Use of noninvasive scores for advanced liver fibrosis can guide the need for hepatic biopsy during bariatric procedures

Background: Patients with obesity are at increased risk for nonalcoholic fatty liver disease (NAFLD). The effectiveness of noninvasive screening tests for ruling out advanced fibrosis (stage 3–4) is unknown. Objectives: To determine the prevalence of advanced fibrosis in patients undergoing routine liver biopsy during bariatric surgery and assess the effectiveness of existing noninvasive risk calculators. Setting: Academic medical center in the United States. Methods: Routine liver biopsies were obtained during first-time bariatric surgery (January 2001–December 2017). Patient demographic characteristics, co-morbidities, and preoperative laboratory values were compiled. Sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) were compared between 3 noninvasive risk calculators for advanced fibrosis: the fibrosis-4 index, NAFLD fibrosis score, and aminotransferase-to-platelet ratio index (APRI). Results: Among 2465 patients, the prevalence of advanced fibrosis (stage 3–4) was 3.4%. The mean age was 45.5 years, and the mean body mass index was 46.8. The sensitivity of noninvasive risk calculators ranged from 85% (NAFLD fibrosis score) to 24% (APRI). The NAFLD fibrosis score performed best in screening out advanced fibrosis, with an NPV of 99%. The PPV ranged from 9% to 65%. In this study cohort, the use of the NALFD fibrosis score correctly ruled out advanced fibrosis in 893 (36%) patients, with 13 false negatives. Conclusions: The prevalence of advanced fibrosis in individuals undergoing routine first-time bariatric procedures is 3.4%. Use of the NALFD fibrosis score can rule out advanced fibrosis in one-third of this population, and guide surgical decision-making.