Association of mild cognitive impairment and comorbid depression with postoperative delirium in patients undergoing knee/hip arthroplasty: a prospective cohort study.

BACKGROUND

Postoperative delirium (POD) is common after surgery, involving acute disturbances in attention and cognition. While mild cognitive impairment (MCI) and depression each influence cognition, their combined impact on POD is unclear. We aimed to assess the effect of MCI with comorbid depression on POD and explore whether cerebrospinal fluid (CSF) biomarkers mediate this relationship.

METHODS

This study included 1,464 knee/hip arthroplasty patients divided into four preoperative diagnostic groups: no disease, MCI only, depression only, and MCI with depression. CSF markers were compared between groups, with subgroup analyses by age/gender. POD risk factors were assessed using multifactorial logistic regression, sensitivity analyses, and mediation effect modeling of CSF markers. A POD prediction model was developed and its performance was evaluated via ROC curve analysis, and three-year postoperative survival differences were analyzed.

RESULTS

POD incidence was 13.9% (n = 203). MCI with depression was an independent POD risk factor (OR = 18.56, 95% CI: 8.53-40.77). These patients showed higher T-tau and P-tau, and lower Aβ42 in CSF, with age-related variations. CSF biomarkers partially mediated the association (17.9%-49.9%). The prediction model had an AUC of 0.884 (95% CI: 0.860-0.908). POD patients had significantly lower 3 year survival than non-POD patients, whereas within the POD cohort, MCI with depression was not associated with significantly different mortality.

CONCLUSIONS

MCI with comorbid depression is an independent risk factor for POD, and this association is mediated in part by changes in CSF biomarkers.