Risk Factors for Delirium in Older Adults in the Emergency Department: A Systematic Review and Meta-Analysis

We conducted a systematic review and meta-analysis to identify risk factors for delirium in geriatric patients in the emergency department and to identify emergency department (ED)-based modifiable risk factors for developing delirium during hospitalization. We searched evidence based medicine reviews, EMBASE, MEDLINE, Scopus, and Web of Science for observational studies from the time of their inception to July 2020. We included studies that evaluated potential risk factors for either prevalent or incident delirium among older adults (age ≥ 60 years) presenting to the ED. When appropriate, we meta-analyzed estimates for risk factors using a random-effects model. The certainty of evidence was evaluated using the grading of recommendations assessment, development and evaluation approach. The study's protocol was registered in PROSPERO (CDR42020175261). A total of 4,513 citations were reviewed, and 34 studies met the criteria for inclusion: 27 evaluating risk factors for ED delirium (13,412 patients) and 7 evaluating ED-based risk factors for developing delirium during hospitalization (2,238 patients). The prevalence of ED delirium ranged from 7% to 35%. Four factors had strong associations with ED delirium and were graded as high-certainty evidence, including nursing home residence (4 studies; odds ratio [OR], 3.45; 95% confidence interval [CI], 2.17 to 5.48), cognitive impairment (7 studies; OR, 4.46; 95% CI, 3.38 to 5.89), hearing impairment (3 studies, OR, 2.57; 95% CI, 1.03 to 6.41), and a history of stroke (3 studies; OR, 3.20; 95% CI, 1.17 to 8.75). The rate of developing delirium during hospitalization ranged from 11% to 27%. A length of stay of more than 10 hours in ED was associated with a higher risk of delirium (1 study; OR, 2.23; 95% CI, 1.13 to 4.41). One study reported that severe pain, rather than the use of opioids, was associated with the development of delirium. These findings can be used to prioritize delirium screening in the ED and develop novel ED delirium risk scores or prevention interventions.