Symptomatic smokers without COPD have physiological changes heralding the development of COPD

Small Airway Disease in Pre-Chronic Obstructive Pulmonary Disease with Emphysema: A Cross-Sectional Study

Rationale: Small airway disease is an important pathophysiological feature of chronic obstructive pulmonary disease (COPD). Recently, "pre-COPD" has been put forward as a potential precursor stage of COPD that is defined by abnormal spirometry findings or significant emphysema on computed tomography (CT) in the absence of airflow obstruction. Objective: To determine the degree and nature of (small) airway disease in pre-COPD using microCT in a cohort of explant lobes/lungs. Methods: We collected whole lungs/lung lobes from patients with emphysematous pre-COPD (n = 10); Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage I (n = 6), II (n = 6), and III/IV (n = 7) COPD; and controls (n = 10), which were analyzed using CT and microCT. The degree of emphysema and the number and morphology of small airways were compared between groups, and further correlations were investigated with physiologic measures. Airway and parenchymal pathology was also validated with histopathology. Measurements and Main Results: The numbers of transitional bronchioles and terminal bronchioles per milliliter of lung were significantly lower in pre-COPD and GOLD stages I, II, and III/IV COPD compared with controls. In addition, the number of alveolar attachments of the transitional bronchioles and terminal bronchioles was also lower in pre-COPD and all COPD groups compared with controls. We did not find any differences between the pre-COPD and COPD groups in CT or microCT measures. The percentage of emphysema on CT showed the strongest correlation with the number of small airways in the COPD groups. Histopathology showed an increase in the mean chord length and a decrease in alveolar surface density in pre-COPD and all GOLD COPD stages compared with controls. Conclusions: Lungs of patients with emphysematous pre-COPD already show fewer small airways and airway remodeling even in the absence of physiologic airway obstruction.

The Fagerström Test for Nicotine Dependence, as a prognostic factor, in current smokers with and without COPD: A cross-sectional study in northern Greece

BACKGROUND

Smoking poses the most common risk factor for chronic obstructive pulmonary disease (COPD) and aggravates disease progression. Tobacco dependence inhibits smoking cessation and may affect smoking patterns that increase tobacco exposure and predispose to lung function decline.

AIMS AND OBJECTIVES

We aimed to assess tobacco dependence in current smokers with and without COPD and evaluate its role in disease development.

METHOD

This cross-sectional study was conducted in Greek rural areas. Current smokers completed the Fagerström Test for Nicotine Dependence and were classified into COPD and non-COPD groups based on spirometry parameters.

RESULTS

Among current smokers, 288 participants comprised the non-COPD and 71 the COPD group. Both presented moderate tobacco dependence, but smokers with COPD started to smoke earlier in the morning. Multiple logistic regression analysis revealed higher COPD prevalence in smokers with higher scores in the Fagerström test (odds ratio OR = 1.12, 95% confidence interval [1.01 - 1.24]) and older age (OR = 1.06 [1.03 - 1.09]), independently of pack-years smoking index. Multiple linear regression analysis in smokers with COPD showed that the forced expiratory volume in the 1st second decreased by 2.3% of the predicted value for each point increase in the Fagerström Test and 0.59% for each year of age, independently of participants' sex and pack-years smoking index.

CONCLUSION

The Fagerström score appears to indicate a higher probability for COPD and lung function deterioration when assessed along with age in current smokers. Smoking cessation support programs are fundamental to COPD prevention and management.

Structural features on quantitative chest computed tomography of patients with maximal mid-expiratory flow impairment in a normal lung function population

BACKGROUND

Maximal mid-expiratory flow (MMEF) is an earlier predictor of chronic obstructive pulmonary disease (COPD) development than forced expiratory volume in 1 s (FEV₁). Changes of lung structure in patients with MMEF impairment only is still not clear. Therefore, this study aimed to investigate the structural features of patients with decreased MMEF by quantitative computed tomography (QCT) and develop a predictive model for predicting patients with reduced MMEF in normal lung function population.

METHODS

In this study, 131 patients with normal spirometry results and available volumetric chest CT images were enrolled and divided into the reduced MMEF group (FEV₁/forced expiratory vital capacity (FEV₁/FVC) > 0.7, FEV₁% predictive values (FEV₁%pred) > 80%, MMEF%pred < 80%, n = 52) and the normal MMEF group (FEV₁/FVC > 0.7, FEV₁%pred > 80%, MMEF%pred ≥ 80%, n = 79). The emphysema, small airway disease and medium-size airway parameters were measured by a commercial software. The differences were investigated in clinical features, spirometrical parameters and QCT parameters between the two groups. A nomogram model was constructed based on the results of the multivariable logistic regression model. Spearman's correlation coefficients were calculated between QCT measurements and spirometrical parameters.

RESULTS

There were more males in reduced MMEF group than normal group (P < 0.05). Lung parenchyma parameter (PRM^Emph) and airway-related parameters (functional small airway disease (PRM^fSAD), luminal area of fifth- and sixth- generation airway (LA₅, LA₆) were significantly different between the reduced MMEF group and the normal group (20.2 ± 17.4 vs 9.4 ± 6.7, 3.4 ± 3.5 vs 1.9 ± 2.0, 12.2 ± 2.5 vs 13.7 ± 3.4, 7.7 ± 2.4 vs 8.9 ± 2.8, respectively, all P < 0.01). After multivariable logistical regression, only sex (odds ratio [OR]: 2.777; 95% confidence interval [CI]:1.123-3.867), PRM^fSAD (OR:1.102, 95%CI:1.045-1.162) and LA₆ (OR:0.650, 95%CI:0.528-0.799) had significant differences between the two groups (P < 0.05) and a model incorporating with the three indicators was constructed (area under curve, 0.836). Correlation analysis showed MMEF%pred had mild to moderate correlation with airway-related measurements.

CONCLUSION

In normal lung function population, patients with reduced MMEF have potential medium-size and small airway changes, and MMEF%pred is significantly associated with airway-related CT parameters. The nomogram incorporating with sex, PRM^fSAD and LA₆ has good predictive value and offers more objective evidences in a group with reduced MMEF.

Impaired exercise capacity in individuals with non-obstructive small airway dysfunction

Background

Whether individuals with non-obstructive spirometry-defined small airway dysfunction (SAD) have impaired exercise capacity is unclear, particularly in never-smokers. This study clarifies the degree of impaired exercise capacity and its potential cause in individuals with non-obstructive SAD.

Methods

This community-based, multiyear cross-sectional study analyzed data collected in Guangdong, China from 2012-2019 by the National Science and Technology Support Plan Program. Measurements of exercise capacity [peak work rate and peak oxygen uptake ( V ˙ O 2peak )] in participants with non-obstructive spirometry-defined SAD (n=157) were compared with those in controls (n=85) and Global Initiative for Chronic Obstructive Lung Disease (GOLD) I patients (n=239). Subgroup analyses were performed by smoking status.

Results

The risk of impaired exercise capacity was significantly higher in participants with non-obstructive SAD [ V ˙ O 2peak <84%predicted, adjusted odds ratio (aOR) =2.53; 95% confidence interval (CI): 1.42-4.52] than in controls but was not significantly different from that in GOLD I patients. Results were consistent within subgroups of smoking status (ever-smokers: non-obstructive SAD vs. controls, aOR =2.44; 95% CI: 1.08-5.51; never-smokers: non-obstructive SAD vs. controls, aOR =2.38, 95% CI: 1.02-5.58). Participants with non-obstructive SAD had a significantly lower peak work rate (β=-10.5; 95% CI: -16.3 to -4.7) and V ˙ O 2peak (%predicted, β=-4.0; 95% CI: -7.7 to -0.2) and tended to have higher ventilatory equivalents for carbon dioxide at the ventilatory threshold ( V ˙ E / V ˙ CO 2AT , β=1.1; 95% CI: -0.1 to 2.3) when compared with controls. Both peak work rate and V ˙ O 2peak were negatively correlated with V ˙ E / V ˙ CO 2AT .

Conclusions

Although not meeting the current criteria for chronic obstructive pulmonary disease, individuals with non-obstructive SAD have impaired exercise capacity that may be associated with ventilatory inefficiency regardless of smoking status.

Small airway function measured using forced expiratory flow between 25% and 75% of vital capacity and its relationship to airflow limitation in symptomatic ever-smokers: a cross-sectional study

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is diagnosed and its severity graded by traditional spirometric parameters (forced expiratory volume in 1 s (FEV₁)/forced vital capacity (FVC) and FEV₁, respectively) but these parameters are considered insensitive for identifying early pathology. Measures of small airway function, including forced expiratory flow between 25% and 75% of vital capacity (FEF_25-75), may be more valuable in the earliest phases of COPD. This study aimed to determine the prevalence of low FEF_25-75 in ever-smokers with and without airflow limitation (AL) and to determine whether FEF_25-75 relates to AL severity.

METHOD

A retrospective analysis of lung function data of 1458 ever-smokers suspected clinically of having COPD. Low FEF_25-75 was defined by z-score<-0.8345 and AL was defined by FEV₁/FVC z-scores<-1.645. The severity of AL was evaluated using FEV₁ z-scores. Participants were placed into three groups: normal FEF_25-75/ no AL (normal FEF_25-75/AL-); low FEF_25-75/ no AL (low FEF_25-75/AL-) and low FEF_25-75/ AL (low FEF_25-75/AL+).

RESULTS

Low FEF_25-75 was present in 99.9% of patients with AL, and 50% of those without AL. Patients in the low FEF_25-75/AL- group had lower spirometric measures (including FEV₁ FEF_25-75/FVC and FEV₃/FVC) than those in the normal FEF_25-75/AL- group. FEF_25-75 decreased with AL severity. A logistic regression model demonstrated that in the absence of AL, the presence of low FEF_25-75 was associated with lower FEV₁ and FEV₁/FVC even when smoking history was accounted for.

CONCLUSIONS

Low FEF_25-75 is a physiological trait in patients with conventional spirometric AL and likely reflects early evidence of impairment in the small airways when spirometry is within the 'normal range'. FEF_25-75 likely identifies a group of patients with early evidence of pathological lung damage who warrant careful monitoring and reinforced early intervention to abrogate further lung injury.

Chronic Bronchitis Affects Outcomes in Smokers without Chronic Obstructive Pulmonary Disease (COPD)

Background. Chronic bronchitis (CB) importantly affects outcomes in smokers with COPD, but the effects on smokers without COPD are less well known and less emphasized. The aim of our study was to investigate the possible effects of CB on clinical outcomes in smokers without COPD (noCOPD) and compare them with the effects in smokers with COPD (COPD). Methods. For that purpose, we studied 511 smokers, 302 with and 209 without COPD, followed for 10 years in an academic COPD ambulatory setting. Chronic bronchitis was defined as the presence of cough and sputum production for at least 3 months in each of two consecutive years. All subjects underwent clinical and functional examination with spirometry, diffusion capacity (DLco), 6-min walking test (6MWT), mMRC Dyspnoea Scale, COPD Assessment Test (CAT), and recording of annual frequency of exacerbations. All-cause mortality during follow-up was recorded. Results. 27% of noCOPD and 45% of COPD had CB. noCOPD with CB had lower FEV₁ and DLco, worse 6MWT, more dyspnoea, a higher number of exacerbations and lower survival than noCOPD without CB. CB did not affect FEV₁ decline in noCOPD but it significantly did in COPD. Conclusions. The presence of chronic bronchitis in smokers without COPD will significantly affect symptoms, quality of life, and survival, underlining the importance of recognizing the condition and managing it accordingly.