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Automated Measurement of Pulmonary Emphysema and Small Airway Remodeling in Cigarette Smoke-exposed Mice
Published on: January 16, 2015
Clinical and Prognostic Differences in Mild to Moderate COPD With and Without Emphysema
Huajing Yang1, Yuqiong Yang2, Fengyan Wang2
1State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, National Center for Respiratory Medicine, Guangzhou Institute of Respiratory Health, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China; Guangzhou National Lab, Guangzhou, Guangdong, China.
Background:
The clinical and prognostic characteristics of mild-to-moderate COPD with and without emphysema remain inadequately investigated.
Research Question:
Do the clinical and prognostic characteristics differ between mild-to-moderate COPD with and without emphysema?
Study Design And Methods:
We obtained clinical data of 989 participants with mild-to-moderate COPD from the Subpopulations and Intermediate Outcome Measures in COPD Study (SPIROMICS). They were categorized into two groups based on their baseline low-attention lung voxels with a density < -950 Hounsfield units of < 5% on CT scans: mild-to-moderate COPD with emphysema (EC) group and mild-to-moderate COPD without emphysema (NEC) group. Linear mixed-effects models were used to assess the differences in the decline of lung function, health-related quality of life, and quantitative CT indexes between these two groups. Zero-inflated negative binomial regressions were used to evaluate the rates of acute respiratory exacerbations between the groups.
Results:
Among participants with mild-to-moderate COPD, 428 (43.3%) exhibited emphysema on CT scans. The annual decline in FEV1 was -56.1 mL/y for the EC group and -46.9 mL/y for the NEC group, with a nonsignificant between-group difference of 9.1 mL/y (95% CI, -24.0 to 5.7 mL/y). The rate of emphysema progression in the EC group was significantly lower than in the NEC group (natural logarithm(%LAA-950), -0.173%; 95% CI, -0.252% to -0.094%). The EC group also showed a more pronounced annual increase in the St. George's Respiratory Questionnaire score (0.9 points) compared with the NEC group. The EC group had a higher rate of acute respiratory exacerbations (0.36 per person-year) than the NEC group (0.25 per person-year), with a rate ratio of 1.42 (95% CI, 1.27-1.54).
Interpretation:
The EC group did not have accelerated rates of decline in FEV1, but they experienced significantly worse health-related quality of life and a higher rate of acute respiratory exacerbations. The nonemphysema subtype demonstrated increased emphysema progression.
Clinical Trial Registration:
ClinicalTrials.gov; No.: NCT01969344; URL: www.
Clinicaltrials:
gov.
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