The effect of intraoperative hypotension on postoperative delirium: a meta-analysis and systematic review

Background Postoperative delirium (POD) is a common complication linked to poor outcomes, yet its relationship with intraoperative hypotension (IOH) remains unclear. The objective of this study was to clarify the association between intraoperative IOH and POD. Method We searched four databases (PubMed, EMBASE, Cochrane Library, and Web of Science) from their inception to June 14, 2025. Randomized controlled trials (RCTs) and observational studies were included when IOH was incorporated as a predictive variable for POD in adult patients undergoing elective surgery under general anesthesia. Risk ratio (RR) and odds ratio (OR) were calculated using a random-effect model separately in RCTs and observational studies. Results In total, thirty out of 1,261 studies were included for the systematic review, of which 18 studies were eligible for quantitative meta-analysis. The remaining 12 studies were excluded due to incompatible data formats: eight used continuous metrics, and four lacked extractable effect estimates. IOH was significantly associated with an elevated risk of POD in both RCTs (RR: 1.89, 95%CI: 1.31–2.74) and observational studies (OR: 2.48, 95%CI: 1.64–3.75). Subgroup analysis of observational studies revealed that IOH defined by absolute threshold (OR: 4.11, 95%CI: 2.05–8.24) and mean arterial pressure (MAP) (OR: 2.90, 95%CI: 1.56–5.39) was related to a higher risk of POD. This heterogeneity was further explored by meta-regression, which identified the threshold nature of the IOH definition as a significant source of heterogeneity and a key effect modifier ( p = 0.048). Conclusion Our meta-analysis demonstrates a statistically significant association between IOH and increased risk of POD. However, substantial methodological heterogeneity across the included studies limits the robustness of these findings. The current evidence should therefore be interpreted as exploratory, highlighting the need for more standardized investigations in this field. Systematic review registration Identifier CRD42023424166.