Prevalence and prognostic meaning of interstitial lung abnormalities in remote CT scans of patients with interstitial lung disease treated with antifibrotic therapy

Objectives To describe the prevalence and characteristics of interstitial lung abnormalities (ILA) in CT scans performed prior to the initiation of antifibrotics in a series of patients with interstitial lung disease (ILD), and to identify characteristics apparent on early CT scans that could help to predict outcomes. Methods We conducted a retrospective observational study. The original cohort consisted of 101 patients diagnosed with ILD and treated with antifibrotics in a tertiary hospital. Patients were included if they had a thoracic CT scan performed at least one year before initiation of therapy. They were classified radiologically in three groups: without ILA, with radiological ILA and extensive abnormalities. ILA were classified as subpleural fibrotic, subpleural non-fibrotic and non-subpleural. The initial scan and the latest CT scan performed before treatment were read for assessing progression. The relationship between CT findings of fibrosis and the radiological progression rate and mortality were analyzed. Results We included 50 patients. Only 1 (2%) had a normal CT scan, 25 (50%) had extensive alterations and 24 (48%) had radiological criteria for ILA, a median of 98.2 months before initiation of antifibrotics, of them 18 (75%) had a subpleural fibrotic pattern. Significant bronchiectasis and obvious honeycombing in the lower zones were associated with shorter survival (p = 0.04). Obvious honeycombing in the lower zones was also significantly (p < 0.05) associated with a faster progression rate. Conclusions Fibrotic ILAs are frequent in remote scans of patients with clinically relevant ILD, long before they require antifibrotics. Findings of traction bronchiectasis and honeycombing in the earliest scans, even in asymptomatic patients, are related to mortality and progression later on.