Residual lung abnormalities were detected in nearly 11% of Covid-19 patients who had been hospitalized due to Covid-19, according to a study published in American Journal of Respiratory and Critical Care Medicine.^1-3

The UK Interstitial Lung Disease (UKILD) study was conducted to examine the prevalence of residual lung abnormalities in people hospitalized with COVID-19. The risk of residual lung damage was also determined in patients who did not undergo a CT scan. In this study, researchers analysed 209 follow-up thoracic CT scans of patients who had earlier been hospitalized for Covid-19, for residual abnormal lung patterns such as ground glass opacities and reticulations, specifically more than 10% lung involvement. Their median age was 58 years; 68% of the study population was male. These patients had been a part of the Post-HOSPitalisation COVID Study (PHOSP-COVID). Patients who had been diagnosed with interstitial lung disease before being hospitalized for Covid were excluded from the UKILD study. Data was collected from March 2021 to October 2021.

Out of the 3700 patients in the cohort, 209 had a thoracic CT scan. Of these, 164 people (79.6%) had more than 10% involvement of lung with residual lung abnormalities at a median of 119 days after hospital discharge. The risk factors for residual lung abnormalities in patients with CT scan were identified as abnormal findings on chest X-ray with relative risk of 1.21, percent predicted DLco less than 80% with RR of 1.25 and severe Covid-19 at the time of hospitalization requiring ventilation support with RR of 1.27. Men were more likely to have residual lung abnormalities greater than 10% with RR of 1.42. A similar risk was observed in patients aged 60 years and older with RR of 1.22.

These three risk factors were used to determine the risk of residual lung abnormalities in the  remaining 3491 patients who did not have a CT scan. All three risk factors were present in 14 patients and were categorized as very high risk; 143 had two risk factors (high risk), 116 had either an abnormal chest x-ray or ppDLCO<80% (moderate risk), while 1256 just had severe illness (low risk). The rest (n=1962) of the patients in this group did not have any of the three risk factors and were considered to be at very low risk. The moderate to very-high risk of residual lung abnormalities was estimated to be 7.8%. The post-hospitalization prevalence, which was calculated to be 8.5% increased to 11.7% in sensitivity analysis.

When patients with CT evidence of lung damage were compared with at-risk patients without CT scan, 45% were not administered invasive oxygen supplementation at the time of admission compared to 44.3% of patients at risk.

This study highlights the high prevalence of residual lung abnormalities in patients who had been hospitalized because of Covid-19. It has also delineated risk factors that are associated with residual lung damage. Up to 11% of patients were found to have lung fibrosis after they had recovered from the acute illness. Persons at risk should be regularly and closely monitored for timely detection and assessment of progression or resolution over time. The authors note, “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.”²

References

1. Stewart I, et al. Residual Lung Abnormalities Following COVID-19 Hospitalization: Interim Analysis of the UKILD Post-COVID Study. Am J Respir Crit Care Med. 2022 Dec 1. doi: 10.1164/rccm.202203-0564OC.
2. American Thoracic Society Press Release, Dec. 2, 2022, https://www.thoracic.org/about/newsroom/press-releases/journal/2022/lung-damage-after-covid-19-hospitalization.php. Accessed on Dec. 16, 2022.
3. https://www.healio.com/news/pulmonology/20221206/lung-abnormalities-persist-after-covid19-hospitalization-even-without-severe-illness. Dec. 6, 2022, Accessed on Dec. 16, 2022.