Introduction With a quarter of the UK population estimated to have some degree of NAFLD, there is a need for a robust and economical population based screen to identify individuals with advanced fibrosis. It is recognised that many patients with NAFLD have normal-range ALT levels. Non-invasive scoring systems may exclude advanced disease without the need for liver biopsy, however reliability of these tests in this population has not been determined.
Aim To assess performance of several simple non-invasive tests for fibrosis in patients with biopsy-proven NAFLD and normal ALT levels.
Method Patients who were reviewed in the Freeman Hospital fatty liver clinic between 1999 and 2009 were included. Liver biopsies were assessed using the Kleiner score. The AST/ALT ratio, BARD, FIB-4 and NAFLD fibrosis scores were calculated from blood tests taken within 6 months of liver biopsy.
Results 305 patients were included (70 with normal ALT [ALT <30 IU/l for females and ALT <45 IU/l for males] and 235 with raised ALT). 24% of subjects with normal ALT and 17% with raised ALT had advanced fibrosis (Kleiner stage 3–4). Patients with normal ALT were significantly younger (p=0.004) and had lower BMI (p=0.03) than those with raised ALT. The area under ROC curve (AUROC), sensitivity, specificity, positive and negative predictive values for a diagnosis of advanced fibrosis using each score is shown in Abstract OP11 table 1. In addition, the proportion of patients with a score below the cut-off who would avoid liver biopsy is displayed. The specificity of the AST/ALT ratio, BARD and NAFLD fibrosis scores for advanced fibrosis was low in patients with normal ALT, which would result in a high proportion of patients with mild disease having a liver biopsy. FIB-4 score performed best overall.
Conclusion The FIB-4 score performed well in patients with normal or raised ALT, reliably excluding advanced fibrosis and reducing the need for liver biopsy. Therefore, the FIB-4 score may be an appropriate tool for use in primary care to triage patients with NAFLD who need referral for further assessment. Further validation in a general practice cohort is underway.
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