Objective:To evaluate the association between preoperative serum β 2-microglobulin (β 2MG) concentrations and postoperative delirium (POD) in elderly patients. Methods:The study selected patients who underwent knee or hip arthroplasty under spinal-epidural anesthesia on an elective basis at Qingdao Municipal Hospital from May 2021 to November 2022. The patients were divided into a POD group and a non-POD group based on the occurrence of POD. The study was conducted as part of the Perioperative Neurocognitive Impairment and Biomarkers Lifestyle Cohort, which was a nested case-control study. The study collected baseline data from two groups of patients and analyzed the differences between them. Logistic regression was used to identify the risk factors for POD. The stability of the regression model was tested using sensitivity analysis. The mediation model was used to examine whether cerebrospinal fluid (CSF) biomarkers mediated the relationship between β 2MG and POD. The receiver operating characteristic curve was drawn and the area under the curve was calculated to evaluate the accuracy of preoperative β 2MG concentrations and CSF biomarker concentration in predicting POD. Results:There were 57 cases in POD group and 449 cases in non-POD group. The results of logistic regression analysis showed that the increased β 2MG and CSF total tau protein (t-tau) concentrations were risk factors for POD, and the increased CSF β-amyloid 42 concentration was a protective factor for POD after adjustment for multiple confounders such as age, gender, education, Mini-Mental State Examination, history of hypertension and infusion volume ( P<0.05). The results of mediation analysis showed that the serum β 2MG′s effect on POD was partly mediated by t-tau (18.1%). The results of the receiver operating characteristic curve showed that the area under the curve of the β 2MG concentration combined with the CSF biomarker concentration was 0.742. Conclusions:Elevated preoperative serum β 2MG concentration is a risk factor for POD in elderly patients, and the relationship may be partly mediated by CSF t-tau.

Objective:To evaluate the relationship between preoperative serum bilirubin concentrations and postoperative delirium (POD) in the patients undergoing knee or hip replacement.Methods:Medical records from 413 patients undergoing knee or hip arthroplasty were selected from August 2020 to October 2023 at Qingdao Municipal Hospital using a nested case-control design based on the PNDABLE study cohort. The patients were divided into POD group ( n=77) and non-POD group ( n=336) according to whether POD occurred. Univariate analysis was used to analyze the influencing factors. Logistic regression was used to identify the risk factors for POD. The significance of mediation effect was tested. The receiver operating characteristic curve was drawn to evaluate the accuracy of risk factors in predicting POD. Results:There were significant differences in age, education time, ratio of diabetes history, Memorial Delirium Assessment Scale score, total bilirubin concentration, direct bilirubin concentration, indirect bilirubin concentration, Aβ 42 concentration, p-tau concentration, t-tau concentration, Aβ 42/p-tau ratio and Aβ 42/t-tau ratio between POD group and non-POD group ( P<0.05). The results of logistic regression analysis showed that preoperative serum total bilirubin, direct bilirubin and indirect bilirubin were risk factors for POD ( P<0.05). The results of mediation effects showed that the concentration of total tau protein in CSF partly mediated the relationship between high serum total bilirubin, direct bilirubin and indirect bilirubin concentrations and POD. The area under the receiver operating characteristic curve of total bilirubin, direct bilirubin and indirect bilirubin combined with CSF biomarker concentrations in predicting POD was 0.83 ( P<0.001). Conclusions:Preoperative elevated concentrations of total bilirubin, direct bilirubin and indirect bilirubin are risk factors for POD in the patients undergoing knee or hip replacement. CSF t-tau concentration has a partly mediating role in the association between serum total bilirubin, direct bilirubin and indirect bilirubin concentrations and the development of POD.

Objective:To evaluate the relationship between physical activity (PA) and postoperative delirium (POD) in elderly patients undergoing knee or hip arthroplasty.Methods:The study was conducted as part of the Perioperative Neurocognitive Impairment and Biomarkers Lifestyle Cohort, which was a nested case-control study. Medical records from elderly patients undergoing elective knee or hip arthroplasty under spinal-epidural anesthesia at Qingdao Municipal Hospital from August 2022 to August 2023 were collected. The patients were divided into a POD group ( n=89) and a non-POD group ( n=221) based on the occurrence of POD. Peripheral blood samples were collected before surgery, and the cerebrospinal fluid (CSF) 2 ml was extracted after successful puncture under spinal-epidural anesthesia for determination of the concentrations of amyloid-β 42 (Aβ 42), total tau protein (t-tau), and phosphorylated tau protein (p-tau) by enzyme-linked immunosorbent assay. Logistic regression was used to analyze the influencing factors of POD, and the mediation analysis was conducted to examine the mediating role of CSF biomarker in the relationship between PA and POD. Results:Logistic regression analysis showed that the increased concentration of CSF biomarkers Aβ 42 ( OR=0.997, P=0.006), elevated ratio of Aβ 42/t-tau ( OR=0.642, P=0.003), elevated ratio of Aβ 42/p-tau ratio ( OR=0.872, P=0.001) and PA ( OR=0.374, P=0.001) were protective factors for POD, while the elevated concentrations of t-tau ( OR=1.006, P=0.001) and p-tau ( OR=1.030, P=0.011) were risk factors for POD after adjusting for multi-confounders such as hypertension, diabetes, history of drinking, years of education and Mini-Mental State Examination score. The results of the mediation analysis showed that Aβ 42 (20%), t-tau (16%), Aβ 42/t-tau (23%) and Aβ 42/p-tau (28%) played mediating roles in the relationship between PA and POD. Conclusions:PA is a protective factor for POD in elderly patients undergoing knee or hip arthroplasty and CSF biomarkers may play a mediating role in the relationship between PA and POD.

Objective:To evaluate the relationship between the preoperative sleep quality and postoperative delirium (POD) in elderly patients.Methods:Three hundred and eighty-nine patients of either sex, aged 65-90 yr, with American Society of Anesthesiologists Physical Status classification Ⅰ or Ⅱ, who underwent elective knee/hip arthroplasty under combined spinal-epidural anesthesia in Qingdao Municipal Hospital from May 2022 to October 2023, were selected. The Pittsburgh Sleep Quality Index scale was applied at 1 day before surgery to assess the sleep quality within 1 month before surgery. The cerebrospinal fluid (CSF) specimens 2 ml were withdrawn from the subarachnoid space before anesthesia for determination of the concentrations of biomarkers (β-amyloid), total tau protein [t-tau], and phosphorylated tau protein [p-tau]) by enzyme-linked immunosorbent assay. Patients were divided into POD group and non-POD group based on whether delirium occurred within 7 days after surgery. Logistic regression was used to identify the risk factors for POD, and the sensitivity analysis was used to test the stability of the regression models. The mediation model was used to examine whether CSF biomarkers mediated the link between sleep quality and POD. The accuracy of preoperative sleep quality and CSF biomarker concentrations in predicting the occurrence of POD was evaluated by plotting the receiver operating characteristic curve and calculating the area under the curve.Results:Two hundred and seventy-nine patients were finally included, with 33 patients in POD group and 246 patients in non-POD group. The results of logistic regression analysis showed that shorter sleep duration, use of hypnotics, daytime dysfunction within 1 month before surgery, elevated t-tau concentrations in CSF, and elevated p-tau concentrations in CSF were risk factors for POD after adjusting for multiple confounding factors such as age, sex, body mass index, years of education, Mini-Mental State Examination score, and VAS score. The results of mediating effect showed that the effect of use of hypnotics and daytime dysfunction within 1 month before surgery on POD was partially mediated by p-tau concentrations in CSF (>10%). The area under the curve of combination of daytime dysfunction, sleep duration, use of hypnotics within 1 month before surgery, and CSF biomarker concentrations in predicting POD was 0.979.Conclusions:Shortened sleep duration, use of hypnotic, and daytime dysfunction with 1 month before surgery are risk factors for POD in elderly patients, and the association between use of hypnotics and daytime dysfunction and POD is partially mediated by p-tau in CSF.

Objective:To evaluate the relationship between preoperative SARS-CoV-2 vaccination and postoperative delirium(POD) in the patients.Methods:A total of 938 participants of either sex, aged 50-90 yr, weighing 50-90 kg, of American Society of Anesthesiologists Physical Status classificationⅠorⅡ, with preoperative Mini-Mental State Examination score ≥24, without communication barriers, undergoing elective knee or hip joint replacement under combined spinal-epidural anesthesia from June 2020 to June 2022 in Qingdao Municipal Hospital, were enrolled. The vaccination with SARS-CoV-2 inactivated vaccine within 6 months before operation was recorded. The cerebrospinal fluid 2 ml was extracted after the puncture needle was successfully inserted into the subarachnoid space for determination of the concentrations of Aβ42, total tau protein (t-tau), and phosphorylated tau protein (p-tau) by enzyme-linked immunosorbent assay (by enzyme-linked immunosorbent assay). The Aβ42/t-tau and Aβ42/p-tau ratios were calculated. POD was assessed using the Confusion Assessment Method twice a day within 7 days after surgery or before discharge.The patients were divided into POD group and non-POD group according to whether they developed POD. The risk factors of which P values were less than 0.20 in the univariate logistic regression would enter the multivariate logistic regression analysis to investigate the relationship between SARS-CoV-2 vaccine and level of cerebral spinal fluid (CSF) biomarkers and POD. Results:Eight hundred and seventy-four patients were finally enrolled in the analysis, of which 169 patients developed POD, with an incidence of 19.3%.The results of logistic regression showed that vaccination with SARS-CoV-2 inactivated vaccine within 6 months before operation, preoperative concentrations of Aβ42 in CSF, and increase in Aβ42/t-tau and Aβ42/p-tau ratios were protective factors for POD, and preoperative elevated concentrations of t-tau and p-tau in CSF were risk factors for POD ( P<0.05). After gender, age, preoperative Mini-Mental State Examination score, years of education, history of drinking, hypertension, diabetes mellitus and coronary heart disease were added to eliminate the influence of confounding factors, the results still showed that vaccination with SARS-CoV-2 inactivated vaccine within 6 months before operation was a protective factor for POD. Conclusions:Vaccination with SARS-CoV-2 inactivated vaccine within 6 months before operation is a protective factor for POD in patients.

Objective:To evaluate the relationship between hippocampal macrophage polarization and perioperative neurocognitive disorders in mice with tibial fractures.Methods:Forty-five clean-grade healthy male C57/BL6 mice, aged 5-7 months, were divided into 3 groups ( n=15 each) using the random number table method: control group (group C), anesthesia group (group A) and anesthesia surgery group (group AS). Group C received no treatment. Group A was anesthetized with isoflurane inhaled for 15 min. In AS group, intramedullary nail fixation of tibial fracture was performed under anesthesia through inhalation of 2% isoflurane. Morris water maze test and open field test were performed before anesthesia/on 1 day before surgery and after anesthesia/on 1, 3 and 7 days after operation. Five mice were randomly selected after the behavioral experiments were completed at each time point, and hippocampal tissues were taken after the animals were sacrificed for determination of the expression of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), IL-6, chemokine (c-c motif) ligand 12 (CCL2), CCL5, CCL8, iNOS and Arg-1 mRNA (by quantitative real-time polymerase chain reaction), expression of iNOS and Arg-1 proteins (by Western blot), and percentage of CD11b, CD45, CD86 and CD206 cells in hippcampal area (by immunofluorescence staining). Results:Compared with group C, the escape latency was significantly prolonged after operation, the number of crossing the platform was reduced after operation, the expression of TNF-ɑ, IL-6, CCL5 and CCL8 mRNA and iNOS protein and mRNA was up-regulated, the expression of Arg-1 protein and mRNA was down-regulated, the percentages of CD11b + CD45 + cells and CD11b + CD86 + cells in the hippocampus were increased, and the percentages of CD11b + CD206 + cells were decreased in AS group ( P<0.05), and no significant change was found in the parameters mentioned above in group A ( P>0.05). Compared with group A, the escape latency was significantly prolonged after surgery, the frequency of crossing the platform was reduced after surgery, the expression of iNOS mRNA was up-regulated, the percentages of CD11b + CD45 + cells and CD11b + CD86 + cells were increased, and the percentages of CD11b + CD206 + cells were decreased in AS group ( P<0.05). Conclusions:The occurrence of PND may be related to increased polarization to M1 macrophages in the hippocampus and decreased polarization to M2 macrophages in mice with tibial fracture, which further leads to central inflammatory responses.

Objective:To evaluate the relationship between preoperative estimated glomerular filtration rate (eGFR) and postoperative delirium (POD) in the patients.Methods:Six hundred and twenty-five patients, aged ≥60 yr, of American Society of Anesthesiologists Physical Status classification Ⅰ-Ⅱ, scheduled for elective total knee and hip arthroplasty under combined spinal-epidural anesthesia, were included. Peripheral blood samples were collected before surgery, and serum creatinine levels were measured by the sarcosine oxidase method, and eGFR was calculated using the MDRD equation. After successful spinal-epidural puncture, cerebrospinal fluid 2 ml was collected for determination of β-amyloid 42 (Aβ42), total tau protein (T-tau) and phosphorylated tau protein (P-tau) by enzyme-linked immunosorbent assay. The patients were divided into POD group and non-POD group (NPOD group) according to the occurrence of POD. The logistic regression analysis was used to identify the risk factors for POD, and the mediating effect of CSF biomarkers was analyzed. The receiver operating characteristic (ROC) curve was drawn to evaluate the accuracy of eGFR and biomarkers in predicting POD.Results:A total of 514 patients were finally enrolled in this study, and the incidence of POD was 16.7%. The logistic regression analysis showed that decreased eGFR and increased levels of P-tau and T-tau in CSF were risk factors for POD, while increased CSF Aβ42 level, Aβ42/P-tau ratio and Aβ42/T-tau ratio were protective factors for POD after adjusting for multiple confounding variables ( P<0.05). Analysis of mediating effet: The direct effect of eGFR on POD was -0.0 005 267, the total effect was 0.0 046 446, T-tau had a partly mediating role and the mediating effect accounted for 11.3% of the total effect. The area under the ROC curve of eGFR and CSF biomarker in predicting POD was 0.812( P<0.001). Conclusions:Preoperative decrease in eGFR is a risk factor for POD, and T-tau in CSF serves as a key mediator in the relationship between eGFR and POD.

Objective:To evaluate the relationship between preoperative serum albumin concentrations and postoperative delirium (POD) in the patients undergoing total knee/hip arthroplasty.Methods:Five hundred patients of both sexes, aged 50-90 yr, with body mass index of 50-80 kg, of American Society of Anesthesiologists Physical Status classification Ⅰ or Ⅱ, undergoing elective total knee or hip replacement under combined spinal-epidural anesthesia in our hospital from December 2021 to December 2022, were selected. Cerebrospinal fluid (CSF) samples were collected after successful subarachnoid puncture for determination of amyloid-beta 42 (Aβ42), total tau protein (T-tau) and phosphorylated tau protein (P-tau) concentrations using enzyme-linked immunosorbent assay. Confusion Assessment Method and Memorial Delirium Assessment Scale were used to evaluate the occurrence and severity of POD at 1-7 days after surgery (or before discharge), and the patients were divided into POD group and non-POD group (NPOD group). Logistic regression analysis was used to identify the risk factors for POD. The accuracy of plasma albumin concentration and CSF biomarker concentration in predicting POD was evaluated by the receiver operating characteristic (ROC) curve, and the mediating effect of CSF biomarker was analyzed.Results:A total of 343 patients were finally enrolled in the study, and the incidence of POD was 23.3%. There were statistically significant differences in age, preoperative plasma albumin concentration and Memorial Delirium Assessment Scale score in POD group as compared with NPOD group ( P<0.05). Before and after adjusting for confounding factors, decreased plasma albumin and increased concentrations of P-tau and T-tau in CSF before operation were the risk factors for POD, and increased concentrations of Aβ42, Aβ42/P-tau and Aβ42/T-tau ratio in CSF were protective factors for POD. The area under the ROC curve of preoperative plasma albumin concentrations in predicting POD was 0.668, and the area under the ROC curve of preoperative plasma albumin concentrations combined with CSF biomarker concentrations in predicting POD was 0.810 ( P<0.05). The direct effect of plasma albumin on POD was -0.009 869 2, the total effect was 0.029 443 7, and the mediating effect of P-tau accounted for 33.53% of the total effect. Conclusions:Decreased preoperative plasma albumin concentration is a risk factor for POD, and P-Tau in CSF serves as a key mediator in the relationship between serum albumin concentrations and postoperative delirium in the patients undergoing total knee/hip arthroplasty.

Objective:To evaluate the relationship between preoperative serum cystatin C (Cys C) concentration and postoperative delirium (POD) in the patients.Methods:Three hundred and ninety patients, aged >50 yr, of American Society of Anesthesiologists Physical Status classification Ⅰor Ⅱ, scheduled for elective knee and hip replacement under combined spinal-epidural anesthesia, with Mini-Mental State Examination scores >23 at 1 day before operation, were included in the study. Peripheral blood samples were collected before operation, and the serum Cys C concentration was measured by the latex-enhanced immunoturbidimetric assay. The cerebrospinal fluid (CSF) 2 ml was collected after successful spinal-epidural puncture for determination of amyloid-β 42 (Aβ42), total tau (T-tau) and phosphorylated tau (P-tau) concentrations by enzyme-linked immunosorbent assay. The patients were divided into POD group and non-POD group according to whether POD occurred. The logistic regression analysis was used to identify the risk and protective factors for POD, and the mediating effect of CSF biomarkers was analyzed. The receiver operating characteristic curve was drawn to evaluate the accuracy of serum Cys C concentration and combination of serum Cys C conceatration and CSF biomarker concentration in predicting POD.Results:Three hundred and twenty-seven patients were finally enrolled, and the incidence of POD was 13.5%. The results of logistic regression showed that increased serum Cys C concentration and increased concentrations of P-tau and T-tau in CSF were risk factors for POD, while increased concentration of Aβ42 and increased Aβ42/P-tau ratio and Aβ42/T-tau ratio in CSF were protective factors for POD ( P<0.05) after adjusting for multiple confounding variables such as age, sex, years of education, Mini-Mental State Examination score, smoking history, drinking history, hypertension and diabetes history. The mediation analysis showed that the relationship between serum Cys C concentration and POD was mediated by T-tau concentration in CSF (11.1%) and by Aβ42/T-tau ratio in CSF (18.0%). The area under the receiver operating characteristic curve of serum Cys C and CSF biomarker concentrations in predicting POD was 0.807 ( P<0.001). Conclusions:Increase in preoperative serum Cys C concentration is a risk factor for POD. T-tau concentration and Aβ42/T-tau ratio in CSF serve as the key mediators in the relationship between preoperative serum Cys C concentration and POD.

Objective:To evaluate the relationship between the preoperative neutrophil/lymphocyte ratio(NLR) and postoperative delirium (POD)in elderly patients.Methods:Nine hundred and thirty-seven patients, undergoing elective knee or hip arthroplasty under combined spinal and epidural anesthesia, in whom Mini-Mental State Examination was completed at 1 day before operation, with Mini-Mental State Examination score≥24, were selected. Elbow venous blood samples were collected before surgery, neutrophils and lymphocytes were counted, and the ratio of neutrophils to lymphocytes was calculated.Cerebrospinal fluid (CSF) 2 ml was extracted after successful spinal-epidural puncture for measurement of preoperative amyloid beta40 (Aβ40), amyloid beta42 (Aβ42), total Tau (T-tau), and phosphorylated Tau (P-tau) by enzyme-linked immunosorbent assay. POD was assessed by Confusion Assessment Method, and the severity of POD was assessed by the Memorial Delirium Assessment Scale.The logistic regression equation was used to identify the risk factors for POD, and the mediating effect of CSF biomarkers was analyzed. Sensitivity analysis was used to test the stability of the results. The receiver operating characteristic curve was introduced, and the area under the curve was calculated to evaluate the accuracy of preoperative NLR in predicting POD.Results:A total of 853 patients were finally enrolled in this study, and 17.4% patients developed POD. Logistic regression analysis showed that the increased levels of NLR ( OR 1.141, 95% confidence interval [ CI] 1.033-1.260, P=0.010), P-tau in CSF ( OR 1.093, 95% CI 1.076-1.110, P<0.001) and T-tau in CSF( OR 1.003, 95% CI 1.001-1.005, P<0.001) were risk factors for POD, while the increased level of Aβ42 in CSF( OR 0.998, 95% CI 0.997-1.000, P=0.028) was a protective factor for POD after adjusting for multiple confounding factors. Analysis of mediating effect: T-tau and P-tau in CSF were the mediating factors in the relationship between NLR and POD with the mediating effects of 0.011 9 and 0.020 0 respectively, and the proportion of mediating effect was 46.1% and 53.1% respectively.The receiver operating characteristic curve showed that the area under the curve of NLR and combination of NLR and CSF biomarkers in predicting POD was 0.711 and 0.939 respectively. Conclusions:Increased preoperative NLR level is a risk factor for POD, and combination of NLR and CSF biomarkers shows a higher accuracy in predicting POD. T-tau and P-tau in CSF serve as the key mediators in the relationship between NLR and POD.