e-Lung CT biomarkers are associated with outcomes in fibrotic interstitial lung diseases

Background The e-Lung weighted reticulovascular score (WRVS) is an automated CT biomarker that quantifies interstitial lung disease (ILD) severity and is associated with prognosis in patients with idiopathic pulmonary fibrosis (IPF). Aims To evaluate WRVS as a prognostic factor in patients with non-IPF fibrotic ILD (fILD). Methods The test cohort comprised patients from the Open Source Imaging Consortium and the validation cohort, patients recruited to the prospective German CoWorker ILD registry. Associations between baseline and serial WRVS with future forced vital capacity (FVC) decline and survival were tested. Results Median survival was 7.1 and 6.1 years in the test (n=302) and validation (n=378) cohorts respectively. Baseline WRVS was associated with mortality in test (HR 1.11, [1.08–1.14], (p<0.001), C-index 0.75) and validation (HR 1.12, [1.09–1.15], (p<0.001), C-index 0.72) cohorts. A threshold WRVS of ≥15% was associated with mortality in both cohorts (HR 4.77, (3.11–7.31), p<0.001, C-index 0.71) and (HR 3.49, [2.48–4.91], p<0.001, C-index 0.63). After adjustment for FVC, age and sex, baseline WRVS was associated with future FVC decline or death (OR 1.13, [1.06–1.21], p<0.001, C-index 0.72) and (OR 1.18, [1.11–1.25], p<0.001, C-Index 0.72) in test and validation cohorts respectively. A rise in WRVS of 3% on serial CT was associated with mortality in both test (HR 5.69, [2.77–11.70], p<0.001, C-index 0.75) and validation cohorts (HR 1.99, [1.09–3.65], p=0.026), C-index 0.57). Conclusion In patients with non-IPF fILD, the e-Lung WRVS biomarker is associated with mortality and FVC decline when applied to baseline HRCT scans replicating previous studies in IPF. Patients with an increase in WRVS of 3% on serial CT scans have significantly increased risk of mortality.