Correlation analysis between plasma biomarkers albumin, fibrinogen, and their ratio with postoperative delirium in patients undergoing non-cardiac surgery: a systematic review and meta-analysis

Objectives: This meta -analysis aimed to investigate the correlation between plasma biomarkers, such as albumin and fibrinogen, and their ratio with postoperative delirium (POD) in patients undergoing non -cardiac surgery. Methods: Relevant observational cohort studies were systematically searched in PubMed, EMBASE, CINAHL, and the Cochrane Library databases as of March 2023. This meta -analysis was conducted using RevMan 5.4.1 and Stata 15.0 software. For continuous variables with non -uniform units, the standardized mean difference (SMD) and 95% confidence intervals (CIs) were used; otherwise, the mean difference (MD) and 95% CIs were employed. The Newcastle -Ottawa Scale (NOS) was applied to assess the quality of included literature. Results: Eighteen studies encompassing 7,011 patients were included. The meta -analysis revealed significantly lower albumin levels (sixteen studies, 5,813 patients, SMD = -0.45, 95% CI = -0.64 to -0.26, P < 0.00001, I-2 = 80%) and albumin -fibrinogen ratio (AFR) (four studies, 824 patients, MD = -0.62, 95% CI = -0.76 to -0.48, P = 0.56, I-2 = 0%) in the delirious group. Conversely, higher fibrinogen concentrations (two studies, 441 patients, MD = 0.13, 95% CI = 0.02 to 0.24, P = 0.69, I-2 = 0%) were observed in the delirious group. Due to high heterogeneity in albumin levels (P < 0.00001, I-2 = 80%), we conducted a subgroup and sensitivity analysis, and confirmed that the association of albumin levels was not influenced by surgery type, design or delirium evaluation instruments. Conclusions: Preoperative albumin, fibrinogen and AFR levels were associated with POD, potentially aiding in identifying high -risk patients and playing a key role in preventing POD.