The effects of early postoperative neurocognitive disorders on clinically relevant outcomes: a meta-analysis

Background: Early postoperative neurocognitive disorders (ePND) include emergence delirium, defined as a very early onset postoperative delirium, and emergence agitation, defined as motor arousal. These ways of anesthesia emergence are poorly investigated although they are probably associated with unfavorable outcomes. This meta-analysis aimed to assess the impact of ePND on clinically relevant outcomes. Methods: A systematic search of studies published over the past 20 years was carried out in Medline, PubMed, Google Scholar and Cochrane Library. We included studies describing adults with emergence agitation and/or emergence delirium and reporting at least one of the following: mortality, postoperative delirium, length post-anesthesia care unit or hospital stay. The internal validity, risk of bias, and certainty of evidence were assessed. Results: A total of 16,028 patients from 21 prospective observational studies and 1 case-control retrospective study were included in this meta-analysis. The rate of ePND occurrence was 13 % (from 21 studies excluding the case-control study). The mortality rate was 2.4 % in patients with ePND vs 1.2 % in normal emergence group (RR = 2.6, p = 0.01, very low quality of evidence). Postoperative delirium was 29 % in patients with ePND vs 4.5 % in patients with normal emergence (RR = 9.5, p < 0.001, I2 = 93%). Patients with ePND had a prolonged length of post-anesthesia care unit (p = 0.004) and hospital stay (p < 0.001). Conclusions: This meta-analysis suggests that ePND is associated with a doubled risk of mortality and with a 9-fold increased risk of postoperative delirium.