Stronger Associations of Centrilobular Than Paraseptal Emphysema With Longitudinal Changes in Diffusing Capacity and Mortality in COPD.

Abstract

The factors associated with longitudinal changes in diffusing capacity remain unclear among patients with COPD. Centrilobular emphysema (CLE) and paraseptal emphysema (PSE) are major emphysema subtypes that may have distinct clinical-physiological impacts in these patients. Are CLE and PSE differently associated with longitudinal changes in diffusing capacity and mortality in patients with COPD? This pooled analysis included 399 patients with COPD from two prospective observational COPD cohorts. CLE and PSE were visually assessed on CT scan according to the Fleischner Society statement. The diffusing capacity and transfer coefficient of the lung for carbon monoxide (Dlco and K_CO) and FEV₁ were evaluated at least annually over a 5-year period. Mortality was recorded over 10 years. Longitudinal changes in FEV₁, Dlco, and K_CO and mortality were compared between mild or less severe and moderate or more severe CLE and between present and absent PSE in each Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage. The Dlco and K_CO decline was weakly associated with FEV₁ and greater in GOLD stage 3 or higher than in GOLD stages 1 and 2. Furthermore, moderate or more severe CLE, but not present PSE, was associated with steeper declines in Dlco for GOLD stages 1 and 3 or higher and K_CO for all GOLD stages independent of age, sex, height, and smoking history. The moderate or more severe CLE, but not present PSE, was associated with additional FEV₁ decline and higher 10-year mortality among patients with GOLD stage 3 or higher. A CT scan finding of moderate or more severe CLE, but not PSE, was associated with a subsequent accelerated impairment in diffusing capacity and higher long-term mortality in severe GOLD stage among patients with COPD.