The effect of emphysema on lung function and survival in patients with idiopathic pulmonary fibrosis

Background and objective: In this study the prevalence, lung function and prognosis of IPF combined with emphysema were evaluated. Methods: Consecutive patients with usual interstitial pneumonia (UIP) on high‐resolution computed tomography (HRCT), with or without emphysema, were assessed retrospectively. The area of fibrosis in the base of the lungs was assessed by HRCT as minimal (<2 cm from the subpleura), moderate (≥2 cm from the subpleura, <1/3 of the area of the base of the lungs) or severe (≥1/3 of the area of the base of the lungs). Results: Among 660 patients with UIP on HRCT, 221 showed upper‐lobe emphysema. Pulmonary function results for patients with UIP and UIP/emphysema, respectively, were: FVC, 71.8% and 87.1%; FEV1%, 86.7% and 87.9%; and DL_CO, 74.3% and 65.2% of predicted. The relationship between FVC, the extent of fibrosis and survival was investigated in 362 patients with records of pulmonary function tests and no lung cancer at the time of entry into the study. Although the extent of fibrosis was similar between the groups, 71.3% of UIP patients met the lung volume criteria for IPF (FVC <80% of predicted), whereas only 26.5% of UIP/emphysema patients met the lung volume criteria for IPF. Median survival was 7.5 years in the UIP group and 8.5 years in the UIP/emphysema group. Conclusions: Emphysema was a common finding in patients with UIP. Patients with UIP and emphysema had greater lung volumes and better survival compared with those with UIP alone.