Noninvasive Evaluation of Liver Function in Morbidly Obese Patients

Insulin Resistance Is the Main Characteristic of Metabolically Unhealthy Obesity (MUO) Associated with NASH in Patients Undergoing Bariatric Surgery

(1) Background: Metabolically healthy obesity (MHO) is a concept that applies to obese patients without any elements of metabolic syndrome (metS). In turn, metabolically unhealthy obesity (MUO) defines the presence of elements of metS in obese patients. The components of MUO can be divided into subgroups regarding the elements of inflammation, lipid and glucose metabolism and cardiovascular disease. MUO patients appear to be at greater risk of developing non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) compared to MHO patients. The aim of this study was to evaluate the influence of different MUO components on NAFLD and NASH in patients with morbid obesity undergoing bariatric surgery. (2) Methods: 141 patients undergoing bariatric surgery from September 2015 and October 2021 at RWTH Aachen university hospital (Germany) were included. Patients were evaluated pre-operatively for characteristics of metS and MUO (HbA1c, HOMA, CRP, BMI, fasting glucose, LDL, TG, HDL and the presence of arterial hypertension). Intraoperatively, a liver biopsy was taken from the left liver lobe and evaluated for the presence of NAFLD or NASH. In ordinal regression analyses, different factors were evaluated for their influence on NAFLD and NASH. (3) Results: Mean BMI of the patients was 52.3 kg/m² (36-74.8, SD 8.4). Together, the parameters HbA1c, HOMA, CRP, BMI, fasting glucose, LDL, TG, HDL and the presence of arterial hypertension accounted for a significant amount of variance in the outcome, with a likelihood ratio of χ² (9) = 41.547, p < 0.001, for predicting the presence of NASH. Only HOMA was an independent predictor of NASH (B = 0.102, SE = 0.0373, p = 0.007). Evaluation of steatosis showed a similar trend (likelihood ratio χ² (9) = 40.272, p < 0.001). Independent predictors of steatosis were HbA1c (B = 0.833, SE = 0.343, p = 0.015) and HOMA (B = 0.136, SE = 0.039, p < 0.001). (4) Conclusions: The above-mentioned model, including components of MUO, was significant for diagnosing NASH in patients with morbid obesity undergoing bariatric surgery. Out of the different subitems, HOMA independently predicted the presence of NASH and steatosis, while HbA1c independently predicted steatosis and fibrosis. Taken together, the parameter of glucose metabolism appears to be more accurate for the prediction of NASH than the parameters of lipid metabolism, inflammation or the presence of cardiovascular disease.

Application of Scores Assessing Histological Activity and Estimated Long-Term Risk Analysis of Hepatic Decompensation of Non-Alcoholic Fatty Liver Disease in Individuals Undergoing Bariatric Surgery

BACKGROUND

Histological scores can estimate disease staging, allowing a standardization of the assessment of non-alcoholic fatty liver disease (NAFLD). The prediction of risk of NAFLD progression is relevant to allow the planning of interventions.

OBJECTIVE

To analyze the application of the Iowa NAFLD decompensation risk score, the NAFLD activity score (NAS), and steatosis-activity-fibrosis score (SAF) and to assess correlations between these scores.

METHODS

This is a retrospective cross-sectional study enrolling 76 individuals who underwent bariatric surgery at a tertiary university hospital. Liver biopsy was performed during procedures; histological scores were then assessed. The Iowa score was calculated using age, diabetes, and platelet count.

RESULTS

89.5% were female and mean age was 39.1 ± 9.6 years. Mean BMI was 38.2 ± 3.7 kg/m². Steatosis (92.1%), hepatocellular ballooning (93.4%), lobular inflammation (93.4%), and fibrosis (97.4%) were the commonest histopathological findings. According to NAS, 22.4% had definite non-alcoholic steatohepatitis (NASH). According to SAF, 89.5% had moderate or severe NAFLD. The mean risks of NAFLD decompensation at 5, 10, and 12 years were 0.8%, 2.5%, and 2.9%, respectively. The group whose risk of decompensation was above 10% comprised 2.6% and 5.3% at 10 and 12 years, respectively. The severity assessed by SAF significantly associated with definite NASH diagnosis through NAS (p < 0.001). Iowa score did not correlate with both NAS/SAF scores.

CONCLUSION

The Iowa score demonstrated that individuals with obesity present with a significant long-term risk of NAFLD-related events. There were high rates of moderate/severe forms of NAFLD assessed by NAS and SAF scores. There were no significant correlations between Iowa and NAS/SAF scores.

Clinical implications of hepatic structure and function evaluation based on vibration-controlled transient elastography and liver maximum function capacity test in patients with nonalcoholic fatty liver disease

BACKGROUND AND AIMS

Transient elastography [vibration-controlled transient elastography (VCTE)] noninvasively guides risk stratification in patients with nonalcoholic fatty liver disease (NAFLD). Patients with nonalcoholic steatohepatitis (NASH) and fibrosis can be identified using the FAST-score. The liver maximum function test (LiMAx) could be helpful in more precise risk stratification. This pilot study evaluated VCTE, FAST-score, and LiMAx in NAFLD patients.

METHODS

NAFLD patients prospectively underwent VCTE and LiMAx. The cutoffs for high fibrosis risk were 9.3/9.6 kPa (M/XL-probe) and 331 dB/m for steatosis. A FAST-score greater than 0.67 was used to identify patients with NASH and LiMAx values below 315 μg/kg/h for impaired liver function.

RESULTS

In total, 57 NAFLD patients (BMI 32 ± 6 kg/m2; 60% diabetes) were included. High risk for fibrosis and steatosis was observed in 26/57 and 28/57 cases, respectively. Overall, 19/57 patients presented impaired liver function. However, 14/26 of patients with a high risk for fibrosis had impaired liver function compared to 5/31 of those without (P = 0.0026). Similarly, 12/18 patients at high risk for NASH had impaired liver function compared to 7/39 without (P < 0.001). The subgroup with diabetes had a liver stiffness a factor of 1.8 higher, FAST-score was 0.13 higher and LiMAx values were 66 μg/kg/h lower compared to nondiabetics.

CONCLUSION

There is a significant correlation between the functional liver capacity (LiMAx) and the structural liver assessment by VCTE. In cases with high liver stiffness or FAST-score, low LiMAx results may identify NAFLD patients at risk for disease progression and reduce the risk of false-positive categorization.

The triglycerides and glucose (TyG) index: A new marker associated with nonalcoholic steatohepatitis (NASH) in obese patients

AIM

Diagnosis of nonalcoholic steatohepatitis (NASH) relies on liver biopsy. Noninvasive tools would be useful to target patients to refer for a biopsy. We aimed to determine the diagnostic value of the triglycerides and glucose (TyG) index, an insulin-resistance indicator, to predict NASH.

METHODS

Our study included grade II-III obese patients aged 18-65 years undergoing bariatric surgery and included in the COMET (COllection of MEtabolic Tissues) biobank (NCT02861781). Liver biopsies performed during bariatric surgery were collected from the biobank along with blood derivatives. Biopsies were analysed according to the steatosis, activity and fibrosis (SAF) scoring system to diagnose NASH, nonalcoholic fatty liver disease (NAFLD), and fibrosis. Logistic regression models were performed to identify factors predicting NASH, NAFLD, and fibrosis.

RESULTS

Of 238 analysed subjects (mean age 43±12 years, 33.6% men), 29% had type 2 diabetes. Steatosis was present in 67.2%, while NASH and advanced fibrosis (stage F3) were diagnosed in 18.1% and 2.9% respectively. TyG index was independently associated with NASH (odds ratio (OR): 4.7 [95% confidence interval: 2.3;9.5] P < 0.0001), NAFLD (OR: 2.0 [1.1;3.7] P = 0.03) and stages 2-3 fibrosis (OR: 4.0 [1.5;10.8] P = 0.007). NASH was also predicted by gamma-glutamyl transferase (GGT) with an area under the ROC curve: 0.79 [0.71;0.87 P = 0.04] for GGT and TyG index combined.

CONCLUSION

In our cohort of severely obese patients, TyG index, when associated with GGT level, exhibited high diagnostic performance to predict NASH. Although validation in larger populations is needed, this result may be of considerable clinical value to predict need for liver biopsy.

Effect of disease stage and treatment outcomes on the dynamics of liver functions during and after treatment of hepatitis C with directly acting antivirals

BACKGROUND

Virus C infection is recently treated successfully with plenty of direct antiviral agents (DAAs). We aimed to evaluate the effect of disease stage and treatment outcome on the dynamics of liver functions during treatment of hepatitis C with DAAs.

METHODS

We reported the liver function in 2354 subjects diagnosed as chronic hepatitis C before, during and after treatment with different DAAs regimens. Patients were classified into two groups according to treatment response with further subclassification according to the presence or absence of cirrhosis, and changes in liver functions were compared in each group and subgroup.

RESULTS

Totally 2213 (94%) achieved sustained virological response (SVR) to DAAs therapy with significant improvement in all liver biochemistry. Also, there was an improvement in the non-SVR group's liver enzymes in relapsers during and after treatment; however, there was no improvement in serum albumin. We noticed a slight increase in serum bilirubin at weeks 4 and 8 for both groups.

CONCLUSION

DAAs therapy is associated with improvement of the liver biochemical profile and improved outcome in the majority of chronic hepatitis C virus patients due to suppression of viral replication. However, the long-term impact of DAAs therapy needs to be further evaluated.

Comparison of Liver Recovery After Sleeve Gastrectomy and Roux-en-Y-Gastric Bypass

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is a common condition in patients with obesity. Bariatric surgery has often been proposed as a viable treatment option, but the ideal surgical procedure remains unclear. Inconsistently, reports on postoperative deterioration of liver function put further doubt on which technique to apply. Aim of this study was to assess the impact of Roux-en-Y-gastric bypass (RYGB) and sleeve gastrectomy (SG) on the postoperative recovery of liver function.

METHODS

A total of 175 patients with obesity that underwent bariatric surgery in our institution were included in this prospective cohort study. BMI, laboratory values, and liver function capacity (using LiMAx) were assessed preoperatively and at 6 and 12 months postoperatively. Generalized linear model (GLM) was performed to determine variables influencing liver function capacity after the operation.

RESULTS

Prior to operations, 64% of patients presented with a diminished liver function capacity, as measured by LiMAx test. Liver function capacity significantly recovered after 12 months in the SG group (300 μg/kg/h preop vs. 367 μg/kg/h postop) but not in the RYGB group (306 μg/kg/h preop vs. 349 μg/kg/h). Preoperative factors impeding liver function recovery included type 2 diabetes mellitus (T2DM), weight, male sex, AST/thrombocyte ratio (APRI), and gamma-glutamyltransferase (GGT).

CONCLUSION

Bariatric surgery, especially sleeve gastrectomy, leads to an improvement of liver function. However, in some patients with T2DM, higher preoperative weight and male sex postoperative deterioration of liver function capacity may occur.

Development and Validation of a Novel Scoring System for Noninvasive Nonalcoholic Steatohepatitis Detection in Bariatric Patients

INTRODUCTION

Nonalcoholic fatty liver disease covers a broad spectrum. Simple steatosis has usually a benign course while nonalcoholic steatohepatitis (NASH) can progress into hepatocellular carcinoma, and cirrhosis. Therefore, differentiating patients with benign steatosis and NASH is crucial. Liver biopsy, the usual gold standard for NASH diagnosis, cannot be used as a screening method due to its associated risks. This is especially problematic for obese patients with a prevalence of nonalcoholic fatty liver disease (NAFLD) in >80% of patients. The aim of this study was therefore to develop and validate a noninvasive NASH screening test in a cohort of high-risk, morbidly obese patients.

METHODS

This prospective study examined diagnostic accuracy in accordance with STARD guidelines. 112 liver biopsies were consecutively assigned to either a training or validation cohort. Using the Bedossa histological scoring system, the cohorts were subdivided into NASH versus NAFLD/No NAFLD. Predictors of NASH were evaluated with receiver operating characteristic (ROC) curves. A model was then constructed using a backward stepwise logistic regression and evaluated in an independent validation cohort.

RESULTS

53.5% of the patients had NASH and 4 patients had cirrhosis. Mean body mass index (BMI) was 49.8 ± 7.5 kg/m2. Backward stepwise logistic regression identified 4 parameters associated with the presence of NASH: alanin-aminotransferase, albumin, BMI, and triglycerides. The noninvasive NASH detection score (NI-NASH-DS) had an ROC of 0.851 and 0.727 in the training and validation cohorts, respectively. Sensitivity and specificity were 77.1% and 88% in the training cohort and 88% and 48% in the validation cohort which was much better than the established noninvasive scores.

DISCUSSION/CONCLUSION

The NI-NASH-DS is easy-to-use, inexpensive, and noninvasive and can reliably detect NASH in patients with morbid obesity. Due to its simplicity, it can be used frequently and repeatedly.

Baseline Presence of NAFLD Predicts Weight Loss after Gastric Bypass Surgery for Morbid Obesity

Background. Bariatric surgery is a widely used treatment for morbid obesity. Prediction of postoperative weight loss currently relies on prediction models, which mostly overestimate patients’ weight loss. Data about the influence of Non-alcoholic fatty liver disease (NAFLD) on early postoperative weight loss are scarce. Methods. This prospective, single-center cohort study included 143 patients receiving laparoscopic gastric bypass surgery (One Anastomosis-Mini Gastric Bypass (OAGB-MGB) or Roux-en-Y Gastric Bypass (RYGB)). Liver biopsies were acquired at surgery. NAFLD activity score (NAS) assigned patients to “No NAFLD”, “NAFL” or “NASH”. Follow up data were collected at 3, 6 and 12 months. Results. In total, 49.7% of patients had NASH, while 41.3% had NAFL. Compared with the No NAFLD group, NAFL and NASH showed higher body-mass-index (BMI) at follow-up (6 months: 31.0 kg/m² vs. 36.8 kg/m² and 36.1 kg/m², 12 months: 27.0 kg/m² vs. 34.4 and 32.8 kg/m²) and lower percentage of total body weight loss (%TBWL): (6 months: 27.1% vs. 23.3% and 24.4%; 12 months: 38.5% vs. 30.1 and 32.6%). Linear regression of NAS points significantly predicts percentage of excessive weight loss (%EWL) after 6 months (Cologne-weight-loss-prediction-score). Conclusions. Histopathological presence of NAFLD might lead to inferior postoperative weight reduction after gastric bypass surgery. The mechanisms underlying this observation should be further studied.

Evaluation of NAFLD and fibrosis in obese patients - a comparison of histological and clinical scoring systems

Background

Non-alcoholic fatty liver disease (NAFLD) is a frequent condition in obese patients and regularly progresses to non-alcoholic steatohepatitis (NASH) and subsequent cirrhosis. Histologic evaluation is the gold standard for grading and staging, but invasive biopsies are associated with obvious risks. The aim of this study was to evaluate different non-invasive tools for screening of NAFLD and fibrosis in obese patients.

Methods

In a prospective cohort study liver specimens of 141 patients were taken during bariatric surgery. Serological parameters and clinical data were collected and the following scores calculated: NASH clinical scoring system (NCS), aspartate aminotransferase to platelet ratio index (APRI), FIB-4 as well as NAFLD fibrosis score (NFS). Liver function capacity was measured preoperatively by LiMAx test (enzymatic capacity of cytochrome P450 1A2). Intraoperative liver biopsies were classified using NAFLD activity score (NAS) and steatosis, activity and fibrosis (SAF) score.

Results

APRI was able to differentiate between not NASH and definite NASH with a sensitivity of 74% and specificity of 67% (AUROC 0.76). LiMAx and NCS also showed significant differences between not NASH and definite NASH. No significant differences were found for NFS and Fib-4. APRI had a high sensitivity (83%) and specificity (76%) in distinguishing fibrosis from no fibrosis (AUROC = 0.81). NCS and Fib-4 also revealed high AUROCs (0.85 and 0.67), whereas LiMAx and NFS did not show statistically significant differences between fibrosis stages. Out of the patients with borderline NASH in the histologic NAS score, 48% were classified as NASH by SAF score.

Conclusions

APRI allows screening of NAFLD as well as fibrosis in obese patients. This score is easy to calculate and affordable, while conveniently only using routine clinical parameters. Using the NAS histologic scoring system bears the risk of underdiagnosing NASH in comparison to SAF score.

Preoperative versus intraoperative diagnosis of hiatal hernia in bariatric population

BACKGROUND

Hiatal hernia is frequently encountered intraoperatively during bariatric surgery. There is scarce research pertaining to the diagnostic accuracy of a preoperative diagnostic modality in comparison to intraoperative diagnosis, along with patient characteristics and related factors contributing to hiatal hernia.

OBJECTIVE

To identify the prevalence and associations of hiatal hernia in the bariatric patient population, we compared the diagnostic accuracy of upper gastrointestinal series and esophagogastroduodenoscopy with the intraoperative findings across various patient characteristics.

SETTING

Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program, Teaching Hospital, New York, USA.

METHODS

Retrospective study of patients from 2015 to 2018 who met National Institutes of Health criteria for bariatric surgery.

RESULTS

There were 1094 patients included (135 males, 959 females), with an age range of 18 to 74 years. The diagnostic accuracy was determined by a sensitivity of 64.71% (95% confidence interval [CI] .55-.70), specificity of 74.38% (95% CI .71-.70), positive predictive value of 29.86% (95% CI .24-.30), negative predictive value of 92.59% (95%CI .89-90), likelihood ratio of 2.526, and P value < .0001 for esophagogastroduodenoscopy; a sensitivity of 14.02% (95% CI .08-0), specificity of 98.23% (95% CI .96-.90), positive predictive value of 71.43% (95% CI .50-.80), negative predictive value of 78.35% (95% CI .74-.80), likelihood ratio 7.921, and P value < .0001 were used for upper gastrointestinal series. Hiatal hernia with age <60 years was 17.09% versus 48.44% at >60 years (P < .0001). Hiatal hernia incidence was 17% in Hispanics, 22.5% in Caucasians, and 23.10% in blacks.

CONCLUSION

The prevalence of hiatal hernia is 18.92%. There is strong association between hiatal hernia and age and ethnicity and no association based on sex and body mass index. The diagnostic accuracy of upper gastrointestinal series is very low compared with that of esophagogastroduodenoscopy for hiatal hernia. Preoperative diagnosis of hiatal hernia in the bariatric population is not required based on our study. Not only does it lessen the economic burden, patient wait time, and discomfort of an additional study, but preoperative diagnosis does not change, alter, or aid in the intraoperative management of hiatal hernia considering the suboptimal accuracy of preoperative diagnostics, thus deeming them unwarranted.