Pulmonary function and survival in idiopathic vs secondary usual interstitial pneumonia

Chest. 2014 Sep;146(3):775-785. doi: 10.1378/chest.13-2388.


Background: The usual interstitial pneumonia (UIP) pattern of lung injury may occur in the setting of connective tissue disease (CTD), but it is most commonly found in the absence of a known cause, in the clinical context of idiopathic pulmonary fibrosis (IPF). Our objective was to observe and compare longitudinal changes in pulmonary function and survival between patients with biopsy-proven UIP found in the clinical context of either CTD or IPF.

Methods: We used longitudinal data analytic models to compare groups (IPF [n = 321] and CTD-UIP [n = 56]) on % predicted FVC (FVC %) or % predicted diffusing capacity of the lung for carbon monoxide (Dlco %), and we used both unadjusted and multivariable techniques to compare survival between these groups.

Results: There were no significant differences between groups in longitudinal changes in FVC % or Dlco % up to diagnosis, or from diagnosis to 10 years beyond (over which time, the mean decrease in FVC % per year [95% CI] was 4.1 [3.4, 4.9] for IPF and 3.5 [1.8, 5.1] for CTD-UIP, P = .49 for difference; and the mean decrease in Dlco % per year was 4.7 [4.0, 5.3] for IPF and 4.3 [3.0, 5.6] for CTD-UIP, P = .60 for difference). Despite the lack of differences in pulmonary function, subjects with IPF had worse survival in unadjusted (log-rank P = .003) and certain multivariable analyses.

Conclusions: Despite no significant differences in changes in pulmonary function over time, patients with CTD-UIP (at least those with certain classifiable CTDs) live longer than patients with IPF--an observation that we suspect is due to an increased rate of mortal acute exacerbations in patients with IPF.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Aged
  • Biopsy
  • Female
  • Humans
  • Idiopathic Pulmonary Fibrosis / mortality*
  • Idiopathic Pulmonary Fibrosis / physiopathology*
  • Kaplan-Meier Estimate
  • Longitudinal Studies
  • Lung / pathology
  • Lung / physiopathology*
  • Lung Diseases, Interstitial / mortality*
  • Lung Diseases, Interstitial / physiopathology*
  • Male
  • Middle Aged
  • Multivariate Analysis
  • Pulmonary Diffusing Capacity / physiology
  • Respiratory Function Tests
  • Survival Rate
  • Vital Capacity / physiology