Performance of 2D-SWE for the Diagnosis of Liver Fibrosis in Adults Undergoing Bariatric Surgery

Background: Several studies have reported fibrosis as the main determinant of mortality in NASH. Among the new approaches being used to diagnose liver fibrosis is 2D-Shear Wave Elastography (2D-SWE); however, there is no consensus on the best cut-off points for each degree of fibrosis) and more evidence is needed regarding its performance in the Latino population. For this reason, this study aimed to assess the diagnostic performance of 2D-SWE for liver fibrosis in adults with obesity who underwent bariatric surgery. Methods: We conducted a cross-sectional study on patients with obesity who underwent bariatric surgery between 2020-and 2021. Liver stiffness measurement (LSM) was reported as the mean (M) of valid measurements in kilopascals (kPa) made with the 2D-SWE. The outcome was biopsy-proven liver fibrosis. ROC (Receiver Operating Characteristic) curves were constructed for significant fibrosis (F>2) and advanced fibrosis (F>3), with their respective area under the curve (AUC). To obtain the best cut-off point for each scenario, we used the Youden index. The 95% confidence intervals (95% CI) for each cut-off point were estimated by bootstrap with 1000 replications. Results: We analyzed data from 227 patients. The mean age was 37.8 ± 11.1 years and 65.2% were women. A total of 126 (55.5%) had F1, 83 (36.6%) F2, 17 (7.5%) F3 and 1 (0.4%) had F4. Overall, the AUC for significant and advanced fibrosis was 0.54 (95% CI: 0.47 - 0.62) and 0.73 (95% CI: 0.60 - 0.87), respectively. For advanced fibrosis, higher AUC were found among women (AUC: 0.82; 95% CI: 0.59 - 1.00) and among patients with morbid obesity (AUC: 0.78; 95% CI: 0.61 - 0.99). The cut-off points of 2D-SWE for advanced fibrosis in all the sample, only women and only adults with morbid obesity were 5.14 (95% CI: 1.76 - 8.52), 7.55 (95% CI: 4.33 - 10.77) and 10.44 (95% CI: 5.11 - 15.77), respectively. Conclusions: 2D-SWE is a promising tool for diagnosing advanced liver fibrosis in candidates for bariatric surgery, mainly in the female population and in adults with morbid obesity.