Comparison of Two sTRAtegies For the Non-Invasive Diagnosis of advanCed Liver Fibrosis in NAFLD

Overview

NAFLD, closely linked to overweight and insulin resistance, has reached 25% prevalence worldwide. Advanced liver fibrosis(ALF) must be accurately diagnosed in NAFLD because it defines a subgroup of patients with impaired prognosis, and these patients need a specific management to prevent the occurrence of liver-related complication. Relatively few NAFLD patients develop ALF and it is a challenge for physicians to identify them. Liver biopsy is the reference for liver fibrosis evaluation but this invasive procedure cannot be first-line used in NAFLD. Non-invasive diagnosis of liver fibrosis is now available, especially liver stiffness measurement (LSM) with Fibroscan and blood fibrosis tests. However, Fibroscan is a costly device available only in few specialized centres with thus poor accessibility in face of the large NAFLD population. Blood fibrosis tests can be performed by every physician and are distinguished as "complex" or "simple". Because they include specialized biomarkers, complex blood fibrosis tests are accurate for the diagnosis of ALF but they are quite expensive and not reimbursed, with therefore limited use in clinical practice. Simple blood fibrosis tests have the advantage to include cheap and easy-to-obtain biomarkers with simple calculation thanks to free websites or smartphone applications. Simple blood fibrosis tests are globally less accurate than complex blood fibrosis tests or Fibroscan but, used with a high-sensitivity cut-off, they have the high interest of being able to accurately rule out advanced fibrosis in a significant proportion of NAFLD patients. Recently, two sequential diagnostic procedures have been developed for the diagnosis of ALF with the idea to combine the advantages of the different kind of fibrosis tests: the FIB4-Fibroscan (FIB4-FS) and the eLIFT-FibroMeterVCTE (eLIFT-FMVCTE) algorithms. These algorithms include as first-line procedure a simple blood fibrosis test (FIB4 or eLIFT) which identifies the patients who require a further second-line evaluation with a more accurate non-invasive test (Fibroscan or FibroMeterVCTE). Liver biopsy is finally used as third-line procedure in patients for whom the diagnosis remains undetermined. Such algorithms have the advantage to limit the use of complex fibrosis tests only to a subset of at risk-patients. The TRAFIC study compare two strategies for the diagnosis of ALF in NAFLD patients: the FIB4-Fibroscan algorithm and the eLIFT-FibroMeterVCTE algorithm

FIB4-FS and the eLIFT-FMVCTE were previosuly directly compared in a database of biopsy-proven NAFLD patients. These two algorithms showed a very good \>80% diagnostic accuracy for advanced fibrosis and a very low \<15% rate of liver biopsy requirement. The eLIFT-FMVCTE had a significantly higher diagnostic accuracy (84.6% vs 80.6%, p=0.15), was more specific, and provided higher negative and positive predictive value and higher non-invasive diagnostic accuracy. Finally, these preliminary results suggested the eLIFT-FMVCTE was most suitable for clinical practice than the FIB4-FS. However, because almost all these patients from this preliminary comparative study came from the population where the eLIFT-FMVCTE was developed with thus an optimism bias, the results from this direct comparison require further validation. Therefore, FIB4-FS and the eLIFT-FMVCTE algorithms must now be evaluated and compared in an independent population of NAFLD patients to determine which strategy is the best one for clinical practice.