Suboptimal reliability of liver biopsy evaluation has implications for randomized clinical trials

•Liver biopsy is a critical inclusion criteria and outcome measure in NASH studies.•Reader variability was tested in 678 biopsies from a NASH study of MSDC-0602K.•Kappas were poor for the diagnosis of NASH, its resolution and fibrosis improvement.•Almost half of the patients would have been excluded from entry by 1 of the readers.•Poor reliability allows improper entry, misclassification, and diminishes treatment effect.