Applicability and precautions of use of liver injury biomarker FibroTest. A reappraisal at 7 years of age

Four populations were studied: 954 blood donors (P1), 7,494 healthy volunteers (P2), 345,695 consecutive worldwide sera (P3), including 24,872 sera analyzed in a tertiary care centre (GHPS) (P4). Analytical procedures of laboratories with RFPN > 5% and charts of P4 patients in with RFPN were reviewed.The prevalence of RFPN was 0.52% (5/954; 95%CI 0.17-1.22) in P1, 0.51% (38/7494; 0.36-0.70) in P2, and 0.97% (3349/345695; 0.94-1.00) in P3. Three a priori high-risk populations were confirmed: 1.97% in P4, 1.77% in HIV centre and 2.61% in Sub-Saharan origin subjects. RFPN was mostly associated with low haptoglobin (0.46%), and high apolipoproteinA1 (0.21%). A traceability study of a P3 laboratory with RFPFN > 5% permitted to correct analytical procedures.The mean applicability rate of Fibrotest was 99.03%. Independent factors associated with the high risk of false positives/negatives were HIV center, subSaharan origin, and a tertiary care reference centre, although the applicability rate remained above 97%.Due to the limitations of liver biopsy biomarkers are widely used as a non-invasive alternative in patients with chronic liver disease to assess fibrosis stage and necroinflammatory activity [1-3]. One of the most validated serum biomarkers, Fibrotest-Actitest (FT-AT), was introduced on the market in September 2002 and has been widely prescribed since then [2-4]. The French Heath Authorities (HAS) have recommended the following precautions of use for FT: (1) the laboratory that performs the test must use the appropriate assay technique and ensure proper quality control (e.g. with regard to sample storage), and (2) the person who prescribes the test must consider confounding factors when interpreting test results. Patients should have no intercurrent illness, in particular acute inflammation, hemolysis, or Gilbert's syndrome, and should be taking no medications that are known to cause elevated bilirubin levels [3].The aim of the "precautions of use" is to reduce the n