They found that a combination of deep muscle aches, an increase in a liver enzyme called ALT, and elevated levels of hemoglobin could be an early warning sign of severe lung disease.
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The coronavirus pandemic has forced doctors to make difficult decisions about which patients get immediate medical care.
In New York City, where more than 38,000 cases have been reported, hospitals are reserving tests for patients with severe illness, while patients with mild cases — which can still be painful and long-lasting — have been told to stay home. But doctors still know very little about the symptoms that serve as warning signs in the lead-up to a severe case of COVID-19.
A new study from researchers at New York University used predictive analytics to determine the early signs of severe lung disease among COVID-19 patients. The researchers determined that three symptoms, taken together, were strong predictors of acute respiratory distress syndrome (ARDS), a life-threatening lung injury that might require a patient to be intubated.
The first factor was a slight increase in ALT, a enzyme that can signal the presence of liver damage or inflammation. The second was deep muscle aches — known clinically as "myalgia." The third factor was higher levels of hemoglobin, a protein that transports oxygen through the blood.
"Our hope is to assist doctors in that first stage to be able to identify who may become sick of the many mild cases," Megan Coffee, an infectious disease clinician and lead author of the study, told Business Insider.
The study analyzed records from 53 hospitalized patients in Wenzhou, China. Most of the patients were in their thirties or forties and nearly two-thirds were men.
While typical symptoms of COVID-19 include a fever, dry cough, and difficulty breathing, body aches are the next most common symptom, according to the World Health Organization. The agency reported in February that 14% of coronavirus patients experience body aches or joint pain.
As a clinician, Coffee said she's now paying more attention to patients who show these symptoms — but all three must be present for someone to have an early risk of severe lung disease.
Flagging severe cases could lower emergency visits
On their own, the three mild symptoms don't normally set off alarm bells for clinicians, Coffee said.
"Body aches wouldn't be the first thing that I would ask about," she said. "I would of course always ask about shortness of breath before anything because that's somebody who has to be immediately helped."
But determining whether a patient is likely to get worse could help hospitals decide which cases to monitor.
"Hospitals are just so overstretched that if someone doesn't immediately need oxygen, they may not be able to find a place for them," Coffee said. "But they might be able to say, 'You really need to check back in tomorrow.'"
Doctors could then treat a patient before their case becomes critical, thereby lessening the burden on emergency rooms.
"We're not by any means trying to replace doctors' decisions," Anasse Bari, a clinical assistant professor at NYU who co-authored the study, told Business Insider. "We just want to arm doctors with tools to see quickly if this is a severe case and predict outcomes."
Patients with severe lung disease saw symptoms worsen after 5 to 8 days
On average, patients in the NYU study were admitted to the hospital three days after their symptoms started.
The majority had a fever and dry cough, though about a third developed a wet cough. Less than a quarter of patients had wheezing or difficulty breathing. Only a few patients had body aches, a sore throat, or diarrhea.
The study found that most patients developed mild symptoms at first. In severe cases, symptoms like shortness of breath, pneumonia, and ARDS typically appeared five to eight days into the illness.
Around 88% of patients had white patches called "ground glass" on their CT scans, which signaled the presence of fluid in their lungs.
But only five of the patients — all of whom were men — developed severe lung disease.
Upon arrival at the hospital, the men displayed a fever, cough, wheezing, and shortness of breath. Each one also had "ground glass" on his CT scan.
Older men are more likely to develop deadly cases, but age and gender weren't strong predictors of severe lung disease
Data from China, South Korea, and Italy suggests that more men are dying of the coronavirus than women. One possible explanation is that men report higher rates of smoking. Men also have higher rates of preexisting conditions, such as high blood pressure and diabetes.
But the NYU researchers ultimately determined that gender wasn't a strong predictor of severe lung disease.
"Even though everyone who had ARDS was male, most of the men in the study did not develop ARDS," Coffee said.
The researchers also found that age wasn't a strong warning sign, either — even though the death rate for the coronavirus is significantly higher among older patients.
But the predictions could change depending on where patients are located.
"As soon as we get data from the US, we'll be able to re-run the model and see if we learn something else," Bari said. "We hope that we will start collaborating very soon with hospitals in New York City."
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