A formula that predicts Covid-19 patients’ chances of surviving has been developed by British researchers.
It will save lives by personalising therapy based on their profile, say scientists.
The ‘risk identification tool’ divides those admitted to hospital into four distinct groups – ranging from low to very high.
In the lowest category, one in every hundred is at risk of dying – compared to ten in the ‘intermediate’. This soars to 31 and 62 in a hundred for ‘high’ and ‘very high’ risk patients, respectively.
Senior author Professor Ewen Harrison, of Edinburgh University, said: “As doctors, we want to identify groups of patients most at risk of dying from Covid-19.
“If we can do that at the front door of the hospital, then treatment can be better planned. This easy-to-use tool will help doctors make decisions to provide patients with the optimal care.”
It was built by the ISARIC Coronavirus Clinical Characterisation Consortium using data from some 35,000 patients.
Clinical information was collected and tests carried out on admission to 260 hospitals across England, Wales and Scotland between February and May.
All the participants met the criteria for one of the four groups. It’s the world’s largest study of Covid-19.
Factors that identify a person’s ‘4C mortality score’ – their risk of dying – include age, sex, number of pre existing conditions, respiratory rate and the results of two blood tests.
The categorisations open the door to new pathways, said the researchers. For example, it might be more appropriate for low-risk individuals to be treated at home.
On the other hand, those at high or very high risk may benefit from more aggressive drugs, such as the use of antivirals and early admission to critical care.
Co lead author Dr Antonia Ho, of the University of Glasgow, said: “This simple tool will help doctors at the front door to make informed decisions on how to manage patients with Covid-19.
“On one hand, allow targeting of early treatment and admission to critical care in patients at high risk of dying, and conversely, identifying low-risk patients that may be safely managed at home.”
The tool described in the BMJ will help clinical staff choose the best course of treatment.
Its accuracy was tested and confirmed using data from a further 22,000 patients hospitalised from the end of May to the end of June.
Until now, there has not been a way to assess risk. Existing tools for pneumonia or sepsis are unreliable owing to the differences between diseases.
Previous attempts have had limited success due to small sample sizes and lack of formal validation.
ISARIC is a global network of clinicians and scientists who have been preparing since 2012 for a pandemic such as this.
Co author Prof Calum Semple, of the University of Liverpool, said: “This winter is likely to see great pressures on our health services, with staff being redeployed to less familiar acute care areas.
“In these difficult circumstances the 4C mortality score is likely to be a valuable tool for supporting decisions that allowing prompt escalation of care to those most likely to benefit.
“The scale of success of the ISARIC 4C study is testament to the group’s commitment in preparing for pandemic public health research.”
The researchers pointed out that the tool can only be used on hospital patients – not within the community.
Co-lead author Dr Stephen Knight, of Edinburgh University, said: “This accurate and simple risk identification tool, applicable across all groups within society, will help detect at risk individuals quickly on arrival to hospital.
“As importantly, we will be able to reassure and potentially treat at home those patients who fall within the low risk group.”
Previous research has shown those with pre-existing illnesses face the greatest risk. Deaths among under 65s with no other illnesses are remarkably uncommon.
Prof Fiona Watt, executive chair of the Medical Research Council which part funded the project, said: “These results highlight the benefits of being prepared in advance of the emergence of new pandemics such as Covid-19.”
Finding out more about the differences in risk faced by various members of the community is going to be crucial as we move forward.
Minister for Innovation Lord Bethell, an Edinburgh graduate, said: “Protecting the most vulnerable from Covid-19 is a priority which is why we’re supporting valuable research like this to help doctors make the best possible decisions for NHS patients.
“I am delighted to see my former university leading the way on it.
“We look forward to seeing how this new tool can help clinicians target treatments more effectively for coronavirus patients admitted to hospital now and in the future, potentially saving countless lives.”