Delirium is an acute clinical syndrome with diverse and multi-factorial etiologies. It has high prevalence in hospitalized patients and it is associated with serious adverse outcomes, increasing morbidity and mortality. Delirium requires a differential diagnosis with a wide range of mental disorders.

To evaluate cases referred to liaison psychiatry in Hospital José Joaquim Fernandes, in regard to the frequency, cause and misdiagnoses of delirium.

A retrospective analysis of liaison psychiatric referral from January to August 2016.

The overall referral consisted of a total of 111 cases. Delirium was the second most frequent referral (21.6%), after depression. Half of patients had an advanced age (71–90 years). A total of 44.8% of patients with delirium were misdiagnosed and the referral causes were “depression”, “dementia”, “aggressive behavior”, “agitation” and “schizophrenic psychosis”. The majority of patients were referred by internal medicine. The most frequent underlying conditions were: postoperative (27.6%), respiratory diseases (24.1%) and sepsis (17.2%).

Delirium is one of the most frequent diagnoses in liaison psychiatry. This study supports the statement that delirium is often not recognized and that is misdiagnosed as a primary psychiatric illness, mainly, dementia or mood disorder. Although delirium is classified in ICD-10 as a psychiatric diagnosis and clinically manifests with a wide range of neuropsychiatric abnormalities, it is secondary to a medical/surgical disorder that requires urgent approach by the respective specialty.

The authors have not supplied their declaration of competing interest.