Prevalence, clinical features, and risk factors of delusions in patients with delirium

Delirium may be divided into multiple subtypes with different pathological factors. This study aimed to focus on the delirium subtype in which delusions are conspicuous and explore its prevalence, clinical characteristics, and risk factors.

The subjects were 601 delirium cases referred to the department of psychiatry over 5 years at a general hospital. The Delirium Rating Scale-Revised-98 was used to assess the delusions in patients with delirium, and the features of delusions (delusional form, object, and content) were examined. Multiple regression analysis was applied to determine whether individual factors were associated with the delusions.

A total of 78 patients with delirium experienced delusions (13.0%). Most were classified as delusion of reference, such as persecution or poisoning, and 84.3% of patients believed that the persecutors were medical staff members. Older age (p < 0.001), female gender (p < 0.001), and living alone (p < 0.001) were significantly associated with delusions in patients with delirium.

The content of delusions was rooted in the distress caused by the patients' medical situation, and the features and risk factors of the delusions suggested a formal similarity with late paraphrenia and "lack-of-contact paranoia." Psychological interventions that consider the isolation, anxiety, and fear behind delusions may be necessary in the care and treatment of these patients.