Excessive daytime sleepiness in Parkinson's disease: A systematic review and meta-analysis

To provide a robust estimate of the prevalence of excessive daytime sleepiness (EDS) and its clinical correlates in patients with Parkinson's disease (PD).We searched the PubMed and Embase databases for studies investigating the prevalence and clinical correlates of EDS from inception to March 01, 2020. Quality assessment was performed using the Newcastle-Ottawa quality assessment scale. Random-effects models were set to pool the risk estimates. Sensitivity analyses were performed to evaluate the stability of the outcomes.After screening 1367 titles and abstracts, 59 studies involving 12,439 participants were included in the systematic review and meta-analysis. The pooled prevalence of EDS in PD was 35.1%, which was higher in South America, North America, Europe, and Australia than that in Asia. Compared to patients without EDS, patients with EDS had higher effect size on disease duration (0.76 years; 95% CI: 0.16-1.37, I2 = 68.8%), Hoehn and Yahr (HY) stage (0.23 grade; 95% CI: 0.11-0.34, I2 = 69.1%), Unified PD Rating Scale (UPDRS)-III (3.02 points; 95% CI: 1.53-4.51, I2: 61.2%), levodopa equivalent daily dose (LEDD) (141.46 mg; 95% CI: 64.17-218.77, I2 = 86.1%), depression symptoms (Hedges' g = 0.35; 95% CI: 0.15-0.55, I2 = 72.0%) and male sex (OR = 1.50; 95% CI: 1.30-1.72, I2 = 0).Our results showed that approximately one-third of patients with PD had EDS, which may be associated with the severity of the disease, depression, and male sex, or a combination of neurodegeneration and medication.