Abstract
Background Idiopathic pulmonary fibrosis (IPF) with coexistent emphysema, termed combined pulmonary fibrosis and emphysema (CPFE) may associate with reduced forced vital capacity (FVC) declines compared to non-CPFE IPF patients. We examined associations between mortality and functional measures of disease progression in two IPF cohorts. Methods Visual emphysema presence (>0% emphysema) scored on computed tomography identified CPFE patients (CPFE/non-CPFE: derivation cohort n=317/n=183, replication cohort n=358/n=152), who were subgrouped using 10% or 15% visual emphysema thresholds, and an unsupervised machine-learning model considering emphysema and interstitial lung disease extents. Baseline characteristics, 1-year relative FVC and diffusing capacity of the lung for carbon monoxide (DLCO) decline (linear mixed-effects models), and their associations with mortality (multivariable Cox regression models) were compared across non-CPFE and CPFE subgroups.
Results In both IPF cohorts, CPFE patients with ≥10% emphysema had a greater smoking history and lower baseline DLCO compared to CPFE patients with <10% emphysema. Using multivariable Cox regression analyses in patients with ≥10% emphysema, 1-year DLCO decline showed stronger mortality associations than 1-year FVC decline. Results were maintained in patients suitable for therapeutic IPF trials and in subjects subgrouped by ≥15% emphysema and using unsupervised machine learning. Importantly, the unsupervised machine-learning approach identified CPFE patients in whom FVC decline did not associate strongly with mortality. In non-CPFE IPF patients, 1-year FVC declines ≥ 5% and ≥ 10% showed strong mortality associations. Conclusion When assessing disease progression in IPF, DLCO decline should be considered in patients with ≥10% emphysema and a ≥ 5% 1-year relative FVC decline threshold considered in non-CPFE IPF patients.
Original language | English |
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Article number | 2300127 |
Number of pages | 14 |
Journal | European Respiratory Journal |
Volume | 63 |
Issue number | 4 |
DOIs | |
Publication status | Published - Apr 2024 |