AB029. Clinical utility of a molecular diagnostic in evaluation of interstitial lung disease

Background: The accurate diagnosis of idiopathic pulmonary fibrosis (IPF) continues to be challenging due to its overlapping features with other interstitial lung diseases (ILDs). With the approval of pirfenidone and nintedanib for treatment of IPF, there is greater urgency to identify patients with IPF without requiring surgical lung biopsy (SLB). In this study, we evaluated the clinical utility of a genomic classifier under development to identify usual interstitial pneumonia (UIP), the pathology pattern associated with IPF, using bronchoscopically collected samples.

Methods: A national survey was conducted from March 17–20, 2015 among 76 pulmonologists from ILD centers and non-specialty clinics. The survey described a genomic test with high precision for detecting UIP pattern using bronchoscopically collected samples. Physicians were asked about diagnostic/treatment next steps on four ILD patient cases representing confident UIP, possible UIP, possible UIP vs. hypersensitivity pneumonitis (HP), and connective tissue disease related ILD and how the genomic test would alter management.

Results: Physicians’ likelihood of using the genomic test varied with the method of sampling. Ninety-one percent of physicians reported they would likely use the test if it required bronchoalveolar lavage (BAL), compared with 85% for transbronchial biopsy (TBB), and 63% for SLB. Across four clinical scenarios, a positive genomic test result significantly increased treatment with pirfenidone/nintedanib and reduced biopsies. The largest impact occurred in the possible UIP cases with an increase in treatment from 11% to 46% (P<0.001) and a decrease in biopsies from 59% to 26% (P<0.001). A positive test in the setting of confident UIP raised treatment recommendation from 47% to 70% (P<0.001) and decreased biopsies from 42% to 18% (P<0.001), suggesting its utility even in cases with high pre-test probability for UIP. A negative test result was less impactful on management than a positive one.

Conclusions: The introduction of an innovative genomic diagnostic test had a strong clinical impact on management approaches for ILD. Utilization of such diagnostic tools may decrease the need for biopsies and increase appropriate diagnosis and treatment of IPF.

Keywords: Idiopathic pulmonary fibrosis (IPF); lung diseases; genomic diagnostic test; usual interstitial pneumonia (UIP)