Reduced metabolic flexibility is a predictor of weight gain among liver transplant recipients.

Metabolic flexibility is the ability to match biofuel availability to utilization and is inversely associated with increased metabolic burden among liver transplant (LT) recipients. The present study evaluated the impact of metabolic flexibility on weight gain following LT. LT recipients were enrolled prospectively (n = 47) and followed for 6 months. Metabolic flexibility was measured using whole-room calorimetry and is expressed as a respiratory quotient (RQ). Peak RQ represents maximal carbohydrate metabolism and occurs in the post-prandial state, while trough RQ represents maximal fatty acid metabolism occurring in the fasted state. The clinical, metabolic, and laboratory characteristics of the study cohort of lost weight (n = 14) and gained weight (n = 33) were similar at baseline. Patients who lost weight were more likely to reach maximal RQ (maximal carbohydrate oxidation) early and rapidly transitioned to trough RQ (maximal fatty acid oxidation). In contrast, patients who gained weight had delayed time to peak RQ and trough RQ. In multivariate modeling, time to peak RQ (ß-coefficient 0.509, p = 0.01), time from peak RQ to trough RQ (ß-coefficient 0.634, p = 0.006), and interaction between time to peak RQ to trough RQ and fasting RQ (ß-coefficient 0.447, p = 0.02) directly correlated with the severity of weight gain. No statistically significant relationship between peak RQ, trough RQ, and weight change was demonstrated. Inefficient transition between biofuels (carbohydrates and fatty acids) is associated with weight gain in LT recipients that is independent of clinical metabolic risk. These data offer novel insight into the physiology of obesity after LT with the potential to develop new diagnostics and therapeutics.

Evaluation of liver stiffness measurement-based scores in liver transplantation recipients.

Combining bioclinical parameters with liver stiffness measurement (LSM) has improved the diagnostic performance of vibration-controlled transient elastography (VCTE) for detection of advanced fibrosis in patients with chronic liver disease. However, this approach has not yet been tested in liver transplantation (LT) recipients. Thus, the aim of this study was to evaluate the diagnostic performance of combining LSM-based scores with LSM alone for the detection of advanced fibrosis in LT recipients. Adult LT recipients with a liver biopsy, VCTE, and clinical data necessary to construct LSM-based fibrosis models (FibroScan-AST [FAST], AGILE-3+, and AGILE-4) were included ( n = 132). The diagnostic statistics for advanced fibrosis (fibrosis stage 0-2 vs. 3-4) were determined by optimal cut-off using the Youden index. The area under the receiver operating characteristic curve (AUROC) for LSM was 0.94 (95% confidence interval [95% CI], 0.89-0.99), FAST was 0.65 (95% CI, 0.50-0.79), AGILE-3+ was 0.90 (95% CI, 0.83-0.97), and AGILE-4 was 0.90 (95% CI, 0.83-0.97). No statistically significant differences were noted between the AUROC of LSM versus LSM-based scores. The false-positive rates for AGILE-3+ and AGILE-4 were 14.5% and 11.8% compared with 8.3% for LSM alone. The false-positive rates in LSM-based scores were higher among patients with diabetes mellitus, higher AST levels, and lower platelet counts. The LSM-based scores did not improve the diagnostic performance of LSM alone in LT recipients for the detection of advanced fibrosis. This lack of improvement in diagnostic performance results from the impact of immunosuppression on bioclinical profile and underscores the importance of developing LSM-based scores that are specific to LT patients.