Associations between postoperative cognitive dysfunction, serum interleukin-6 and postoperative delirium among patients after coronary artery bypass grafting: A mediation analysis.

BACKGROUND: POCD is a common complication among patients who underwent coronary artery bypass graft (CABG), it is linked to loss of independence and reduced quality of life.

AIMS AND OBJECTIVES: To examine the association between postoperative cognitive dysfunction (POCD), postoperative delirium (POD) and interleukin-6 (IL-6).

DESIGN: A prospective cohort study.

METHODS: Patients who underwent elective isolated CABG were enrolled. POCD was assessed by a set of cognitive function tools. Delirium was assessed using the CAM-ICU. The logistic regression analyses were used to identify the predictive value of POD or IL-6 on POCD. The path analysis was used to analyse the relationship among POD, IL-6 and POCD.

RESULTS: A total of 212 patients were enrolled, with 25.0% of patients developing POD and 32.5% developing POCD. The multiple logistic regression analysis revealed that patients with POD had a four-fold increased hazard of POCD (OR = 3.655), and patients with IL-6 ≥ 830.50 pg/mL at the 6th hours after surgery had a 5-fold increased risk of experiencing POCD (OR = 5.042). However, the mediation effect of POD between IL-6 and POCD was not statistically significant (β = 0.059, p = .392).

CONCLUSIONS: POD and IL-6 at the 6th hour after surgery (≥830.50 pg/mL) are two potent predictors for POCD, while POD did not play a mediation effect between IL-6 and POCD.

RELEVANCE TO CLINICAL PRACTICE: Early identification of risk factors (e.g., delirium assessment and testing for serum IL-6 levels) by clinical nurses for POCD may contribute to the clinical practice for the targeted prevention nursing strategies.