Does a calculated "NAFLD fibrosis score" reliably negate the need for liver biopsy in patients undergoing bariatric surgery?

Background: Nonalcoholic fatty liver disease (NAFLD) represents the most common cause of chronic liver disease in the USA. Biopsy has been the standard for determining fibrosis but is invasive, costly, and associated with risk. Previous studies report a calculated "NAFLD fibrosis scores" (cNFS) as a means to overcome the need for biopsy. We compared cNFS versus biopsy-pathological scoring for patients undergoing bariatric surgery.

Methods: We retrospectively reviewed patients with available preoperative labs and patient information undergoing Roux-en-Y gastric bypass (RYGBP) surgery at a single institution over a 5.5-year period. Biopsy samples were blind scored by a single hepatopathologist and compared with scores calculated using a previously reported cNFS.

Results: Of the 225 patients that met the inclusion criteria, the mean body mass index was 44.6 ± 5.4 kg/m(2) and 85 % were female. Using the cNFS, 39.6 % of patients were categorized into low fibrosis, 52 % indeterminate, and 8.4 % high fibrosis groups. Analysis of fibrosis by pathology scoring demonstrated 2 of 89 (2.2 %) and 7 of 110 (3.4 %) had significant fibrosis in the low and intermediate groups, respectively. Conversely, in the high fibrosis group calculated by cNFS, only 6 of 19 (31.6 %) exhibited significant fibrosis by pathology scoring.

Conclusions: No definitive model for accurately predicting presence of NAFLD and fibrosis currently exits. Furthermore, under no circumstances should a clinical "NAFLD fibrosis score" replace liver biopsy at this time for RYGBP patients.