Abstract Rationale Interstitial lung abnormalities (ILA) are incidentally-detected nondependent CT changes in asymptomatic individuals without preexisting interstitial lung disease (ILD), where 30-70% of cases progress. It is critical to identify individuals with ILA who are likely to progress for improved clinical management. We recently demonstrated that amongst ILA patients, endobronchial optical coherence tomography (EB-OCT)-detected microscopic usual interstitial pneumonia (UIP) and probable UIP are strongly predictive of disease progression, including progression to idiopathic pulmonary fibrosis (IPF). We also showed microscopic small airway loss in early IPF detected by EB-OCT. Here, we use microscopic, large-volume EB-OCT imaging to assess small airway loss in vivo in ILA subjects as compared with early IPF and non-ILD control subjects. Methods EB-OCT was performed in 8 ILA, 11 early IPF, and 5 non-ILD control subjects, matched by age and sex. IPF subjects had mild restrictive disease (mean FVC: 84.8% predicted). ILA subjects were asymptomatic, without evidence of restriction (mean FVC: 90.6% predicted). EB-OCT was acquired bronchoscopically in multiple, distinct imaging sites bilaterally. Number of bronchioles per cm3 was quantified for all imaging sites. Annual clinical follow-up data (up to 5 years) from the ILA cohort was assessed to determine subsequent progression and ILD diagnosis. Results EB-OCT was performed in 60 IPF, 48 ILA, and 33 control imaging sites. On follow-up, 2 ILA subjects had no progression symptomatically, radiologically, or by PFTs for 5 years; 6 ILA subjects progressed on subsequent HRCT; and 2 ILA subjects progressed to clinical IPF diagnosis. Compared to control subjects (mean: 11.2 bronchioles/cm3; SD: 6.2), there was significant bronchiole reduction in IPF subjects (43% loss; mean: 6.4/cm3; SD: 3.5; p 0.001). Bronchiole count in ILA subjects who progressed was similar to that of IPF subjects (mean: 6.9/cm3; SD: 2.1; p = 0.066) and significantly reduced compared to control subjects (39% loss; p 0.001). In ILA subjects who did not progress, bronchiole count was statistically indistinguishable from control subjects (mean: 8.3/cm3; SD: 2.3, p = 0.136). Conclusion EB-OCT demonstrated ∼40% bronchiole loss in ILA subjects who progressed and 43% bronchiole loss in early IPF, when compared to control subjects. ILA subjects who did not progress over 5-year follow-up did not exhibit significant bronchiole reduction compared to controls. These findings demonstrate small airway loss in presymptomatic ILA that ultimately progressed on follow-up, suggesting that small airway abnormalities may play an early role in the commencing stages of disease pathogenesis and have potential to be a prognostic indicator of progression in ILA. This abstract is funded by: None
Berigei et al. (Fri,) studied this question.