Attenuation Levels of Lung Fields in Quantitative Computed Tomography Evaluation Are Associated With Overall Survival and the Incidence of Acute Exacerbation in Combined Pulmonary Fibrosis and Emphysema: A Single-Center Retrospective Observational Study.

BACKGROUND AND AIMS: Combined pulmonary fibrosis and emphysema (CPFE) is characterized by the coexistence of emphysematous lesions and fibrotic interstitial lung disease. We assessed the relationships of quantitative computed tomography (CT)-derived measures with clinical characteristics and outcomes in CPFE. METHODS: At a single institution, 129 patients with CPFE were evaluated retrospectively. Baseline CT data were available for the entire cohort; 71 patients underwent repeat CT approximately 1 year later. The evaluated CT measures were low attenuation volume percentage (LAV%), high attenuation volume percentage (HAV%), diseased lung volume percentage (DLV%), erector spinae muscle cross-sectional area (ESMCSA), and the main pulmonary artery-to-aorta diameter ratio. Associations of baseline values and annualized changes with overall survival and acute exacerbation incidence were examined. RESULTS: None of the baseline quantitative CT measures was associated with the risk of death. In contrast, annualized changes in LAV%, HAV%, and DLV% were associated with the risk of death. Overall survival was shorter among patients with an annual DLV% increase of at least 1.5%. At baseline, HAV% and DLV% were associated with acute exacerbation incidence; in the longitudinal analysis, associations were observed for annualized changes in LAV%, HAV%, DLV%, and ESMCSA. CONCLUSION: In CPFE, annualized changes in LAV%, HAV%, and DLV% were associated with mortality and acute exacerbation incidence in their respective models. An annual DLV% increase of at least 1.5% was associated with shorter overall survival. Quantitative CT attenuation indices can inform risk assessment in CPFE.