Utility and appropriateness of the fatty Liver Inhibition of progression ( FLIP) Algorithm and Steatosis, Activity, and Fibrosis ( SAF) Score in the evaluation of Biopsies of Nonalcoholic Fatty Liver Disease

Biopsy is still the gold standard for the diagnosis of nonalcoholic steatohepatitis but thedefinition may vary among pathologists, a drawback especially in evaluation of biopsiesfor clinical trials. We previously developed a scoring system (steatosis, activity, fibrosis[SAF]) allowing the use of an algorithm (fatty liver inhibition of progression [FLIP])for the classification of liver injury in morbid obesity. The aim of this study was todetermine whether the use of the SAF score and FLIP algorithm can decrease interobservervariations among pathologists. In a first session, pathologists categorized 40 liverbiopsies of patients with nonalcoholic fatty liver disease (NAFLD) according to theirown experience. In a second reading session, each pathologist reclassified the same slidesby using the FLIP algorithm and SAF score, blinded to their first evaluation. Theexperiment was repeated with two different groups of pathologists at varying levels oftraining in liver pathology. The percentage of biopsy interpretation concordant with referenceevaluation increased from 77% to 97% in Group 1 and from 42% to 75% inGroup 2 after the use of the SAF score and FLIP algorithm. The strength of concordancein classification increased in Group 1 from moderate (j50.54) to substantial(j50.66) and from fair (j50.35) to substantial (j50.61) in Group 2 with applicationof the algorithm. With regard to the SAF score, concordance was substantial inGroup 1 for steatosis (j50.61), activity (j50.75), and almost perfect for fibrosis(j50.83 after pooling 1a, 1b, and 1c together into a single score F1). Similar trendswere observed in Group 2 (j50.54 for S, j50.68 for A, and j50.72 for F). Conclusion:The FLIP algorithm based on the SAF score should decrease interobserver variationsamong pathologists and are likely to be implemented in pathology practice.(HEPATOLOGY 2014;60:565-575)