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The vast majority of hospitalized COVID-19 patients show lung damage 6 weeks after discharge, but this proportion drops significantly after 12 weeks, suggesting that the lungs have a self-repair mechanism, researchers report.
“We know from other lung studies that lungs have the potential to recover from inflammation,” said investigator Sabina Sahanic, MD, a clinical PhD student at University Clinic in Innsbruck, Austria. “Specialists knew we’d have to wait some weeks to clarify this and estimate how good the resolution is. And we are very happy to see a good resolution.”
The 86-patient preliminary analysis — believed to be the first prospective study tracking lung and heart outcomes in COVID-19 patients — also showed that shortness of breath is the most common symptom 6 weeks after discharge, affecting 47% of patients, followed by coughing, affecting 15%. At 12 weeks, only 39% of patients were still experiencing shortness of breath, but 15% were still coughing.
“The 12-week timeline is particularly important because in many other lung diseases at this time point, we can estimate resolution or recovery,” Sahanic told Medscape Medical News.
But “we have no definition here of what is long-term,” she said. “We are really early in the pandemic phase, at 3 months, and we do not know how long diseased lungs [from COVID-19] will react to other infections.”
“There are some uncertainties remaining, of course,” added Sahanic, who presented the findings at the virtual European Respiratory Society (ERS) International Congress 2020.
She and her team wanted to analyze persistent pulmonary impairment after COVID-19 infection in part because 30% of survivors of the SARS outbreak in 2002/03 experienced such lingering effects. Their research is ongoing, and they expect to gather 24-week postdischarge results from more than 150 patients.
The study participants — average age, 61 years; 65% men — were hospitalized for COVID-19 at three centers in Austria from late April to early June. Nearly half had a smoking history and 65% were overweight or obese. Average hospital stay was 13 days, 20% of patients were treated in an ICU, and 19% required mechanical ventilation.
Six and 12 weeks after discharge, participants underwent clinical exams, lung function tests, CT scanning of their lungs, echocardiograms, and blood tests to analyze oxygen and carbon dioxide levels.
Notably, CT scans at 6 weeks showed lung damage from inflammation and coronavirus-induced fluid accumulation — which shows up as “ground glass” patches — in 88% of patients. At 12 weeks, this measure dropped to 56%. The severity of overall lung damage dropped from 8 points on 6-week CT scans to 4 points on 12-week CT scans.
There was also improvement in lung function from 6-week to 12-week follow-up.
|Table. Participants Whose Lung Function Measures Were Less Than 80% of Normal at Follow-up|
|Measure||6 Weeks||12 Weeks|
|Forced expiratory volume in 1 second (FEV₁)||23%||21%|
|Forced vital capacity (FVC)||28%||19%|
|Diffusing capacity of the lungs for carbon monoxide (DLCO)||33%||22%|
No signs of progressive pulmonary fibrosis were observed in any participants, Sahanic reported.
However, the link between COVID-19 and heart damage was less obvious on follow-up testing. Although serum NT-proBNP, D-dimer, and ferritin levels were clearly elevated, echocardiograms, which showed ventricular diastolic dysfunction in nearly 60% of patients, did not prove the damage caused specifically by coronavirus, she said.
Instead, heart dysfunction could be due to overall COVID-19 disease. Many recovering ICU patients exhibit overall diastolic insufficiency, Sahanic noted.
“There is relief that our patients do not suffer severe virus-related heart disease,” she said, adding that larger trials are needed to establish the frequency of COVID-related organ damage.
These findings drive home the need to implement structured follow-up care for COVID-19 patients, researchers say. Understanding the long-term lung effects might also prompt clinicians to treat symptoms and any lung damage earlier in the disease course, and could shape how they counsel patients.
“If GPs or specialists find a pneumonia, they can give good perspective to the patient,” said coinvestigator Judith Löffler-Ragg, MD, also from University Clinic in Innsbruck.
“We still have to wait to see what happens with residual lung lesions, but we have preliminary data showing that there is resolution of so-called damage,” she told Medscape Medical News.
She acknowledged, though, that the research was limited by the small patient cohort.
Still, the study’s prospective approach is a particular strength, because few studies have tracked COVID-19 patients in this manner, said ERS President Thierry Troosters, PhD, from Katholieke Universiteit Leuven in Flanders, Belgium.
“When a new disease occurs, it is important to map out the short- and longer-term consequences of the condition. In the case of SARS-CoV2, a new lung disease with significant impact on other organ systems, that is all the more important,” he told Medscape Medical News.
“The cohort is still small,” he added, but gradually, clinicians will “get better insight into the natural history of the infection and the long-term consequences for patients.”
“It is not very surprising that a significant pulmonary insult has long-lasting consequences in many patients,” Troosters said. “It is good to see, and reassuring, that in many patients there was an avenue to improvement.”
Sahanic, Löffler-Ragg, and Troosters disclosed no relevant financial relationships.
European Respiratory Society (ERS) International Congress 2020: Abstract OA4143. Presented September 7, 2020.