FIB-4 Reliability in Patients With Severe Obesity: Lower Cutoffs Needed?

ABSTRACT

BACKGROUND: Liver biopsy is the gold standard to evaluate hepatic fibrosis; however, it has many drawbacks, especially in patients with severe obesity. Noninvasive testing such as the FIB-4 score is increasingly being used as the initial screening tool to identify patients at risk for advanced fibrosis. The broader applicability of FIB-4 and the precision of its cutoff values remain uncertain in metabolic dysfunction-associated steatotic liver disease and patients with severe obesity. Our study explored the correlation between FIB-4 scores and intraoperative liver biopsy in patients with severe obesity undergoing bariatric surgery. METHODS: A total of 632 patients with severe obesity underwent preoperative vibration-controlled transient elastography and intraoperative liver biopsy during bariatric surgery from January 2020 to August 2021. Variables collected included patient demographics, laboratory values, abdominal ultrasound, vibration-controlled transient elastography, and liver biopsy results. ANOVA 1-way test, χ2 tests, and Fisher exact tests were used for quantitative and qualitative variables, respectively. The 95% CIs for the mean FIB-4 scores were used to generate surrogate cutoff values. The proposed FIB-4 cutoffs for F0-1, F2, F3, and F4 were 0.62 (CI 0.59, 0.64), 0.88 (0.74, 1.01), 1.24 (0.94, 1.54), and 1.53 (0.82, 2.24), respectively. Area under the curve (AUC) methods were used to compare traditional to proposed cutoff values. RESULTS: Applying the traditional FIB-4 cutoffs to approximate advanced fibrosis yielded an AUC of 0.5748. Use of the proposed FIB-4 cutoffs increased the AUC to 0.6899. The proposed FIB-4 cutoffs correctly identified 40 patients with biopsy-proven advanced fibrosis (F3-F4), all of which would have been missed using traditional cutoffs. CONCLUSION: Our study revealed that the use of the currently accepted FIB-4 cutoffs as the screening modality for identifying patients with advanced fibrosis due to metabolic dysfunction-associated steatotic liver disease is insufficient and will result in missing patients with histologically confirmed advanced fibrosis. Use of the revised FIB-4 scores should be considered to diagnose patients with severe obesity at high risk of liver disease progression.