Importance of fractional exhaled nitric oxide in the differentiation of asthma-COPD overlap syndrome, asthma, and COPD

The Role of Bioactive Small Molecules in COPD Pathogenesis

Chronic obstructive pulmonary disease (COPD) is recognized as a predominant contributor to mortality worldwide, which causes significant burdens to both society and individuals. Given the limited treatment options for COPD, there lies a critical realization: the imperative for expeditious development of novel therapeutic modalities that can effectively alleviate disease progression and enhance the quality of life experienced by COPD patients. Within the intricate field of COPD pathogenesis, an assortment of biologically active small molecules, encompassing small protein molecules and their derivatives, assumes crucial roles through diverse mechanisms. These mechanisms relate to the regulation of redox balance, the inhibition of the release of inflammatory mediators, and the modulation of cellular functions. Therefore, the present article aims to explore and elucidate the distinct roles played by different categories of biologically active small molecules in contributing to the pathogenesis of COPD.

New markers in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD), a global healthcare and socioeconomic burden, is a multifaceted respiratory disorder that results in substantial decline in health status and life quality. Acute exacerbations of the disease contribute significantly to increased morbidity and mortality. Consequently, the identification of reliable and effective biomarkers for rapid diagnosis, prediction, and prognosis of exacerbations is imperative. In addition, biomarkers play a crucial role in monitoring responses to therapeutic interventions and exploring innovative treatment strategies. Although established markers such as CRP, fibrinogen and neutrophil count are routinely used, a universal marker is lacking. Fortunately, an increasing number of studies based on next generation analytics have explored potential biomarkers in COPD. Here we review those advances and the need for standardized validation studies in the appropriate clinical setting.

Association of IL-33 in modeling type-2 airway inflammation and pulmonary emphysema in mice

We developed pulmonary emphysema and a type 2 airway inflammation overlap mouse model. The bronchoalveolar lavage (BAL) interleukin 13 (IL-13), IL-4, and IL-5 levels in the overlap model were higher than in the pulmonary emphysema model and lower than in the type 2 airway inflammation model, but IL-33 level in the lung was higher than in other models. IL-33 and interferon-γ (IFNγ) in lungs may control the severity of a type 2 airway inflammation in lung.

Overuse of long-acting β2-agonist/inhaled corticosteroids in patients with chronic obstructive pulmonary disease: time to rethink prescribing patterns

Chronic obstructive pulmonary disease (COPD) is one of the leading causes of morbidity and mortality globally. In the major revision of the Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2023 report, the scientific committee concluded that the use of long-acting β2-agonist/inhaled corticosteroids (LABA/ICS) is not encouraged in patients with COPD. However, current prescribing patterns reveal significant use of LABA/ICS. In this paper, the evidence behind the current practice and the latest treatment recommendations is reviewed. We compare the efficacy and safety of combination therapy with long-acting muscarinic antagonist (LAMA) and LABA vs LABA/ICS and note that LAMA/LABA combinations have reduced the annual rate of moderate/severe exacerbations, delayed the time to first exacerbation, and increased post-dose FEV1 vs ICS-based regimens. The GOLD 2023 report recommends treatment with LABA and LAMA combination (preferably as a single inhaler) in patients with persistent dyspnea, with initiation of ICS in patients based on the symptoms (dyspnea and exercise intolerance as indicated by modified Medical Research Council [mMRC] score ≥ 2 and COPD Assessment Test [CAT™] > 20), blood eosinophil count (≥ 300 cells/µL), and exacerbation history (history of hospitalizations for exacerbations of COPD and ≥ 2 moderate exacerbations per year despite appropriate long-acting bronchodilator maintenance therapy). We describe practical recommendations for primary care physicians to optimize therapy for their patients and prevent overuse of ICS-based regimens. We advocate adherence to current recommendations and a greater focus on effective treatments to successfully control symptoms, minimize exacerbation risk, preserve lung function, maximize patient outcomes, and reduce the burden of drug-related adverse events.

Exhaled Nitric Oxide as Biomarker of Type 2 Diseases

Nitric oxide (NO) is a short-lived gas molecule which has been studied for its role as a signaling molecule in the vasculature and later, in a broader view, as a cellular messenger in many other biological processes such as immunity and inflammation, cell survival, apoptosis, and aging. Fractional exhaled nitric oxide (FeNO) is a convenient, easy-to-obtain, and non-invasive method for assessing active, mainly Th2-driven, airway inflammation, which is sensitive to treatment with standard anti-inflammatory therapy. Consequently, FeNO serves as a valued tool to aid the diagnosis and monitoring of several asthma phenotypes. More recently, FeNO has been evaluated in several other respiratory and/or immunological conditions, including allergic rhinitis, chronic rhinosinusitis with/without nasal polyps, atopic dermatitis, eosinophilic esophagitis, and food allergy. In this review, we aim to provide an extensive overview of the current state of knowledge about FeNO as a biomarker in type 2 inflammation, outlining past and recent data on the application of its measurement in patients affected by a broad variety of atopic/allergic disorders.

Blood Eosinophils and Exhaled Nitric Oxide: Surrogate Biomarkers of Airway Eosinophilia in Stable COPD and Exacerbation

In recent years, tremendous efforts have been devoted to characterizing the inflammatory processes in chronic obstructive pulmonary disease (COPD) in order to provide more personalized treatment for COPD patients. While it has proved difficult to identify COPD-specific inflammatory pathways, the distinction between eosinophilic and non-eosinophilic airway inflammation has gained clinical relevance. Evidence has shown that sputum eosinophil counts are increased in a subset of COPD patients and that these patients are more responsive to oral or inhaled corticosteroid therapy. Due to feasibility issues associated with sputum cell profiling in daily clinical practice, peripheral blood eosinophil counts and fractional exhaled nitric oxide levels have been evaluated as surrogate biomarkers for assessing the extent of airway eosinophilia in COPD patients, both in stable disease and acute exacerbations. The diagnostic value of these markers is not equivalent and depends heavily on the patient’s condition at the time of sample collection. Additionally, the sensitivity and specificity of these tests may be influenced by the patient’s maintenance treatment. Overall, eosinophilic COPD may represent a distinct disease phenotype that needs to be further investigated in terms of prognosis and treatment outcomes.

lncRNA-NEAT1 Sponges miR-128 to Promote Inflammatory Reaction and Phenotypic Transformation of Airway Smooth Muscle Cells

OBJECTIVE

Pediatric asthma is still a health threat to the children. Long noncoding RNA-NEAT1 (lncRNA-NEAT1) was reported to be positively correlated with the severity of asthma. We aimed to study the effects and mechanism of lncRNA-NEAT1on inflammatory reaction and phenotypic transformation of airway smooth muscle cells (ASMCs) in the bronchial asthma.

METHOD

The degree of lncRNA-NEAT1 and miR-128 mRNA in children with bronchial asthma and healthy individuals was tested by qRT-PCR. After the inflammatory reaction and phenotypic transformation of PDGF-BB-induced ASMCs, the expression of lncRNA-NEAT1 or miR-128 in the AMSC was disturbed in the AMSC. Subsequently, the expression of lncRNA-NEAT1 and miR-128 was detected by the way of qRT-PCR, and western blot was applied to measure the expression of MMP-2, MMP-9, α-SMA, calponin, NF-κB, and so on in the cells. The content of TNF-α, IL-1β, IL-6, and IL-8 in the cell culture supernatant was checked by ELISA. MTT, Transwell, and flow cytometry were used to detect cell proliferation, migration, and apoptosis. Further, the targeting relations between lncRNA-NEAT1 and miR-128 were evaluated by the dual-luciferase reporter assay.

RESULT

In the sputum of children with bronchial asthma, lncRNA-NEAT1 was significantly upregulated while miR-128 was rapidly downregulated. Besides, lncRNA-NEAT1 and miR-128 were competitively combined and, for their expression, negatively correlated.

CONCLUSION

lncRNA-NEAT1 sponges miR-128 to boost PDGF-BB-induced inflammatory reaction and phenotypic transformation of ASMCs to aggravate the occurrence and development of childhood bronchial asthma.

Diagnostic value of fractional exhaled nitric oxide in differentiating the asthma-COPD overlap from COPD: a systematic review and meta-analysis

BACKGROUND

Patients with asthma-COPD overlap (ACO) account for 15-20% of chronic obstructive pulmonary disease (COPD), and the incidence increases with age. Patients with ACO have worse outcomes without proper treatment than those with COPD alone. However, the current diagnostic criteria of ACO are mainly based on symptom features and lack of objective indicators. Recently, several studies have demonstrated that fractional exhaled nitric oxide (FeNO) was higher in ACO than in COPD alone. Thus, this study aims to determine the diagnostic value of FeNO in differentiating ACO from COPD and assisting clinical decision-making.

METHODS

We conducted searches in the databases including PubMed, Web of Science, Cochrane Library, and Embase to extract original studies.

RESULTS

In all, 10 studies involving 1335 participants were included in this meta-analysis. FeNO level was significantly higher in ACO patients than in patients with COPD alone (WMD = 11.15ppb, 95%CI = 9.01‒13.28; I² = 18.0%, p = 0.000). The sensitivity and specificity of FeNO in distinguishing ACO from COPD were both 0.71, and the area under the receiver-operating characteristic curve (AUC) was 0.76, indicating that FeNO has moderate diagnostic accuracy in differentiating ACO from COPD.

CONCLUSION

FeNO as an inflammatory biomarker is effective in differentiating ACO from COPD and assisting in clinical decision-making.

Single-Walled Carbon Nanotube-Based Biosensors for Detection of Bronchial Inflammation

Inflammation is a protective mechanism against invading pathogens and tissue damage. However, the inflammatory process is implicated in a wide range of diseases affecting all organs and body systems. Nitric oxide — a multifunctional signaling molecule that plays a critical role in systemic blood pressure homeostasis, prevention of platelet aggregation, antimicrobial resistance, immunoregulation, tumor suppression and as a neurotransmitter — is used as a surrogate marker for inflammation. However, the most commonly used Griess assay is an indirect and expensive method for the determination of nitric oxide concentration. Hence, single-walled carbon nanotube-based biosensors have been explored as real-time, sensitive, selective and safe methods to determine nitric oxide released during the inflammatory process. In this review, we explore current developments in single-walled carbon nanotube-based biosensors for the detection of nitric oxide in exhaled breath as a direct and noninvasive test for detection of bronchial inflammation.

ACO (Asthma-COPD Overlap) Is Independent from COPD, a Case in Favor: A Systematic Review

Asthma and chronic obstructive pulmonary disease (COPD) are now recognized to be able to co-exist as asthma-COPD overlap (ACO). It is clinically relevant to evaluate whether patients with COPD concurrently have components of asthma in primary care. This is because: (i) ACO is a relatively common condition among asthma (over 40 years of age) or COPD irrespective of its diagnosis criteria; (ii) patients with ACO can have higher frequency of exacerbation and more rapid decline in lung function than those with asthma or COPD; and (iii) asthmatic features such as eosinophilic airway inflammation are promising indicators for prediction of inhaled corticosteroid-responsiveness in COPD. The aim of this review to evaluate diagnostic markers for ACO. We searched PubMed for articles related to ACO published until 2020. Articles associated with diagnostic biomarkers were included. We identified a total of 25 studies, some of which have revealed that a combination of biomarkers such as fractional exhaled nitric oxide and serum immunoglobulin E is useful to discern type 2 inflammation in the airways of COPD. Here, we review the current understanding of the clinical characteristics, biomarkers and molecular pathophysiology of ACO in the context of how ACO can be differentiated from COPD.

Preparation of defected SWCNTs decorated with en-APTAS for application in high-performance nitric oxide gas detection

We demonstrate highly sensitive and selective chemiresistive-type NO gas detection using defected single-walled carbon nanotubes (SWCNTs) decorated with N-[3-(trimethoxysilyl)propyl]ethylene diamine (en-APTAS) molecules. The defected SWCNTs were prepared via furnace annealing at 700 °C and confirmed by transmission electron microscopy. A single en-APTAS molecule has two amine groups acting as adsorption sites for NO gas, which can improve the NO response. The NO response was further enhanced when the defected SWCNTs were utilized because NO sensing reactions could occur on both the inner and outer walls of the defected SWCNTs. The en-APTAS decoration improved the NO response of the SWCNT-based gas sensing devices by 2.5 times; when the defected SWCNTs were used, the NO response was further improved by 3 times. Meanwhile, the recovery performance in a time-resolved response curve was significantly improved (45 times) via a simple rinsing process with ethanol. Specifically, the fabricated device did not respond to carbon monoxide (CO) or BTEX gas (i.e., a mixture of benzene, toluene, ethyl benzene, and xylene), indicating its high selectivity to NO gas. The results show the possibility of a high-performance SWCNT-based NO gas sensor applicable to healthcare fields requiring ppb-level detection, such as in vitro diagnostics (IVDs) of respiratory diseases.

The Value of Inflammatory Biomarkers in Differentiating Asthma-COPD Overlap from COPD

Purpose

To evaluate the accuracy of inflammatory biomarkers in differentiating patients with asthma-COPD overlap (ACO) from those with COPD alone.

Methods

Clinical data of 134 patients with COPD and 48 patients with ACO admitted to the First Affiliated Hospital of Xi'an Jiaotong University from January 2016 to June 2019 were retrospectively analyzed. Receiver operating characteristic (ROC) curve analysis was performed to determine the best cut-off values of fractional exhaled nitric oxide (FeNO), blood eosinophil counts (EOS), and neutrophil to lymphocyte ratio (NLR) for differentiating between ACO and COPD alone. Spearman correlation analysis was conducted to evaluate the relationships between these inflammatory biomarkers and the forced expiratory volume in one second/prediction (FEV₁%pred).

Results

FeNO and EOS in the ACO patients were significantly higher than those in the COPD patients (FeNO: median 37.50 vs 24.50 ppb, P < 0.001; EOS: median 0.20 vs 0.10 ×10⁹/L, P = 0.004). FeNO was positively correlated with FEV₁%pred (r = 0.314, P = 0.030), while NLR was negatively correlated with FEV₁%pred (r = -0.372, P = 0.009) in patients with ACO. In addition, a positive correlation between FeNO and EOS was also found in ACO, especially in patients without history of inhaled corticosteroids (ICS) use (r = 0.682, P < 0.001). The optimal cut-off value of FeNO was 31.5 ppb (AUC = 0.758, 95% CI = 0.631-0.886) in patients with smoking history, with 70.0% sensitivity and 89.9% specificity for differentiating ACO from COPD. In patients without history of ICS use, the best cut-off value of FeNO was 39.5 ppb (AUC = 0.740, 95% CI = 0.610-0.870), with 58.3% sensitivity and 84.9% specificity. Among patients without history of ICS use and smoking, 27.5 ppb was optimal cut-off level for FeNO (AUC = 0.744, 95% CI = 0.579-0.908) to diagnose ACO, with 81.8% sensitivity and 60.7% specificity, and the sensitivity was improved to 91.7% when FeNO was combined with EOS.

Conclusion

The inflammatory biomarkers FeNO and EOS can be used as indicators for differentiating between ACO and COPD alone.

The State of the Nitric Oxide Cycle in Respiratory Tract Diseases

This review describes the unique links of the functioning of the nitric oxide cycle in the respiratory tract in normal and pathological conditions. The concept of a nitric oxide cycle has been expanded to include the NO-synthase and NO-synthase-independent component of its synthesis and the accompanying redox cascades in varying degrees of reversible reactions. The role of non-NO-synthase cycle components has been shown. Detailed characteristics of substrates for the synthesis of nitric oxide (NO) in the human body, which can be nitrogen oxides, nitrite and nitrate anions, and organic nitrates, as well as nitrates and nitrites of food products, are given. The importance of the human microbiota in the nitric oxide cycle has been shown. The role of significant components of nitrite and nitrate reductase systems in the nitric oxide cycle and the mechanisms of their activation and deactivation (participation of enzymes, cofactors, homeostatic indicators, etc.) under various conditions have been determined. Consideration of these factors allows for a detailed understanding of the mechanisms underlying pathological conditions of the respiratory system and the targeting of therapeutic agents. The complexity of the NO cycle with multidirectional cascades could be best understood using dynamic modeling.

The Value of FENO Measurement for Predicting Treatment Response in Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Background

Fractional exhaled nitric oxide (FENO) has been shown to be a marker of airway inflammation in various pulmonary diseases, including chronic obstructive pulmonary disease (COPD). In this study, we assessed the FENO level in patients with acute exacerbations of COPD (AECOPD) and analyzed the predictive value of the FENO level for treatment response.

Methods

Demographic data were collected at admission. FENO, lung function, blood gases, COPD Assessment Test (CAT), and modified Medical Research Council (mMRC) scores were measured at admission and on day 7. At the second visit, the patients were asked to report their health status; scores ranged from 1 to 5, representing "much better", "slightly better", "no change", "slightly worse", and "much worse", respectively. The treatment response was evaluated based on the patient's reported health status (responders were those who reported much better and slightly better) and lung function (responders were those who presented an increase in FEV1 over 200 mL).

Results

A total of 182 patients were recruited into the analysis. The FENO level positively correlated with an increase in FEV1 and FEV1% (r = 0.291, p < 0.001 and r = 0.205, p = 0.005, respectively), but negatively correlated with a decrease in the COPD Assessment Test (CAT) score (r = -0.197, p = 0.008) and patient-reported health status (rho = -0.408, p<0.001). An inverse correlation was observed between FENO concentrations at admission and the length of hospital stay. The cut-off point for differentiating responders, identified by health status, was 18 ppb, with the sensitivity being 89.7% and specificity 88.9%.

Conclusion

FENO levels, determined at hospital admission, are potential to predict the overall treatment response in AECOPD patients, including remission in subjective patient-reported health statuses and, also, improvements in lung function.

Registry Number

ChiCTR-ROC-16,009,087 (http://www.chictr.org.cn/).

Predictive Value of Exhaled Nitric Oxide and Blood Eosinophil Count in the Assessment of Airway Eosinophilia in COPD

Purpose

Fractional exhaled nitric oxide (FENO50) level and peripheral blood eosinophil count may serve as indicators of airway eosinophilia. The aim of this study was to estimate the diagnostic value of these markers for detecting airway eosinophilia in patients with stable chronic obstructive pulmonary disease (COPD) and those experiencing an acute exacerbation (AECOPD).

Patients and Methods

FENO50 levels, sputum and blood eosinophil counts were assessed in 53 clinically stable ex-smoker COPD patients and 67 ex-smoker COPD patients experiencing a severe exacerbation. In AECOPD, clinical variables were measured at the time of hospital admission and discharge following treatment.

Results

In stable COPD, blood eosinophil count but not FENO50 level was found to be a good predictor of airway eosinophilia (area under the receiver operating characteristic curve [ROC AUC]: ≥0.82). The sensitivity and the specificity of the test ranged between 75% and 98%, the negative predictive value (NPV) was high (>90%). In AECOPD, FENO50 was predictive for airway eosinophilia (ROC AUC: >0.8) with high NPV (>88%), but with lower sensitivity and specificity (64-70%). In contrast, the predictive accuracy of blood eosinophil count for airway eosinophilia in AECOPD was modest (ROC AUC: 0.54-0.63). The combined use of the two markers provided only limited additional benefit. Correlation analyses supported ROC curve findings.

Conclusion

In stable COPD the peripheral blood eosinophil count, while in AECOPD the FENO50 level is a good surrogate marker of airway eosinophilia.

Role of Type2 Inflammatory Biomarkers in Chronic Obstructive Pulmonary Disease

Airway inflammation in chronic obstructive pulmonary disease (COPD) is typically thought to be driven by Type1 immune responses, while Type2 inflammation appears to be present in definite proportions in the stable state and during exacerbations. In fact, some COPD patients showed gene expression of Type2 inflammation in the airway, and this subset was associated with the inhaled corticosteroid (ICS) response. Interestingly enough, the relationship between COPD and diseases associated with Type2 inflammation from the perspective of impaired lung development is increasingly highlighted by recent epidemiologic studies on the origin of COPD. Therefore, many researchers have shown an interest in the prevalence and the role of existent Type2 biomarkers such as sputum and blood eosinophils, exhaled nitric oxide fraction, and atopy, not only in asthma but also in COPD. Although the evidence about Type2 biomarkers in COPD is inconsistent and less robust, Type2 biomarkers have shown some potential when analyzing various clinical outcomes or therapeutic response to ICS. In this article, we review the existent and emerging Type2 biomarkers with clinically higher applicability in the management of COPD.

An official JRS statement: The principles of fractional exhaled nitric oxide (FeNO) measurement and interpretation of the results in clinical practice

Nitric oxide (NO) is produced in the body and has been shown to have diverse actions in the abundance of research that has been performed on it since the 1970s, leading to Furchgott, Murad, and Ignarro receiving the Nobel Prize in Physiology or Medicine in 1998. NO is produced by nitric oxide synthase (NOS). NOS is broadly distributed, being found in the nerves, blood vessels, airway epithelium, and inflammatory cells. In asthma, inflammatory cytokines induce NOS activity in the airway epithelium and inflammatory cells, producing large amounts of NO. Measurement of fractional exhaled nitric oxide (FeNO) is a simple, safe, and quantitative method of assessing airway inflammation. The FeNO measurement method has been standardized and, in recent years, this noninvasive test has been broadly used to support the diagnosis of asthma, monitor airway inflammation, and detect asthma overlap in chronic obstructive pulmonary disease (COPD) patients. Since the normal upper limit of FeNO for healthy Japanese adults is 37 ppb, values of 35 ppb or more are likely to be interpreted as a signature of inflammatory condition presenting features with asthma, and this value is used in clinical practice. Research is also underway for clinical application of these measurements in other respiratory diseases such as COPD and interstitial lung disease. Currently, there remains some confusion regarding the significance of these measurements and the interpretation of the results. This statement is designed to provide a simple explanation including the principles of FeNO measurements, the measurement methods, and the interpretation of the measurement results.

Fractional Exhaled Nitric Oxide as an Inflammatory Biomarker in Chronic Obstructive Pulmonary Disease (COPD) with or without Concurrent Diagnosis of Asthma: The Canadian Cohort Obstructive Lung Disease (CanCOLD)

We studied whether fractional exhaled nitric oxide (F _ENO) can differentiate chronic obstructive pulmonary disease (COPD) with concurrent diagnosis of asthma from COPD-only as well as its ability to predict disease severity and progression. This study was embedded in the Canadian Cohort Obstructive Lung Disease (CanCOLD). Subjects of ≥40 years old completed F _ENO measurements were subdivided into four groups, including COPD (N = 86 [COPD-only (N = 35) and COPD with concurrent diagnosis of asthma (N = 51)], healthy (N = 72), and at risk (N = 151). Three of the most common clinical definitions were used for characterizing COPD with concurrent diagnosis of asthma: 1) atopy and self-reported physician diagnosis of asthma, 2) ≥12% and ≥200 ml post-bronchodilator FEV1; 3) self-reported physician diagnosis of asthma. F _ENO values were classified using quartiles and the American Thoracic Society (ATS) guideline 2011. Compared to COPD-only, more COPD with concurrent diagnosis of asthma had a significant F _ENO50 level of [Formula: see text] 33.5 ppb (fourth quartile) than COPD-only (p = 0.045, 0.011, and 0.006, for definition 1, 2, and 3, respectively). Considering the ATS guideline 2011, fewer COPD with concurrent diagnosis of asthma had F _ENO50 < 25 than COPD-only, which was statistically significant with definition 1 and 3 (p = 0.038 and 0.026, respectively). F _ENO as a biomarker has the potential to be used as a complementary value for differentiating COPD with concurrent diagnosis of asthma from COPD-only. Further studies should be conducted on validated definitions of COPD with concurrent diagnosis of asthma, which may include a reference to the type of airway inflammation in addition to the clinical definition.

Clinical Features of Chronic Obstructive Pulmonary Disease with High Fractional Exhaled Nitric Oxide

Background

The fractional exhaled nitric oxide (FENO) test is useful in asthma patients. However, a few studies on its usefulness in chronic obstructive pulmonary disease (COPD) patients have been reported. We analyzed the FENO level distribution and clinical characteristics according to the FENO level in COPD patients.

Methods

From December 2014 to June 2019, COPD patients who underwent pulmonary function and FENO tests at Chonnam National University Hospital were retrospectively evaluated for FENO, comorbidities, asthma history, blood eosinophil, and pulmonary function test. The high FENO group was defined as those with FENO level>25 parts per billion (ppb).

Results

A total of 849 COPD patients (mean age, 70.3±9.4 years) were included. The mean forced expiratory volume at 1 second was 66.5±21.7% and the mean FENO level was 24.3±20.5 ppb. Patients with FENO ≤25 ppb were 572 (67.4%) and those with FENO >25 ppb were 277 (32.6%). Blood eosinophil percentage was significantly higher (4.2±4.8 vs. 2.7±2.5, p<0.001) in patients with the high FENO group than the low FENO group. The high FENO group revealed a significantly higher frequency of patients with blood eosinophil percentage >3% (46.9% vs. 34.8%, p=0.001) and asthma history (25.6% vs. 8.6%, p<0.001) than the lower FENO group. Asthma history, blood eosinophil percentage >3%, and positive bronchodilator response (BDR) were independent risk factors for the high FENO level (adjusted odds ratio [aOR], 3.85; p<0.001; aOR, 1.46; p=0.017; and aOR, 1.57, p=0.034, respectively) in the multivariable analysis.

Conclusion

The FENO level distribution varied in COPD patients and the mean FENO value was slightly elevated. Asthma history, eosinophil percent, and positive BDR were independent risk factors for the high FENO level.

Fraction of Exhaled Nitric Oxide Is Elevated in Patients With Stable Chronic Obstructive Pulmonary Disease: A Meta-analysis

BACKGROUND

Fraction of exhaled nitric oxide (FeNO) is a noninvasive indicator of eosinophilic airway inflammation and has been used for the diagnosis and treatment of asthma. The levels of FeNO are controversial in patients with stable chronic obstructive pulmonary disease (COPD). Accordingly, this study aimed to assess FeNO levels in patients with stable COPD.

MATERIALS AND METHODS

A search of the Medline, Embase, Web of Science, ClinicalTrials.gov and The Cochrane Library databases was performed in August 2019. The literature search was restricted to articles published in English. Studies were included if they reported data addressing FeNO levels in patients with stable COPD and healthy controls. Review Manager version 5.3 (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark) was used for meta-analysis.

RESULTS

A total of 19 studies were included. Analysis revealed that FeNO levels in patients with stable COPD were higher than those in the healthy control group (mean difference [MD] 2.49 [95% confidence interval {CI} 0.99-4.00]; P < 0.05), those in nonsmoking patients with stable COPD were higher than those in the healthy control group (MD 5.04 [95% CI 2.19-7.89]; P < 0.05) and those in smoking patients with stable COPD were not higher than those in the healthy control group (MD 0.30 [95% CI -2.81 to 3.41]; P = 0.85). FeNO measured using a chemiluminescence analyzer in nonsmoking patients with stable COPD was higher than those in the healthy control group (MD 4.84 [95% CI 1.83-7.86]; P < 0.05).

CONCLUSIONS

Findings suggested that FeNO levels in patients with stable COPD were elevated, and that smokers exhibited decreased levels.

Exhaled Nitric Oxide in Patients with Stable Chronic Obstructive Pulmonary Disease: Clinical Implications of the Use of Inhaled Corticosteroids

Background

Fractional exhaled nitric oxide (FeNO) is regarded as a potential biomarker for identifying eosinophilic inflammation. We aimed to evaluate the clinical implication of FeNO and its influence on inhaled corticosteroids (ICS) prescription rate in Korean chronic obstructive pulmonary disease (COPD) patients.

Methods

FeNO level and its association with clinical features were analyzed. Changes in the prescription rate of ICS before and after FeNO measurement were identified.

Results

A total of 160 COPD patients were divided into increased (≥25 parts per billion [ppb], n=74) and normal (<25 ppb, n=86) FeNO groups according to the recommendations from the American Thoracic Society. Compared with the normal FeNO group, the adjusted odds ratio for having history of asthma without wheezing and with wheezing in the increased FeNO group were 2.96 (95% confidence interval [CI], 1.40–6.29) and 4.24 (95% CI, 1.37–13.08), respectively. Only 21 out of 74 patients (28.4%) with increased FeNO prescribed ICS-containing inhaler and 18 of 86 patients (20.9%) with normal FeNO were given ICS-containing inhaler. Previous exacerbation, asthma, and wheezing were the major factors to maintain ICS at normal FeNO level and not to initiate ICS at increased FeNO level.

Conclusion

Increased FeNO was associated with the history of asthma irrespective of wheezing. However, FeNO seemed to play a subsidiary role in the use of ICS-containing inhalers in real-world clinics, which was determined with prior exacerbation and clinical features suggesting Th2 inflammation.

Asthma-COPD Overlap and Chronic Airflow Obstruction: Definitions, Management, and Unanswered Questions

Asthma-chronic obstructive pulmonary disease (COPD) overlap (ACO) is a common clinical presentation of chronic airways disease in which patients show some features usually associated with asthma, and some usually associated with COPD. There is ongoing debate over whether ACO is a discrete clinical entity, or if it is part of a continuum of airways disease. Furthermore, there is considerable variation among current definitions of ACO, which makes diagnosis potentially challenging for clinicians. Treating ACO may be equally challenging because ACO is an understudied population, and the evidence base for its management comes largely from asthma and COPD studies, the relevance of which deserves careful consideration. In this review, we synthesize the various approaches to ACO diagnosis and evaluate the role of currently available diagnostic tests. We describe the potential benefits of existing asthma and COPD therapies in treating patients with ACO, and the value of a "treatable traits" approach to ACO management. Throughout the review, we highlight some of the pressing, unanswered questions surrounding ACO that are relevant to the clinical community. Ultimately, addressing these questions is necessary if we are to improve clinical outcomes for this complex and heterogeneous patient population.

The relationship between inflammatory markers and spirometric parameters in ACOS, Asthma, and COPD

Objective: The inflammatory mechanisms underpinning asthma-chronic obstructive pulmonary disease (COPD) overlap syndrome (ACOS) have not been fully elucidated. Here, we examined the levels of cysteinyl leukotrienes (cys-LTs), prostaglandin D2 (PG-D2), prostaglandin E2 (PG-E2), interleukin 5 (IL-5), and a disintegrin and metalloprotease domain (ADAM 33) in ACOS patients to determine the relationship between levels of these inflammatory markers and pulmonary functions.Methods: Blood samples were obtained from asthma, COPD, and ACOS patients who received combined therapy and were stable for the last month to measure cys-LTs, PG-D2, PG-E2, IL-5, and ADAM33 levels. Differences between groups and their correlations with pulmonary function tests were evaluated.Results: In total, 24 ACOS, 27 asthma, and 35 COPD patients were included. . PG-D2 levels were higher in ACOS (120.9 ± 117.2 ng/L) and asthma (119.6 ± 111.7 ng/L) patients than in COPD (82.6 ± 46.7 ng/L) patients (p = 0.036 and p = 0.038, respectively). In ACOS patients, PG-D2, cys-LTs, and ADAM33 levels were negatively correlated with FEV1/FVC% values (p = 0.021, p = 0.008, and p = 0.028, respectively). In COPD patients, a negative correlation was detected between PG-E2 and FEV1/FVC% (p = 0.007), whereas positive correlations were detected between IL-5 and pulmonary function tests, including FVC, FVC%, FEV1, FEV1%, FEF25-75, and FEF25-75% (p = 0.047, p = 0.005, p = 0.002, p = 0.002, p = 0.010, and p = 0.005, respectively). In asthma patients, cys-LTs levels were negatively correlated with FEV1 and FEF25-75 values (p = 0.045 and p = 0.037, respectively).Conclusions: PG-D2 levels may be a valuable biomarker to differentiate COPD in asthma and ACOS patients.

Clinical utility of ultrahigh fractional exhaled nitric oxide in predicting bronchial hyperresponsiveness in patients with suspected asthma

BACKGROUND

Fractional exhaled nitric oxide (FeNO) is a non-invasive biomarker for airway eosinophilic inflammation. However, the clinical value of ultrahigh FeNO (≥100 parts per billion (ppb)) in predicting asthma is never explored. We aimed to investigate the value of ultrahigh FeNO as a predictor of bronchial hyperresponsiveness (BHR), an important index for asthma diagnosis.

METHODS

A retrospective cohort study was conducted on 259 patients with suspected asthma who received the examination of FeNO, spirometry, bronchial provocation test (BPT) and differential cell count of induced sputum. Patients were stratified by FeNO value: ultrahigh (group A:≥100 ppb), high (group B: 50-99 ppb), intermediate (group C: 26-49 ppb) and normal (group D:≤25 ppb). The positive rates of BPT and sputum eosinophils percentage (Eos%) were compared among four cohorts. The correlations between FeNO and sputum Eos% were measured.

RESULTS

A significant higher positive rate of BPT was observed in group A (90.91%) than all others (B: 51.43%, C: 31.43%, D: 28.13%, all p<0.01). Referring to group D, the ORs of positive BPT in groups A, B and C were 26.84, 2.84 and 1.05. Sputum Eos% in group A (19.75 (7.00, 46.25)) is higher than that in others (B: 3.50 (1.00, 12.75), C: 1.13 (0.06,3.50), D: 0.50 (0.00, 2.13)). FeNO correlates with sputum Eos% in groups A and B, but not group C or D.

CONCLUSIONS

Ultrahigh FeNO correlates with BHR and could serve as a practical alternative to methacholine challenge to support an asthma diagnosis in patients with suspected asthma in primary care.

Nonallergic Triggers and Comorbidities in Asthma Exacerbations and Disease Severity

Asthma triggers are exogenous or endogenous factors that could worsen asthma acutely to cause an exacerbation, or perpetuate chronic symptoms and airflow limitation. Because it is well known that recent asthma exacerbations and poor symptom control are strong predictors of future disease activity, it is not surprising that the number of (allergic or nonallergic) asthma triggers in the environment correlates with the disease-related quality of life. There is a need to identify and avoid specific triggers as the centerpiece of disease management, especially in those with heightened sensitivity to certain factors.

Asthma features in severe COPD: Identifying treatable traits

AIM

Biological therapies developed for severe asthma may have a role in COPD patients with asthma features.

METHOD

We carried out a prospective, consecutive, cross-sectional analysis of 80 patients with severe COPD GOLD IV/D.

RESULTS

We studied 80 patients (48.8% female), aged 57.6 ± 5.1 years, ex-smokers with 35.7 ± 21.2 pack years, BMI 22.3 ± 3.5 kg/m², FEV₁ of 0.61 ± 0.2 L (21.1 ± 5.6% pred), pO₂ 52.4 ± 8.4 mmHg, and BODE 6.9 ± 1.7. 68% had >2 moderate or severe exacerbations annually. 16.1% (5/31) patients showed FEV₁ reversibility of >12% and >200 ml despite maximal therapy, 33% (15/45) had FENO ≥22.5 ppb, 33% (24/73) had serum IgE ≥100 I.E./ml and there was positive allergen sensitization in 51.5% (35/68). Blood eosinophilia of ≥150 cells/μl was seen in 47% (35/74). Induced sputum showed eosinophilia of ≥2% in 56% (14/24) with respiratory pathogens in 63.8% (30/47). We identified 12 (15%) patients with asthma-COPD overlap. Of these, 10 (83.3%) had frequent exacerbations and these patients had significantly more severe exacerbations requiring NIV or ICU than those without asthma features (p < 0.005).

CONCLUSION

We detected asthma features in a substantial subset of stable patients with severe COPD. Asthma features were associated with more severe exacerbation despite optimal COPD therapy, representing potential candidates for targeted therapy with anti- IgE or anti-IL5.

Current appraisal of single inhaler triple therapy in COPD

A single inhaler containing inhaled corticosteroid (ICS)/long-acting beta-agonist (LABA)/long-acting muscarinic antagonist (LAMA) is a more convenient way of delivering triple therapy in patients with COPD. Single triple therapy has been shown to be superior at reducing exacerbations and improving quality of life compared to LABA/LAMA, especially in patients with a prior history of frequent exacerbations and blood eosinophilia, who have ICS responsive disease. The corollary is that patients with infrequent exacerbations who are noneosinophilic may be safely de-escalated from triple therapy to LABA/LAMA without loss of control. Pointedly, there is a substantially increased risk of pneumonia associated with the triple therapy containing fluticasone furoate but not beclometasone dipropionate or budesonide. Since triple therapy is also better than ICS/LABA at reducing exacerbations and improving lung function, symptoms, and quality of life, this brings into question the rationale for using ICS/LABA. Hence, we propose a simplified pragmatic decision process based on symptoms, prior to exacerbation history, and blood eosinophils to select which patients should be given a single triple inhaler or LABA/LAMA. Differences in patient preference of inhaler device, formulations and drugs will also determine which triple inhaler prescribers elect to use.

Psoriasis and Respiratory Comorbidities: The Added Value of Fraction of Exhaled Nitric Oxide as a New Method to Detect, Evaluate, and Monitor Psoriatic Systemic Involvement and Therapeutic Efficacy

Psoriasis is a chronic inflammatory systemic disease characterized by a wide range of comorbidities. Respiratory comorbidities are currently poorly characterized and with discordant results. The systemic state of inflammation caused by psoriasis acts de novo on respiratory tissues and amplifies preexisting inflammation from asthma or chronic obstructive pulmonary disease. Because the lungs act as a gas exchanger between the internal and external environment, the impact of chronic psoriasis inflammation may be easily assessed through the analysis of exhaled breath. The fraction of exhaled nitric oxide test (FeNO) is a potential noninvasive solution that can provide quantitative and qualitative indices of respiratory airway inflammation. FeNO is routinely used to screen and manage asthmatic patients. Recent pilot studies contain encouraging data that underscore its possible use with systemic inflammatory nonpulmonary diseases, such as psoriasis. FeNO may therefore be a useful tool to evaluate underestimated airway inflammation and at the same time globally evaluate the impact of systemically antipsoriatic therapies.

Clinical utility of fractional exhaled nitric oxide and blood eosinophils counts in the diagnosis of asthma-COPD overlap

Background

Asthma-COPD overlap (ACO) is difficult to diagnose because it is characterized by persistent airflow limitation, and patients present with several manifestations that are usually associated with both asthma and COPD. In this retrospective study, we aimed to evaluate the diagnostic accuracy of fractional exhaled nitric oxide (FeNO) and blood eosinophil counts for the clinical diagnosis of ACO.

Patients and methods

A total of 121 patients were divided into two study groups, COPD alone or ACO, which was based on criteria from the joint document by the Global Initiative for Asthma and the Global initiative for chronic Obstructive Lung Disease. From July 2014 to April 2017, FeNO levels and blood eosinophil counts were measured in specimens from patients naïve to inhaled corticosteroids (ICS) and those using ICS. Receiver operating characteristic curve analysis was used to determine the cutoff values of FeNO and blood eosinophil levels that provided the best differential diagnosis between ACO and COPD.

Results

Among a total of 121 patients, 65 patients were diagnosed with COPD and 56 patients with ACO. The FeNO level was higher in patients with ACO than in patients with COPD (median 24.5 vs 16.0 ppb, respectively; P<0.01). Among patients naïve to ICS, the area under the receiver operating characteristic curve of FeNO values was 0.726, and the optimal diagnostic cutoff level of FeNO was 25.0 ppb, with 60.6% sensitivity and 87.7% specificity for differentiating ACO from COPD. FeNO (≥25.0 ppb) combined with blood eosinophil counts (≥250/μL) showed 96.1% specificity.

Conclusion

These results demonstrate that the FeNO level combined with blood eosinophil count is useful for the differential diagnosis between ACO and COPD.

Investigating Fractional Exhaled Nitric Oxide in Chronic Obstructive Pulmonary Disease (COPD) and Asthma-COPD Overlap (ACO): A Scoping Review

Chronic obstructive pulmonary disease (COPD) is the most common fixed airflow limitation. Individuals may present with the features of both asthma and COPD called asthma-COPD overlap (ACO) with more severity and worse health-related quality of life than COPD or asthma. One of the promising biomarkers that could be used in clinical practice to differentiate ACO from COPD is fractional exhaled nitric oxide (F_ENO). The role of Fractional exhaled nitric oxide (F_ENO) in COPD/ACO remains unknown. This scoping review aims to investigate the role of F_ENO measurement to differentiate COPD from ACO, to anticipate disease severity/progression and treatment response. A structured comprehensive literature search was performed in major databases including Medline, EMBASE, CINAHL, Cochrane Library, Web of Science, and BIOSIS from 2005 onwards. Thirty-eight studies were retrieved. Based on the synthesis of the reviewed literature, six themes emerged. Thirty-four articles covered more than one theme. From which, 24 articles were on modifying factors in F_ENO measurement, 18 on F_ENO in COPD compared with healthy subjects, and seven on F_ENO in ACO compared with COPD, 22 on F_ENO and disease severity/progression,12 on F_ENO and biomarkers, and eight on F_ENO and treatment response. F_ENO measurement cannot be used alone in the clinical settings of COPD patients. Although F_ENO level is higher in ACO patients than COPD-only, it is still unclear if there is a F_ENO cut-off that can be used to make the diagnosis of ACO and/or to guide therapy with inhaled corticosteroids/glucocorticoids in COPD patients.

Diagnostic value of fractional exhaled nitric oxide for asthma-chronic obstructive pulmonary disease overlap syndrome

To examine the difference in the fractional exhaled nitric oxide (FeNO) between chronic obstructive pulmonary disease (COPD) patients with asthma-COPD overlap syndrome (ACOS) and patients with Non-ACOS COPD (Non-ACOS) and to investigate the correlation between FeNO levels and the differential cell counts of eosinophils in induced sputum, in order to explore the diagnostic value of FeNO in ACOS.A prospective, case-control study was performed on 53 cases of ACOS group and 53 cases of Non-ACOS group in the Respiratory Medicine Outpatient of Zhangzhou Municipal TCM Hospital, Affiliated to Fujian University of Traditional Chinese Medicine. The FeNO levels and induced sputum cell counts were determined and the correlation between FeNO levels and eosinophile percentage was analyzed by Pearson linear correlation analysis.The FeNO levels in patients with ACOS (37[24.5-53.0]) ppb were significantly higher than those of patients with Non-ACOS (20 [15.5-24.5] ppb) (P < .01). Also, the percentage of eosinophils in induced sputum in the ACOS group (5.70 [1.50-17.62]%) were significantly higher than those of the Non-ACOS group (0.50 [0.00-1.00]%) (P < .01). FeNO in both groups correlated positively with the percentage of eosinophils in induced sputum (P < .01), with a correlation coefficient r of 0.521. The area under the receiver operating curve of FeNO for the diagnosis of ACOS phenotype was 0.815 (P < .01), the sensitivity and specificity reach highest when the cut off value was 25.50 ppb.The FeNO in patients from the ACOS group were significantly higher than those in Non-ACOS group and were moderately correlated with the percentage of eosinophils in induced sputum. The results indicated that FeNO may be used as a diagnostic index for ACOS, in addition to the induced sputum.

Clinical and inflammatory characteristics of Asthma-COPD overlap in workers with occupational asthma

INTRODUCTION

Although Asthma-COPD Overlap (ACO) has been described among populations of subjects with COPD or asthma, ACO has never been described among a population of subjects with occupational asthma (OA).

OBJECTIVES

The aims of this study were to: 1. identify ACO in a population of subjects with OA; and 2. compare the clinical characteristics between ACO and OA.

METHODS

This retrospective study included all subjects diagnosed with OA between 2000 and 2017 in an OA referral center. Occupational Asthma-COPD Overlap (OACO) was defined as post-bronchodilator FEV1/FVC < 70% and smoking history ≥ 10 pack-years, along with a diagnosis of OA.

RESULTS

Three hundred and four subjects were included, 262 (86.2%) were classified as OA and 42 (13.8%) as OACO. OA subjects presented higher sputum eosinophil counts after a specific-inhalation challenge than subjects with OACO (median [IQR]: 6.5 [17.0] vs 2.3 [3.5]). After adjusting for confounding factors, subjects with OACO were older (OR: 1.10 [1.05; 1.14]) and were taking higher doses of inhaled corticosteroids than OA subjects (OR, 5.20 [1.77; 16.48]). Subjects with OACO were less often atopic than OA subjects (OR, 0.19 [0.07; 0.62]).

CONCLUSIONS

Subjects with OACO constitute a distinct clinical and inflammatory phenotype from subjects with OA.

Investigating fractional exhaled nitric oxide (FeNO) in chronic obstructive pulmonary disease (COPD) and asthma-COPD overlap (ACO): a scoping review protocol

INTRODUCTION

During the last decade, many articles have been published, including reviews on fractional exhaled nitric oxide (FeNO) use and utility in clinical practice and for monitoring and identifying eosinophilic airway inflammation, especially in asthma, and evaluating corticosteroid responsiveness. However, the exact role of FeNO in patients with chronic obstructive pulmonary disease (COPD) and its ability to distinguish patients with COPD and those having concomitant asthma, that is, asthma-COPD overlap (ACO) is still unclear and needs to be defined. Due to the broad topics of FeNO in chronic airway disease, we undertook a scoping review. The present article describes the protocol of a scoping review of peer-reviewed published literature specific to FeNO in COPD/ACO over the last decade.

METHODS AND ANALYSIS

We used Joanna Briggs Institute Reviewers' Manual scoping review methodology as well as Levac et al's and Arksey et al's framework as guides. We searched a variety of databases, including Medline, Embase, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Cochrane Library, Web of Science, and BioSciences Information Service (BIOSIS) on 29 June 2016. Additional studies will be recognised by exploring the reference list of identified eligible studies. Screening of eligible studies will be independently performed by two reviewers and any disagreement will be solved by the third reviewer. We will analyse the gathered data from article bibliographies and abstracts.

ETHICS AND DISSEMINATION

To investigate the body of published studies regarding the role of FeNO in patients with COPD and its usefulness in the clinical setting, a scoping review can be used as a modern and pioneer model, which does not need ethics approval. By this review, new insights for conducting new research specific to FeNO in COPD/ACO population will emerge. The results of this study will be reported in the scientific meetings and conferences, which aim to provide information to the clinicians, primary care providers and basic science researchers.

Comparison of fractional exhaled nitric oxide levels in chronic obstructive pulmonary disease, bronchial asthma and healthy subjects of Nepal

INTRODUCTION

Fractional exhaled nitric oxide levels in exhaled breath can indicate ongoing eosinophilic airway inflammation, specifically in asthma. But its utility is being explored for central airway inflammations, including chronic obstructive pulmonary disease. Normal levels of fractional exhaled nitric oxide (F_ENO₅₀) have been defined in different studies but not in Nepal. This study compares F_ENO₅₀ levels in normal subjects, asthma and chronic obstructive pulmonary disease.

METHODS

Single breath estimation of F_ENO₅₀ was measured by a handheld electrochemical sensor-based device in normal non-smoking adults (n = 106), clinically controlled asthma (n = 106) and stable chronic obstructive pulmonary disease (n = 106).

RESULTS

The geometric mean for F_ENO₅₀ was 14 parts per billion (ppb) with a median of 16 ppb, first quartile at 11 ppb and third quartile at 20 ppb in normal non-smoking adults. The values were 31 ppb (geometric mean), 34 ppb (median), 17 ppb (first quartile) and 79 ppb (third quartile) in clinically controlled asthma. Similarly the values were 10 ppb (geometric mean), 11 ppb (median), 6 ppb (first quartile) and 17 ppb (third quartile) in stable chronic obstructive airway disease. The log-transformed data showed significantly higher F_ENO₅₀ levels in the asthma group compared with the normal (p < 0.001) and chronic obstructive airway disease (p < 0.001). However, levels were similar between healthy and chronic obstructive airway disease groups (p = 0.08).

CONCLUSIONS

F_ENO₅₀ levels were higher in bronchial asthma (despite disease control) than in normal non-smoking adults and subjects with stable chronic obstructive pulmonary disease. Levels of F_ENO₅₀ were similar between the chronic obstructive airway disease and normal groups.

Management of the Asthma-COPD Overlap Syndrome (ACOS): a Review of the Evidence

PURPOSE OF REVIEW

Examine the definition of the asthma-COPD overlap syndrome (ACOS) and current treatment strategies.

RECENT FINDINGS

Patients with the ACOS have a lower quality of life and suffer from more complications than those affected by either disease alone. Diagnosis of ACOS is difficult because of the clinical similarities between the two diseases and the various phenotypes that comprise the syndrome. Defining treatment strategies for ACOS has been challenging because many clinical trials for asthma therapy have purposefully excluded patients with features of COPD, and COPD clinical trials have not included patients who might have an asthmatic component to their disease. Therefore, there are few randomized treatment trials which have included patients who have ACOS. Smoking cessation and appropriate vaccinations are cornerstone therapies, and pharmacologic therapy has focused on bronchodilators and inhaled corticosteroids. The role of biologics, such as omalizumab and IL-5 antagonists, in ACOS treatment is still being defined. As of now, with the paucity of randomized control trials guiding treatment strategies, the Global Initiative for Asthma (GINA) and Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines recommend treating ACOS according to the dominant phenotype.

Understanding COPD-overlap syndromes

INTRODUCTION

Chronic obstructive pulmonary disease accounts for a large burden of lung disease. It can 'overlap' with other respiratory diseases including bronchiectasis, fibrosis and obstructive sleep apnea (OSA). While COPD alone confers morbidity and mortality, common features with contrasting clinical outcomes can occur in COPD 'overlap syndromes'. Areas covered: Given the large degree of heterogeneity in COPD, individual variation to treatment is adopted based on its observed phenotype, which in turn overlaps with features of other respiratory disease states such as asthma. This is coined asthma-COPD overlap syndrome ('ACOS'). Other examples of such overlapping clinical states include bronchiectasis-COPD ('BCOS'), fibrosis-COPD ('FCOS') and OSA-COPD ('OCOS'). The objective of this review is to highlight similarities and differences between the COPD-overlap syndromes in terms of risk factors, pathophysiology, diagnosis and potential treatment differences. Expert commentary: As a consequence of COPD overlap syndromes, a transition from the traditional 'one size fits all' treatment approach is necessary. Greater treatment stratification according to clinical phenotype using a precision medicine approach is now required. In this light, it is important to recognize and differentiate COPD overlap syndromes as distinct disease states compared to individual diseases such as asthma, COPD, fibrosis or bronchiectasis.

A Belgian survey on the diagnosis of asthma-COPD overlap syndrome

INTRODUCTION

Patients with chronic airway disease may present features of both asthma and COPD, commonly referred to as asthma-COPD overlap syndrome (ACOS). Recommendations on their diagnosis are diffuse and inconsistent. This survey aimed to identify consensus on criteria for diagnosing ACOS.

METHODS

A Belgian expert panel developed a survey on ACOS diagnosis, which was completed by 87 pulmonologists. Answers chosen by ≥70% of survey respondents were considered as useful criteria for ACOS diagnosis. The two most frequently selected answers were considered as major criteria, others as minor criteria. The expert panel proposed a minimal requirement of two major criteria and one minor criterion for ACOS diagnosis. Respondents were also asked which criteria are important for considering inhaled corticosteroids prescription in a COPD patient.

RESULTS

To diagnose ACOS in COPD patients, major criteria were "high degree of variability in airway obstruction over time (change in forced expiratory volume in 1 second ≥400 mL)" and "high degree of response to bronchodilators (>200 mL and ≥12% predicted above baseline)". Minor criteria were "personal/family history of atopy and/or IgE sensitivity to ≥1 airborne allergen", "elevated blood/sputum eosinophil levels and/or increased fractional exhaled nitric oxide", "diagnosis of asthma <40 years of age"; "symptom variability", and "age (in favor of asthma)". To diagnose ACOS in asthma patients, major criteria were "persistence of airflow obstruction over time (forced expiratory volume in 1 second/forced vital capacity ratio <0.7)" and "exposure to noxious particles/gases, with ≥10 pack-years for (ex-)smokers"; minor criteria were "lack of response on acute bronchodilator test"; "reduced diffusion capacity"; "limited variability in airway obstruction"; "age >40 years"; "emphysema on chest computed tomography scan".

CONCLUSION

Specific criteria were identified that may guide physicians to a more uniform diagnostic approach for ACOS in COPD or asthma patients. These criteria are largely similar to those used to prescribe inhaled corticosteroids in COPD.