Prevalence, incidence and mortality of delirium in patients with COVID-19: A systematic review and meta-analysis

Shao, Shih-Chieh; Lai, Chien-Cheng; Chen, Yi-Hung; Chen, Yung-Chang; Hung, Ming-Jui; Liao, Shu-Chen

Background: Attention should be paid to delirium in COVID-19 patients, especially older people, since advanced age poses increased risk of both delirium and COVID-19-related death. Objective: This study aims to summarize the evidence on prevalence, incidence and mortality of delirium in COVID-19 patients. Methods: We conducted a comprehensive literature search on Pubmed and Embase from inception to December 1, 2020. Three independent reviewers evaluated study eligibility and data extraction, and assessed study quality. Outcomes were analyzed as proportions with 95% confidence interval (CI). We also compared mortality differences in COVID-19 patients using odds ratio. Results: In total, we identified 48 studies with 11,553 COVID-19 patients from 13 countries. Pooled prevalence, incidence and mortality rates for delirium in COVID-19 patients were 24.3% (95% CI: 19.4–29.6%), 32.4% (95% CI: 20.8–45.2%) and 44.5% (95% CI: 36.1–53.0%), respectively. For patients aged over 65 yrs, prevalence, incidence and mortality rates for delirium in COVID-19 patients were 28.2% (95% CI: 23.5–33.1%), 25.2% (95% CI: 16.0–35.6%) and 48.4% (95% CI: 40.6–56.1%), respectively. For patients under 65 yrs, prevalence, incidence and mortality rates for delirium in COVID-19 patients were 15.7% (95% CI: 9.2–23.6%), 71.4% (95% CI: 58.5–82.7%) and 21.2% (95% CI: 15.4–27.6%), respectively. Overall, COVID-19 patients with delirium suffered higher risk of mortality, compared to those without delirium (OR: 3.2, 95% CI: 2.1–4.8). Conclusion: Delirium developed in almost 1 out of 3 COVID-19 patients, and was associated with 3-fold overall mortality. Our findings suggest that first-line healthcare providers should systematically assess delirium and monitor related symptoms among COVID-19 patients.