Large numbers of people are being discharged from hospital following COVID-19 without assessment of recovery. In 384 patients (mean age 59.9 years; 62% male) followed a median 54 days post discharge, 53% reported persistent breathlessness, 34% cough and 69% fatigue. 14.6% had depression. In those discharged with elevated biomarkers, 30.1% and 9.5% had persistently elevated d-dimer and C reactive protein, respectively. 38% of chest radiographs remained abnormal with 9% deteriorating. Systematic follow-up after hospitalisation with COVID-19 identifies the trajectory of physical and psychological symptom burden, recovery of blood biomarkers and imaging which could be used to inform the need for rehabilitation and/or further investigation.

The aim of this study was to compare radiology-based prediction models in rheumatoid arthritis-related interstitial lung disease (RAILD) to identify patients with a progressive fibrosis phenotype.RAILD patients had computed tomography (CT) scans scored visually and using CALIPER and forced vital capacity (FVC) measurements. Outcomes were evaluated using three techniques, as follows. 1) Scleroderma system evaluating visual interstitial lung disease extent and FVC values; 2) Fleischner Society idiopathic pulmonary fibrosis (IPF) diagnostic guidelines applied to RAILD; and 3) CALIPER scores of vessel-related structures (VRS). Outcomes were compared to IPF patients.On univariable Cox analysis, all three staging systems strongly predicted outcome (scleroderma system hazard ratio (HR) 3.78, p=9×10−5; Fleischner system HR 1.98, p=2×10−3; and 4.4% VRS threshold HR 3.10, p=4×10−4). When the scleroderma and Fleischner systems were combined, termed the progressive fibrotic system (C-statistic 0.71), they identified a patient subset (n=36) with a progressive fibrotic phenotype and similar 4-year survival to IPF. On multivariable analysis, with adjustment for patient age, sex and smoking status, when analysed alongside the progressive fibrotic system, the VRS threshold of 4.4% independently predicted outcome (model C-statistic 0.77).The combination of two visual CT-based staging systems identified 23% of an RAILD cohort with an IPF-like progressive fibrotic phenotype. The addition of a computer-derived VRS threshold further improved outcome prediction and model fit, beyond that encompassed by RAILD measures of disease severity and extent.

Short running head: IPF baseline outcome prediction Word count: 4310 wordsThis article has an online data supplement, which is accessible from this issue's table of content online at www.atsjournals.org At a Glance: Quantification of CT parenchymal patterns in idiopathic pulmonary fibrosis using computer tools has been suggested as a method that can improve on mortality prediction using visual CT scoring. As computer technology advances, it has now become possible to study CT parenchymal features that have no visual correlate. Our study demonstrates that computer-derived vessel-related structure scores can outperform current gold-standard measures of outcome in idiopathic pulmonary fibrosis such as forced vital capacity decline. Specifically, we demonstrate that using thresholds of computer-derived vessel-related structure scores for cohort enrichment can identify idiopathic pulmonary fibrosis patients that respond to antifibrotic medication with reduced FVC decline and improved survival.Importantly, the vessel-related structure thresholds would be able to reduce idiopathic pulmonary fibrosis drug-trial population sizes by 26% thereby dramatically reducing study costs. JJ and AUW were also involved in the conception and design of the study.BJB, RK and SR invented and developed CALIPER. They were involved in processing the raw CT scans and in generation of figures but were not involved with the analysis or interpretation of the data in the study. When used as a cohort enrichment tool, a CALIPER VRS score >4.4% of the lung was able to reduce the requisite sample size of an IPF drug trial by 26%. Conclusions:Our study has validated a new quantitative CT measure in IPF patients fulfilling drug trial entry criteria, the VRS scores, that outperformed current goldstandard measures of outcome. When used for cohort enrichment in an IPF drugtrial setting, VRS threshold scores can reduce a required IPF drug trial population size by 25%, thereby limiting prohibitive trial costs. Importantly VRS scores identify patients in whom antifibrotic medication prolongs life and reduces forced vital capacity decline. 6

To validate the British Society of Thoracic Imaging issued guidelines for the categorisation of chest radiographs for coronavirus disease 2019 (COVID-19) reporting regarding reproducibility amongst radiologists and diagnostic performance. MATERIALS AND METHODS: Chest radiographs from 50 patients with COVID-19, and 50 control patients with symptoms consistent with COVID-19 from prior to the emergence of the novel coronavirus were assessed by seven consultant radiologists with regards to the British Society of Thoracic Imaging guidelines. RESULTS: The findings show excellent specificity (100%) and moderate sensitivity (44%) for guideline-defined Classic/Probable COVID-19, and substantial interobserver agreement (Fleiss' k¼0.61). Fair agreement was observed for the "Indeterminate for COVID-19" (k¼0.23), and "Non-COVID-19" (k¼0.37) categories; furthermore, the sensitivity (0.26 and 0.14 respectively) and specificity (0.76, 0.80) of these categories for COVID-19 were not significantly different (McNemar's test p¼0.18 and p¼0.67). CONCLUSION: An amalgamation of the categories of "Indeterminate for COVID-19" and "Non-COVID-19" into a single "not classic of COVID-19" classification would improve interobserver agreement, encompass patients with a similar probability of COVID-19, and remove the possibility of labelling patients with COVID-19 as "Non-COVID-19", which is the presenting radiographic appearance in a significant minority (14%) of patients.

No abstract

AimsAutoimmune conditions such as rheumatoid arthritis-related interstitial lung disease (RA-ILD) have been linked to the existence of emphysema in never-smokers. We aimed to quantify emphysema prevalence in RA-ILD never-smokers and investigate whether combined pulmonary fibrosis and emphysema (CPFE) results in a worsened prognosis independent of baseline disease extent.MethodsRA-ILD patients presenting to the Royal Brompton Hospital (n = 90) and Asan Medical Center (n = 155) had CT's evaluated for a definite usual interstitial pneumonia (UIP) pattern, and visual extents of emphysema and ILD.ResultsEmphysema, identified in 31/116 (27%) RA-ILD never-smokers, was associated with obstructive functional indices and conformed to a CPFE phenotype: disproportionate reduction in gas transfer (DLco), relative preservation of lung volumes. Using multivariate logistic regression, adjusted for patient age, gender and ILD extent, emphysema presence independently associated with a CT-UIP pattern in never-smokers (0.009) and smokers (0.02).On multivariate Cox analysis, following adjustment for patient age, gender, DLco, and a CT-UIP pattern, emphysema presence (representing the CPFE phenotype) independently associated with mortality in never-smokers (p = 0.04) and smokers (p < 0.05).Conclusion27% of RA-ILD never-smokers demonstrate emphysema on CT. Emphysema presence in never-smokers independently associates with a definite CT-UIP pattern and a worsened outcome following adjustment for baseline disease severity.

BackgroundMosaic attenuation on computed tomography (CT) has been identified in international guidelines as an important diagnostic feature of fibrotic hypersensitivity pneumonitis (FHP) as opposed to idiopathic pulmonary fibrosis (IPF). However, mosaic attenuation comprises several different radiological signs (low-density lobules, preserved lobules, air trapping and the so-called “headcheese sign”) which may have differing diagnostic utility. Furthermore, the extent of mosaic attenuation required to distinguish these two diagnoses is uncertain and thresholds of mosaic attenuation from international guidelines have not been validated.MethodsInspiratory and expiratory CT scans were evaluated by two readers in 102 patients (IPF n=57; FHP n=45) using a semiquantitative scoring system for mosaic attenuation. Findings were validated in an external cohort from a secondary referral institution (IPF n=34; FHP n=28).ResultsLow-density lobules and air trapping were a frequent finding in IPF, present in up to 51% of patients. A requirement for increasing extent of low-density lobules and air trapping based on guidelines (American Thoracic Society and Fleischner Society) was associated with increased specificity for the diagnosis of FHP (0.96 and 0.98, respectively) but reduced sensitivity (0.16 and 0.20, respectively). The headcheese sign was found to be highly specific (0.93) and moderately sensitive (0.49) for a high-confidence diagnosis of FHP. The high specificity of the headcheese sign was maintained in the validation cohort and when patients with other CT features of FHP were excluded.ConclusionMosaic attenuation is a frequent finding in IPF. However, the headcheese sign can be confidently considered as being inconsistent with a diagnosis of IPF and specific for FHP.

At a Glance Scientific knowledge on the subject: Numerous studies of the respiratory microbiome in IPF have reported associations between changes in bacterial burden, microbial communities, disease progression and mortality. CHP is a pathogenically and prognostically distinct disorder compared to IPF but phenotypically is still characterised by irreversible fibrotic destruction of the lung parenchyma. Despite the phenotypic overlap between the two diseases no study has examined whether the respiratory microbiota differs between individuals with these conditions.