Utility and limitations of APRI and FIB 4 to predict staging in a cohort of nonselected outpatients with hepatitis

de Oliveira AC, et al. in this issue of Annals of Hepatology focus on the usefulness of AST-to-platelet ratio index (APRI) and Fibrosis-4(FIB4) values as predictive algorithms in patients with C hepatitis.1,2 Chronic hepatitis C virus infection (CHC) is currently the leading cause of liver cirrhosis, hepatocellular carcinoma and represents an of indication for liver transplantation. CHC therefore represents a major burden of care worldwide. Due to elevated costs of new antiviral agents, a careful stadiation of liver injury is required in the treatment decision making process, which is still mainly based on liver histology from biopsy specimens during an invasive procedure which carries some risks and sampling errors and is not well accepted by patients. Therefore, the identification of noninvasive markers is being actively investigated. At this aim, WHO suggests the use of simple algorithms, i.e. APRI and FIB4 (AST, ALT, platelet count, and patient age) score for staging CHC, in view of their convenience, easy access, and validated accuracy in developing countries. Fibrotest®, and transient elastography, although perform well, are costly techniques not yet diffused in lowand middle-income countries. In this paper, the authors assessed the value of APRI and FIB4 tests in identifying fibrotic livers in a cohort of non-selected CHC patients (798 adult outpatients analyzed retrospectively) who underwent a prior liver biopsy and histology (Metavir) in a referral center at São Paulo, Brazil. The predominant form (> 71%) was genotype 1. At histology, 288 patients (36%) had no fibrosis or showed early-stage fibrosis (F0 F1), 64% of patients had significant fibrosis (> F2) with 44% showing advanced fibrosis and 28% cirrhosis. Using the recommended cut off values, approximately 30 40% of the patients could not be correctly classified. In the remainder, either APRI or FIB4 alone correctly diagnosed 80 85% of cases (the AUROC for significant fibrosis, advanced fibrosis, and cirrhosis were 0.809, 0.819, and 0.815, respectively for the APRI test and 0.803, 0.836 and 0.852, respectively for FIB4). As reported, FIB4 performed better for advanced fibrosis, APRI lower and upper values performed better for diagnosis of cirrhosis, although a better AUROC was obtained by FIB4 test. Sequential use of the APRI and FIB4 tests did not provide a further advantage. However, combined application of the tests improved their discriminant ability for the different degrees of hepatic fibrosis and reduced the number of incorrectly diagnosed cases. In conclusion, de Oliveira, et al. show that APRI or FIB4 tests for detection of hepatic fibrosis may be a viable alternative to liver biopsy in routine practice and in referral centers in lowand middle-income countries to select CHC patients who are candidate for treatment. Despite relatively good accuracy, approximately one-third of patients could not be assessed by both methods as the obtained values were not located between the given cutoff points. This subgroup of CHC patients would require additional diagnostic methods to assess liver fibrosis and to decide for treatment option.