Interstitial lung damage following COVID-19 hospitalisation: an interim analysis of the UKILD Post-COVID study.

IntroductionShared characteristics between COVID-19 and pulmonary fibrosis, including symptoms, genetic architecture, and circulating biomarkers, suggests interstitial lung disease (ILD) development may be associated with SARS-CoV-2 infection. MethodsThe UKILD Post-COVID study planned interim analysis was designed to stratify risk groups and estimate the prevalence of Post-COVID Interstitial Lung Damage (ILDam) using the Post-HOSPitalisation COVID-19 (PHOSP-COVID) Study. Demographics, radiological patterns and missing data were assessed descriptively. Bayes binomial regression was used to estimate the risk ratio of persistent lung damage >10% involvement in linked, clinically indicated CT scans. Indexing thresholds of percent predicted DLco, chest X-ray findings and severity of admission were used to generate risk strata. Number of cases within strata were used to estimate the amount of suspected Post-COVID ILDam. ResultsA total 3702 people were included in the UKILD interim cohort, 2406 completed an early follow-up research visit within 240 days of discharge and 1296 had follow-up through routine clinical review. We linked the cohort to 87 clinically indicated CTs with visually scored radiological patterns (median 119 days from discharge; interquartile range 83 to 155, max 240), of which 74 people had ILDam. ILDam was associated with abnormal chest X-ray (RR 1.21 95%CrI 1.05; 1.40), percent predicted DLco<80% (RR 1.25 95%CrI 1.00; 1.56) and severe admission (RR 1.27 95%CrI 1.07; 1.55). A risk index based on these features suggested 6.9% of the interim cohort had moderate to very-high risk of Post-COVID ILDam. Comparable radiological patterns were observed in repeat scans >90 days in a subset of participants. ConclusionThese interim data highlight that ILDam was not uncommon in clinically indicated thoracic CT up to 8 months following SARS-CoV-2 hospitalisation. Whether the ILDam will progress to ILD is currently unknown, however health services should radiologically and physiologically monitor individuals who have Post-COVID ILDam risk factors.