Breakthrough: Blood Test Shows Potential to Predict Risk of Long-Term COVID-19 Lung Complications
UVA Health researchers have discovered a potential way to predict which patients with severe COVID-19 are likely to recover well and which are likely to suffer “long-haul” lung problems, a finding that could better personalize treatments for individual patients.
UVA’s new research also eases concern that severe COVID-19 could trigger relentless, ongoing lung scarring akin to the chronic lung disease known as idiopathic pulmonary fibrosis, in which continuing lung damage eventually proves fatal.
“We are excited to find that people with long-haul COVID have an immune system that is totally different from people who have lung scarring that doesn’t stop,” said researcher Dr. Catherine A. Bonham, a pulmonary and critical care expert and scientific director of UVA Health’s Interstitial Lung Disease Program. “This offers hope that even patients with the worst COVID do not have progressive scarring of the lung that leads to death.”
Long-Haul COVID-19
Up to 30% of patients hospitalized with severe COVID-19 continue to suffer persistent symptoms months after recovering from the virus. Many of these patients develop lung scarring – some early on in their hospitalization, and others within six months of their initial illness, prior research has found.
Bonham and her collaborators wanted to better understand why this scarring occurs, determine if it is similar to progressive pulmonary fibrosis and see if there is a way to identify patients at risk.
Researchers followed 16 UVA Health patients who survived severe COVID-19, including 14 who were hospitalized and placed on a ventilator during treatment. All had trouble breathing and suffered fatigue and abnormal lung function at their first outpatient checkup.
After six months, researchers found that the patients could be divided into two groups. One group’s lung health improved, prompting the researchers to label them “early resolvers.” The other group, dubbed “late resolvers,” continued to suffer lung problems and pulmonary fibrosis.
Looking at blood samples taken before the recovery paths diverged, the team found that late resolvers had significantly fewer immune cells known as monocytes – white blood cells that play a critical role fending off disease – circulating in their blood. The cells were abnormally depleted in patients who continued to suffer lung problems compared both to those who recovered and healthy control subjects.
The decrease in monocytes also correlated with the severity of the patients’ ongoing symptoms. That suggests that doctors may be able to use a simple blood test to identify patients likely to suffer long-haul COVID and to improve their care.
“About half of the patients we examined still had lingering, bothersome symptoms and abnormal tests after six months,” Bonham said. “We were able to detect differences in their blood from the first visit, with fewer blood monocytes mapping to lower lung function.”
The researchers also wanted to determine if severe COVID-19 could cause progressive lung scarring like idiopathic pulmonary fibrosis. They found the two conditions had very different effects on immune cells, suggesting that even though symptoms were similar, the underlying causes were very different. This held true in patients with the most persistent long-haul COVID-19 symptoms.
“Idiopathic pulmonary fibrosis is progressive and kills patients within three to five years,” Bonham said. “It was a relief to see that all our COVID patients, even those with long-haul symptoms, were not similar.”
Because of the small numbers of participants in UVA’s study, and because they were mostly male (for easier comparison with idiopathic pulmonary fibrosis, a disease that strikes mostly men), the researchers say larger studies with other medical centers are needed to bear out the findings.
Still, they are hopeful that their new discovery will provide doctors a useful tool to identify COVID-19 patients at risk for long-haul lung problems and help guide them to recovery.
“We are only beginning to understand the biology of how the immune system impacts pulmonary fibrosis,” Bonham said. “My team and I were humbled and grateful to work with the outstanding patients who made this study possible.”
Findings Published
The researchers have published their findings in the scientific journal Frontiers in Immunology. The research team consisted of Grace C. Bingham, Lyndsey M. Muehling, Chaofan Li, Yong Huang, Shwu-Fan Ma, Daniel Abebayehu, Imre Noth, Jie Sun, Judith A. Woodfolk, Thomas H. Barker and Bonham. Noth disclosed that he has received personal fees from Boehringer Ingelheim, Genentech and Confo unrelated to the research project. In addition, he has a patent pending related to idiopathic pulmonary fibrosis. Bonham and all other members of the research team had no financial conflicts to disclose.