Discovery of four COVID-19 risk groups helps guide treatment
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People who are admitted to hospital with COVID-19 can be divided into four distinct groups, according to data from the world's largest study of patients with the disease.

Researchers identified the groups using clinical information and tests carried out upon arrival at hospital to predict the patients' risk of death—ranging from low to very high.

A COVID-19 risk identification tool—the most accurate to date—has been designed using the groupings to help clinical staff choose the best course of treatment for patients admitted to hospital.

The tool was built by the ISARIC Coronavirus Clinical Characterisation Consortium involving researchers from Universities of Edinburgh and Imperial College London using data from some 35,000 patients admitted to hospital who met the criteria for one of the four groups.

The tool was then tested and confirmed to be accurate using data from a further 22,000 hospitalised patients.

Some of the data used to identify which group a person falls into—and, therefore, their risk of dying—included age, sex, the number of pre-existing conditions, respiratory rate on admission, and the results of two blood tests.

One in every hundred patients in the low-risk group was found to be at risk of dying. It was 10 in a hundred patients in the intermediate-risk group, 31 in a hundred in the high-risk group and 62 in a hundred in the very high-risk group.

The categorisations make new treatment pathways possible, researchers say. For example, it might be more appropriate for those who fall into the low-risk subgroup to be treated at home. In contrast, people in the high or very high risk groups could benefit from more aggressive treatment, such as the use of antivirals and early admission to critical care.

Until now there has not been an accurate risk tool for COVID-19 patients. Existing tools for pneumonia or sepsis do not offer accurate predictions due to the differences between diseases.

Previous attempts to build a risk prediction tool for COVID-19 have had limited success due to small sample sizes and lack of formal validation. One limitation of this new tool, however, is that it can only be used on hospital patients and not within the community.