Delirium is a key symptom of Covid-19 in frail, older people and could be used as a possible early warning sign, according to new analysis from King's College London

The study, published in the journal Age and Ageing, is based on analysis of data from the COVID Symptom Study app and patients admitted to St Thomas’ Hospital in London.

The researchers analysed data from two groups of older people aged 65 or over from March through May. The first group included 322 patients admitted to hospital with Covid-19 who had tested positive for Covid-19, while the second comprised 535 users of the COVID Symptom Study app who reported having had a positive test result.

They found that older adults admitted to hospital who were classified as frail according to a standard scale were more likely to have had delirium as one of their symptoms than people of the same age who were not classed as frail. Delirium, along with tiredness and breathlessness, were also more common in frailer users of the COVID Symptom Study app with Covid-19, compared with fitter people of the same age.

Screening for delirium needed for older adults

A third of app users experiencing delirium did not report suffering the ‘classic’ Covid-19 symptoms of cough and fever, while delirium was the only symptom for around one in five (18.9%) of hospitalised patients.

Frailty in the group of hospitalised patients was measured using the Clinical Frailty Scale (CFS) test, which is administered by a doctor. COVID Symptom Study App users were asked to complete a short questionnaire asking about their health, which is comparable to the CFS.

This is the first study showing that delirium is a likely symptom of Covid-19 in frail older adults, although the precise biological connection between the two conditions still needs to be understood. The findings also highlight the need for systematic assessment of frailty for older people, along with awareness and screening for delirium for this vulnerable population in hospitals, care homes and the community.

Dr Claire Steves from King’s College London said: “The past six months have shown us that COVID-19 can spread catastrophically through care homes. Knowing that delirium is a symptom in frail, elderly people will help families and carers spot the signs earlier of COVID-19 and act appropriately and put in place infection control measures such as isolation, increased hygiene and personal protective equipment to protect this highly vulnerable group.”