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Background: Small airway dysfunction (SAD) and impaired diffusion capacity of the lungs for carbon monoxide ( D LCO ) are positively associated with a worse prognosis. Individuals with both dysfunctions have been identified in clinical practice and it is unknown whether they have worse health status or need management. We conducted this study to explore the association between SAD and impaired D LCO , and the difference between the groups with two dysfunctions, with either one dysfunction and with no dysfunction., Methods: This study involved subjects partly from those who had returned for the third-year follow-up (up to December 2022) of the Early Chronic Obstructive Pulmonary Disease study and those who newly participated. We assessed diffusion capacity, questionnaire, exacerbations, spirometry, impulse oscillometry (IOS) and computed tomography (CT). Impaired D LCO was defined as D LCO <80% predicted. Spirometry-defined SAD was defined using the percent predicted values of maximal mid-expiratory flow, and forced expiratory flow at 50% and 75% of forced vital capacity, at least two of these three values being <65% predicted after the use of a bronchodilator. IOS-defined SAD was defined when the difference in resistance at 5 and 20 Hz was >0.07 kPa·L -1 ·s. CT-defined SAD was defined when the percentage of expiratory low-attenuation areas <-856 HU comprised ≥15% of the total lung volume. Covariate analyses and logistic regression were performed to assess the association between impaired D LCO and SAD., Results: This study involved 581 subjects. The occurrence of both spirometry- and CT-defined SAD was significantly higher in subjects with impaired D LCO than normal D LCO . Subjects with two dysfunctions were associated with worse preceding year's exacerbations than controls., Conclusions: Impaired diffusion capacity is positively associated with SAD. Subjects with impaired diffusion capacity and SAD may have a worse health status and need additional management., Competing Interests: Conflict of interest: All of the authors declare no competing interests., (Copyright ©The authors 2025.)

Rationale: Previous studies have identified exercise intolerance in patients with mild-to-moderate chronic obstructive pulmonary disease (COPD). The associations of exercise tolerance with lung function decline and acute exacerbation risk in mild-to-moderate COPD is unclear, especially in the community population. Objectives: We evaluated exercise tolerance in mild-to-moderate COPD and analyzed its associations with respiratory health outcomes. Methods: We analyzed data from the Early Chronic Obstructive Pulmonary Disease community-based study of patients with mild-to-moderate COPD (post- bronchodilator FEV 1 /FVC <0.70 and FEV 1 ≥50% predicted). Patients who completed questionnaires, spirometry, and cardiopulmonary exercise testing at baseline were included. Annual exacerbation assessment and spirometry testing were conducted for 2 years consecutively. Exercise tolerance was defined as the percentage of predicted peak oxygen uptake ( VO 2peak %predicted). We analyzed the association between exercise tolerance, annual lung function decline, and acute exacerbation risk. Measurements and Main Results: Overall, 338 patients were included in the baseline analysis, and 319 completed the 2-year follow-up. The mean and standard deviation (SD) of VO 2peak %predicted was 79.8±13.7. Low VO 2peak %predicted was associated with more chronic respiratory symptoms, worse lung function, severe emphysema, and air trapping at baseline. During the 2-year follow-up, a decrease of 13.7% (1-SD) in VO 2peak %predicted was associated with a decline in pre-bronchodilator FEV 1 /FVC (difference=0.4%, 95% CI: 0.1%-0.7%, P= 0.003), and higher total exacerbation risk (relative risk [RR]=1.25, 95% CI: 1.08-1.46, P=0.004) after adjustment. Conclusions: Mild-to-moderate COPD patients with exercise intolerance have worse respiratory health outcomes, for which a low exercise tolerance as a prognostic marker.

Background: Impaired ventilatory efficiency during exercise is a predictor of mortality in chronic obstructive pulmonary disease. However, little is known about the clinical features and associated factors of impaired ventilatory efficiency in China., Methods: We conducted a cross-sectional community-based study in China and collected demographic and clinical information, cardiopulmonary exercise testing, spirometry, and CT data. Impaired ventilatory efficiency was defined by a nadir ventilatory equivalent for CO 2 production above the upper limit of normal. Multivariable linear and logistic regression models were used to explore the clinical features and associated factors of impaired ventilatory efficiency., Results: The final analyses included 941 subjects, 702 (74.6%) of whom had normal ventilatory efficiency and 239 (25.4%) had impaired ventilatory efficiency. Participants with impaired ventilatory efficiency had more chronic respiratory symptoms, poorer lung function and exercise capacity, and more severe emphysema (natural logarithm transformation of the low-attenuation area of the lung with attenuation values below -950 Hounsfield units, logLAA -950 : 0.19±0.65 vs -0.28±0.63, p<0.001) and air trapping (logLAA -856 : 1.03±0.65 vs 0.68±0.70, p<0.001) than those with normal ventilatory efficiency. Older age (60-69 years, OR 3.10 (95% CI 1.33 to 7.21), p=0.009 and 70-80 years, OR 6.48 (95% CI 2.56 to 16.43), p<0.001 vs 40-49 years) and smoking (former, OR 3.19 (95% CI 1.29 to 7.86), p=0.012; current, OR 4.27 (95% CI 1.78 to 10.24), p=0.001 vs never) were identified as high risk factors of impaired ventilatory efficiency., Conclusions: Impaired ventilatory efficiency was associated with poorer respiratory characteristics. Longitudinal studies are warranted to explore the progression of individuals with impaired ventilatory efficiency., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: The relationship between airway inflammation in chronic obstructive pulmonary disease (COPD) and clinical characteristics remains unclear. This study aimed to investigate the airway inflammatory phenotypes in COPD and their association with clinical characteristics., Methods: 895 patients with COPD were recruited from Guangdong Province, China in this study. Each patient underwent questionnaire interviews, spirometry testing, CT scans and induced sputum examination. Classification of airway inflammation phenotypes was based on sputum inflammatory cell counts. Covariance analysis was applied to assess associations with airway inflammation phenotypes., Results: In this study, we found that neutrophilic phenotype (NP, 58.0%) was the most common airway inflammation phenotype in patients with COPD, followed by mixed granulocytic phenotype (MGP, 32.6%), eosinophilic phenotype (EP, 5.4%) and paucigranulocytic phenotype (PP, 4.0%). Compared with NP patients, those with MGP exhibited more frequent chronic respiratory symptoms, and a higher proportion of individuals classified under Global Initiative for Chronic Obstructive Lung Disease stages 3 and 4. After adjusting for confounding factors, MGP patients had lower lung function, and more severe emphysema and air trapping. On the contrary, patients with PP had the best pulmonary function and less emphysema and air trapping., Conclusions: NP was the most common airway inflammation phenotype in patients with COPD. Patients with MGP had more respiratory symptoms, greater loss of lung function, and more severe emphysema and gas trapping compared with those with NP. Meanwhile, PP may be a phenotype of mild damage to lung structure in patients with COPD., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

The associations between anxiety, depression, and the prognosis of COPD remain uncertain. The present study aims to investigate the associations of anxiety and depression with 30-day readmission rates and acute exacerbations of COPD (AECOPD). Four databases were searched to identify relevant studies published before 13 March 2024. Studies that report on the impact of anxiety and depression on the prognosis of AECOPD were included. The pooled effect size and its 95% confidence interval (CI) were calculated using a random effects model. The primary outcomes were 30-day readmission and AECOPD within the first year after discharge in COPD patients. Of the 5,955 studies screened, 14 studies were included in the analysis. Patients with anxiety had a higher risk of AECOPD within the first year after discharge compared to those without anxiety (HR: 2.10, 95% CI: 1.28-3.45, p  = 0.003). Patients with depression also had a higher risk of AECOPD within the first year after discharge (HR: 1.36, 95% CI: 1.10-1.69, p  = 0.004). Similar results were observed in the associations of anxiety and depression with 30-day readmission. Our results suggested that anxiety and depression were associated with an increased risk of 30-day readmission and AECOPD in patients with COPD.