Emphysema affects FVC decline rate in idiopathic pulmonary fibrosis
Emphysema to an extent of ≥10 percent influences both the annual decline rate and the prognostic significance of forced vital capacity (FVC) in idiopathic pulmonary fibrosis (IPF), suggests a study. Such extent may be used to define combined pulmonary fibrosis and emphysema (CPFE).
The extent of emphysema was ≥5 percent, ≥10 percent and ≥15 percent in 53 (25 percent), 23 (11 percent) and 12 (6 percent) patients. Those with emphysema to an extent of ≥5 percent were more likely to be male and ever-smokers. They also had more preserved lung volume and lower rates of FVC decline compared to those with no or trivial emphysema.
The FVC decline rate significantly predicted mortality in patients with no or trivial emphysema (hazard ratio [HR], 0.933; p<0.001) and in those with an extent of emphysema ≥5 percent (HR, 0.906; p<0.001). However, the diffusing capacity of the lung for carbon monoxide was the most significant prognostic factor in patients with emphysema to an extent of ≥10 percent (HR, 0.972; p=0.040) and ≥15 percent (HR, 0.942; p=0.023).
A 10-percent cutoff value for the extent of emphysema made the most significant difference in the annual FVC decline rate in IPF patients.
This study observed and measured the extent of emphysema on high-resolution computed tomography scans and by a texture-based automated quantification system, respectively, in 209 IPF patients. The impact of differences in the extent of emphysema on the annual decline rate and prognostic significance of lung function parameters was analysed.
“CPFE is characterized by preserved lung volume and slower lung function decline. However, it is unclear at what extent emphysema begins to impact respiratory physiology and prognostic characteristics in IPF,” the authors noted.