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

Yuanlong Wang¹Qian He¹Kun Fu²Yanlin Bi¹Bin Wang¹Wenjie Kong¹Shuhui Hua¹Jian Kong¹Xv Shanling¹Hongyan Gong¹Jiahan Wang¹Chuan Li¹Yanan Lin¹Xu Lin^1*

• ¹Qingdao Municipal Hospital, Qingdao, China
• ²Haier Group (China), Qingdao, Shandong Province, China

Postoperative delirium (POD) is a commonly occurring condition in the postoperative period. Therefore, the study intends to investigate the relationship between B2M and POD and the effect of B2M 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 B2M levels were measured utilizing a latex-enhanced immunoturbidimetric assay. Total tau protein (T-tau), phosphorylated tau protein (P-tau), and amyloid β plaque 42 (Aβ42) 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. Risk factors were screened based on multivariate logistic regression, nomograms were drawn, and internal validation was performed to test model efficacy. Patients presenting with POD were grouped according to B2M level and followed up for three years postoperatively for their survival and Kaplan-Meier survival curves were plotted.The prevalence of POD was 7.23%. Serum B2M levels were higher in POD patients compared to non-POD (NPOD) patients (P=0.01). The results of the logistic regression analysis indicated that B2M (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. B2M and POD were partially associated through the mediation of CSF T-tau (10.0%). The K-M survival curves showed that patients with high B2M who developed POD had a higher mortality rate three years after surgery (P = 0.031).In summary, B2M may be a risk factor for POD, which might be mediated in part by CSF T-tau.