Patients with suspected DILI were enrolled in the DILIN Prospective Study and data were collected as previously described (5 (link)). Patients or their next of kin provided written informed consent which included pathology review. If available, up to 10 unstained re-cuts of liver tissue (needle or wedge biopsies, explanted native livers and autopsies) obtained at investigator discretion were sent to the central pathology core laboratory (NCI) for repeat staining and storage. Slides were stained with hematoxylin and eosin, Masson trichrome, reticulin, iron, copper and periodic acid-Schiff (PAS) with diastase. Biopsies were reviewed by the central hepatic pathologist (DEK) who was blinded to all clinical information including the name(s) of the implicated drugs. All liver tissues received the same predefined structured histological evaluation. This systematic evaluation of 48 separate histologic features was divided into seven broad categories: inflammation, necrosis/cell injury, fibrosis, steatosis, cholestasis, vascular injury, and other findings including evaluation of special stains (Supplementary Table 1 )(10 ). The number of portal areas (complete and partial) was recorded as a measure of biopsy adequacy. The diagnostic classification used (Supplementary Table 2 ) was based on published descriptions of pathologic changes in DILI (11 , 12 ). Standard hepatopathological diagnostic criteria (13 ) were used to define patterns of injury. The overall injury pattern was classified into one of 18 patterns: acute hepatitis, chronic hepatitis, acute cholestasis, chronic cholestasis, cholestatic hepatitis (mixed hepatocellular and cholestatic injury), granulomatous changes, steatosis (macrovesicular or microvesicular), steatohepatitis, coagulative/confluent necrosis (zonal or non-zonal), massive/sub-massive necrosis, vascular injury, hepatocellular alteration, nodular regenerative hyperplasia, mixed or otherwise unclassifiable injury, minimal non-specific changes, and absolutely normal.
For the purposes of the current analysis, a biopsy was eligible for inclusion if it was obtained within six months of the protocol-defined DILI onset date and was adequate in the pathologist’s opinion to assign a pattern of injury. Tissues from explants or autopsies were excluded. If two biopsies qualified from the same patient, the larger biopsy was used. Once the biopsy data from blinded review was recorded, additional information was abstracted from the DILIN prospective database including the patient age, sex and laboratory data (alanine aminotransferase (ALT), alkaline phosphatase (Alk P) and total bilirubin) at the time of DILI onset and at or around the time of liver biopsy (within 7 days). The biochemical injury pattern (hepatocellular, mixed or cholestatic) was calculated as the ratio (R) of ALT to Alk P normalized by their respective upper limits of normal from laboratory data at the time of onset. If a suspected case had undergone causality determination (9 (link)) then the causality score, severity score and implicated medications were also obtained from the database.
For the purposes of the current analysis, a biopsy was eligible for inclusion if it was obtained within six months of the protocol-defined DILI onset date and was adequate in the pathologist’s opinion to assign a pattern of injury. Tissues from explants or autopsies were excluded. If two biopsies qualified from the same patient, the larger biopsy was used. Once the biopsy data from blinded review was recorded, additional information was abstracted from the DILIN prospective database including the patient age, sex and laboratory data (alanine aminotransferase (ALT), alkaline phosphatase (Alk P) and total bilirubin) at the time of DILI onset and at or around the time of liver biopsy (within 7 days). The biochemical injury pattern (hepatocellular, mixed or cholestatic) was calculated as the ratio (R) of ALT to Alk P normalized by their respective upper limits of normal from laboratory data at the time of onset. If a suspected case had undergone causality determination (9 (link)) then the causality score, severity score and implicated medications were also obtained from the database.
