Scientists identify biomarkers which could predict severity of Covid-19 in infected patients in ICU

• A study has found six proteins that can predict mortality in Covid-19 ICU patients
• Using proteomics, this could help doctors prescribe more effective treatment
• Covid-19 ICU patients in the study had a 40% chance of death from the virus

The moment you're admitted to the ICU because of Covid-19, your chances of dying increase significantly.

But what if doctors could predict how severely a patient would be affected by the virus if they ended up in the ICU?

A new study in Critical Care Explorations identified some important physiological protein biomarkers that can predict the likelihood of Covid-19 causing the death of an ICU patient. 

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Proteomics

Researchers collected blood samples from ICU patients in the London Health Sciences Centre who were infected with the coronavirus and compared them to those of uninfected individuals.

They then used proteomics to determine who was more likely to succumb to Covid-19. Proteomics is the study of proteins in cells, their identification and how they interact with biological systems. 

"Protection and/or restoration of the endothelial glycocalyx, as well as platelet adhesion inhibitors, may improve microvascular functioning during Covid-19," write the authors.

"Although the more common inflammatory and thrombotic proteins contributing to Covid-19 pathophysiology have been identified, a plethora of protein mediators have yet to be investigated and may hold critically important information to improve Covid-19 outcomes."

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40% mortality rate

In this study, not only was proteomics effective at predicting mortality, but it was also able to easily differentiate between ICU patients that were Covid-19 positive and ones that were negative.

The data was analysed via machine learning to sort through the noisy data and predict outcomes.

"The Covid-19 negative ICU patients had significantly higher unilateral pneumonia, whereas Covid-19 positive ICU patients were more likely to have bilateral pneumonia," found the researchers.

"Sepsis was 'confirmed' by infectious pathogen identification in only 20% of Covid-19 positive ICU patients, whereas sepsis was 'suspected' in the remaining 80%. A mortality rate of 40% was determined for Covid-19 positive ICU patients."

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Six key proteins

In total, they analysed 1 161 plasma proteins and found six top proteins that predicted ICU survival or death with 100% accuracy.

These are:

• CLM-1 – transmembrane glycoprotein that can help reduce the chances of an inflammatory reaction
• IL12RB1 – expressed on natural killer cells and activated T-cells that provide resistance to pathogens invading cells
• CD83 – part of the immunoglobulin family and forms on immune cells that can be degraded by viral infection 
• FAM3B – normally helps with insulin secretion but can help fuel cytokine storms
• IGF1R – a transmembrane tyrosine kinase receptor also influenced by insulin
• OPTC – small leucine-rich protein that binds collagen and influences cell adhesion

These proteins were more elevated in patients who ended up dying, and knowing this beforehand could help guide doctors on more effective treatment.

Limitations

There are some limitations to the study. The researchers only focused on critically ill patients and didn't look at the proteins' ability to predict outcomes pre-ICU. Their sample size was also incredibly small with low demographic diversity, and their only outcome focus was death.

They advise that larger studies look at other outcomes as well, like long-term functionality of survivors. 

"Despite the exploratory nature of our study, the data generated suggest that these six proteins could be considered for further investigation as potential disease severity and/or outcome biomarkers, and they may be useful for patient stratification in clinical interventional trials."

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