Table 2. Cox proportional hazard analysis of risk factors for the development of pneumonia in patients with COPD (univariate analysis).

Wall area (%)=wall area/(wall area+lumen area)×100. Mean lung density ratio=mean lung density ratio of full expiration and inspiration.

COPD: chronic obstructive pulmonary disease; HR: hazard ratio; CI: confidence interval; SGRQ: St George's Respiratory Questionnaire; FEV₁: forced expiratory volume in 1 second; V₉₅₀: volume fraction (%) of the lung below –950 Hounsfield unit.