Objective To explore the values of brain fatty-type acid binding protein (B-FABP) and kallikrein-6 (KLK6) in peripheral blood in predicting postoperative cognitive dysfunction (POCD) of senile patients with hip replacement.

Methods A total of 145 senile patients with hip replacement were selected, and they were divided into POCD group (n=39) and non-POCD group (n=106) according to result of the Montreal Cognitive Assessment (MoCA) at 7 days after surgery. The levels of serum B-FABP and KLK6 before surgery as well as 3 and 7 days after surgery were compared between two groups; the Pearson method was used to analyze the correlation between serum indicators and the MoCA scores at different time points; the single factor and multivariate Logistic regression analysis were used to determine the influencing factors for occurrence of POCD; the receiver operatingcharacteristic (ROC) curve was used to analyze the diagnostic efficiency of serum indicators for POCD.

Results At 3 and 7 days after surgery, the B-FABP levels in the POCD group were significantly higher than that in the non-POCD group, while the KLK6 levels were significantly lower than that in the non-POCD group (P < 0.05). Pearson correlation analysis showed that cognitive impairment score was negatively correlated with the B-FABP at 3 and 7 days after surgery (r=-0.469, -0.341, P < 0.05), while was positively correlated with the KLK6 at 3 and 7 days after surgery (r=0.891, 0.473, P < 0.05). The results of Logistic regression analysis showed that B-FABP at 3 days after surgery (OR=1.898, 95%CI, 1.202 to 2.997), B-FABP at 7 days after surgery (OR=1.669, 95%CI, 1.125 to 2.474), KLK6 at 3 days after surgery (OR=0.676, 95%CI, 0.553 to 0.828), and KLK6 at 7 days after surgery (OR=0.604, 95%CI, 0.400 to 0.912) were the influencing factors for the occurrence of POCD. The ROC curve showed that when the critical value of B-FABP at 3 days after surgery was 156.34 ng/L, the corresponding sensitivity was 69.23%, the specificity was 70.75%, and the area under the curve (AUC) was 0.801 (95%CI, 0.750 to 0.852); when the critical value of B-FABP at 7 days after surgery was 133.02 ng/L, the corresponding sensitivity was 71.79%, specificity was 71.70%, and AUC was 0.760 (95%CI, 0.707 to 0.812); when the critical value of KLK6 at 3 days after surgery was 5.52 μg/L, the corresponding sensitivity was 58.97%, specificity was 60.38%, and AUC was 0.631 (95%CI, 0.564 to 0.698); when the critical value of KLK6 at 7 days after surgery was 6.01 μg/L, the corresponding sensitivity was 61.54%, specificity was 63.21%, and AUC was 0.708 (95%CI, 0.645 to 0.772); based on the Logistic regression results, a risk prediction model for the combined application of the above four indicators was established, and when the critical value of the model was 1.29 (excluding the constant term), the corresponding sensitivity was 82.05%, specificity was 80.19%, and AUC was 0.869 (95%CI, 0.831 to 0.907).

Conclusion Serum B-FABP and KLK6 are closely related to the occurrence of POCD in patients with hip replacement, single and combined detection can effectively predict the occurrence of POCD, and clinical intervention should be performed according to the indicators.