Chronic Respiratory Symptoms with Normal Spirometry. A Reliable Clinical Entity?

Therapeutic efficacy and pharmacological mechanism of Bailing capsule on chronic obstructive pulmonary disease: a meta-analysis and network pharmacology

CONTEXT

Bailing capsule, derived from Cordyceps sinensis (Berk.) Sacc. (Clavicipitaceae), has shown potential in the treatment of chronic obstructive pulmonary disease (COPD), a prevalent respiratory disorder.

OBJECTIVE

This study elucidates the efficacy and mechanism of action of the use of Bailing capsules in the treatment of COPD using meta-analysis and network pharmacology.

MATERIALS AND METHODS

A meta-analysis of randomized controlled trials (RCTs) was performed. The treatment group received Bailing capsules alongside standard therapy, while the control group received standard therapy or in combination with other traditional Chinese medicines. Efficacy outcomes included lung function, exercise tolerance, acute exacerbation risk, and quality of life. Network pharmacology and molecular docking identified key targets of Bailing capsules.

RESULTS

The meta-analysis of 27 RCTs showed significant improvements in the treatment group for forced expiratory volume in 1 s (FEV1), FEV1/FVC ratio, and the 6-min walk test (6MWT). Additionally, there was a marked reduction in acute COPD attacks and an improvement in quality of life. Meanwhile, network pharmacological analysis identified SRC, HIF1A, NFKB1, HDAC2, and PRKACA, as the potential core targets for Bailing capsules in the treatment of COPD.

DISCUSSION AND CONCLUSION

Bailing capsules have shown promising results in the treatment of stable COPD. Future studies should focus on large-scale, multicenter RCTs to confirm the long-term benefits and safety of Bailing capsules.

Low smoking exposure and development and prognosis of COPD over four decades: a population-based cohort study

BACKGROUND

A diagnosis of COPD is mainly considered in individuals with >10 pack-years of smoking. We tested the hypothesis that low smoking exposure, below the critical threshold of 10 pack-years, increases risk of COPD and leads to poor prognosis.

METHODS

We followed non-obstructed adult smokers from the Copenhagen City Heart Study for COPD, defined as a forced expiratory volume in 1 s (FEV1)/forced vital capacity <0.70 and FEV1 <80% predicted, and for related clinical outcomes. First, we followed individuals for 5 years according to baseline smoking for risk of developing COPD, and thereafter for up to four decades for severe exacerbations and death.

RESULTS

In 6098 non-obstructed smokers, 1781 (29%) developed COPD after 5 years of follow-up: 23% of individuals with <10 pack-years of smoking at baseline, 26% of those with 10-19.9 pack-years, 30% of those with 20-39.9 pack-years and 39% of those with ≥40 pack-years. During four decades of follow-up, we recorded 620 exacerbations and 5573 deaths. Compared to individuals without COPD with <10 pack‑years of smoking, multivariable adjusted hazard ratios (HRs) for exacerbations were 1.94 (95% CI 1.36-2.76) in those without COPD and ≥10 pack-years, 2.83 (95% CI 1.72-4.66) in those with COPD and <10 pack-years, 4.34 (95% CI 2.93-6.43) in those with COPD and 10-19.9 pack-years, 4.39 (95% CI 2.98-6.46) in those with COPD and 20-39.9 pack-years and 4.98 (95% CI 3.11-7.97) in those with COPD and ≥40 pack-years. Corresponding HRs for all-cause mortality were 1.20 (95% CI 1.10-1.32), 1.31 (95% CI 1.13-1.53), 1.59 (95% CI 1.40-1.79), 1.81 (95% CI 1.62-2.03) and 1.81 (95% CI 1.55-2.10).

CONCLUSION

Low smoking exposure below the critical threshold of 10 pack-years increases risk of COPD in middle-aged adults within 5 years, and these individuals have increased risk of severe exacerbation and early death over four decades.

Mortality and readmission risk for hospitalised patients with acute exacerbation of COPD with and without spirometric obstruction: a longitudinal observational study in China

OBJECTIVE

To compare the clinical features and outcomes in patients with pre-chronic obstructive pulmonary disease (COPD) and COPD hospitalised for confirmed or suspected acute exacerbation of COPD (AECOPD).

DESIGN

A multicentre, longitudinal observational cohort study.

SETTING

Data were obtained from the AECOPD Inpatient Registry Study in China.

PARTICIPANTS

5896 patients hospitalised for AECOPD between 2017 and 2021.

OUTCOMES

Patients were divided into the COPD (n=5201) and pre-COPD (n=695) groups according to the lung function test results. The outcomes of interest included all-cause, respiratory disease-related and cardiovascular disease-related deaths as well as readmissions within 30 days and 12 months after discharge. Cumulative incidence functions were used to estimate the risk of cause-specific mortality and readmission. Multivariate hazard function models were used to determine the association between lung function and outcomes.

RESULTS

There were significant between-group differences in the symptoms at admission and medication use during hospitalisation. However, there was no significant between-group difference in the 30-day all-cause mortality (0.00 vs 2.23/1000 person-month (pm), p=0.6110) and readmission (33.52 vs 30.64/1000 pm, p=0.7175). Likewise, the 30-day and 12-month cause-specific outcomes were not significantly different between groups (30-day readmission with acute exacerbation (AE): 26.07 vs 25.11/1000 pm; 12-month all-cause mortality: 0.20 vs 0.93/1000 pm; all-cause readmission: 11.49 vs 13.75/1000 pm; readmission with AE: 9.15 vs 11.64/1000 pm, p>0.05 for all comparisons). Cumulative incidence curves revealed no significant between-group differences in the 30-day and 12-month prognosis (p>0.05). Multivariate analysis revealed no significant association of lung function categories with 30-day and 12-month mortality or readmission (p>0.05 for all effect estimations).

CONCLUSIONS

Patients with pre-COPD have mild symptoms and similar risks for mortality and readmission during follow-up as patients with COPD. Patients with pre-COPD should receive optimal therapies before the occurrence of irreversible damage.

CT pectoralis muscle area is associated with DXA lean mass and correlates with emphysema progression in a tobacco-exposed cohort

INTRODUCTION

Muscle loss is an important extrapulmonary manifestation of COPD. Dual energy X-ray absorptiometry (DXA) is the method of choice for body composition measurement but is not widely used for muscle mass evaluation. The pectoralis muscle area (PMA) is quantifiable by CT and predicts cross-sectional COPD-related morbidity. There are no studies that compare PMA with DXA measures or that evaluate longitudinal relationships between PMA and lung disease progression.

METHODS

Participants from our longitudinal tobacco-exposed cohort had baseline and 6-year chest CT (n=259) and DXA (n=164) data. Emphysema was quantified by CT density histogram parenchymal scoring using the 15th percentile technique. Fat-free mass index (FFMI) and appendicular skeletal mass index (ASMI) were calculated from DXA measurements. Linear regression model relationships were reported using standardised coefficient (β) with 95% CI.

RESULTS

PMA was more strongly associated with DXA measures than with body mass index (BMI) in both cross-sectional (FFMI: β=0.76 (95% CI 0.65 to 0.86), p<0.001; ASMI: β=0.76 (95% CI 0.66 to 0.86), p<0.001; BMI: β=0.36 (95% CI 0.25 to 0.47), p<0.001) and longitudinal (ΔFFMI: β=0.43 (95% CI 0.28 to 0.57), p<0.001; ΔASMI: β=0.42 (95% CI 0.27 to 0.57), p<0.001; ΔBMI: β=0.34 (95% CI 0.22 to 0.46), p<0.001) models. Six-year change in PMA was associated with 6-year change in emphysema (β=0.39 (95% CI 0.23 to 0.56), p<0.001) but not with 6-year change in airflow obstruction.

CONCLUSIONS

PMA is an accessible measure of muscle mass and may serve as a useful clinical surrogate for assessing skeletal muscle loss in smokers. Decreased PMA correlated with emphysema progression but not lung function decline, suggesting a difference in the pathophysiology driving emphysema, airflow obstruction and comorbidity risk.

Evidence of seasonal changes in airborne particulate matter concentration and occupation-specific variations in pulmonary function and haematological parameters among some workers in Enugu Southeast Nigeria: a randomized cross-sectional observational study

Background

Upsurge in cardiopulmonary dysfunctions in Enugu, Nigeria, involved mainly cement workers, automobile spray painters, woodworkers, and Cleaners and was worsened in the dry season, suggesting the need for an occupation-specific characterization of the disease features and seasonal evaluation of air quality for prevention and management.

Methods

We conducted a randomized cross-sectional study of eighty consenting participants (in Achara Layout, Enugu), comprising 20 cement workers (39.50 ± 14.95 years), 20 automobile spray painters (40.75 ± 9.85 years), 20 woodworkers (52.20 ± 9.77 years), and 20 cleaners (42.30 ± 9.06 years). The air quality, some haematological (fibrinogen-Fc, and C-reactive protein-CRP), and cardiopulmonary parameters were measured and analyzed using ANCOVA, at p < 0.05.

Results

The dry season particulate matter (PM) in ambient air exceeded the WHO standards in the New layout [PM₁₀ = 541.17 ± 258.72 µg/m³; PM_2.5 = 72.92 ± 25.81 µg/m³] and the University campus [PM₁₀ = 244 ± 74.79 µg/m³; PM_2.5 = 30.33 ± 16.10 µg/m³], but the former was twice higher. The PM differed significantly (p < 0.05) across the sites. Forced expiratory volume at the first second (FEV₁) (F = 6.128; p = 0.001), and Peak expiratory flow rate (PEFR) (F = 5.523; p = 0.002), differed significantly across the groups. FEV₁/FVC% was < 70% in cement workers (55.33%) and woodworkers (61.79%), unlike, automobile spray painters (72.22%) and cleaners (70.66%). FEV₁ and work duration were significantly and negatively related in cement workers (r = -0.46; r2 = 0.2116; p = 0.041 one-tailed). CRP (normal range ≤ 3.0 mg/L) and Fc (normal range—1.5–3.0 g/L) varied in cement workers (3.32 ± 0.93 mg/L versus 3.01 ± 0.85 g/L), automobile spray painters (2.90 ± 1.19 mg/L versus 2.54 ± 0.99 mg/L), woodworkers (2.79 ± 1.10 mg/L versus 2.37 ± 0.92 g/L) and cleaners (3.06 ± 0.82 mg/L versus 2.54 ± 0.70 g/L).

Conclusion(s)

Poor air quality was evident at the study sites, especially in the dry season. Cement workers and automobile spray painters showed significant risks of obstructive pulmonary diseases while woodworkers had restrictive lung diseases. Cement workers and cleaners recorded the highest risk of coronary heart disease (CRP ≥ 3.0 mg/L). The similarity in Fc and CRP trends suggests a role for the inflammation-sensitive proteins in the determination of cardiovascular risk in cement workers and cleaners. Therefore, there are occupation-specific disease endpoints of public health concern that likewise warrant specific preventive and management approaches among the workers.

Comparing Racial Differences in Emphysema Prevalence Among Adults With Normal Spirometry: A Secondary Data Analysis of the CARDIA Lung Study

BACKGROUND

Computed tomography (CT) imaging complements spirometry and may provide insight into racial disparities in respiratory health.

OBJECTIVE

To determine the difference in emphysema prevalence between Black and White adults with different measures of normal spirometry results.

DESIGN

Observational study using clinical data and spirometry from the CARDIA (Coronary Artery Risk Development in Young Adults) study obtained in 2015 to 2016 and CT scans done in 2010 to 2011.

SETTING

4 U.S. centers.

PARTICIPANTS

Population-based sample of Black and White adults.

MEASUREMENTS

Self-identified race and visually identified emphysema on CT in participants with different measures of "normal" spirometry results, calculated using standard race-specific and race-neutral reference equations.

RESULTS

A total of 2674 participants (485 Black men, 762 Black women, 659 White men, and 768 White women) had both a CT scan and spirometry available for analysis. Among participants with a race-specific FEV1 between 80% and 99% of predicted, 6.5% had emphysema. In this group, emphysema prevalence was 3.9-fold (95% CI, 2.1- to 7.1-fold; 15.5% vs. 4.0%) higher among Black men than White men and 1.9-fold (CI, 1.0- to 3.8-fold; 6.6% vs. 3.4%) higher among Black women than White women. Among participants with a race-specific FEV1 between 100% and 120% of predicted, 4.0% had emphysema. In this category, Black men had a 6.4-fold (CI, 2.2- to 18.7-fold; 13.9% vs. 2.2%) higher prevalence of emphysema than White men, whereas Black and White women had a similar prevalence of emphysema (2.6% and 2.0%, respectively). The use of race-neutral equations to identify participants with an FEV1 percent predicted between 80% and 120% attenuated racial differences in emphysema prevalence among men and eliminated racial differences among women.

LIMITATION

No CT scans were obtained during the most recent study visit (2015 to 2016) when spirometry was done.

CONCLUSION

Emphysema is often present before spirometry findings become abnormal, particularly among Black men. Reliance on spirometry alone to differentiate lung health from lung disease may result in the underrecognition of impaired respiratory health and exacerbate racial disparities.

PRIMARY FUNDING SOURCE

National Institutes of Health.

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

Background

COPD is a major health problem, mainly due to cigarette smoking. Most studies in COPD are dedicated to fully developed COPD in older subjects, even though development of COPD may start soon after smoking initiation. Therefore, there is a need to diagnose this “early disease” by detecting the initial events responsible for ultimate development of COPD.

Methods

Measurement of maximum mid expiratory flow between 25 and 75% of vital capacity (MMEF) in a routine spirometry, which detects small airways disease, was used to investigate if MMEF abnormalities in smokers without COPD (noCOPD) would relate to respiratory symptoms and identify smokers that might progress to COPD. For this purpose we studied 511 smokers, 302 COPD and 209 noCOPD, followed long term with spirometry including MMEF, diffusing capacity of the lung for carbon monoxide (D_LCO), 6-min walk test (6MWT), Medical Research Council Dyspnoea Scale and COPD Assessment Test. Three spirometries V1,V2 and V3 (5±2.5 and 10±4 years apart from V1) were performed to assess functional decline and development of COPD.

Results

65% of noCOPD had an abnormal MMEF (<80%) and 38% an abnormal D_LCO. The NoCOPD with MMEF <80% group performed worse in the 6MWT (p=0.01), was more dyspnoeic (p=0.01) and had higher prevalence of chronic bronchitis than the noCOPD with MMEF>80% group (p=0.04). 21% of noCOPD with MMEF <80% and 2.7% with MMEF>80% developed COPD by V3 (p=0.0004).

Conclusions

The MMEF, a functional test available in a routine spirometry, can detect early lung abnormalities and identify the subset of symptomatic smokers with pathological changes that might lead to COPD.

In symptomatic smokers with normal FEV₁/FVC, an abnormal FEF_25–75% (MMEF), which reflects early lung abnormalities, could be used as a biomarker for disease progression and impending risk of COPD developmenthttps://bit.ly/39y0smC

Association Between Non-obstructive Chronic Bronchitis and Incident Chronic Obstructive Pulmonary Disease and All-Cause Mortality: A Systematic Review and Meta-Analysis

Background

Chronic bronchitis in patients with chronic obstructive pulmonary disease (COPD) is associated with poor respiratory health outcomes. However, controversy exists around whether non-obstructive chronic bronchitis (NOCB) is associated with airflow obstruction, lung function decline, and all-cause mortality in ever smoker or never smoker.

Research Question

This systematic review and meta-analysis aimed to clarify the relationship between NOCB and incident COPD, lung function decline, and all-cause mortality, and to quantify the magnitude of these associations.

Study Design and Methods

We searched PubMed, Embase, and Web of Science for studies published up to October 1, 2021. Eligibility screening, data extraction, and quality assessment of the retrieved articles were conducted independently by two reviewers. Studies were included if they were original articles comparing incident COPD, lung function decline, and all-cause mortality in normal spirometry with and without chronic bronchitis. The primary outcomes were incident COPD and all-cause mortality. The secondary outcomes were respiratory disease-related mortality and lung function decline. Pooled effect sizes and 95% confidence intervals (CIs) were calculated using the random-effects model.

Results

We identified 17,323 related references and included 14 articles. Compared with individuals without NOCB, individuals with NOCB had an increased risk of incident COPD (odds ratio: 1.98, 95% CI: 1.21–3.22, I² = 76.3% and relative risk: 1.44, 95%CI: 1.13–1.85, I² = 56.1%), all-cause mortality (hazard ratio [HR]: 1.38, 95%CI: 1.26–1.51, I² = 29.4%), and respiratory disease-related mortality (HR: 1.88, 95%CI: 1.37–2.59, I² = 0.0%). Data on the decline in lung function could not be quantitatively synthesized, but the five articles that assessed the rate of decline in lung function showed that lung function declines faster in individuals with NOCB. The mean difference in the additional decline in forced expiratory volume in 1 s ranged from 3.6 to 23.2 mL/year.

Interpretation

Individuals with NOCB are at a higher risk of incident COPD and all-cause mortality than individuals without NOCB, highlighting the crucial need for strategies to screen for and reduce NOCB risk.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/ PROSPERO, identifier CRD42020202837

Airway mucin MUC5AC and MUC5B concentrations and the initiation and progression of chronic obstructive pulmonary disease: an analysis of the SPIROMICS cohort

BACKGROUND

We previously described the contributions of increased total airway mucin concentrations to the pathogenesis and diagnosis of the chronic bronchitic component of chronic obstructive pulmonary disease (COPD). Here, we investigated the relative contribution of each of the major airway gel-forming mucins, MUC5AC and MUC5B, to the initiation, progression, and early diagnosis of airways disease in COPD.

METHODS

SPIROMICS was a multicentre, observational study in patients aged 40-80 years recruited from six clinical sites and additional subsites in the USA. In this analysis, MUC5AC and MUC5B were quantitated by stable isotope-labelled mass spectrometry in induced sputum samples from healthy never-smokers, ever-smokers at risk for COPD, and ever-smokers with COPD. Participants were extensively characterised using results from questionnaires, such as the COPD assessment test (CAT) and St George's Respiratory Questionnaire; quantitative CT, such as residual volume/total lung capacity ratio (RV/TLC) and parametric response mapping-functional small airway disease (PRM-fSAD); and pulmonary function tests, such as FEV1, forced vital capacity (FVC), and forced expiratory flow, midexpiratory phase (FEF25-75%). Absolute concentrations of both MUC5AC and MUC5B were related to cross-sectional (baseline, initial visit) and 3-year follow-up longitudinal data, including lung function, small airways obstruction, prospective acute exacerbations, and smoking status as primary outcomes. This study is registered with ClinicalTrials.gov (NCT01969344).

FINDINGS

This analysis included 331 participants (mean age 63 years [SEM 9·40]), of whom 40 were healthy never-smokers, 90 were at-risk ever-smokers, and 201 were ever-smokers with COPD. Increased MUC5AC concentrations were more reliably associated with manifestations of COPD than were MUC5B concentrations, including decreased FEV1 and FEF25-75%, and increased prospective exacerbation frequency, RV/TLC, PRM-fSAD, and COPD assessment scores. MUC5AC concentrations were more reactive to cigarette smoke exposure than were MUC5B concentrations. Longitudinal data from 3-year follow-up visits generated a multivariate-adjusted odds ratio for two or more exacerbations of 1·24 (95% CI 1·04-1·47, p=0·015) for individuals with high baseline MUC5AC concentration. Increased MUC5AC, but not MUC5B, concentration at baseline was a significant predictor of FEV1, FEV1/FVC, FEF25-75%, and CAT score decline during the 3-year follow-up. Moreover, current smokers in the at-risk group showed raised MUC5AC concentrations at initial visits and decreased lung function over 3 years. By contrast, former smokers in the at-risk group showed normal MUC5AC concentrations at the initial visit and preserved lung function over 3 years.

INTERPRETATION

These data indicate that increased MUC5AC concentration in the airways might contribute to COPD initiation, progression, exacerbation risk, and overall pathogenesis. Compared with MUC5B, greater relative changes in MUC5AC concentrations were observed as a function of COPD severity, and MUC5AC concentration seems to be an objective biomarker to detect disease in at-risk and pre-COPD individuals. These data suggest that MUC5AC-producing pathways could be potential targets for future therapeutic strategies. Thus, MUC5AC could be a novel biomarker for COPD prognosis and for testing the efficacy of therapeutic agents.

FUNDING

National Institutes of Health; National Heart, Lung, and Blood Institute.

COPD Diagnosis: Time for Disruption

Articulating a satisfactory definition of a disease is surprisingly difficult. Despite the alarming individual, societal and economic burden of chronic obstructive pulmonary disease (COPD), diagnosis is still largely based on a physiologically dominated disease conception, with spirometrically determined airflow limitation as a cardinal feature of the disease. The diagnostic inaccuracy and insensitivity of this physiological disease definition is reviewed considering scientific developments of imaging of the respiratory system in particular. Disease must be approached as a fluid concept in response to new scientific and medical discoveries, but labelling as well as mislabelling someone as diseased, will have enormous individual, social and financial implications. Nosology of COPD urgently needs to dynamically integrate more sensitive diagnostic procedures to detect the breadth of abnormalities early in the disease process. Integration of broader information for the identification of abnormalities in the respiratory system is a cornerstone for research models of underlying pathomechanisms to create a breakthrough in research.

Chronic airflow limitation and its relation to respiratory symptoms among ever-smokers and never-smokers: a cross-sectional study

BACKGROUND

The diagnosis of chronic obstructive pulmonary disease is based on the presence of persistent respiratory symptoms and chronic airflow limitation (CAL). CAL is based on the ratio of forced expiratory volume in 1 s to forced vital capacity (FEV₁:FVC) after bronchodilation, and FEV₁:FVC less than the fifth percentile is often used as a cut-off for CAL. The aim was to investigate if increasing percentiles of FEV₁:FVC were associated with any respiratory symptom (cough with phlegm, dyspnoea or wheezing) in a general population sample of never-smokers and ever-smokers.

METHODS

In a cross-sectional study comprising 15 128 adults (50-64 years), 7120 never-smokers and 8008 ever-smokers completed a respiratory questionnaire and performed FEV₁ and FVC after bronchodilation. We calculated their z-scores for FEV₁:FVC and defined the fifth percentile using the Global Lung Function Initiative (GLI) reference value, GLI₅ and increasing percentiles up to GLI₂₅. We analysed the associations between different strata of percentiles and prevalence of any respiratory symptom using multivariable logistic regression for estimation of OR.

RESULTS

Among all subjects, regardless of smoking habits, the odds of any respiratory symptom were elevated up to the GLI_15-20 strata. Among never-smokers, the odds of any respiratory symptom were elevated at GLI_<5 (OR 3.57, 95% CI 2.43 to 5.23) and at GLI_5-10 (OR 2.57, 95% CI 1.69 to 3.91), but not at higher percentiles. Among ever-smokers, the odds of any respiratory symptom were elevated from GLI_<5 (OR 4.64, 95% CI 3.79 to 5.68) up to GLI_≥25 (OR 1.33, 95% CI 1.00 to 1.75).

CONCLUSIONS

The association between percentages of FEV₁:FVC and respiratory symptoms differed depending on smoking history. Our results support a higher percentile cut-off for FEV₁:FVC for never-smokers and, in particular, for ever-smokers.

Bronchial Diseases are Insufficiently Defined with the Term COPD

This paper discusses the basic thoughts behind the so-called diagnosis of COPD in relation to cause and course of the disease and questions the value of this functional defined terminology. Instead, the terminology should be based on morphology in the broadest sense including all methods suitable to describe pathological processes to understand the cause of bronchial diseases. The diagnosis COPD is only helpful in relation to therapeutic measures.

Impaired Respiratory Health and Life Course Transitions From Health to Chronic Lung Disease

Primary prevention and interception of chronic lung disease are essential in the effort to reduce the morbidity and mortality caused by respiratory conditions. In this review, we apply a life course approach that examines exposures across the life span to identify risk factors that are associated with not only chronic lung disease but also an intermediate phenotype between ideal lung health and lung disease, termed "impaired respiratory health." Notably, risk factors such as exposure to tobacco smoke and air pollution, as well as obesity and physical fitness, affect respiratory health across the life course by being associated with both abnormal lung growth and lung function decline. We then discuss the importance of disease interception and identifying those at highest risk of developing chronic lung disease. This work begins with understanding and detecting impaired respiratory health, and we review several promising molecular biomarkers, predictive symptoms, and early imaging findings that may lead to a better understanding of this intermediate phenotype.

Normal Routine Spirometry Can Mask COPD/Emphysema in Symptomatic Smokers

BACKGROUND

Recent studies have emphasized the difficulty of early detection of chronic obstructive pulmonary disease (COPD) in symptomatic smokers with normal routine spirometry. This includes post-bronchodilator normal forced expiratory volume in 1 second (FEV1)(L)≥80% predicted, forced vital capacity (FVC)(L)≥80% predicted, and FEV1/FVC ≥70% or greater than age corrected lower limit of normal (LLN). However, in COPD the pathologic site of small airway obstruction and emphysema begins in the small peripheral airways ≤2 mm id which normally contribute <20% of total airway resistance.

METHODS

Expiratory airflow at high and low lung volumes post-bronchodilator were measured and correlated with lung computed tomography (CT) and lung pathology (6 patients) in 16 symptomatic, treated smokers, and all with normal routine spirometry.

RESULTS

Despite normal routine spirometry, all16 patients had isolated, abnormal forced expiratory flow at 75% of FVC (FEF75) using data from Knudson et al, Hankinson et al NHAMES III, and Quanjer et al and the Global Lung Function Initiative. This reflects isolated detection of small airways obstruction and/or emphysema. Measuring airflow at FEF50 detected only 8 of 16 patients, maximal expiratory flow at 25%-75% of FVC (MEF25-75) only 4 of 16, residual volume (RV) 4 of 16, and RV to total lung capacity ratio only 2 of 16. There was excellent correlation between limited lung pathology and lung CT for absence of emphysema.

CONCLUSION

This study confirms our earlier observations that detection of small airways obstruction and/or emphysema, in symptomatic smokers with normal routine spirometry, requires analysis of expiratory airflow at low lung volumes, including FEF75. Dependence upon normal routine spirometry may result in clinical and physiologic delay in the diagnosis and treatment in symptomatic smokers with emphysema and small airways obstruction.

Goals of COPD treatment: Focus on symptoms and exacerbations

Chronic obstructive pulmonary disease (COPD) is currently a leading cause of death worldwide, and its burden is expected to rise in the coming years. Common COPD symptoms include dyspnea, cough and/or sputum production. Some patients may experience acute worsening of symptoms (known as an exacerbation), and therefore require additional therapy. Exacerbations are mainly triggered by respiratory infections and environmental factors. Healthcare professionals face many challenges in COPD management, including the heterogeneity of the disease and under-reporting of symptoms. The authors review these challenges and provide recommendations for the best methods to assess COPD. The goals of COPD treatment include recognising the impact that both symptoms and exacerbations have on patients' lives when considering optimal patient-focused management. The review discusses the need for COPD management strategies to include both pharmacologic and non-pharmacologic approaches and provides recommendations for monitoring treatment outcomes and adjusting management strategies accordingly. Novel treatment strategies including precision medicine and point-of-care testing are also discussed.

Prognostic significance of chronic respiratory symptoms in individuals with normal spirometry

Normal spirometry is often used to preclude airway disease in individuals with unspecific respiratory symptoms. We tested the hypothesis that chronic respiratory symptoms are associated with respiratory hospitalisations and death in individuals with normal spirometry without known airway disease.We included 108 246 randomly chosen individuals aged 20-100 years from a Danish population-based cohort study. Normal spirometry was defined as a pre-bronchodilator forced expiratory volume in 1 s/forced vital capacity ratio ≥0.70. Chronic respiratory symptoms included dyspnoea, chronic mucus hypersecretion, wheezing and cough. Individuals with known airway disease, i.e. chronic obstructive pulmonary disease and/or asthma, were excluded (n=10 291). We assessed risk of hospitalisations due to exacerbations of airway disease and pneumonia, and respiratory and all-cause mortality, from 2003 through 2018.52 999 individuals had normal spirometry without chronic respiratory symptoms and 30 890 individuals had normal spirometry with chronic respiratory symptoms. During follow-up, we observed 1037 hospitalisations with exacerbation of airway disease, 5743 hospitalisations with pneumonia and 8750 deaths, of which 463 were due to respiratory disease. Compared with individuals with normal spirometry without chronic respiratory symptoms, multivariable adjusted hazard ratios for individuals with normal spirometry with chronic respiratory symptoms were 1.62 (95% CI 1.20-2.18) for exacerbation hospitalisations, 1.26 (95% CI 1.17-1.37) for pneumonia hospitalisations, 1.59 (95% CI 1.22-2.06) for respiratory mortality and 1.19 (95% CI 1.13-1.25) for all-cause mortality. There was a positive dose-response relationship between number of symptoms and risk of outcomes. Results were similar after 2 years of follow-up, for never-smokers alone, and for each symptom separately.Chronic respiratory symptoms are associated with respiratory hospitalisations and death in individuals with normal spirometry without known airway disease.

Animal Models Reflecting Chronic Obstructive Pulmonary Disease and Related Respiratory Disorders: Translating Pre-Clinical Data into Clinical Relevance

Chronic obstructive pulmonary disease (COPD) affects the lives of an ever-growing number of people worldwide. The lack of understanding surrounding the pathophysiology of the disease and its progression has led to COPD becoming the third leading cause of death worldwide. COPD is incurable, with current treatments only addressing associated symptoms and sometimes slowing its progression, thus highlighting the need to develop novel treatments. However, this has been limited by the lack of experimental standardization within the respiratory disease research area. A lack of coherent animal models that accurately represent all aspects of COPD clinical presentation makes the translation of promising in vitrodata to human clinical trials exceptionally challenging. Here, we review current knowledge within the COPD research field, with a focus on current COPD animal models. Moreover, we include a set of advantages and disadvantages for the selection of pre-clinical models for the identification of novel COPD treatments.

Spirometric indices of early airflow impairment in individuals at risk of developing COPD: Spirometry beyond FEV1/FVC

Spirometry is the current gold standard for diagnosing and monitoring the progression of Chronic Obstructive Pulmonary Disease (COPD). However, many current and former smokers who do not meet established spirometric criteria for the diagnosis of this disease have symptoms and clinical courses similar to those with diagnosed COPD. Large longitudinal observational studies following individuals at risk of developing COPD offer us additional insight into spirometric patterns of disease development and progression. Analysis of forced expiratory maneuver changes over time may allow us to better understand early changes predictive of progressive disease. This review discusses the theoretical ability of spirometry to capture fine pathophysiologic changes in early airway disease, highlights the shortcomings of current diagnostic criteria, and reviews existing evidence for spirometric measures which may be used to better detect early airflow impairment.

Lung function trajectories and chronic obstructive pulmonary disease: current understanding and knowledge gaps

PURPOSE OR REVIEW

Population-based studies have shown a significant heterogeneity in patients with chronic obstructive pulmonary disease (COPD), regarding both the attainment of maximal lung function and the subsequent decline over time. This review will highlight recent advances in the understanding of lung function trajectory in COPD, focusing on factors that influence peak adult lung function, markers of accelerated lung function decline and pharmacologic interventions in early phases of the disease.

RECENT FINDINGS

Recent data have shown that individuals with lower lung function early in life will go on to develop lower forced expiratory volume in 1 s (FEV1) in adulthood. Smoking can amplify the effect of specific childhood exposures on maximal adult lung function. Clinical symptoms such as chronic mucous hypersecretion and the biomarker club cell secretory protein have been associated with lung function decline over time. New computed tomography imaging markers also show promise as a way to detect early small airway disease, but need to be examined more longitudinally. In addition to these advances, a slower decline in FEV1 has been demonstrated in two randomized clinical trials studying tiotropium and inhaled fluticasone.

SUMMARY

A better understanding of lung function development and eventual decline in those at risk for progression to COPD will aide in a precision medicine approach, in which markers for those at risk of low maximal lung function and accelerated decline are identified. Targeted therapy can then be used early to modify disease activity and outcomes.

Systemic Markers of Inflammation in Smokers With Symptoms Despite Preserved Spirometry in SPIROMICS

BACKGROUND

Chronic respiratory symptoms and exacerbation-like events are common among ever-smokers without airflow limitation on spirometry. The pathobiology of respiratory disease in this subgroup remains poorly defined, but may be due to underlying inflammation that overlaps with COPD or asthma. We hypothesized that symptoms, exacerbations, and functional measures of disease severity among smokers with preserved spirometry would be associated with markers of systemic inflammation, similar to what is reported in bone fide COPD, rather than elevated type 2 inflammation, which is often present in asthma.

METHODS

We measured inflammatory markers associated with COPD (C-reactive protein [CRP], fibrinogen, soluble tumor necrosis factor receptors [sTNFRSF1A and sTNFRSF1B], and blood/sputum neutrophils) and type 2 inflammation (IgE and blood/sputum eosinophils) in smokers with preserved spirometry (postbronchodilator FEV₁/FVC ≥ 0.70) from the Subpopulations and Intermediate Outcome Measures In COPD Study (SPIROMICS). We evaluated the relationship of these markers with respiratory symptom burden (dichotomized by a COPD assessment test score cutoff of 10, diagnosis of chronic bronchitis), exacerbations, 6-minute walk distance, and lung function on the basis of FEV₁.

RESULTS

CRP was associated with increased symptom burden (on the basis of COPD assessment test score and diagnosis of chronic bronchitis) and a greater number of exacerbations in the year before study enrollment. sTNFRSF1A was associated with symptom burden on the basis of COPD assessment test score. CRP and sTNFRSF1A levels negatively correlated with 6-minute walk distance. IgE and eosinophils were not associated with these outcomes.

CONCLUSIONS

Markers of inflammation including CRP and sTNFRSF1A are enriched among symptomatic smokers with preserved spirometry, suggesting an overlap with the underlying pathophysiology of COPD.

Use of a Cross-Sectional Survey in the Adult Population to Characterize Persons at High-Risk for Chronic Obstructive Pulmonary Disease

Rationale/Objective: The Behavioral Risk Factor Surveillance System (BRFSS) health survey has been used to describe the epidemiology of chronic obstructive pulmonary disease (COPD) in the US. Through addressing respiratory symptoms and tobacco use, it could also be used to characterize COPD risk.

METHODS

Four US states added questions to the 2015 BRFSS regarding productive cough, shortness of breath, dyspnea on exertion, and tobacco duration. We determined COPD risk categories: provider-diagnosed COPD as self-report, high-risk for COPD as ≥10 years tobacco smoking and at least one significant respiratory symptom, and low risk was neither diagnosed COPD nor high risk. Disease burden was defined by respiratory symptoms and health impairments. Data were analyzed using multiple logistic regression models with age as a covariate.

RESULTS

Among 35,722 adults ≥18 years, the overall prevalence of COPD and high-risk for COPD were 6.6% and 5.1%. Differences among COPD risk groups were evident based on gender, race, age, geography, tobacco use, health impairments, and respiratory symptoms. Risk for disease was seen early where 3.75% of 25⁻34 years-old met high-risk criteria. Longer tobacco duration was associated with an increased prevalence of COPD, particularly >20 years. Seventy-nine percent of persons ≥45 years-old with frequent shortness of breath (SOB) reported having or being at risk of COPD, reflecting disease burden.

CONCLUSION

These data, representing nearly 18% of US adults, indicates those at high risk for COPD share many, but not all of the characteristics of persons diagnosed with the disease and demonstrates the value of the BRFSS as a tool to define lung health at a population level.

Outcomes for symptomatic non-obstructed individuals and individuals with mild (GOLD stage 1) COPD in a population based cohort

BACKGROUND

We aimed to study the adverse outcomes of symptomatic and asymptomatic non-obstructed individuals and those with mild COPD longitudinally in participants from three Latin-American cities.

METHODS

Two population-based surveys of adults with spirometry were conducted for these same individuals with a 5- to 9-year interval. We evaluated the impact of respiratory symptoms (cough, phlegm, wheezing or dyspnea) in non-obstructed individuals, and among those classified as Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage 1, COPD on exacerbation frequency, mortality and FEV1 decline, compared with asymptomatic individuals without airflow obstruction or restriction.

RESULTS

Non-obstructed symptomatic individuals had a marginal increased risk of mortality (HR 1.3; 95% CI 0.9-1.94), increased FEV1 decline (-4.5 mL/year; 95% CI -8.6, -0.4) and increased risk of 2+ exacerbations in the previous year (OR 2.6; 95% CI 1.2-6.5). Individuals with GOLD stage 1 had a marginal increase in mortality (HR 1.5; 95% CI 0.93-2.3) but a non-significant impact on FEV1 decline or exacerbations compared with non-obstructed individuals.

CONCLUSIONS

The presence of respiratory symptoms in non-obstructed individuals was a predictor of mortality, lung-function decline and exacerbations, whereas the impact of GOLD stage 1 was mild and inconsistent. Respiratory symptoms were associated with asthma, current smoking, and the report of heart disease. Spirometric case-finding and treatment should target individuals with moderate-to-severe airflow obstruction and those with restriction, the groups with consistent increased mortality.

COPD: time to improve its taxonomy?

Due to well-conducted epidemiological studies and advances in genetics, molecular biology, translational research, the advent of computed tomography of the lungs and bioinformatics, the diagnosis of chronic obstructive pulmonary disease (COPD) as a single entity caused by susceptibility to cigarette smoke is no longer tenable. Furthermore, the once-accepted concept that COPD results from a rapid and progressive loss of lung function over time is not true for a sizeable proportion of adults with the disease. Now we know that some genetic predisposition and/or different environmental interactions (nutritional, infectious, pollution and immunological) may negatively modulate post-natal lung development and lead to poorly reversible airflow limitation later in life, consistent with COPD. We believe it is time to rethink the taxonomy of this disease based on the evidence at hand. To do so, we have followed the principles outlined in the 1980s by J.D. Scadding who proposed that diseases can be defined by four key characteristics: 1) clinical description (syndrome), 2) disorder of structure (morbid anatomy), 3) disorder of function (pathophysiology) and 4) causation (aetiology). Here, we propose a pragmatic approach to the taxonomy of COPD based on different processes that result in a similar syndromic presentation. It can accommodate changes over time, as the pathobiology that may lead to COPD expands. We hope that stakeholders in the field may find it useful to better define the patients now boxed into one single entity, so that specific studies can be designed and conducted for each type of COPDs.

Natural history of COPD: gaps and opportunities

Understanding the natural history of a disease is as important as knowing its cause(s) for effective disease prevention and treatment. Yet, our current understanding of the natural history of chronic obstructive pulmonary disease (COPD) is incomplete and often controversial. This article discusses the current gaps, and hence opportunities for research, in this field. In particular, it discusses the following six specific questions. 1) Is COPD a “single” disease? 2) Is COPD “only” a lung disease? 3) When does COPD begin or what is “early” COPD? 4) How does COPD “progress”? 5) How do we assess disease “severity”? 6) Can COPD be prevented (beyond smoking cessation) or its course be modified once detected?

A new review series starts in ERJ Open Research: “Gaps in our understanding of COPD”http://ow.ly/CFSD30gpXs8

The EASI model: A first integrative computational approximation to the natural history of COPD

The natural history of chronic obstructive pulmonary disease (COPD) is still not well understood. Traditionally believed to be a self-inflicted disease by smoking, now we know that not all smokers develop COPD, that other inhaled pollutants different from cigarette smoke can also cause it, and that abnormal lung development can also lead to COPD in adulthood. Likewise, the inflammatory response that characterizes COPD varies significantly between patients, and not all of them perceive symptoms (mostly breathlessness) similarly. To investigate the variability and determinants of different “individual natural histories” of COPD, we developed a theoretical, multi-stage, computational model of COPD (EASI) that integrates dynamically and represents graphically the relationships between exposure (E) to inhaled particles and gases (smoking), the biological activity (inflammatory response) of the disease (A), the severity (S) of airflow limitation (FEV₁) and the impact (I) of the disease (breathlessness) in different clinical scenarios. EASI shows that the relationships between E, A, S and I vary markedly within individuals (through life) and between individuals (at the same age). It also helps to delineate some potentially relevant, but often overlooked concepts, such as disease progression, susceptibility to COPD and issues related to symptom perception.

In conclusion, EASI is an initial conceptual model to interpret the longitudinal and cross-sectional relationships between E, A, S and I in different clinical scenarios. Currently, it does not have any direct clinical application, thus it requires experimental validation and further mathematical development. However, it has the potential to open novel research and teaching alternatives.

What does endotyping mean for treatment in chronic obstructive pulmonary disease?

Chronic obstructive pulmonary disease (COPD) is a complex and heterogeneous disease, both at the clinical and biological level. However, COPD is still diagnosed and treated according to simple clinical measures (level of airflow limitation, symptoms, and frequency of previous exacerbations). To address this clinical and biological complexity and to move towards precision medicine in COPD, we need to integrate (bioinformatics) and interpret (clinical science) the vast amount of high-throughput information that existing technology provides (systems biology and network medicine) so diagnosis, stratification, and treatment of patients with COPD can occur on the basis of their pathobiological mechanism (ie, endotypes). Therefore, this Series paper discusses a possible new taxonomy of COPD, the role of endotypes and associated biomarkers and phenotypes, the gaps (and opportunities) in existing knowledge of COPD pathobiology, how systems biology and network medicine can improve understanding of the disease and help to identify relevant endotypes and their specific biomarkers, and how endotypes and their biomarkers can improve the precision, effectiveness, and safety of the treatment of patients with COPD.

Small airway dysfunction in smokers with stable ischemic heart disease

BACKGROUND

A higher prevalence of airflow limitation (AL) has been described in patients with ischemic heart disease (IHD). Although small airway dysfunction (SAD) is an early feature of AL, there is little information about its occurrence in IHD patients. Our objective was to describe the prevalence of SAD in IHD patients, while comparing patient-related outcomes and future health risk among IHD patients with AL, SAD and normal lung function.

METHODS

In 118 consecutive smoking patients with stable IHD, comorbidities, utilization of healthcare resources, current treatment, blood biochemistry and health status were recorded. SAD was evaluated by impulse oscillometry, and pre- and post-bronchodilator spirometry was performed.

RESULTS

The prevalence of AL and SAD were 20.3 (95% CI, 13.1-27.6%) and 26.3% (95% CI, 18.3-34.2%), respectively. Compared to the normal lung function group, patients with SAD and without AL had lower spirometric values, poorer quality of life and higher levels of C-reactive protein (CRP), as well as increased cardiovascular risk and more vascular age. In patients with normal spirometry, the presence of SAD was independently associated with pack-years, HDL-cholesterol and CRP levels.

CONCLUSION

In patients with IHD, the presence of SAD is common and that it is associated with reduced health status and increased future cardiac risk.

The boundaries of mild chronic obstructive pulmonary disease (COPD): design of the searching clinical COPD onset (SOON) study

INTRODUCTION

Clinical onset of chronic obstructive pulmonary disease (COPD) is the point at which the disease is first identifiable by physicians. It is a poorly defined stage which seems to include both mild spirometric and non-spirometric disease, and could be described as early grade COPD, for practical purposes. While dyspnoea; chronic bronchitis and CT imaging evidence of emphysema and airway disease may be present very early, the lone significance of dyspnoea, the most relevant symptom in COPD in identifying these individuals, has been scarcely assessed.The Searching Clinical COPD Onset (SOON) Study was designed primarily to detect clinical, physiological and structural differences between dyspnoeic and non-dyspnoeic individuals with early grade COPD. It is hypothesised that presence of dyspnoea in early disease may identify a subtype of individuals with reduced exercise capacity, notwithstanding of their spirometry results. In addition, dyspnoeic individuals will share worse quality of life, lower physical activity, greater lung hyperinflation greater emphysema and airway thickness and reduced peripheral muscle mass than their non-dyspnoeic counterpart.

METHODS AND ANALYSIS

SOON is a monocentric study, with a cross sectional design aimed at obtaining representative samples of current or ex-smoker-adults aged ≥45 and ≤80 years. Two hundred and forty participants will be enrolled into four strata, according to normal spirometry or mild spirometric obstruction and presence or not of dyspnoea modified Medical Research Council score ≥1. The primary outcome will be the difference between dyspnoeic and non-dyspnoeic individuals on the 6-min walk test performance, regardless of their spirometry results. To account for the confounding effect of heart failure on dyspnoea, stress echocardiography will be also performed. Secondary outcomes will include clinical (quality of life, physical activity), physiological (exercise testing) and structural characteristics (emphysema, airway disease and peripheral muscle mass by CT imaging).

ETHICS AND DISSEMINATION

The Institutional Ethics Committee from Pontificia Universidad Católica de Chile has approved the study protocol and signed informed consent will be obtained from all participants. The findings of the trial will be disseminated through relevant peer-reviewed journals and international conference presentations.

TRIAL REGISTRATION NUMBER

NCT03026439.

Asthma and smoking-induced airway disease without spirometric COPD

Due to the high prevalence rates of cigarette smoking and asthma, current and ex-smokers frequently develop chronic airway disease without spirometric evidence of chronic obstructive pulmonary disease (COPD), either alone or associated with asthma. This review considers the classification, clinical outcomes, inflammatory and imaging variables, phenotypes, and management of current and ex-smokers with airway disease without COPD, focusing on overlaps in those with and without asthma. These individuals have more respiratory symptoms, worse quality of life, increased exacerbation rates, reduced lung function and more comorbidities than never-smokers with asthma or healthy never-smokers. As well as clinical features, airway inflammatory and structural changes in smoking-induced airway disease without COPD overlap with those found in smokers with asthma. Cigarette smoking is associated with worse clinical outcomes in some phenotypes of asthma. Management involves public health measures to control exposure to tobacco smoke, personal advice on smoking cessation and the use of appropriate targeted therapies, although evidence is limited on their effectiveness. Understanding the mechanisms, natural history and management of current and ex-smokers with asthma and smoking-induced airway disease without COPD is a priority for future research.