The impact of general and regional anesthesia on the incidence of post-operative cognitive dysfunction and post-operative delirium: a systematic review with meta-analysis.

Post-operative cognitive complications such as delirium have been consistently associated with poor short and long term outcomes, and the role of anesthesia, particularly the role of general versus regional anesthesia, remains unclear. The objective of this systematic review with meta-analysis was to compare the influence of general, regional, or a combination of anesthesia on the development of Post-Operative Cognitive Dysfunction (POCD) and Post-Operative Delirium (POD). Standard bibliographic databases were searched and complimented by hand searching of original and review article references. Included studies were randomized controlled trials comparing general to regional (spinal, epidural, or intravenous block) or a combination of these in a cohort who were pre-operatively cognitively normal and had an average age exceeding fifty. Where POD was the principle outcome, studies must have employed the DSM or ICD criteria. Where POCD was the principal outcome, this was defined as any objective cognitive impairment. Twenty one studies were considered suitable for inclusion. There was no effect of anesthesia type on the odds ratio of developing POD (0.88, 0.51-1.51 with 95% confidence) however general anesthesia was marginally non-significantly associated with POCD (odds ratio of 1.34, 0.93-1.95 with 95% confidence). There was no evidence of publication bias. In conclusion, it appears that general anesthesia, compared to others, may increase the risk of developing POCD; however this has not been shown for POD. Possible reasons for this finding have been explored. This data would advocate for the use of regional anesthesia wherever possible especially in people otherwise vulnerable to developing cognitive symptoms.