Psychiatric symptomatology after delirium: a systematic review

Delirium is an acute and usually transient severe neuropsychiatric syndrome associated with significant long-term physical morbidity. However, its chronic psychiatric sequelae remain poorly characterized. To investigate the prevalence of psychiatric symptoms, namely anxiety, depressive, and post-traumatic stress disorder (PTSD) symptoms after delirium, a systematic literature search of MEDLINE, EMBASE and PsycINFO databases was performed independently by two authors in March 2016. Bibliographies were hand-searched, and a forward-and backward-citation search using Web of Science was performed for all included studies. Of 6411 titles, we included eight prospective cohort studies, including 370 patients with delirium and 1073 without delirium. Studies were heterogeneous and mostly included older people from a range of clinical groups. Consideration of confounders was variable. The prevalence of depressive symptoms was almost three times higher in patients with delirium than in patients without delirium (22.2% vs 8.0%, risk ratio = 2.79; 95% confidence interval = 1.36-5.73). There was no statistically significant difference between the prevalence of anxiety symptoms between patients with and without delirium. The prevalence of PTSD symptoms after delirium was inconclusive: only one study investigated this and no association between PTSD symptoms after delirium was reported. There is limited published evidence of the prevalence of psychiatric symptoms after non-ICU delirium and the strongest evidence is for depressive symptoms. Further longitudinal studies are warranted to investigate the prevalence of anxiety and PTSD symptoms.