Severe COVID-19 can lead to delirium, US study finds

Washington: A study of 150 patients hospitalised for COVID in the US at the beginning of the pandemic found that 73 per cent had delirium, a serious disturbance in mental state wherein a person is confused, agitated and unable to think clearly.

The study, published in the journal BMJ Open, found that patients with delirium tended to be sicker, with more comorbidities like hypertension and diabetes, and appeared to have more severe COVID-related illness.

"COVID is also associated with a number of other adverse outcomes that tend to prolong hospitalisation and make recovery difficult," said study author Phillip Vlisides, from the University of Michigan in the US.

The researchers used patient medical records and telephone surveys following hospital discharge for a group of patients hospitalised in the intensive care unit between March and May 2020.

They attempted to identify common threads amongst patients who developed delirium.

The researchers noted that the disease itself can lead to reduced oxygen to the brain as well as the development of blood clots and stroke, resulting in cognitive impairment.

Inflammatory markers were greatly increased in patients with delirium. Confusion and agitation could be a result of inflammation of the brain, they said.

"Early on in the pandemic, we weren't performing standard delirium prevention protocols like we usually do," Vlisides said.

"A big reason for that is early on in the pandemic in the pre-vaccine era, we had limited personal protective equipment and were trying to limit COVID exposure and disease transmission," he added.

There was a correlation between the use of sedatives and delirium -- patients with delirium were sedated more often and frequently at higher doses.

"It is common to use IV sedatives in the ICU, particular for patients on a ventilator. However, from talking to nurses, we found that patients with severe COVID were inherently more delirious and agitated at baseline, perhaps prompting more sedative use, said Vlisides.

The study also found that cognitive impairment can persist even after discharge.

Almost a third of patients did not have their delirium marked as resolved in their chart upon leaving the hospital and 40 per cent of these patients required skilled nursing care.

Almost a quarter of patients screened positive for delirium based on assessment by their caretaker. For some patients, these symptoms lasted for months.

This can make managing the recovery process after hospitalisation that much more difficult.

"Whatever creative ways we can implement in delirium prevention protocols is likely to be very helpful," Vlisides said.

"That includes consistent communication with family members, bringing in pictures and objects from home, and video visits if family cannot safely visit," he added.

The take-home message is that for patients hospitalised with severe COVID-19, cognitive impairment -- including depression and delirium -- is highly likely, he added.

"Overall, this study highlights another reason why getting vaccinated and preventing severe illness is so important. There can be long term neurological complications that perhaps we don't talk about as much as we should," Vlisides said.