Older patients with undiagnosed COVID-19 often have delirium — but no other symptoms — when they are admitted to emergency departments, according to a multi-center study. 

Investigators used health data from 817 patients aged 65 or older who were admitted to an emergency department and subsequently received a diagnosis of COVID-19. Almost a third had delirium at admission. In fact, a delirium diagnosis was the main presenting symptom for 16% of patients. What’s more, 37% of those patients did not have other COVID symptoms, such as cough or fever.

Several factors appeared to contribute to whether an older adult with COVID-19 would present with delirium, researchers said. These included assisted living community or skilled nursing facility residence, older age, prior psychoactive medication use, vision or hearing impairment, stroke, and Parkinson’s disease, reported Sharon Inouye, M.D., M.P.H. Delirium at presentation also was significantly linked to an increased risk for poor hospital outcomes, including intensive care unit stay, discharge to a rehabilitation facility and death.

The results suggest that clinicians should include delirium in their checklists of COVID-19 signs and symptoms, said Inouye, of the Hinda and Arthur Marcus Institute for Aging Research at Hebrew SeniorLife and a professor at Harvard Medical School.

“This study demonstrates that delirium is not only a common symptom of COVID-19 but also may be the leading and possibly sole symptom in older persons,” Inouye said. 

Delirium is the sudden onset of confusion and reduced awareness. Despite the overall prevalence of delirium in older people admitted to emergency care, the condition often is missed and is tied to extended hospitalization and increased morbidity, the researchers said.

The study was published in JAMA Network Open / Emergency Medicine.