The UK Interstitial Lung Disease Long-COVID19 study (UKILD-Long COVID): understanding the burden of Interstitial Lung Disease in Long COVID.

The COVID-19 pandemic has caused significant worldwide mortality and morbidity with >1 million people infected and >170,000 people hospitalised in the UK. Current estimates suggest 10-20% of non-hospitalised patients and 40-60% of hospitalised patients have long term symptoms, including breathlessness and fatigue, so-called "Long COVID". Emerging radiological and physiological features suggest Interstitial Lung diseases (ILD) including organising pneumonia and pulmonary fibrosis occur in up to 20% of hospitalised patients, although the precise burden and natural history of Long COVID related ILD (LCILD) is not clear. Given the large number of patients with persisting breathlessness there is an urgent need to identify and prevent the development LCILD. To improve outcomes for survivors of COVID-19 we will a) determine the prevalence of ILD following COVID-19, stratified by severity of infection and treatment, b) describe the phenotypes, c) determine the natural history and d) identify pathomechanisms and biomarkers of LCILD. Patients with documented COVID-19 will be recruited and the proportion of patients with symptoms, signs and investigations consistent with ILD between 3 and 6 months will be documented. In patients where ILD is suspected clinically this will be confirmed by Computerised Tomography (CT) scanning and patients will be stratified by pre-existing ILD, hospitalisation status, and therapy received. A subgroup of patients with proven LCILD will be re-consented for 12-month follow-up and deep phenotyping including 129Xenon-MRI and bronchoalveolar lavage. These data will define the burden of LCILD and inform the design of clinical trials to assess potential therapies to modulate progression of LCILD.