Correlation of β2-microglobulin with postoperative delirium and 3-year mortality undergoing knee or hip replacement surgery: a prospective cohort study

Introduction Postoperative delirium (POD) is a commonly occurring condition in the postoperative period. Therefore, the study intends to investigate the relationship between B 2 M and POD and the effect of B 2 M levels on three-year postoperative mortality in patients with POD. Methods Postoperatively, the Confusion Assessment Method (CAM) and the Monumental Delirium Assessment Scale (MDAS) were used to assess the incidence and severity of POD. Preoperative plasma B 2 M levels were measured utilizing a latex-enhanced immunoturbidimetric assay. Total tau protein (T-tau), phosphorylated tau protein (P-tau), and amyloid β plaque 42 (Aβ 42 ) were detected in preoperative cerebrospinal fluid (CSF) by enzyme-linked immunosorbent assay. Logistic regression equations were applied to examine the risk factors linked to POD. Patients presenting with POD were grouped according to B 2 M level and followed up for 3 years postoperatively for their survival and Kaplan–Meier survival curves were plotted. Results The prevalence of POD was 7.23%. Serum B 2 M levels were higher in POD patients compared to non-POD (NPOD) patients ( p = 0.01). The results of the logistic regression analysis indicated that B 2 M ( OR = 1.394, 95% CI = 1.017–1.910, p = 0.002) and T-tau ( OR = 1.006, 95% CI = 1.002–1.011, p = 0.007) posed a risk for POD. B 2 M and POD were partially associated through the mediation of CSF T-tau (10.0%). The K-M survival curves showed that patients with high B 2 M who developed POD had a higher mortality rate 3 years after surgery ( p = 0.031). Conclusion In summary, B 2 M may be a risk factor for POD, which might be mediated in part by CSF T-tau.