The Evaluation of Interstitial Abnormalities in Group B of the 2011 Global Initiative for Chronic Obstructive Lung Disease (GOLD) Classification of Chronic Obstructive Pulmonary Disease (COPD)

OBJECTIVE: In 2011, the Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification categorized chronic obstructive pulmonary disease (COPD) patients into 4 groups. A report demonstrated that the mortality in Group B was higher than that in Group C. Ischemic heart disease and cancer were suggested to be the cause. The aim of the present study was to test the hypothesis that interstitial lung abnormalities (ILAs) are more prevalent in Group B than Group C and that they may be responsible for the higher mortality in Group B. METHODS: Patients were selected based on their pulmonary function test results. The inclusion criterion was a forced expiratory volume in 1 second (FEV(1))/forced vital capacity (FVC) of ＜70% after the inhalation of a bronchodilator. Patients without a smoking history or computed tomography (CT) scan were excluded. The medical records of the patients were retrospectively reviewed, and the selected patients were categorized into Groups A to D. High-resolution CT scans were used to investigate the presence of ILAs and determine the low attenuation area (LAA). RESULTS: Among the 349 COPD patients, ILAs were detected in 10.3% of the patients in Group A, 22.5% of the patients in Group B, 5.6% of the patients in Group C, and 23.1% of the patients in Group D. In Group B, the frequency of ILAs was significantly higher and the area affected by the ILAs was significantly greater in comparison to Group C. Among the patterns of interstitial abnormalities, the area of honeycombing in Group B was significantly greater than that in Group C. Furthermore, among the patients in Group B, the LAA in the ILA-positive patients was significantly greater than that in the ILA-negative patients. CONCLUSION: In Group B, the area occupied by ILAs-especially honeycombing-was greater than that in Group C. This contributed to the preserved %FEV(1) and possibly to the poorer prognosis of the patients in Group B.