Influence of radiological emphysema on lung function test in idiopathic pulmonary fibrosis

Abstract

Introduction: Idiopathic pulmonary fibrosis (IPF) is one of the most frequent interstitial lung disease. Emphysema can be associated with IPF as described in the «Combined pulmonary fibrosis and emphysema» syndrome.

Aim: The primary endpoint of this retrospective cohort study was to evaluate the impact of the association of IPF and emphysema on lung function tests parameters (FVC, TLC, FEV1, FEV1/FVC and DLCO). The secondary endpoint was to assess the impact of the associated radiological emphysema on lung function parameters used in the du Bois prognostic score recently developed by Ron du Bois et al.

Method: We retrospectively reviewed the medical files of 98 patients with lung fibrosis who were followed in our University Hospital with access to pharmacological studies and lung transplantation from 1981 to 2011. Fifty six patients were considered for analysis. The collected data included gender, age, smoking history and respiratory hospitalizations. We also analysed their pulmonary functional parameters along with radiological characteristics, in particular the presence of emphysema which was assessed on thoracic high resolution CT scan. The du Bois score was retrospectively calculated from these data.

Results: TLC and FVC at diagnosis were significantly higher in the IPF-E group compared to the IPF group (respectively 86.6 ± 17.2% pv versus 72.0 ± 15.0% pv; p: 0.004 and 86.8 ± 18.4% pv versus 72.6 ± 20.6% pv; p: 0.020). The [Formula: see text] used in the calculation of the du Bois prognostic score was significantly higher in the IPF-E group. By cons, [Formula: see text] was not statistically different between the two groups.

Conclusion: Radiological emphysema associated with IPF had an impact on pulmonary function tests. Despite this difference, the du Bois score was not statistically different between these two groups. Nevertheless, after one year of follow up, the patients with emphysema were in a subclass with a lower mortality rate than those without emphysema.

Keywords: Emphysema; Idiopathic pulmonary fibrosis; Lung function tests; du Bois score.