Comparison between non-invasive methods and liver histology to stratify liver fibrosis in obese patients submitted to bariatric surgery.

Abstract Background Obesity is a multifactorial disease characterized by fat accumulation, usually associated with non-alcoholic fatty liver disease, which can lead to advanced fibrosis or even cirrhosis. Bariatric surgery (BS) is a treatment approved for weight loss in morbidly obese patients. However, complications from this modality of treatment have been reported and liver cirrhosis connotes more risk procedure. Aims Evaluate non-invasive methods transient elastography (THE) and scores to establish the degree of liver fibrosis in patients submitted to BS, comparing their performance with liver histology. Methods We calculated liver fibrosis by non-invasive scores AST to platelet ration index (APRI), fibrosis-4 (FIB-4) and non-alcoholic fatty liver disease (NAFLD) score and THE before and 6 months after the bariatric surgery. The results were compared to liver histology. Results We included 85 patients, 69.4% females, with a mean age of 36 years, with a mean body mass index (BMI) of 41 kg/m2. The non-invasive scores were able to exclude clinically significant fibrosis in 85.9% (APRI) and advanced fibrosis in 96.5% (FIB-4) and 51.8% (NAFLD score). When comparing with the histological findings, the correlation with elastography was 45.9% for the same degree of fibrosis, with high negative predictive value (94.4%) in pre-surgical analysis. In the post-surgical analysis, the correlation with histology was 69.4% for THE and the negative predictive value to exclude clinically significant fibrosis was 98.5%. Conclusion THE showed low correlation with histology in the pre-surgical analysis. All the methods had better results in post bariatric evaluation comparing with pre-bariatric data and the non-invasive FIB-4 score showed the best of them.