Centrilobular emphysema (CLE), but not paraseptal emphysema (PSE), is associated with a faster rate of impairment of diffusing capacity and poor prognosis in patients with chronic obstructive pulmonary disease (COPD), according to study findings published in Chest.
Researchers sought to assess whether centrilobular emphysema and paraseptal emphysema are differently associated with long-term changes in DLCO and mortality in patients with COPD. Toward that end, they conducted a pooled analysis of 2 prospective observational cohorts of patients with COPD in Japan (Kyoto University cohort study and Hokkaido COPD cohort study).
Researchers compared annual changes in diffusing capacity of the lung for carbon monoxide (DLCO) and transfer coefficient of the lung for carbon monoxide (KCO) among patients with Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages 1, 2, and 3 or more. They also assessed whether CLE without PSE on baseline computed tomography may be associated with longitudinal changes in DLCO and KCO for 5 years and with 10-year mortality for GOLD stages 1, 2, and 3 or more.
Participants were at least 40 years of age with a smoking history of at least 10 pack-years and were diagnosed with COPD based on GOLD criteria (ie, postbronchodilator forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) <0.7). All lung function tests were performed at least annually.
A total of 399 patients with COPD were included: 87 with GOLD stage 1 COPD; 183 with GOLD stage 2, and 129 with GOLD stage 3 or more. The prevalence of at least moderate CLE increased with the progression in GOLD stages, and the prevalence of PSE remained similar for all stages. Patients with PSE were more likely to have at least moderate CLE compared with those without PSE in GOLD stage 1 and GOLD stage 2, but not in GOLD stages 3 or more.
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These findings deepen our understanding of the association of emphysema subtypes with pathophysiological disease progression and might help to improve the clinical management of patients with COPD.
The cohort had a median of 6 lung function tests (interquartile range [IQR], 5-9) during the 5 years. Weak correlations were observed between annual FEV1 changes and DLCO or KCO. FEV1 decreases were greater for patients with GOLD stage 1 vs GOLD stages 2 and 3 or more, and the reduction in DLCO and KCO increased with the progression in GOLD stages.
In patients with GOLD stages 3 or more, the longitudinal decrease in FEV1 was greater among the patient group with at least moderate CLE compared with the group of patients having CLE that was mild at most; however, this was not the case for patients with GOLD stage 1 or 2. For patients with GOLD stages 2 and 3 or more, the longitudinal decline in DLCO and KCO was greater among patients who had at least moderate CLE vs the group of patients having CLE that was mild at most; however, this was not the case for patients with GOLD stage 1.
CLE, but not PSE, was associated with a greater reduction in FEV1 for patients in GOLD stages 3 or more in multivariable models that included CLE and PSE. In addition, CLE, but not PSE, was associated with a greater decrease in KCO for patients in all GOLD stages and in DLCO for patients with GOLD stages 1 and 3 or more.
After a median of 8.9 years, 114 deaths occurred. Patients with GOLD stages 3 or more had a significantly worse prognosis vs those with GOLD stages 1 and 2. Among patients with GOLD stages 3 or more, having at least moderate CLE was associated with increased mortality; however, this was not true for patients with GOLD stage 1 or 2.
Mortality rates were not different between patients with and without PSE, regardless of the patients’ GOLD stage. According to multivariable Cox proportional hazards models, having at least moderate CLE, but not PSE, was associated with increased mortality in patients with GOLD stages 3 and over.
Among several limitations, more than 90% of participants were male, the number of cardiovascular deaths was relatively small compared with other studies, and all participants were Japanese.
“These findings deepen our understanding of the association of emphysema subtypes with pathophysiological disease progression and might help to improve the clinical management of patients with COPD,” stated the investigators.
Disclosure: The Hokkaido COPD Cohort Study is supported in part by Nippon Boehringer Ingelheim and Pfizer. Some of the study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.
