A single non‐invasive model to diagnose non‐alcoholic fatty liver disease ( NAFLD ) and non‐alcoholic steatohepatitis ( NASH )

Background and Aim Non‐alcoholic steatohepatitis ( NASH ) is the progressive form of non‐alcoholic fatty liver disease ( NAFLD ). A liver biopsy is considered the “gold standard” for diagnosing/staging NASH . Identification of NAFLD / NASH using non‐invasive tools is important for intervention. The study aims were to: develop/validate the predictive performance of a non‐invasive model (index of NASH [ ION ]); assess the performance of a recognized non‐invasive model (fatty liver index [ FLI ]) compared with ION for NAFLD diagnosis; determine which non‐invasive model ( FLI , ION , or NAFLD fibrosis score [ NFS ]) performed best in predicting age‐adjusted mortality. Methods From the N ational H ealth and N utrition E xamination S urvey III database, anthropometric, clinical, ultrasound, laboratory, and mortality data were obtained ( n  = 4458; n  = 861 [19.3%] NAFLD by ultrasound) and used to develop the ION model, and then to compare the ION and FLI models for NAFLD diagnosis. For validation and diagnosis of NASH , liver biopsy data were used ( n  = 152). Age‐adjusted C ox proportional hazard modeling estimated the association among the three non‐invasive tests ( FLI , ION , and NFS ) and mortality. Results FLI 's threshold score > 60 and ION's threshold score > 22 had similar specificity ( FLI  = 80% vs   ION  = 82%) for NAFLD diagnosis; FLI  < 30 (80% sensitivity) and ION  < 11 (81% sensitivity) excluded NAFLD . An ION score > 50 predicted histological NASH (92% specificity); the FLI model did not predict NASH or mortality. The ION model was best in predicting cardiovascular/diabetes‐related mortality; NFS predicted overall or diabetes‐related mortality. Conclusions The ION model was superior in predicting NASH and mortality compared with the FLI model. Studies are needed to validate ION .