Prevalence and risk factors of delirium in psychiatric patients with critical illness

•Delirium is a serious neuropsychiatric syndrome, which can lead to poor outcomes, research about delirium in psychiatric patients with critical illness is rare.•Delirium prevalence was about 33% in psychiatric patients with critical illness.•The organic mental disorder, infectious disease, electrolyte disturbance, cerebrovascular disease, and liver or kidney dysfunction were the risk factors for delirium in psychiatric patients with critical illness.•The use of olanzapine or haloperidol showed no relevance to delirium.