Development and Validation of a Clinical, CT, Genomic Classifier and BAL Scoring System for Diagnosing IPF

The utility of incorporating a usual interstitial pneumonia (UIP) genomic classifier (GC) and bronchoalveolar lavage (BAL) cell count analysis alongside traditional clinical-imaging assessment in aiding in the multidisciplinary diagnosis of IPF in patients with a non-definite HRCT UIP pattern is uncertain.We reviewed consecutive adult patients presenting with fibrotic interstitial lung disease (fILD) and non-definite HRCT UIP pattern who underwent BAL and GC. The initial fILD diagnoses were re-evaluated after bronchoscopy and a final multidisciplinary consensus diagnosis was provided. We created a clinical score by analyzing fILD clinical characteristics, GC, and BAL results from 139 National Jewish Health (NJH) patients and validated it at the University of Arizona, n=52. A multivariable model was developed and assessed using receiver operating characteristic curves.43/139 (31%) and 29/52 (56%) of patients in the derivation and validation cohort, respectively, were diagnosed with IPF after bronchoscopy, and 85/139 (61%) and 32/52 (61%) had a change in treatment, respectively. Compared to non-IPF, IPF patients had a similar progression-free survival (HR, 1.50; 95%CI, 0.76, 2.95). The final model, assigned a score to eight predictors: age, sex, HRCT probable UIP pattern, exposures, connective tissue disease signs/symptoms, Velcro crackles, CG results, and BAL lymphocyte and monocyte count. The final score demonstrated an AUC of 0.90 (95% CI 0.85 to 0.95) in the derivation cohort and 0.91 (95% CI 0.83 to 0.99) in the validation cohort.The clinical-HRCT-BAL-GC IPF score may accurately estimate the post-test probability of IPF in patients with a non-definite HRCT UIP pattern.