Efficacy of sleep interventions on postoperative delirium: a systematic review and meta-analysis of randomized controlled trials

Sleep disturbances are risk factors for postoperative delirium (POD), and sleep interventions have been proposed as potential preventive measures. However, the effectiveness of sleep interventions in preventing POD is uncertain. We performed a systematic literature search using the PubMed, Embase, and Cochrane Library databases from inception until December 24, 2022. We included randomized controlled trials on sleep interventions and POD in adult surgery patients. The screening of titles, abstracts, and full texts was performed independently by two reviewers. Another two reviewers independently performed the data extraction and assessed the risk of bias. Pooled-effect estimates were calculated with a random effect model. Our primary outcome was POD, which was assessed with the confusion assessment method (CAM), CAM for the intensive care unit (CAM-ICU), or other delirium assessment tools. We used trial sequential analysis to control for type I and II statistical errors. We also conducted prespecified subgroup analyses, according to the type of intervention, efficacy of the intervention on postoperative sleep, sample size, participant age, delirium assessment tool used, and the type of surgery. Data were obtained from 25 trials, including 4799 participants. Sleep interventions had a statistically significant difference in the incidence of POD (relative risk (RR) = 0.60; 95% confidence interval (CI), 0.46–0.77; I 2 = 58%). Stratified analyses indicated that the beneficial effects of sleep interventions were evident in trials where the interventions promoted postoperative sleep (RR = 0.51; 95% CI, 0.36–0.71) as compared to trials that did not (RR = 1.01; 95% CI, 0.77–1.31) ( p -value for interaction between subgroups = 0.004). Our primary analysis demonstrated that in adult patients following elective surgery, interventions that improved postoperative sleep, as compared to the standard care or placebo groups, were associated with a lower risk of POD. However, such evidences are limited by the heterogeneity among trials and the small sample sizes of some trials. Graphical Abstract