,13 have used histological fibrosis grade as the standard for comparison, we should be aware of an important question regarding the discrepancy between the interpretation of LB and non-invasive fibrosis prediction models. The histological grading system generally concentrates on the architectural changes in the liver parenchyma due to fibrosis progression, whereas non-invasive fibrosis prediction models seem to be related to the total amount of fibrosis. Thus, it can introduce a different bias to compare them directly. Second, nearly all of the studies of the non-invasive prediction of liver fibrosis
have been cross-sectional, and their performance is reported using the AUROC for significant KU-57788 supplier fibrosis or cirrhosis, with corresponding cut-off liver stiffness values and diagnostic indices, including sensitivity, specificity, and positive
and negative predictive values. However, further development of alternative non-invasive methods for predicting liver fibrosis will be restricted if physicians rely solely on the results of cross-sectional studies. Because LB itself is an imperfect gold standard, achieving an Selleckchem PI3K inhibitor AUROC close to 1 in an analysis based on LB data is impossible, even when certain serologic fibrosis markers, formulae, and TE or TE-based models measure liver fibrosis perfectly. Thus, if one insists that a certain newly-identified non-invasive
fibrosis prediction marker or model has an AUROC of 1 (perfect concordance with LB data), the imperfection of the model is proven Racecadotril paradoxically. That is, although many of the reported non-invasive fibrosis prediction models with an AUROC over about 0.9 might have already been perfect in predicting liver fibrosis, we who believe LB to be the gold standard, have failed to recognize this. Furthermore, comparing two tests with different AUROC, even in the same population, is difficult because the small differences in AUROC do not necessarily mean that one non-invasive model with a lower AUROC has an inferior performance to that of the other models with a high AUROC, due to the imperfection of LB as a gold standard. Who knows whether this small difference in the AUROCs is caused by the non-invasive models, LB, or both. Third, since the perfect gold standard has yet to be determined, the validation of non-invasive serologic fibrosis markers, formulae, and TE or TE-based models using cross-sectional studies is inevitably limited. Only longitudinal studies using unequivocal clinical end-points related to the progression of liver fibrosis, such as decompensation events, hepatocellular carcinoma development, or liver-related death, can confirm the clinical relevance of the newly-proposed fibrosis prediction models.