Postoperative serum thioredoxin concentrations correlate with delirium and cognitive dysfunction after hip fracture surgery in elderly patients.

Background: Oxidative stress correlates with occurrence and development of postoperative delirium (POD) and cognitive dysfunction (POCD). Thioredoxin (TRX) is a potent anti-oxidant and its circulating concentrations reflect extent of brain injury. We determined the relation of serum TRX concentrations to POD and POCD in elderly patients undergoing hip fracture surgery.

Methods: In this prospective, observatory study, TRX concentrations in preoperative and postoperative serum from 192 patients and serum from 192 controls were measured using an enzyme-linked immunosorbent assay. The relationship between TRX concentrations and risk of POD and POCD was assessed using a multivariate analysis.

Results: As compared to the controls, postoperative, but not preoperative serum TRX concentrations were significantly increased in the patients. Furthermore, postoperative TRX concentrations and age were identified as the independent predictors for POD and POCD. Also, area under receiver operating characteristic curve (AUC) of postoperative TRX concentrations was obviously higher than that of age in the prediction of POD and POCD. Additionally, in a combined logistic-regression model, TRX concentrations significantly improved the AUCs of age to predict POD and POCD.

Conclusions: TRX in postoperative serum may be a potential biomarker to predict POD and POCD in elder patients undergoing hip fracture surgery.