Evaluation Of The Fast Score In Patients With Nonalcoholic Fatty Liver Disease And High Liver Stiffness Measurements

INTRODUCTION: Liver stiffness measurement (LSM) by vibration controlled transient elastography (VCTE) has changed the management of patients with suspected nonalcoholic fatty liver disease (NAFLD) in terms of risk stratification. Patients with NAFLD and elevated LSM ≥10 kPa are considered high-risk and require further intervention including pharmacotherapy once available. Recently, the FAST score was introduced as a new method to risk stratify patients with NAFLD with patients with high FAST ≥0.67 being considered high-risk and those with FAST ≤0.35 being considered low risk. The aim of the current study was to evaluate the concordance between VCTE and the new FAST score in patients with high LSM. METHODS: Our cohort consisted of consecutive patients who presented for evaluation of fatty liver were included. All had Fibroscan to measure CAP and LSM + AST within 6 months. Only patients with high LSM ≥10 kPa were included in this analysis. The M and XL Fibroscan probes were used based on the machine’s recommendation. Nominal and continuous variables were analyzed with chi-squared and 2-sided T-tests. RESULTS: A total of 665 patients presented with suspected fatty liver, 67.6% were female, 29.8% had diabetes, 58.2% had hypertension, and 46.8% had metabolic syndrome (MetS). A total of 138 patients (20.8%) had LSM ≥10 indicating advanced fibrosis. Of these patients, only 50 (36.2%) had FAST ≥0.67 indicating concordant results. More importantly, 25 patients (18.1%) with LSM ≥10 had FAST ≤0.35 indicating discordant results. Interestingly, 24/25 (96%) of patients in this group had AST < 30 U/L. Additionally, 63 patients (45.6%) with LSM ≥10 had indeterminate FAST between 0.35-0.67. In this cohort, when comparing patients with FAST ≥0.67 to those with FAST ≤0.35, patients with elevated FAST ≥0.67 had lower platelets (231.1 vs 279.9, P = 0.01), higher ALT (104.0 vs 25.2, P < 0.01), and higher ferritin (279.4 vs 100.9, P = 0.01). There was no significant difference in gender or likelihood to have diabetes, hypertension, dyslipidemia, or metabolic syndrome (P > 0.05 for all). CONCLUSION: In patient with LSM indicating high risk for advanced fibrosis, the FAST score showed concordant results in only one third of patients and to our surprise 18% would have been considered low risk based on FAST despite having high LSM. The FAST score should not be used alone to risk-stratify patients with fatty liver especially in those with AST < 30 U/L and providers should be familiar with LSM cutoffs and interpretation.