Progression of probable UIP and UIP on HRCT

Purpose: To determine patterns of progression of probable Usual Interstitial Pneumonitis (UIP).

Methods: This HIPPA compliant, IRB-approved study draws patients from our Fibrosis Registry. All patients with a consensus diagnosis of Idiopathic Pulmonary Fibrosis (IPF) were included. Most recent CT scans and all earlier CT scans were reviewed to determine the fibrosis grade in each lobe based on probable UIP (pUIP) findings of ground glass opacities, traction bronchiolectasis and reticulations or UIP findings of subpleural basilar predominant fibrosis with honeycombing (HC) and absence of features that would suggest an alternative diagnosis.

Results: 103 patients with a working diagnosis of IPF are the focus of this report. Among the 68 with pUIP on the initial CT, 32 (47%) progressed; median time to progression was 51 months. The risk of HC progression, adjusted for gender, of patients with emphysema was 2.53 times higher than patients without emphysema (HR = 2.53, 95% CI: 1.06-6.02). Among the 35 with HC on the initial CT scan, 20 (57%) progressed to more advanced HC; median time to progression was 31 months. Increased pulmonary artery size was significantly associated with an elevated risk for more advanced HC progression (HR = 1.16, 95% CI: 1.04-1.31).

Conclusion: Ground glass opacities, traction bronchiolectasis and reticulations, a "Probable UIP Pattern" by ATS criteria progressed to UIP in 47% of patients on follow-up imaging.