Clinical Characteristics Analysis In Patients With Combined Pulmonary Fibrosis And Emphysema

Objective Combined pulmonary fibrosis and emphysema（CPFE）is not rare in clinic,but there are relatively few studies on it.The purpose of this study was to analyze the lung function characteristics of CPFE patients and study the correlation between their lung function and high resolution CT（HRCT）quantitativity,so as to improve clinicians’ understanding of this disease.Methods This study was a case-control study,including 239 patients with CPFE admitted to The First Hospital of Lanzhou University from October 2011 to October 2021,294 patients with idiopathic pulmonary fibrosis（IPF）and 287 patients with emphysema admitted during the same period.The ratio of lung high attenuation zone volume to total lung volume（HAA%）in the CPFE group with HRCT threshold >-700 HZ units（Hu）was used as a parameter to quantify the degree of pulmonary fibrosis.According to HAA% < 5%,≥5%,<10%,≥10%,CPFE patients were divided into mild,moderate,and severe fibrosis subgroups.The ratio of lung low attenuation zone volume to total lung volume（LAA%）with HRCT threshold <-950 HU was used as a parameter to quantify the degree of emphysema.According to LAA%≥10% and <20%,≥20% and < 30% and ≥30%,CPFE patients were divided into mild,moderate and severe emphysema subgroups.The general data and pulmonary artery systolic pressure levels of the CPFE group,IPF group and emphysema group were analyzed and compared,and the lung function indexes of the CPFE group,IPF group and emphysema group,mild,moderate and severe fibrosis subgroup,and mild,moderate and severe emphysema subgroup were compared respectively.The correlation between lung function indexes and HAA%,LAA% and the total severity of parenchymal lung destruction（AA%）by HRCT in CPFE group was analyzed.Results（1）Clinical data of 820 patients were included in this study,239 patients in CPFE group,accounting for 29.1%;IPF group,294 cases,accounting for35.9%;Emphysema group was 287 cases,accounting for 35.0%.The proportion of male,smoking rate and smoking index in CPFE group were higher than those in IPF group（all P < 0.05）,and there was no statistical difference between CPFE group and emphysema group.The pulmonary artery systolic pressure in CPFE group was higher than that in IPF group and emphysema group（all P < 0.05）.There were no significant differences in age and body mass index among the three groups.（2）The RV%,TLC% and RV/TLC% of CPFE group were lower than those of emphysema group（all P < 0.05）,and there was no statistical difference between CPFE group and IPF group.FEV1% and FEV1/FVC in CPFE group were higher than those in emphysema group and lower than those in IPF group（all P <0.05）.DLCO,DLCO%,DLCO/VA and DLCO/VA% in CPFE group were lower than those in IPF group and emphysema group（all P < 0.05）.There was no significant difference in VC% and FVC% among the three groups.（3）In CPFE,HRCT quantification showed that the degree of pulmonary fibrosis gradually increased in mild,moderate and severe fibrosis subgroups,and the average degree of pulmonary fibrosis was 4.58%,6.89% and 13.43%,respectively,with statistical differences among the three groups.The degree of emphysema in the mild,moderate and severe emphysema subgroups was gradually increased by HRCT quantification,and the average degree of emphysema was 14.55%,25% and43.15%,respectively,with statistical differences among the three groups.（4）The pulmonary function of CPFE with different degrees of fibrosis was compared,VC%,TLC%,FVC% and DLCO% in severe fibrosis group were lower than those in moderate fibrosis group（all P < 0.05）,RV% was lower than those in mild and moderate fibrosis group（all P < 0.05）,FEV1/FVC was higher than those in mild and moderate fibrosis group（all P < 0.05）.There were no significant differences in FEV1%,RV/TLC%,DLCO/VA and DLCO/VA% among the three groups.（5）The pulmonary function of CPFE with different degrees of emphysema was compared,FEV1% and FEV1/FVC in severe emphysema group were lower than those in mild or moderate emphysema group（all P < 0.05）,and DLCO,DLCO%,DLCO/VA and DLCO/VA% were lower than those in mild emphysema group（all P <0.05）.There were no significant differences in VC%,RV%,TLC%,RV/TLC% and FVC% among the three groups.（6）The degree of pulmonary fibrosis showed by HRCT in CPFE patients was correlated with VC%,RV%,TLC%,FVC%,DLCO,DLCO%,DLCO/VA and DL CO/VA%（all P < 0.05）.The degree of emphysema showed by HRCT was corr elated with FEV1%,FEV1/FVC,DLCO,DLCO%,DLCO/VA and DLCO/VA%（all P < 0.05）.The overall severity of parenchymal lung destruction showed by HR CT was correlated with VC%,FVC%,FEV1%,FEV1/FVC,DLCO,DLCO%,DLCO/VA and DLCO/VA%（all P < 0.05）.Conclusion 1.CPFE is most common in elderly male patients with a history of heavy smoking and PAH.2.The pulmonary function of CPFE patients was basically normal in lung volume or pulmonary ventilation function,but significantly decreased in diffusion function;3.There was a certain correlation between chest HRCT quantification of CPFE patients and lung function indexes.