Clinical differences in the Global Initiative for Chronic Obstructive Lung Disease Stage 0

SPECT/CT to quantify early small airway disease and its relationship to clinical symptoms in smokers with normal lung function: a pilot study

Introduction

Smokers frequently display respiratory symptoms despite the fact that their pulmonary function tests (PFTs) can be normal. Quantitative lung ventilation single-photon emission computed tomography (SPECT/CT) can provide a quantification of lung ventilatory homogeneity and could prove useful as an early marker of airway disease in smokers. We measured the effects of smoking on regional ventilation distribution in subjects with normal lung function and evaluated whether ventilation distribution in these subjects is related to lung function tests results and clinical symptoms.

Methods

Subjects without any history of respiratory disease were prospectively recruited and separated in two groups: active smokers (AS: ≥10 cigarettes/day and history of ≥15 pack-years) and never smokers (NS: lifetime exposure of <5 cigarettes). All subjects performed PFTs (which had to be normal, defined as z-score values of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), FEV1/FVC ratio, total lung capacity (TLC) residual volume and diffusion capacity (DLCO) all falling between -1.65 and +1.65) and underwent SPECT/CT with Technegas, which generated subject- specific ventilation heterogeneity maps. The area under the compensated coefficient of variation (CV) density curve for CV values > 40%, (AUC-CV40%) was used as the measure of ventilation heterogeneity.

Results

30 subjects were recruited (15 per group). Subjects in the AS group displayed higher dyspnea levels (1 [1-2] vs. 0 [0-1] units on mMRC scale, p < 0.001). AUC- CV40% was significantly higher in the AS group (0.386 ± 0.106 vs. 0.293 ± 0.069, p = 0.004). AUC-CV40% was significantly correlated to FEV1 (rho = -0.47, p = 0.009), DLCO (rho = -0.49, p = 0.006), CAT score (rho = 0.55, p = 0.002) and mMRC score (rho = 0.54, p = 0.002). Subjects with mMRC >0 had higher AUC-CV40% values than those without dyspnea (0.289 ± 0.071 vs. 0.378 ± 0.102, p = 0.006), while FEV1 and DLCO were not different between those groups. ROC analyses showed that the AUC for AUC-CV40% in identifying subjects with mMRC score >0 was 0.78 (95%CI 0.61-0.95, p = 0.009), which was significantly higher than that of FEV1 and DLCO.

Discussion

In smokers with normal lung function, ventilatory inhomogeneities can be quantified using SPECT/CT. AUC-CV40% values are related to lung function decline and to respiratory symptomatology, suggesting a potential role for this marker in the evaluation of symptomatic smokers.

The prevalence of bronchodilator responsiveness of the small airway (using mid-maximal expiratory flow) in COPD - a retrospective study

BACKGROUND

Bronchodilator responsiveness (BDR) using FEV₁ is often utilised to separate COPD patients from asthmatics, although it can be present in some COPD patients. With the advent of treatments with distal airway deposition, BDR in the small airways (SA) may be of value in the management of COPD. We aimed to identify the prevalence of BDR in the SA, utilizing maximal mid-expiratory flow (MMEF) as a measure of SA. We further evaluated the prevalence of BDR in MMEF with and without BDR in FEV₁ and its association with baseline demographics, including conventional airflow obstruction severity and smoking history.

METHODS

Lung function data of ever-smoking COPD patients were retrospectively analysed. BDR was evaluated 20 min after administering 2.5 mg of salbutamol via jet nebulizer. Increase in percent change of ≥ 12% and absolute change of ≥ 200 ml was used to define a BDR in FEV₁, whereas an increase percent change of MMEF ≥ 30% was used to define a BDR in MMEF. Patients were classified as one of three groups according to BDR levels: group 1 (BDR in MMEF and FEV₁), group 2 (BDR in MMEF alone) and group 3 (no BDR in either measure).

RESULT

BDR in MMEF was present in 59.2% of the patients. Of note, BDR in MMEF was present in all patients with BDR in FEV₁ (group 1) but also in 37.9% of the patients without BDR in FEV₁ (group 2). Patients in group 1 were younger than in groups 2 and 3. BMI was higher in group 1 than in group 3. Baseline FEV₁% predicted and FVC % predicted were also higher in groups 1 and 2 than in group 3.

CONCLUSION

BDR in the SA (evaluated by MMEF) is common in COPD, and it is also feature seen in all patients with BDR in FEV₁. Even in the absence of BDR in FEV₁, BDR in MMEF is detected in some patients with COPD, potentially identifying a subgroup of patients who may benefit from different treatment strategies.

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.

Catching "Early" COPD - The Diagnostic Conundrum

Chronic obstructive pulmonary disease (COPD) remains a leading cause of morbidity and mortality worldwide. Despite this, there has been little progress so far in terms of disease-modifying therapies over the last few decades and this is in part due to poor understanding of the definition and mechanisms surrounding early disease before it becomes established and increasingly complex. In this review, the nuances and difficulty in defining early disease in COPD are discussed. There are clear benefits in identifying patients early; however, usually diagnosis is made in the presence of significant lung damage. We consider what can be learned of early disease from COPD studies and highlight the lack of inclusion of young smokers (who may be at risk of COPD) or those with mild disease. We discuss promising clinical measures that are being used in an effort to detect early disease. These include symptom assessment, lung physiology measures and computed tomography (CT) imaging modalities. There is emerging evidence for the role of neutrophils and their proteinases in early COPD. This may form an important biomarker to investigate the pathophysiological processes of early COPD. Given the importance of the early disease, it is recommended that future COPD studies focus on capturing the earliest manifestations of disease, to understand the initiating mechanisms and to identify novel treatment targets.

An overview of exacerbations of chronic obstructive pulmonary disease: Can tests of small airways' function guide diagnosis and management?

Chronic obstructive pulmonary disease (COPD) is common and debilitating. Most patients with COPD experience intermittent, acute deterioration in symptoms which require additional therapy, termed exacerbations. Exacerbations are prevalent in COPD and are associated with poor clinical outcomes including death, a faster decline in lung health, and a reduced quality of life. Current guidelines highlight the need to treat exacerbations promptly and then mitigate future risk. However, exacerbations are self-reported, difficult to diagnose and are treated with pharmacological therapies which have largely been unchanged over 30 years. Recent research has highlighted how exacerbations vary in their underlying cause, with specific bacteria, viruses, and cell types implicated. This variation offers the opportunity for new targeted therapies, but to develop these new therapies requires sensitive tools to reliably identify the cause, the start, and end of an exacerbation and assess the response to treatment. Currently, COPD is diagnosed and monitored using spirometric measures, principally the forced expiratory volume in 1 s and forced vital capacity, but these tests alone cannot reliably diagnose an exacerbation. Measures of small airways' function appear to be an early marker of COPD, and some studies have suggested that these tests might also provide physiological biomarkers for exacerbations. In this review, we will discuss how exacerbations of COPD are currently defined, stratified, monitored, and treated and review the current literature to determine if tests of small airways' function might improve diagnostic accuracy or the assessment of response to treatment.

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.

The relationship of cigarette smoking in Japan to lung cancer, COPD, ischemic heart disease and stroke: A systematic review

Background:  To present up-to-date meta-analyses of evidence from Japan relating smoking to major smoking-related diseases.  Methods:  We restricted attention to lung cancer, chronic obstructive pulmonary disease (COPD), ischemic heart disease (IHD) and stroke, considering relative risks (RRs) for current and ex-smokers relative to never smokers.  Evidence by amount smoked and time quit was also considered.  For IHD and stroke only, studies had to provide age-adjusted RRs, with age-specific results considered.  For each disease we extended earlier published databases to include more recent studies.  Meta-analyses were conducted, with random-effects RRs and tests of heterogeneity presented.  Results:  Of 40 studies, 26 reported results for lung cancer and 7 to 9 for each other disease.  For current smoking, RRs (95%CIs) were lung cancer 3.59 (3.25-3.96), COPD 3.57 (2.72-4.70), IHD 2.21 (1.96-2.50) and stroke 1.40 (1.25-1.57).  Ex-smoking RRs were lower.  Data for lung cancer and IHD showed a clear tendency for RRs to rise with increasing amount smoked and decrease with increasing time quit.  Dose-response data were unavailable for COPD and unclear for stroke, where the association was weaker.  Conclusions:  Compared to studies in other Asian and Western countries, current smoking RRs were quite similar for IHD and stroke.  The comparison is not clear for COPD, where the Japanese data, mainly from cross-sectional studies, is limited.  For lung cancer, the RRs are similar to those in other Asian countries, but substantially lower than in Western countries.  Explanations for this are unclear, but less accurate reporting of smoking by Japanese may contribute to the difference.

Maximal mid-expiratory flow detects early lung disease in α1-antitrypsin deficiency

Pathological studies suggest that loss of small airways precedes airflow obstruction and emphysema in chronic obstructive pulmonary disease (COPD). Not all α₁-antitrypsin deficiency (AATD) patients develop COPD, and measures of small airways function might be able to detect those at risk.Maximal mid-expiratory flow (MMEF), forced expiratory volume in 1 s (FEV₁), ratio of FEV₁/forced vital capacity (FVC), health status, presence of emphysema (computed tomography (CT) densitometry) and subsequent decline in FEV₁ were assessed in 196 AATD patients.FEV₁/FVC, FEV₁ % predicted and lung densitometry related to MMEF % pred (r²=0.778, p<0.0001; r²=0.787, p<0.0001; r²=0.594, p<0.0001, respectively) in a curvilinear fashion. Patients could be divided into those with normal FEV₁/FVC and MMEF (group 1), normal FEV₁/FVC and reduced MMEF (group 2) and those with spirometrically defined COPD (group 3). Patients in group 2 had worse health status than group 1 (median total St George's Respiratory Questionnaire (SGRQ) 23.15 (interquartile range (IQR) 7.09-39.63) versus 9.67 (IQR 1.83-22.35); p=0.006) and had a greater subsequent decline in FEV₁ (median change in FEV₁ -1.09% pred per year (IQR -1.91-0.04% pred per year) versus -0.04% pred per year (IQR -0.67-0.03% pred per year); p=0.007).A reduction in MMEF is an early feature of lung disease in AATD and is associated with impaired health status and a faster decline in FEV₁.

Meta-analysis approach to study the prevalence of chronic obstructive pulmonary disease among current, former and non-smokers

Comparative risk assessment for Chronic Obstructive Pulmonary Disease (COPD) among current, former and non-smokers categories remains controversial and not studied in detail. We conducted a meta-analysis to summarize all the relevant published studies on this topic and to update the association between smoking and prevalence of COPD in current, former and non-smokers. Identification, screening, eligibility and inclusion of articles for the study were conducted as per the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Quality assessment of included studies was undertaken using a scoring sheet. Meta-analysis after the final synthesis of the selected studies was performed using the STATA and Comprehensive Meta-Analysis (CMA) software. Estimates from forty two independent studies reporting 547,391 individuals were identified. Twenty two studies were conducted in Europe, nine in America and ten in Asia and one from New Zealand. The meta-analysis showed that the prevalence of COPD was significantly higher in current smokers compared with former and non-smokers. However, owing to large heterogeneity among the estimates obtained from the studies, stratification was done with respect to continent, diagnostic criteria of COPD and study design which also showed similar results. The stratified analysis also revealed similar trend of results with prevalence of COPD being higher in current smokers as compared to former and non-smokers. The present meta-analysis highlights the positive association between smoking and COPD prevalence. There is an urgent need to implement more effective policies towards the restriction of tobacco use, to reduce the burden of COPD.

Systematic review with meta-analysis of the epidemiological evidence relating smoking to COPD, chronic bronchitis and emphysema

BACKGROUND

Smoking is a known cause of the outcomes COPD, chronic bronchitis (CB) and emphysema, but no previous systematic review exists. We summarize evidence for various smoking indices.

METHODS

Based on MEDLINE searches and other sources we obtained papers published to 2006 describing epidemiological studies relating incidence or prevalence of these outcomes to smoking. Studies in children or adolescents, or in populations at high respiratory disease risk or with co-existing diseases were excluded. Study-specific data were extracted on design, exposures and outcomes considered, and confounder adjustment. For each outcome RRs/ORs and 95% CIs were extracted for ever, current and ex smoking and various dose response indices, and meta-analyses and meta-regressions conducted to determine how relationships were modified by various study and RR characteristics.

RESULTS

Of 218 studies identified, 133 provide data for COPD, 101 for CB and 28 for emphysema. RR estimates are markedly heterogeneous. Based on random-effects meta-analyses of most-adjusted RR/ORs, estimates are elevated for ever smoking (COPD 2.89, CI 2.63-3.17, n = 129 RRs; CB 2.69, 2.50-2.90, n = 114; emphysema 4.51, 3.38-6.02, n = 28), current smoking (COPD 3.51, 3.08-3.99; CB 3.41, 3.13-3.72; emphysema 4.87, 2.83-8.41) and ex smoking (COPD 2.35, 2.11-2.63; CB 1.63, 1.50-1.78; emphysema 3.52, 2.51-4.94). For COPD, RRs are higher for males, for studies conducted in North America, for cigarette smoking rather than any product smoking, and where the unexposed base is never smoking any product, and are markedly lower when asthma is included in the COPD definition. Variations by sex, continent, smoking product and unexposed group are in the same direction for CB, but less clearly demonstrated. For all outcomes RRs are higher when based on mortality, and for COPD are markedly lower when based on lung function. For all outcomes, risk increases with amount smoked and pack-years. Limited data show risk decreases with increasing starting age for COPD and CB and with increasing quitting duration for COPD. No clear relationship is seen with duration of smoking.

CONCLUSIONS

The results confirm and quantify the causal relationships with smoking.

The radiological patterns of interstitial change at an early phase: over a 4-year follow-up

OBJECTIVES

The identification of early phase interstitial changes may influence the understanding of idiopathic interstitial pneumonitis. This study aimed to clarify its radiological patterns and the association with smoking.

METHODS

The subjects underwent low-dose computed tomography to screen lung cancer. The selected subjects with interstitial changes were monitored for the precise morphology of interstitial changes using a high-resolution computed tomography (HRCT) scan. The subjects were classified into normal and abnormal HRCT subjects. The radiological findings on the HRCT scan, serum Klebs von der Lungen-6 (KL-6), surfactant protein (SP)-A, SP-D, pulmonary function, and computed tomography (CT) scores were analyzed. Abnormal HRCT subjects were classified based on the radiological patterns, and were followed-up over a 4-year period.

RESULTS

HRCT abnormalities suggesting interstitial changes were identified in 80 of 3079 subjects. Seven subjects with honeycombing and 14 with combined pulmonary fibrosis and emphysema (CPFE) were identified. The frequencies of sex (male) and smoking in the subjects with honeycombing was higher than that of other patterns. The smoking history and the levels of serum KL-6, SP-A, and SP-D in abnormal HRCT subjects were significantly higher than those in normal HRCT subjects. Thirty-two of 73 abnormal HRCT subjects showed a progression of the CT scores in a chest HRCT over a 4-year period. Eighteen abnormal HRCT current smokers were included in the progression of CT scores.

CONCLUSIONS

HRCT patterns, excluding interlobular septal thickening, show the progression of CT scores. Smokers with CT abnormalities may have a tendency to demonstrate worsening interstitial changes.

How much do GOLD stages reflect CT abnormalities in COPD patients?

PURPOSE

Severity of chronic obstructive pulmonary disease (COPD) can be graded using the classification released in the Global Initiative for Chronic Obstructive Lung Disease (GOLD) report. Such classification is essentially based on spirometry and does not recognise the role of other measures. The aim of this study was to assess whether the GOLD stages correlate with the extent of pulmonary emphysema and other ancillary computed tomography CT features in a population of smokers with stable COPD.

MATERIALS AND METHODS

Based on clinical assessment and lung-function testing, patients were classified according to the GOLD criteria. CT scans were visually evaluated for extent of emphysema and airway abnormalities.

RESULTS

A total of 43 patients were enrolled. The amount of emphysema was described as minimal in six patients with stage 0, and as moderate in seven patients with stage 0. In stages I and II, the extent of emphysema ranged from minimal to severe, whereas we observed the presence of severe emphysema in most patients in stages III and IV. According to the regression model, only CT emphysema extent independently predicted the GOLD stage (r2 = 0.58; p < 0.001). The cutoff value of emphysema extent of 31.5% allowed us to distinguish patients with a GOLD stage > or = III.

CONCLUSIONS

Although we found a significant correlation between CT emphysema extent and GOLD stages, different percentage of emphysema extent can be observed among each GOLD stage. The upper limit of 31.5% of emphysema extent may indicate a boundary for a clinically worsening status.

Utility of single-slice high-resolution CT in upper lung field combined with low-dose spiral CT for lung-cancer screening in the detection of emphysema

OBJECT

The present study was undertaken to evaluate the utility of low-dose spiral CT scanning, combined with single-slice high-resolution CT (HRCT), in the detection of pulmonary emphysema on CT (CTPE) together with screening for lung cancer.

SUBJECTS AND METHODS

For 657 individuals who visited for screening of lung cancer, single-slice HRCT of the upper lung field was added on conventional low-dose spiral CT scanning in order to detect low attenuation area (LAA) visually. The individuals were classified into four groups according to the visual extent of LAA in bilateral upper lung fields: no LAA, subtle PE (0%<LAA%< or =5%), mild PE (5%<LAA%< or =25%) and moderate to severe PE (LAA%>25%), and compared spirometry among the four groups.

RESULTS

LAA was detected in 23.3% of all subjects (subtle PE in 12.2%, mild PE in 9.9% and moderate to severe PE in 1.2%) by adding one HRCT slice whereas only in 6.4 % LAA was detected by conventional low-dose helical CT scanning at 10 mm slice alone. The airway obstruction (FEV1/FVC<70%) was observed only in 1.07%. The severity of emphysema was associated with older age, prevalence of having smoking history and Brinkman index. As the severity of emphysema, the FEV1/FVC, MMEF, and V25/HT showed lower values.

CONCLUSIONS

It is suggested that single-slice HRCT of the upper lung field combined with conventional low-dose spiral CT scanning for screening of lung cancer may also be useful for the detection of LAA, which may promote smoking cessation.