated by a benchmark, which employs the Method of Manufactured Solutions, yielding a novel model problem with a given analytic solution.12

An impaired pituitary–adrenal signalling axis in stable cirrhosis is linked to worse prognosis

Background &amp; Aims: Inadequate adrenal function has been described in patients with cirrhosis. We investigated (i) the pituitary–adrenal axis at different clinical stages and (ii) the clinical impact of decreased serum cortisol levels in stable patients with advanced chronic liver disease (ACLD). Methods: We included 137 outpatients with ACLD undergoing hepatic venous pressure gradient (HVPG) measurement in the prospective VICIS study (NCT03267615). Patients were stratified into six clinical stages: S0: subclinical portal hypertension (PH) (HVPG 6–9 mmHg), S1: clinically significant PH (HVPG ≥10 mmHg) without varices, S2: presence of varices, S3: previous variceal bleeding, S4: previous non-bleeding decompensation, and S5: further decompensation. Results: Fifty-one patients had compensated ACLD (S0: n = 13; S1: n = 12; S2: n = 26), whereas 86 patients had decompensated ACLD (S3: n = 7; S4: n = 46; S5: n = 33). Serum total cortisol (t-Cort) showed a strong correlation with estimated serum free cortisol (f-Cort; Spearman’s ρ: 0.889). With progressive clinical stage, median ACTH levels (from S0: 44.0 pg/ml to S5: 20.0 pg/ml; p = 0.006), t-Cort (from S0: 13.9 μg/dl to S5: 9.2 μg/dl; p = 0.091), and cortisol binding globulin (from S0: 49.3 μg/ml to S5: 38.9 μg/ml; p <0.001) decreased, whereas f-Cort (p = 0.474) remained unchanged. Lower t-Cort levels independently predicted bacterial infections (asHR: 1.11; 95% CI: 1.04–1.19; p = 0.002), further decompensation (asHR: 1.08; 95% CI: 1.02–1.12; p = 0.008), acute-on-chronic liver failure (ACLF; asHR: 1.11; 95% CI: 1.04–1.19; p = 0.002), and liver-related death (asHR: 1.09; 95% CI: 1.01-1.18; p = 0.045). Conclusions: The pituitary–ACTH–adrenal–cortisol axis is progressively suppressed with increasing severity of cirrhosis. Lower t-Cort is an independent risk factor for bacterial infections, further decompensation of ACLF, and liver-related mortality—even in stable outpatients with cirrhosis. Clinical trial number: Vienna Cirrhosis Study (VICIS; NCT: NCT03267615). Impact and Implications: In a cohort of stable outpatients, we observed progressive suppression of the pituitary–adrenal axis with increasing clinical stage of advanced chronic liver disease (ACLD). Increased levels of bile acids and systemic inflammation (assessed by interleukin-6 levels) could be involved in this suppression. Serum total cortisol (t-Cort) was strongly correlated with serum free cortisol (f-Cort) and lower t-Cort levels were independently associated with a higher risk of adverse clinical outcomes, including bacterial infections, further decompensation, acute-on-chronic liver failure, and liver-related death

Lower free triiodothyronine (fT3) levels in cirrhosis are linked to systemic inflammation, higher risk of acute-on-chronic liver failure, and mortality

Background &amp; Aims: Advanced chronic liver disease (ACLD) may affect thyroid hormone homeostasis. We aimed to analyze the pituitary–thyroid axis in ACLD and the prognostic value of free triiodothyronine (fT3). Methods: Patients with ACLD (liver stiffness measurement [LSM] ≥10 kPa) undergoing hepatic venous pressure gradient (HVPG) measurement between June 2009 and September 2022 and available fT3 levels were included. Clinical stages of ACLD were defined as follows: probable ACLD (pACLD; LSM ≥10 kPa and HVPG ≤5 mmHg), S0 (mild portal hypertension [PH]; HVPG 6–9 mmHg), S1 (clinically significant PH), S2 (clinically significant PH with varices), S3 (past variceal bleeding), S4 (past/current non-bleeding hepatic decompensation), and S5 (further decompensation). Results: Among 297 patients with ACLD, 129 were compensated (pACLD, n = 10; S0, n = 33; S1, n = 42; S2, n = 44), whereas 168 were decompensated (S3, n = 12; S4, n = 97; S5, n = 59). Median levels of thyroid-stimulating hormone (TSH) numerically increased with progressive ACLD stage (from 1.2 μIU/ml [pACLD] to 1.5 μIU/ml [S5]; p = 0.152), whereas fT3 decreased (from 3.2 pg/ml [pACLD] to 2.5 pg/ml [S5]; p <0.001). Free thyroxin levels remained unchanged (p = 0.338). TSH (aB 0.45; p = 0.046) and fT3 (aB -0.17; p = 0.048) were independently associated with systemic C-reactive protein levels. Lower fT3 was linked to higher risk of (further) decompensation (adjusted subdistribution hazard ratio [asHR] 0.60; 95% CI 0.37–0.97; p = 0.037), acute-on-chronic liver failure (asHR 0.19; 95% CI 0.08–0.49; p <0.001) and liver-related death (asHR 0.14; 95% CI 0.04–0.51; p = 0.003). Conclusions: Increasing TSH and declining fT3 levels are observed with progressive ACLD stages. The association of TSH and fT3 with systemic inflammation suggests a liver disease-associated non-thyroidal illness syndrome. Lower fT3 levels in patients with ACLD indicate increased risk for decompensation, acute-on-chronic liver failure, and liver-related death. Impact and Implications: In a large well-characterized cohort of patients with advanced chronic liver disease (ACLD), we found a decline of free triiodothyronine (fT3) throughout the clinical stages of ACLD, paralleled by a numerical increase of thyroid-stimulating hormone (TSH). This suggests a progressive development of a non-thyroidal illness syndrome in association with ACLD severity. Importantly, C-reactive protein independently correlated with TSH and fT3, linking thyroid dysbalance in ACLD to systemic inflammation. Lower fT3 indicated an increased risk for subsequent development of hepatic decompensation, acute-on-chronic liver failure, and liver-related death. Clinical trial number: Vienna Cirrhosis Study (VICIS; NCT: NCT03267615)

Two-dimensional shear wave elastography predicts survival in advanced chronic liver disease

OBJECTIVE Liver stiffness measurement (LSM) is a tool used to screen for significant fibrosis and portal hypertension. The aim of this retrospective multicentre study was to develop an easy tool using LSM for clinical outcomes in advanced chronic liver disease (ACLD) patients. DESIGN This international multicentre cohort study included a derivation ACLD patient cohort with valid two-dimensional shear wave elastography (2D-SWE) results. Clinical and laboratory parameters at baseline and during follow-up were recorded. LSM by transient elastography (TE) was also recorded if available. The primary outcome was overall mortality. The secondary outcome was the development of first/further decompensation. RESULTS After screening 2148 patients (16 centres), 1827 patients (55 years, 62.4% men) were included in the 2D-SWE cohort, with median liver SWE (L-SWE) 11.8 kPa and a model for end stage liver disease (MELD) score of 8. Combination of MELD score and L-SWE predict independently of mortality (AUC 0.8). L-SWE cut-off at ≥20 kPa combined with MELD ≥10 could stratify the risk of mortality and first/further decompensation in ACLD patients. The 2-year mortality and decompensation rates were 36.9% and 61.8%, respectively, in the 305 (18.3%) high-risk patients (with L-SWE ≥20 kPa and MELD ≥10), while in the 944 (56.6%) low-risk patients, these were 1.1% and 3.5%, respectively. Importantly, this M10LS20 algorithm was validated by TE-based LSM and in an additional cohort of 119 patients with valid point shear SWE-LSM. CONCLUSION The M10LS20 algorithm allows risk stratification of patients with ACLD. Patients with L-SWE ≥20 kPa and MELD ≥10 should be followed closely and receive intensified care, while patients with low risk may be managed at longer intervals