An apoptosis panel for nonalcoholic steatohepatitis diagnosis

Abstract

Background & aims: The extrinsic death receptor-mediated pathway of apoptosis is involved in nonalcoholic steatohepatitis (NASH) development. Our aims were to create and validate a noninvasive prediction model for NASH diagnosis based on specific circulating markers of apoptosis.

Methods: Our initial cohort consisted of 95 consecutive patients undergoing a liver biopsy for clinically suspected NASH. Blood was obtained from each patient at the time of liver biopsy. Plasma caspase 3 generated cytokeratin-18 fragments (CK-18), soluble Fas (sFas), and soluble Fas ligand (sFasL) were measured. Histology was assessed by an experienced hepatopathologist. The validation cohort consisted of 82 consecutive patients that underwent liver biopsy at the time of bariatric surgery.

Results: Patients with NASH had significantly higher levels of CK-18 and sFas than patients in the "not NASH" group [median (25th, 75th percentile): 508 (280, 846) U/L versus 176 (131, 224) U/L (p<0.001), and 11.8 (7.8, 12.5) ng/ml versus 5.9 (4.8, 8.3) ng/ml (p<0.001), respectively]. A significant positive correlation was revealed between the apoptosis markers and liver histopathology independent of other metabolic factors. A prediction model was generated including CK-18 fragments and sFas levels that showed an AUC of 0.93 and 0.79 in the initial and validation cohorts, respectively. A cutoff value using this model predicted NASH with a sensitivity and specificity of 88% and 89%, respectively.

Conclusions: Quantification of circulating levels of two apoptotic markers accurately predicts the presence of NASH, supporting the potential usefulness of these markers in clinical practice for noninvasive diagnosis of NASH.

Figure 1. An apoptosis panel consisting of plasma CK-18 fragments and sFas levels accurately diagnoses NASH in patients with suspected NAFLD (initial cohort)

The area under the ROC curve is shown for the performance of this panel and its individual components for discriminating NASH from “not NASH”. The panel has an AUC that is significantly higher than the AUC of either CK-18 fragments or sFas alone. The regression formula for prediction of presence of NASH based on this 2-factor model is: Risk score = −6.4894 + 0.0078 × CK-18 fragments (U/L) + 0.4668 × sFas (ng/mL). The best cutoff point is a probability of 36.6% (corresponds to score of −0.5509) that accurately predicts NASH with a sensitivity of 88% and a specificity of 89%. Abbreviation: P, probability.

Figure 2. An apoptosis panel consisting of plasma CK-18 fragments and sFas levels accurately diagnoses NASH in morbidly obese patients undergoing bariatric surgery (validation cohort)

The area under the ROC curve is shown for the performance of this panel for discriminating NASH from “not NASH”.