Evolution of diagnostic UIP computed tomography patterns in idiopathic pulmonary fibrosis: Disease spectrum and implications for survival

Background: Whether current diagnostic computed tomography (CT) patterns in idiopathic pulmonary fibrosis (IPF) represent distinct clinical phenotypes or simply temporal evolution of the same underlying radiologic process is unknown. We studied IPF patients presenting with 'possible' or 'inconsistent' usual interstitial pneumonia (UIP) CT patterns and characterized the frequency and timing of evolution to 'consistent' UIP and its effect on survival. Material and methods: Consecutive IPF patients seen at our institution from 1/1/2005 through 12/31/2013 were assessed for study inclusion. Presenting and serial CT scans were reviewed by two expert radiologists. Baseline and interval clinical data were collated. Results: Ninety one patients (mean age 67.4 years, 59% male) met study criteria with 'possible' and 'inconsistent' UIP CT patterns present in 58 (64%) and 33 (36%) cases, respectively. Twenty nine (32%) transitioned to a 'consistent' UIP pattern over a median of 57 months (interquartile range 33-78 months). Decline in pulmonary function was statistically significant on interval follow-up for those with or without pattern evolution, but no different between them in terms of degree. Evolution to 'consistent' UIP did not confer worse survival from the date of disease diagnosis or date of first CT with 'consistent' UIP pattern. Conclusions: A portion of IPF patients with initial 'possible' or 'inconsistent' UIP CT pattern will go on to develop 'consistent' UIP CT pattern over months to years. Despite this, there appeared to be similar risk and cause of death in those with or without pattern evolution, suggesting similar morbidity across the radiologic spectrum in IPF.