Enhanced Liver Fibrosis (ELF) Panel
What it measures: fibrosis
Who should take it: diagnosed NAFLD/NASH patients
Where to get it: Europe
The Enhanced Liver Fibrosis (ELF) panel, is a blood test developed by Siemens Healthineers that measures fibrosis using serum markers. Though this test is not commercially available in the United States, ELF is typically used to assess the risk of progression to cirrhosis and liver-related clinical events, most commonly to diagnose advanced fibrosis, ≥F2, in patients with NAFLD/NASH.
The ELF test is a panel of three biomarkers: type III procollagen peptide (PIIINP), hyaluronic acid (HA), and tissue inhibitor of metalloproteinase-1 (TIMP1). These values are summarized into a single score, which can be compared to different thresholds for diagnosis. The thresholds recommended by Siemens are 7.7 (lower threshold) and 9.8 (higher threshold). Meta-analysis has shown that the lower threshold of 7.7 had a sensitivity of 0.93 and a specificity of 0.34; this means that 93% with advanced fibrosis will be identified, while 34% of those without advanced fibrosis will be identified. The higher threshold of 9.8 showed a specificity of 0.86 and a sensitivity of 0.65; this means that 86% of those with advanced fibrosis will be identified, while 65% of those without advanced fibrosis will be identified. As you can see, the lower threshold ensures that more people with advanced fibrosis will be accurately identified, at the expense of accurately identifying those without advanced fibrosis.
Interestingly, the National Institute for Health Care and Excellence (NICE), a guideline-publishing public health body in England, sets the threshold for ELF at 10.51. At this value, ELF demonstrates a specificity of 0.93 and sensitivity of 0.51. In other words, a cutoff of 10.51 means that 93% of those with advanced fibrosis will be identified and 51% of those without advanced fibrosis will be identified.
While it is important to consider the effects of these various thresholds, the prevalence of advanced fibrosis in a population also has a significant impact. How much advanced fibrosis is present in a population determines which threshold should be used. In settings with a low prevalence, ELF is a useful tool to rule out NAFLD/NASH patients from having advanced fibrosis and less certain when trying to rule in advanced cirrhosis. At a prevalence >30%, the ability of the test to accurately identify those with advanced cirrhosis is much lower.
 Vali, Yasmin et al., Enhanced liver fibrosis test for the non-invasive diagnosis of fibrosis in patients with NAFLD: A systematic review and meta-analysis, Journal of Hepatology, April 2020, doi: https://doi.org/10.1016/j.jhep.2020.03.036
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