One in ten hospitalised COVID-19 patients have residual fibrotic lung damage that requires ongoing follow-up care, a UK study has found.
Researchers at Imperial College and the National Heart & Lung Institute, London, looked for evidence of abnormal lung patterns on follow-up CT scans from 209 COVID-19 patients discharged from hospital.
Interim findings from the ongoing UKILD Post-COVID study showed that almost 80% had had residual lung abnormalities involving at least 10% involvement of the lung.
In the images analysed, ground glass opacities affected 26% of the lung, reticulations a mean 15%, with residual abnormalities involving a mean of 41% of the lung.
Risk factors for residual fibrotic abnormalities included abnormal chest X-ray (relative risk 1·21), percent predicted DLco >80% (RR 1.25) and severe admission requiring ventilation support (RR 1·27).
When the characteristics of the study participants with CT scans were applied to a wider post-hospitalisation cohort of almost 3,500 people without a CT to stratify risk of residual lung abnormalities, the post-hospitalisation prevalence of lung abnormalities was estimated to be 11.7%.
The study authors said that at the time of the interim analysis it was not possible to determine whether the observed residual lung abnormalities represented early interstitial lung disease (ILD) with potential for progression, or whether they reflect residual pneumonitis that may be stable or resolve over time.
They noted that where linked longitudinal scans were available most patients did not show evidence of substantial improvement, “although such clinically requested CTs may be over-represented by those with slower recovery.”
“For some people these fibrotic patterns may be stable or resolve, while for others they may lead to longer term lung fibrosis progression, worse quality of life and decreased life expectancy. Earlier detection of progression is essential to improving outcomes,” said lead investigator Dr Iain Stewart (PhD).
“Whilst many people experience prolonged breathlessness, the major implication of these findings is that a substantial number of people discharged from a COVID hospitalisation may also have fibrotic abnormalities in their lungs,” he added.
“These results should help concentrate efforts to closely follow at-risk patients. This follow-up should include repeat radiological imaging and lung function testing,” he concluded.
According to the authors writing in the American Journal of Respiratory and Critical Care Medicine: (link here):“The UKILD Post-COVID interim analysis of residual lung abnormalities in patients hospitalised for COVID-19 offers the largest assessment of prevalence in hospitalized individuals to date, and is consistent with findings from a number of smaller studies that demonstrate persistent radiological patterns and impaired gas transfer during the extended follow up of patients with COVID-19. At the time of this interim analysis it is not possible to determine whether the observed residual lung abnormalities represent early interstitial lung disease with potential for progression, or whether they reflect pneumonitis that may be stable or resolve over time.”
“The next phase of the study is a primary analysis, which will be performed at 12 months. At that time, we will also use linked electronic health records of hospital admissions and mortality data to support our analyses. We expect to have the final results in early 2023.”