The mid-infrared spectroscopy: a novel non-invasive diagnostic tool for NASH diagnosis in severe obesity

Abstract Background & Aims This study evaluates the diagnostic performance of an innovative based on mid-infrared (MIR) spectroscopy for diagnosis of NASH (non-alcoholic steatohepatitis). Methods Severely obese patients who underwent a bariatric procedure at the University Hospital of Nice, France (n=395) were prospectively recruited. The clinico-biological characteristics were measured prior to surgery. Liver biopsies were collected during the surgical procedure and assessed by a pathologist. A training group (316 patients, NASH: 16.8%) and a validation group (79 patients, NASH: 16.5%) were randomly defined. MIR spectra were acquired by FEWS technology using chalcogenide glass fiber optic sensors and a spectrometer. This technique is an absorption spectroscopic technique delivering a spectrum that identifies the molecular composition of a sample, defining the patient metabolic fingerprint. Results The Areas Under the Receiver Operating Curve (AUROC) for the diagnosis of NASH were 0.82 and 0.77 in the training and validation groups, respectively. The best threshold was 0.15, which was associated with a sensitivity of 0.75 and 0.69, and a specificity of 0.72 and 0.76. Negative predictive values of 0.94 and 0.93 and positive predictive values of 0.35 and 0.36, as well as correctly classified patient rates of 72 and 75% were obtained in the training and validation groups, respectively. A composite model with AST, triglyceride level, waist circumference to the MIR spectra led to an increase of AUROC (0.88 and 0.84). Conclusions MIR spectroscopy provides good sensitivity and negative predictive values for NASH screening in patients with severe obesity. Lay summary There is an urgent need for non-invasive diagnosis and monitoring of non-alcoholic steatohepatitis (NASH). This study evaluates the performance of SPID™, a new tool for fast NASH diagnosis based on mid-infrared (MIR) spectroscopy. Using serum samples from severely obese patients who underwent a bariatric procedure enabling a concomitant liver biopsy, the MIR spectroscopy model performed well in screening patients for NASH as compared to NASH histologic diagnosis.