Cerebrospinal fluid biomarkers of neuroinflammation and postoperative neurocognitive disorders in patients undergoing orthopaedic surgery: protocol for a systematic review and meta-analysis.

INTRODUCTION: Postoperative neurocognitive disorders (PNDs) are characterised by gradual cognitive decline or change occurring after anaesthesia and surgery, and they are common in patients undergoing orthopaedic surgery. The onset of PNDs has been associated with dementia or other types of neurocognitive disorders in later life. Moreover, cerebrospinal fluid (CSF) biomarkers of neuroinflammation, including amyloid beta-40 peptide, amyloid beta-42 peptide, total tau protein, phosphorylated tau protein and neurofilament light chain, have been reported to be crucial in several high-quality clinical studies on PNDs. However, the role of these biomarkers in the onset of PNDs remains controversial. Therefore, this study aims to determine the association between CSF biomarkers of neuroinflammation and the onset of PNDs in patients undergoing orthopaedic surgery, which will provide novel insights for investigating PNDs and other types of dementia. METHODS AND ANALYSIS: This systematic review and meta-analysis will be conducted in accordance with the Preferred Reporting Items for Systematic Reviewd and Meta-Analyses 2020 statement. Moreover, we will search MEDLINE (via OVID), EMBASE and the Cochrane Library without any language and date restrictions. Observational studies will be included. Two reviewers will independently perform the entire procedure, and disagreements will be settled by discussion between them and consultation with a third reviewer. Standardised electronic forms will be generated to extract data. The risk of bias in the individual studies will be evaluated using the Newcastle-Ottawa scale. All statistical analyses will be performed using the RevMan software or the Stata software. ETHICS AND DISSEMINATION: This study will include peer-reviewed published articles; thus, no ethical issues will be involved. Further, the final manuscript will be published in a peer-reviewed journal. PROSPERO REGISTRATION NUMBER: CRD42022380180.