Risk factors and outcomes of delirium in hospitalized older adults with COVID-19: A systematic review and meta-analysis

Background: Older adults with COVID-19 are more likely to present with atypical symptoms, notably delirium. The main objective of this meta-analysis is to identify risk factors for delirium and outcomes of delirium in hospitalized older adults (65 years or above) with COVID-19. Methods: Comprehensive literature search of Embase, CINAHIL, Medline and Web of Science was performed for published literature until 31st August 2021. Two independent researchers evaluated study eligibility and assessed study quality using the Newcastle Ottawa Scale (NOS) for cohort studies and Joanna Briggs Institute (JBI) critical appraisal tools for case series. The association of various predisposing factors with delirium in this cohort was reported as odds ratio (OR) and its 95% confidence interval (CI). Results: A total of 31 studies from 11 countries were included in this review. Most of the included studies investigated patients from non-ICU settings (n = 24; 77.4%). Frailty (OR 3.52, 95% CI: 1.96–6.31, p<0.0001, I²=71.63%), cognitive impairment including dementia (OR 6.17, 95% CI: 2.92–13.07, p<0.00001, I²=88.63%) and being nursing home residents (OR 1.72, 95% CI: 1.31–2.24, p<0.0001, I²=0) were significantly associated with increased likelihood of developing delirium in older adults with COVID-19. The presence of delirium also significantly increases mortality risk in hospitalized older adults with COVID-19 (OR 2.51, 95% CI: 1.51–4.17, p<0.0001, I²=89.3%). Conclusion: Our review identifies key factors associated with increased risk of developing delirium in hospitalized older adults with COVID-19. Identification of patients at risk of delirium and attention to these factors early during admission may improve outcomes for this vulnerable cohort.