Effect of bariatric surgery on fatty liver disease in obese patients: A prospective one year follow-up study

Bariatric Surgery and Metabolic Status

Background and Objectives: Obesity is associated with numerous co-morbidities, including dyslipidemia, insulin resistance and diabetes mellitus. Bariatric surgery is the mainstay of treatment for obesity as the only method with confirmed long-term effects in weight reduction and the remission of comorbidities. Postoperative recommendations leading to changes in dietary habits and changes in digestion and absorption in the gastrointestinal tract after bariatric surgery may additionally influence the levels of laboratory parameters that reflect the metabolic and nutritional status. The purpose of the study was to analyze the possible influence of changes in dietary habits after bariatric surgery on those laboratory results that reflect the metabolic and nutritional status. Materials and Methods: This was a retrospective study of 88 patients with a history of bariatric surgery. Data were gathered from before the surgery and at 6 months after the surgery and included diet structure and selected laboratory parameters reflecting the metabolic and nutritional status, i.e., levels of fasting glucose, glycated hemoglobin, cholesterol, low- and high-density lipoproteins, triglycerides, alanine and aspartate aminotransferases, proteins, ferrum, ferritin, vitamin B12, folic acid, vitamin D and calcium, the red blood cell count and the hematocrit. Results: Postoperative festive glucose levels were reduced by 14% and were more significant in patients after Roux-en-Y gastric bypass. There was an increase of 22% in concentrations of high-density lipoproteins. Triglyceride concentrations were reduced by 32%. Aminotransferase levels decreased by 43% for alanine aminotransferase and by 14% for aspartate aminotransferase. Among the changes in dietary habits, post-bariatric patients had a reduced consumption of red meat and an increased consumption of fish, milk and dairy products and wholegrain products. Vitamin D and ferrum levels were higher after the surgery, whereas vitamin B12 and folic acid levels remained unchanged. Conclusions: Improved dietary habits of patients after bariatric surgery may lead to changes in laboratory parameters that reflect the ameliorated metabolic and nutritional status of patients after bariatric surgery.

The Role of the Fatty Liver Index (FLI) in the Management of Non-Alcoholic Fatty Liver Disease: A Systematic Review

Currently, non-alcoholic fatty liver disease is the most common liver disease worldwide, with a prevalence of 32%. It is much more common among men (40%) and among patients with metabolic comorbidities such as obesity, diabetes and dyslipidemia. Being an asymptomatic disease, the diagnosis is often established on the basis of imaging methods, with an important role given to abdominal ultrasonography, computed tomography and magnetic resonance imaging. In order to facilitate diagnosis, experts have introduced a series of blood biomarkers. Two biomarker panels are currently validated for the diagnosis of non-alcoholic fatty liver disease: the fatty liver index, and the hepatic steatosis index. The fatty liver index has been in use in medical practice for over 17 years and has demonstrated its accuracy in various studies that compared it with other diagnostic methods, highlighted its role in screening patients with cardiovascular risk and validated the effects of different diets and drugs that are proposed for the treatment of the disease. In the management of non-alcoholic fatty liver disease, the fatty liver index is an important algorithm in the diagnosis and prognosis of patients with metabolic risk. Taking into account the diversity of drugs to be approved in the treatment of non-alcoholic fatty liver disease, the fatty liver index will become an effective tool in monitoring the effects of these therapies.

Visceral adipose tissue and risk of nonalcoholic fatty liver disease: A Mendelian randomization study

OBJECTIVE

Observational studies have shown that visceral adipose tissue (VAT) can increase the risk of nonalcoholic fatty liver disease (NAFLD). However, the causality of this association remains unclear. Therefore, this study aimed to explore the causal association between VAT and NAFLD.

DESIGN

We obtained single-nucleotide polymorphisms strongly associated with VAT (n = 325,153) from large-scale genome-wide association studies. Summary-level data for NAFLD (2275 cases and 375,002 controls) was available from the FinnGen consortium. We applied two-sample Mendelian randomization (MR) to determine the causal association between VAT and NAFLD. The random-effects inverse-variance weighted (IVW) method was used as the main MR approach, with alternate methods including the weighted median (WM) approach and MR-Egger regression. In addition, we conducted sensitivity analyses to assess the robustness of MR analyses.

RESULTS

Genetically predicted higher VAT mass is causally associated with a higher risk of NAFLD. The three analysis results of MR were as follows: IVW (β = 0.665, odds ratio [OR] = 1.944, 95% confidence interval [CI] = 1.482-2.550, p = 1.58e-06], WM (β = 0.615, OR = 1.849, 95% CI = 1.272-2.689, p = 1.29e-03), and MR-Egger (β = 1.250, OR = 3.490, 95% CI = 1.522-7.998, p = 3.52e-03). In the sensitivity analysis, the data showed heterogeneity (p < 0.05) but no pleiotropy (p = 0.145).

CONCLUSION

This study provided genetic evidence that higher VAT mass causally associated with a higher risk of NAFLD. The amount of VAT could be reduced using a therapeutic strategy for managing NAFLD.

Diagnostic Value of Non-invasive Liver Function Tests in Liver Fibrosis and Changes in These Parameters Post-metabolic Surgery

PURPOSE

This study aimed to ascertain the diagnostic accuracy of non-invasive liver function tests in liver fibrosis and assess their changes after metabolic surgery.

MATERIALS AND METHODS

1005 individuals with severe obesity who were referred for metabolic surgery were analysed. All participants had blood samples taken for liver enzymes and lipid profile. In addition, hepatic indexes, including AAR, APRI, NFS and Fibrosis-4 (FIB4), were checked. Furthermore, all participants underwent two-dimensional shear wave elastography (2D-SWE). All investigations were repeated 6-8 months after metabolic surgery. The receiver operating characteristic (ROC) curve and the area under the ROC curve was utilised to determine the optimal cut-off values for baseline study parameters. Logistic regression was applied to predict the relationship between study parameters-as predictors-and change in 2D-SWE.

RESULTS

AST/ALT (AAR) was the most sensitive (79%) pre-operative non-invasive serological marker for detecting liver fibrosis, whereas NAFLD Fibrosis Score (NFS) was the most specific (84%). AST/upper limit of the normal AST range × 100/platelets (× 10⁹/L) (APRI) showed a positive correlation with 2D-SWE post-metabolic surgery (p-value = 0.021). Regression analysis from both adjusted and unadjusted models showed that baseline AAR was a predictor of postoperative liver status in terms of hepatic fibrosis.

CONCLUSION

AAR has a high sensitivity, whereas NFS exhibits a high specificity in diagnosing liver fibrosis. The authors recommend using both investigations in conjunction with 2D-SWE to increase the likelihood of detecting liver fibrosis.

The Effect of Roux-en-Y Gastric Bypass on Non-Alcoholic Fatty Liver Disease Fibrosis Assessed by FIB-4 and NFS Scores-An 11.6-Year Follow-Up Study

Severe obesity is a strong risk factor for non-alcoholic fatty liver disease (NAFLD). Roux-en-Y gastric bypass (RYGB) surgery effectively induces weight loss, but few studies have described the long-term effects of RYGB on NAFLD-related fibrosis. Data from 220 patients with severe obesity operated by RYGB in Central Norway were analysed. Variables incorporated in NAFLD Fibrosis Score (NFS), Fibrosis-4 (FIB-4) index and anthropometric data were collected before surgery and a mean of 11.6 years postoperatively. FIB-4 > 1.3 or NFS > 0.675 were used as cut-off values for advanced fibrosis. Proportions with advanced fibrosis decreased from 24% to 14% assessed by FIB-4 and from 8.6% to 2.3% using NFS, with resolution rates of advanced fibrosis of 42% and 73%, respectively. The shift towards lower fibrosis categories was significant (NFS p < 0.0001; FIB-4 p = 0.002). NFS decreased from −1.32 (IQR −2.33−−0.39) to −1.71 (IQR −2.49−−0.95, p < 0.001) 11.6 years after surgery, whereas FIB-4 did not change: 0.81 (IQR 0.59−1.25) to 0.89 (IQR 0.69−1.16, p = 0.556). There were weak correlations between change in fibrosis scores and weight loss. In conclusion, the majority of patients with advanced fibrosis at baseline had improvement after 11.6 years. Factors associated with reduction in fibrosis were not identified.