A blood test that can predict whether COVID-19 patients will need intensive care or are even likely to survive shortly after showing symptoms has been developed.
If validated in real-life hospital settings, the test could enable doctors to direct life-saving treatment to the neediest patients sooner, boosting their chances of survival. It could also bolster doctors’ confidence in the face of difficult decisions, such as whether to offer palliative care or an ICU bed when hospitals are close to capacity.
Earlier this year, Markus Ralser and colleagues identified 27 proteins in the blood of Covid-19 patients that were present at different levels depending on the severity of their symptoms. Since then, they have followed 160 Covid patients whose blood was tested when they were admitted to hospital to explore whether its protein signature could predict the progression of their illness.
The idea is to provide doctors with a digital picture of how sick a patient is – something you cannot necessarily tell just by looking at them – which could help inform their treatment.
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For instance, in Covid-19, a phenomenon called happy hypoxia means a patient can feel relatively okay but then rapidly deteriorate.
“It turns out that such patients have an early inflammatory response to the infection, which we can measure in the blood and use to say, ‘OK, 40 days down the line, this is your likely outcome’,” Ralser, a professor of biochemistry at the Francis Crick Institute in London and Charité University Medicine in Berlin, said in a monitored report.
“Every day counts with severe Covid, and those people who need intensive care need to get it as soon as possible because this greatly increases their chances of survival,” Ralser said.
Although it is unlikely that a blood test alone would ever be used to dictate which patients are allocated scant intensive care unit beds, it could provide additional data to help inform doctors making these hard decisions.
The proteins were measured using an instrument called a mass spectrometer, which can detect the presence and abundance of hundreds to thousands of proteins in a sample, based on their mass.
Such proteomic analysis enables many more proteins to be measured in blood than with current clinical assays, according to Manuel Mayr, a British Heart Foundation professor of cardiovascular proteomics at King’s College London, who was not involved in the study.
“This can reveal important insights why some Covid-19 patients may have a better or worse prognosis,” he added.
So far, the test has been validated in a further 24 severely ill patients, where it correctly predicted the outcome for 18 of 19 of those who survived and for five of five patients who died.
“We can predict which patients will need oxygen support and ventilator support quite accurately, and we also have markers for patients who are not that severely ill initially, but are at high risk of getting worse,” said Mayr.
