Detection and Early Referral of Patients With Interstitial Lung Abnormalities: An Expert Survey Initiative

Abstract

Background: Interstitial lung abnormalities (ILA) may represent undiagnosed early-stage or subclinical interstitial lung disease (ILD). ILA are often observed incidentally in patients who subsequently develop clinically overt ILD. There is limited information on consensus definitions for, and the appropriate evaluation of, ILA. Early recognition of patients with ILD remains challenging, yet critically important. Expert consensus could inform early recognition and referral.

Research question: Can consensus-based expert recommendations be identified to guide clinicians in the recognition, referral, and follow-up of patients with or at risk of developing early ILDs?

Study design and methods: Pulmonologists and radiologists with expertise in ILD participated in two iterative rounds of surveys. The surveys aimed to establish consensus regarding ILA reporting, identification of patients with ILA, and identification of populations that might benefit from screening for ILD. Recommended referral criteria and follow-up processes were also addressed. Threshold for consensus was defined a priori as ≥ 75% agreement or disagreement.

Results: Fifty-five experts were invited and 44 participated; consensus was reached on 39 of 85 questions. The following clinically important statements achieved consensus: honeycombing and traction bronchiectasis or bronchiolectasis indicate potentially progressive ILD; honeycombing detected during lung cancer screening should be reported as potentially significant (eg, with the Lung CT Screening Reporting and Data System "S-modifier" [Lung-RADS; which indicates clinically significant or potentially significant noncancer findings]), recommending referral to a pulmonologist in the radiology report; high-resolution CT imaging and full pulmonary function tests should be ordered if nondependent subpleural reticulation, traction bronchiectasis, honeycombing, centrilobular ground-glass nodules, or patchy ground-glass opacity are observed on CT imaging; patients with honeycombing or traction bronchiectasis should be referred to a pulmonologist irrespective of diffusion capacity values; and patients with systemic sclerosis should be screened with pulmonary function tests for early-stage ILD.

Interpretation: Guidance was established for identifying clinically relevant ILA, subsequent referral, and follow-up. These results lay the foundation for developing practical guidance on managing patients with ILA.

Keywords: CT; fibrosis; interstitial lung abnormalities; interstitial lung disease; survey.

Figure 1

An example of axial images from the carina (A) and lung base (B) from a patient identified with interstitial lung abnormalities in the context of a chest CT scan ordered for routine cancer surveillance. White arrows highlight regions of subpleural reticulation. This chest CT scan is consistent with an indeterminate usual interstitial pneumonia pattern. The patient eventually developed progressive pulmonary fibrosis based on lung function over a 2-year period and was ultimately started on antifibrotic therapy.

Figure 2

Opinions of experts (n = 42; Survey Two) regarding interstitial lung abnormalities observed on chest CT scans during lung cancer screening: (A) abnormalities that may indicate the presence of ILD; and (B) abnormalities that warrant inclusion of an S-modifier and referral to a pulmonologist. The S-modifier indicates clinically significant or potentially significant noncancer findings. ^aIrrespective of extent or distribution. ILD = interstitial lung disease.

Figure 3

Expert opinions (n = 44; Survey One) regarding practices when asymptomatic patients are referred regarding (A) whether HCRT imaging should be ordered in patients who previously had the indicated CT scan-detected interstitial lung abnormalities; and (B) the types of pulmonary function tests that should be recommended in patients who previously had the same interstitial lung abnormalities detected following HRCT imaging. HRCT = high-resolution CT.

Figure 4

Opinions of experts (n = 42; Survey Two) regarding need for, and type of, screening in asymptomatic patients without crackles on lung auscultation who have the indicated risk factors. HRCT = high-resolution CT.