The FAT score, a fibrosis score of adipose tissue : predicting weight-loss outcome after gastric bypass Bel Lassen, P. Charlotte, F. Liu, Y. Bedossa, P. Le Naour, G. Tordjman, J. Poitou, C. Bouillot, J. L. Genser, L. /Zucker, Jean-Daniel Sokolovska, N. Aron-Wisnewsky, J. Clement, K. Context: Bariatric surgery (BS) induces major and sustainable weight loss in many patients. Factors predicting poor weight-loss response (PR) need to be identified to improve patient care. Quantification of subcutaneous adipose tissue (scAT) fibrosis is negatively associated with post-BS weight loss, but whether it could constitute a predictor applicable in clinical routine remains to be demonstrated. Objective: To create a semiquantitative score evaluating scAT fibrosis and test its predictive value on weight-loss response after Roux-en-Y gastric bypass (RYGB). Methods: We created a fibrosis score of adipose tissue (FAT score) integrating perilobular and pericellular fibrosis. Using this score, we characterized 183 perioperative scAT biopsy specimens from severely obese patients who underwent RYGB (n = 85 from a training cohort; n = 98 from a confirmation cohort). PR to RYGB was defined as <28% of total weight loss at 1 year (lowest tertile). The link between FAT score and PR was tested in univariate and multivariate models. Results: FAT score was directly associated with increasing scAT fibrosis measured by a standard quantification method (P for trend <0.001). FAT score interobserver agreement was good (kappa = 0.76). FAT score >= 2 was significantly associated with PR. The association remained significant after adjustment for age, diabetes status, hypertension, percent fat mass, and interleukin-6 level (adjusted odds ratio, 3.6; 95% confidence interval, 1.8 to 7.2; P = 0.003). Conclusions: The FAT score is a new, simple, semiquantitative evaluation of human scAT fibrosis that may help identify patients with a potential limited weight-loss response to RYGB. 2017 text https://www.documentation.ird.fr/hor/fdi:010084988 fdi:010084988 Bel Lassen P., Charlotte F., Liu Y., Bedossa P., Le Naour G., Tordjman J., Poitou C., Bouillot J. L., Genser L., Zucker Jean-Daniel, Sokolovska N., Aron-Wisnewsky J., Clement K.. The FAT score, a fibrosis score of adipose tissue : predicting weight-loss outcome after gastric bypass. 2017, 102 (7), 2443-2453 EN