OBESITY AND SEVERE STEATOSIS: THE IMPORTANCE OF BIOCHEMICAL EXAMS AND SCORES

ABSTRACT - INTRODUCTION: Nonalcoholic fatty liver disease (NAFLD) is considered a public health problem, mainly in severely obese patients. OBJECTIVE: The aim of the present study was to investigate different biochemical-based scores available and determine which one could best serve as an NAFLD predicting tool in a severely obese population. METHODS: This was a cross-sectional study involving severely obese patients. All patients were evaluated with serum laboratory parameters for 1 week before biopsy, and all patients were treated with intraoperative liver biopsy, during bariatric surgery. RESULTS: A total of 143 severely obese patients were included. The median body mass index (BMI) was 48 kg/m2 (35-65). Diabetes mellitus was present in 36%, and steatosis was present in 93% (severe steatosis in 20%). Only aspartate transaminase (AST) to platelet ratio index (APRI=0.65 (95% CI: 0.55-0.8) and homeostatic model assessment for insulin resistance (HOMA-IR=0.7 (95% CI: 0.58-0.82) showed significant capacity for the prediction of severe steatosis. Hepatic steatosis index (HSI), NAFLD fibrosis score (NAFLDS), alanine aminotransferase (ALT)/AST, and fibrosis-4 (FIB-4) were not able to correctly predict severe steatosis on liver biopsy. APRI showed high specificity of 82% and low sensitivity of 54%. In contrast, HOMA-IR showed high sensitivity of 84% and low specificity of 48%. CONCLUSIONS: NAFLDS, FIB-4, AST/ALT, and HSI have no utility for the evaluation of severe steatosis in severely obese patients. Diabetes and insulin-resistance-related biochemical assessments, such as HOMA-IR, can be used as good screening tools for severe steatosis in these patients. APRI score is the most specific biochemical diagnostic tool for steatosis in severely obese patients and can help clinicians to decide the need for bariatric or metabolic surgery.


RESUMO -
ABSTRACT -Background: The treatment of choice for patients with schistosomiasis with previous episode of varices is bleeding esophagogastric devascularization and splenectomy (EGDS) in association with postoperative endoscopic therapy. However, studies have shown varices recurrence especially after long-term follow-up. Aim: To assess the impact on behavior of esophageal varices and bleeding recurrence after post-operative endoscopic treatment of patients submitted to EGDS. Methods: Thirty-six patients submitted to EGDS were followed for more than five years. They were divided into two groups, according to the portal pressure drop, more or less than 30%, and compared with the behavior of esophageal varices and the rate of bleeding recurrence. Results: A significant reduction on the early and late post-operative varices caliber when compared the pre-operative data was observed despite an increase in diameter during follow-up that was controlled by endoscopic therapy.

Conclusion:
The drop in portal pressure did not significantly influence the variation of variceal calibers when comparing pre-operative and early or late post-operative diameters. The comparison between the portal pressure drop and the rebleeding rates was also not significant. HEADINGS: Schistosomiasis mansoni. Portal hypertension. Surgery. Portal pressure.
Esophageal and gastric varices.

Mensagem central
A desconexão ázigo-portal e esplenectomia apresenta importante impacto na diminuição precoce do calibre das varizes esofágicas na esquistossomose; entretanto, parece que a associação com a terapia endoscópica é a maior responsável pelo controle da recidiva hemorrágica. and insulin-resistance-related biochemical assessments, such as HOMA-IR, can be used as good screening tools for severe steatosis. APRI score is the most specific biochemical diagnostic tool for severe steatosis in severely obese patients and can help clinicians to decide the need for bariatric or metabolic surgery.

Central message
Nonalcoholic fatty liver disease is a clinical condition characterized by excessive lipid deposits in hepatocytes, without significant ethanol intake, in the absence of other etiologies of liver diseases. This study investigated different biochemical-based scores for predicting severe steatosis in a severely obese population.

INTRODUCTION
O besity and overweight are increasing worldwide, and several obesity-related comorbidities are also on the rise 19 . The obese patient has a higher risk for metabolic disorders, including type 2 diabetes mellitus, hypertension, dyslipidemia, and chronic liver disease 8 .
Nonalcoholic fatty liver disease (NAFLD) is a clinical condition characterized by excessive lipid deposits in hepatocytes, without significant ethanol intake, in the absence of other etiologies of liver diseases 14 . Currently, NAFLD occurs in a range of 30-100% in obese adults 18 . In recent years, NAFLD has become the most common cause of liver disease in the Western world and it is already considered a public health problem 8 . NAFLD can progress to steatohepatitis (nonalcoholic steatohepatitis [NASH]), fibrosis, cirrhosis, and potentially to end-stage liver failure or hepatocellular carcinoma (HCC) 22 . In the United States, NASH is the fastest growing reason for liver transplantation 21 .
Although the major risk factors for NAFLD are well established (e.g., age >50 years, obesity, insulin resistance, diabetes mellitus, and metabolic syndrome), the pathological mechanisms by which each of these risk factors causes NAFLD progression to NASH and cirrhosis are unclear 5 . Patients with NAFLD are usually asymptomatic until the condition progresses to liver cirrhosis, which makes early diagnosis challenging 1 .
Liver biopsy remains as the gold-standard diagnostic procedure to detect liver abnormalities compatible with NAFLD and NASH 1 . The main histopathological features of NASH are a combination of steatosis, hepatocyte ballooning, and lobular inflammation. However, performing a liver biopsy in an obese patient has several drawbacks: it is an invasive procedure, with risks of bleeding and bile leaks, and involves the possibility of sampling error 1 . This fact has motivated the development of alternative noninvasive methods, which have been extensively investigated lately. Applying the noninvasive test to predict severe steatosis in severely obese patients could help clinicians to manage these patients, including helping them to decide the need for bariatric or metabolic surgery.
There are several clinical scores primarily based on biochemical markers that can be used to evaluate liver status in severely obese patients 7 The hepatic steatosis index (HSI) is a screening tool for diagnosing steatosis 15 . There are other liver biochemical scores such as fibrosis-4 (FIB-4) 25 , NAFLD fibrosis score (NAFLDS) 2 , aspartate transaminase/alanine aminotransferase (AST/ALT) ratio 16 , and AST to platelet ratio index (APRI) 27 . These scores are used for estimating liver fibrosis, which occurs in most types of chronic liver diseases. Insulin-resistance index (e.g., homeostatic model assessment for insulin resistance [HOMA-IR]) 24 is another biochemical score used for screening insulin resistance, which is usually associated with steatosis 28 . The summary of these formulas is given in Table 1.
However, until the present time, there is no consensus on which is the best way to evaluate a severely obese patient before considering bariatric or metabolic surgery. Previous reports showed that APRI score is associated with advanced fibrosis in obese patients 9 However, a suitable biochemical evaluation for severe steatosis, which could help clinicians to properly manage the severely obese patients, is poorly debated.
The aim of the present study was to investigate different biochemical-based scores available and determine which one could best serve as a severe steatosis predicting tool in a severely obese population.  each score for the prediction of severe steatosis (>66% of fatreplete hepatic cells) was evaluated by the receiver operating characteristic (ROC) curve. The maximum Youden's index was used to determine the best cutoff point for each score. The area under curve (AUC) was measured for each score, and a test for the equality of the AUCs was made using an algorithm suggested by DeLong 9 . ROC regression analysis was performed to identify the influence of covariates.

Baseline characteristics
A total of 143 severely obese patients were included in this study. The median age was 43 years old (19-68), with female predominance (77%). The median BMI was 48 kg/m 2 (35-65). Diabetes mellitus was present in 36% and steatosis was present in 93% (severe steatosis in 20%). The baseline characteristics are given in Table 2.
When comparing the multiple AUCs, the null hypothesis of equality of the AUCs 17 was rejected (p<0.001). Consequently, the APRI AUC and the HOMA-IR AUC were significantly superior to the other scores. Besides, when the test for equality of the APRI AUC and the HOMA-IR AUC was performed, the scores of APRI AUC and HOMA-IR AUC are equivalent (p=0.611). The APRI and HOMA-IR scores according to each steatosis classification are shown as boxplots in Figures 2 and 3, respectively.
The best cutoff point determined by maximum Youden's J statistics was 0.29 for APRI and 17.11 for HOMA-IR. At these cutoff points, APRI showed high specificity of 82% and low sensitivity of 54%. In contrast, HOMA-IR showed high sensitivity of 84% and low specificity of 48% (see Table 4).
Considering high sensitivity of HOMA-IR was related to the high pretest probability, due to the high number of diabetic patients and the known association of steatosis and diabetes or insulin resistance, we performed an ROC regression analysis    to assess possible covariates. The results of regression showed that APRI was not affected by the presence of diabetes mellitus (p=0.068), while HOMA-IR was affected (p<0.001) (see Table 5).
The effects of diabetes mellitus on APRI and HOMA-IR scores are shown in Figures 4 and 5, respectively.

DISCUSSION
This study involving 143 severely obese patients showed that the use of biochemical-based APRI and HOMA-IR scores could help clinicians predict severe steatosis. HSI, NAFLDS, ALT/AST, and FIB-4 are not useful tools for the evaluation of these patients.
At present, liver biopsy is the gold standard for the diagnosis and stratification of the risk of progression to cirrhosis in NAFLD 1 . However, as it is an invasive procedure and associated with the risk for complications, simpler diagnostic methods need to be investigated. Although infrequent, complications after liver biopsy may occur, and 1-3% of complications will require hospitalization 3 . Pain is the most common complication, but most of the major complications are due to hemorrhage. Bleeding is an especially relevant issue in the steatotic liver, since it is prone to major bleeding 26 . Other reported complications include bacteremia, hemobilia, biliary leak, pneumothorax, and hemothorax 20 .
Imaging methods are the most used noninvasive instruments for the diagnosis of steatosis 26 . Ultrasonography (USG) is the most suitable imaging test due to its cost-effectiveness, but it has limitations, as it requires an important infiltration of adipose tissue before observing the signs of steatosis 26 .     ORIGINAL ARTICLE

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Besides, the accuracy reduction with thick panniculus adipose and the dependence on operator and machinery limit their use 26 . Computed tomography (CT) has a sensitivity of 82% and specificity of 100% to diagnose hepatic steatosis when the fat content is more than 30%, but it has the inconvenience of the radiation and limited equipment weight and gantry diameter 26 . Magnetic resonance imaging (MRI) is the most sensitive method to detect increased intrahepatic fat. Unlike USG and CT, it can detect an increase in fat by 3%, but the high cost and low availability limit its use 26 . Transient hepatic elastography (Fibroscan), which is a more sophisticated test, can be used 26 . It is more sensitive to detect lower degrees of steatosis compared with other imaging methods 26 . However, as a disadvantage, the underlying disease, BMI, and type 2 diabetes mellitus can affect the findings and, therefore, should be taken into account in the interpretation of the results 26 . In addition, high cost and limited availability restrict its use 26 .
Biochemical tests for evaluating liver status are especially useful since they are not subject to interexaminer disagreement or subjective analyses. In Brazil, the public healthcare system (SUS) sponsored the bariatric and metabolic surgery (Ministério da Saúde; Portaria #492; Brazil), but it lacks a precise guide, not subjected to observer manipulation, for the surgical treatment of severe hepatic steatosis.
Nones et al. 20 reported that the FIB-4 and NAFLD fibrosis score models had a high negative predictive value (93.48% and 93.61%, respectively) in patients with severe liver fibrosis and concluded that the use of the FIB-4 and NAFLD fibrosis score models in patients with NAFLD allows a diagnosis of severe liver disease to be excluded. Our findings showed these scores in obese patients could not reasonably detect that severe steatosis.
Lee et al. 15 evaluated the HSI as a screening method for detecting steatosis. However, they used ultrasound as the goldstandard method for liver steatosis, instead of liver biopsy. Also, the study population was composed mainly of lean patients (mean BMI: 24.1 kg/m 2 ) different from our sample (BMI: 35-65 kg/m 2 ). Kahl et al. 13 also evaluated nonobese patients, showing high accuracy for detecting steatosis in their tested cohort. All the 92 patients from the cohort of Kahl et al. were nondiabetic 12. Diabetes and insulin resistance have a central role in both steatosis installation and its progression to more advanced stages of the disease such as NASH, which makes it the main pathogenic mechanism of NAFLD 24 . Several methods have been used for diagnosing insulin resistance in humans. Glycemic clamp continues to be the gold-standard procedure 16 . However, its complexity limits its application in daily medical practice 16 . Due to its simple determination and calculation method, HOMA-IR has been the most frequently employed technique in both clinical practice and epidemiological studies 24 .
Due to the high pretest probability (36% of the included patients presented diabetes), HOMA-IR showed high sensitivity in detecting severe steatosis in severely obese patients. ROC regression analysis showed that HOMA-IR has limited value for nondiabetic patients. These findings suggest that HOMA-IR is not suitable for helping clinicians to decide the need for an invasive procedure such as bariatric/metabolic surgery. However, insulin resistance and diabetes should be promptly investigated in obese patients. Before these patients manifest any sign of liver disease progression, HOMA-IR could be a good screening method. Considering liver steatosis is a risk factor for HCC 22 , HOMA-IR could be a screening method to identify those patients who should be enrolled in a surveillance program for HCC.
Patients with a high HOMA-IR score should be advised early to adopt a rigorous diet change. Mardinoglu et al. 17 showed that an isocaloric low-carbohydrate diet with increased protein content in obese subjects with NAFLD leads to downregulation of the fatty acid synthesis pathway and upregulation of folate-mediated one-carbon metabolism and fatty acid oxidation pathways. This diet leads to a dramatic reduction of liver fat resulting from a marked decrease in DNL and an increase in beta-oxidation 17 . Ryan et al. 23 showed that the Mediterranean diet, a diet high in monounsaturated fatty acids, acts on steatosis and insulin sensitivity, even without weight loss, reduces liver steatosis, and improves insulin sensitivity in an insulin-resistant population with NAFLD, compared with current dietary advice. In an animal model study, exercise training conducted concurrently with the high-fat regimen diet completely prevented the accumulation of lipids into the liver 12 .
The therapeutic approach of NAFLD is currently based on lifestyle intervention, whereas there is no consensus on effective pharmacological treatment. Several drugs (e.g., insulin sensitizers, hepatoprotective agents, and lipid-lowering drugs) have been evaluated as potential therapeutic agents, but the results are inconclusive 11 . Liraglutide is associated with a decrease in BMI 11 . However, a recently published meta-analysis confirmed that liraglutide does not significantly affect hepatic fat content 11 .
Collaborative guidelines from the European Association for the Study of the Liver (EASL), European Association for the Study of Diabetes (EASD), and European Association for the Study of Obesity (EASO) suggest that the data are insufficient for evidence-based recommendations for the use of metformin to treat NAFLD 10 . However, some studies have revealed different results on the benefit of using metformin to treat NAFLD. Metformin could theoretically protect against obesity-associated NAFLD through direct effects on decreasing hepatocyte fat deposition and on inhibiting inflammatory responses in both hepatocytes and macrophages 11 . Liver function tests may ameliorate with metformin, but there is no superiority of metformin compared with dietary treatment on liver histology 11 .
The APRI score was initially used for the evaluation of liver cirrhosis 27 . In a meta-analysis of 40 studies, APRI score greater than 1.0 had a sensitivity of 76% and a specificity of 72% to predict cirrhosis 16 . APRI score greater than 0.7 had a sensitivity of 77% and a specificity of 72% to predict significant liver fibrosis 16 . This study showed that the APRI score has also a high specificity for diagnosing severe steatosis in severely obese patients. Patients with >0.29 APRI score should be considered to a more intense therapy for treating liver steatosis. Thus, the APRI value could support indications for bariatric surgery or metabolic surgery in obese patients.
Medical treatment for weight loss with drugs, diet, exercise, and other lifestyle modification measures may have limited efficacy for some patients, especially in the severely obese ones 28 . Surgical therapy has proven to be very effective for achieving sustained weight loss in the severely obese population 19,28,30 . Weight loss after bariatric surgery also results in a significant improvement or complete resolution in the metabolic syndrome markers in a vast majority of patients 19 . Sleeve gastrectomy and RYGB are equally effective for treating NAFLD/NASH regarding the histopathological analysis of fat liver content 4 .
This study has some limitations. It is a single-center study and there was a relatively small sample size. Also, obese patients with BMI <35 kg/m 2 were not included, and certainly some obese patients with BMI <35 kg/m 2 would benefit from metabolic surgery for the treatment of NAFLD.

CONCLUSIONS
NAFLDS, FIB-4, AST/ALT, and HSI have no utility for the evaluation of severe steatosis in severely obese patients. Diabetes and insulin-resistance-related biochemical assessment, such as HOMA-IR, can be used as a good screening tool for severe steatosis in such patients. APRI score is the most specific OBESITY AND SEVERE STEATOSIS: THE IMPORTANCE OF BIOCHEMICAL EXAMS AND SCORES