Relationship of sleep disturbance and postoperative delirium: a systematic review and meta-analysis.

Background: Studies have investigated the relationship between sleep disturbance and postoperative delirium (PD) but have controversial results. A systematic review and meta-analysis have a high level of evidence to comprehensively evaluate the effect of sleep disturbance on PD. Our study aims to provide available evidence regarding the effect of sleep disturbance on PD. Methods: PubMed, Embase, Cochrane Library, and Web of Science databases were searched for relevant studies from database inception to April 28, 2021. The eligible studies were identified according to the "PICOS" principles. Odds ratio (OR) was used to indicate the effect index, and 95% confidence interval (CI) was applied to express the effect size. The heterogeneity was tested. Subgroup analyses, meta-regression, and sensitivity analysis were also applied. Begg's test was used to test potential publication bias. The modified Newcastle-Ottawa Scale (NOS) was used to evaluate the literature quality. Results: Totally, 18 articles including 2,714 patients were enrolled, with most of the included literature being of moderate to high quality. The results of systematic and meta-analysis suggested that sleep disturbance was associated with an increased risk of PD (OR: 3.731; 95% CI: 2.338 to 5.956). Subgroup analysis results demonstrated that sleep disturbance in patients aged <65 years (OR: 6.072; 95% CI: 3.054 to 12.071), aged ≥65 years (OR: 2.904; 95% CI: 1.487 to 5.671), and undergoing cardiac (OR: 3.390; 95% CI: 1.359 to 8.453), orthopedic (OR: 3.943; 95% CI: 2.219 to 7.008), or other surgeries (OR: 4.963; 95% CI: 2.156 to 11.420) increased the risk of PD (all P<0.005). Moreover, increased risk of PD was found for both preoperative (OR: 2.804; 95% CI: 1.517 to 5.184) and postoperative (OR: 6.302; 95% CI: 3.794 to 10.467) sleep disturbance (all P<0.005). No associations between obstructive sleep apnea (OSA; OR: 2.008; 95% CI: 0.753 to 5.354; P=0.164), insomnia (OR: 4.005; 95% CI: 0.636 to 25.203; P=0.139) and risk of PD were observed. Conclusions: Our study indicated the relationship between sleep disturbance and the risk of PD. Patients undergoing surgical treatments should pay attention to their sleep quality. However, more research is needed to confirm its relationship.