Effect of regional versus general anaesthesia on postoperative delirium in elderly patients undergoing surgery for hip fracture: a systematic review

Objective Older patients with hip fractures who are undergoing surgery are at high risk of significant mortality and morbidity including postoperative delirium. It is unclear whether different types of anaesthesia may reduce the incidence of postoperative delirium. This systematic review will investigate the impact of anaesthetic technique on postoperative delirium. Other outcomes included mortality, length of stay, complications and functional outcomes. Design Systematic review of randomised controlled trials and non-randomised controlled studies. Data sources Bibliographic databases were searched from inception to June 2018. Web of Science and ZETOC databases were searched for conference proceedings. Reference lists of relevant articles were checked, and clinical trial registers were searched to identify ongoing trials. Eligibility criteria Studies were eligible if general and regional anaesthesia were compared in patients (aged 60 and over) undergoing hip fracture surgery, reporting primary outcome of postoperative delirium and secondary outcomes of mortality, length of hospital stay, adverse events, functional outcomes, discharge location and quality of life. Exclusion criteria were anaesthetic technique or drug not considered current standard practice; patients undergoing hip fracture surgery alongside other surgery and uncontrolled studies. Results One hundred and four studies were included. There was no evidence to suggest that anaesthesia type influences postoperative delirium or mortality. Some studies suggested a small reduction in length of hospital stay with regional anaesthesia. There was some evidence to suggest that respiratory complications and intraoperative hypotension were more common with general anaesthesia. Heterogeneity precluded meta-analysis. All findings were described narratively and data were presented where possible in forest plots for illustrative purposes. Conclusions While there was no evidence to suggest that anaesthesia types influence postoperative delirium, the evidence base is lacking. There is a need to ascertain the impact of type of anaesthesia on outcomes with an adequately powered, methodologically rigorous study.