The detection, assessment and clinical evolution of interstitial lung abnormalities identified through lung cancer screening

Introduction Interstitial lung abnormalities (ILAs) are common incidental findings in lung cancer screening however their clinical evolution and longer-term outcomes are less clear. The aim of this cohort study was to report five-year outcomes of individuals with ILA identified through a lung cancer screening programme. In addition, we compared patient reported outcome measures (PROMs) in patients with screen-detected ILA to newly diagnosed interstitial lung disease (ILD) to assess symptoms and health-related quality of life (HRQOL).

Methods Individuals with screen-detected ILA were identified and five-year outcomes, including ILD diagnoses, progression-free survival and mortality, were recorded. Risk factors associated with ILD diagnosis were assessed using logistic regression and survival using Cox proportional hazard analysis. PROMs were compared between a subset of patients with ILA and a group of ILD patients.

Results 1,384 individuals underwent baseline low-dose computed tomography (LDCT) screening with 54 (3.9%) identified as having ILA. 22 (40.7%) were subsequently diagnosed with ILD. 14 individuals (25.9%) died, and 28 (53.8%) suffered disease progression within five years. Fibrotic ILA was an independent risk factor for ILD diagnosis, mortality, and reduced progression-free survival. Patients with ILA had lower symptom burden and better HRQOL in comparison to the ILD group. Breathlessness visual analogue score (VAS) was associated with mortality on multivariate analysis.

Conclusions Fibrotic ILA was a significant risk factor for adverse outcomes including subsequent ILD diagnosis. Whilst screen-detected ILA patients were less symptomatic, breathlessness VAS was associated with adverse outcomes. These results could inform risk stratification in ILA.