Reference ranges for exhaled nitric oxide fraction in healthy Japanese adult population

Fractional exhaled nitric oxide distribution and its relevant factors in the general adult population and its healthy subpopulation

Background

Measurement of fractional exhaled nitric oxide (Feno) has been used in the diagnosis and management of asthma. Understanding the distribution of Feno in a larger resident population and its "healthy" subpopulation would contribute to the interpretation of Feno in clinical practice.

Objective

This study aimed to investigate the distribution and its associated factors in the adult population and its healthy subpopulations.

Methods

We conducted a cross-sectional study of 8,638 men and 17,288 women aged 20 years or older living in Miyagi prefecture, Japan. We investigated the distribution of Feno and its associated factors in all subjects, a subpopulation with no history of upper and lower airway diseases (healthy subpopulation 1), and a subpopulation with no history of upper and lower airway diseases, normal lung function, and no positivity for other biomarkers of type 2 inflammation (healthy subpopulation 2).

Results

The distribution of Feno in healthy subpopulations, especially in healthy subpopulation 2 (median [interquartile range], 17 [12-23] with 95th percentile of 36 ppb) was lower than in all subjects (19 [13-26] ppb with 95th percentile of 47 ppb). In healthy subpopulation 1, 10.3% had elevated Feno (≥35 ppb), and elevated Feno was positively associated with factors including obstructive ventilatory defect, blood eosinophilia, house dust mite-specific IgE positivity, and history of hypertension. Male sex was associated with elevated Feno in all subjects and healthy subpopulations.

Conclusion

The distribution of Feno in the healthy subpopulation supports the validity of the criteria (≥35 ppb) currently used in Japan for the diagnosis of asthma.

Pattern recognition of forced oscillation technique measurement results using deep learning can identify asthmatic patients more accurately than setting reference ranges

No official clinical reference values have been established for MostGraph, which measures total respiratory resistance and reactance using the forced oscillation technique, complicating result interpretation. This study aimed to establish a reference range for MostGraph measurements and examine its usefulness in discriminating participants with asthma from controls (participants without any respiratory diseases). The study also aimed to investigate the effectiveness of deep learning in discriminating between the two aforementioned groups. To establish reference ranges, the MostGraph measurements of healthy controls (n = 215) were power-transformed to distribute the data more normally. After inverse transformation, the mean ± standard deviation × 2 of the transformed values were used to establish the reference ranges. The number of measured items outside the reference ranges was evaluated to discriminate patients with asthma (n = 941) from controls. Additionally, MostGraph measurements were evaluated using deep learning. Although reference ranges were established, patients with asthma could not be discriminated from controls. However, with deep learning, we could discriminate between the two groups with 78% accuracy. Therefore, deep learning, which considers multiple measurements as a whole, was more effective in interpreting MostGraph measurement results than use of reference ranges, which considers each result individually.

Effectiveness of exhaled nitric oxide for the prediction of non-invasive left atrial pressure in older people: a cross-sectional cohort study

BACKGROUND

During left-sided heart failure (HF), left atrial and pulmonary venous pressure increase, which may lead to pulmonary congestion. Previous cohort studies, examining participants with symptomatic HF or rheumatic heart disease, suggest a relationship between increased left atrial pressure (LAP) and fractional exhaled nitric oxide (FeNO).

AIM

To examine the strength of association between FeNO and echocardiographic assessment of LAP by the E/e' ratio, to determine if FeNO could be used to identify those with elevated LAP.

DESIGN & SETTING

This cross-sectional cohort study examined a subset of the OxVALVE cohort aged ≥65 years. Data collection was undertaken in primary care practices in central England.

METHOD

Each participant underwent a focused cardiovascular history and clinical examination. Standard transthoracic echocardiographic (TTE) assessment was performed on all participants, with the E/e' ratio calculated to obtain a validated surrogate of LAP. FeNO was measured in 227 participants.

RESULTS

FeNO was higher in males compared with females and no different in participants with asthma, chronic obstructive pulmonary disease (COPD), or those using inhaled steroids. Participants with a high E/e' (>14) were older, with a higher proportion of females than males. There was no relationship between E/e' and FeNO, either when measured as a continuous variable or in the group with high E/e'.

CONCLUSION

FeNO was not found to be an accurate predictor of elevated LAP in a primary care setting.

Sex differences of small airway function and fractional exhaled nitric oxide in patients with mild asthma

BACKGROUND

Sex differences of small airway function (SAF) and fractional exhaled nitric oxide (FeNO) in patients with mild asthma remain unclear.

OBJECTIVE

To evaluate sex differences of SAF and FeNO in patients with mild asthma confirmed by positive methacholine challenge test (MCT) result.

METHODS

This cross-sectional, double-centered, observational study enrolled 1609 adult patients with forced expiratory volume in 1 second greater than or equal to 80% and suspected asthma symptoms. Data of spirometry, FeNO, impulse oscillometry measurements, and peripheral blood test result were compared between males and females. The receiver-operating characteristic curves of SAF parameters and FeNO in predicting positive MCT result were also calculated.

RESULTS

In patients with mild asthma matched by age, males had better SAF but higher FeNO levels than females (60 [29.27%] vs 187 [46.75%] for small airway dysfunction, 78.6% vs 72.0% for forced expiratory flow [FEF]_50%, 67.5% vs 60.1% for FEF_75%, 73.7% vs 67.4% for FEF_25%-75%, and 42.0 ppb vs 29.0 ppb for FeNO, respectively, all P ≤ .001). The FeNO levels in male current smokers were considerably lower than those of nonsmokers. SAF and FeNO values declined more rapidly with age among female than male patients with asthma. The optimal cutoff values of FEF_25%-75%, FEF_50%, and FeNO for predicting a positive MCT result were 81.5%, 86.4%, and 41.0 ppb in males vs 73.7%, 76.9%, and 35.0 ppb in females.

CONCLUSION

In patients with mild asthma, the female patients have worse SAF, lower FeNO levels, and a more prominent decline trend of those parameters with age than males. Sex-specific cutoff values should be considered when SAF parameters (FEF_25%-75%, FEF_50%), alone or combined with FeNO, are used to predict positive MCT result in asthma diagnosis.

Assessment of Personal Relaxation in Indoor-Air Environments: Study in Real Full-Scale Laboratory Houses

The relationship between chemical concentrations in indoor air and the human sense of comfort and relaxation have been reported. We investigated the effect of the sum of volatile organic compounds (ΣVOCs; sum of 79 VOCs) on the level of relaxation in two laboratory houses with almost identical interior and exterior appearances. The electroencephalogram (EEG) was monitored to evaluate the degree of personal relaxation objectively. The experiments were conducted in laboratory houses (LH) A and B with lower and higher levels of ΣVOCs, respectively. A total of 168 healthy volunteers participated, who each performed the task for 20 min, followed by a 10-min break, and EEG was measured during the break. Simultaneously as subjective evaluations, the participants were asked to fill a questionnaire regarding the intensity of odor and preference for the air quality in each LH. The subjective evaluation showed a significant association between ΣVOCs and participants’ relaxation (OR: 2.86, 95%CI: 1.24–6.61), and the objective evaluation indicated that the participants were more relaxed in the LH with lower levels of ΣVOCs than that with higher levels (OR: 3.03, 95%CI: 1.23–7.50). Therefore, the reduction of ΣVOCs and odors in indoor air would have an effect, which is the promotion of relaxation.

Abundant TNF-LIGHT expression in the airways of patients with asthma with persistent airflow limitation: Association with nitrative and inflammatory profiles

BACKGROUND

The role of the inflammatory secretory protein TNF-LIGHT (LIGHT) in the molecular mechanisms underlying persistent airflow limitation (PAL) in asthma remains unclear. We hypothesized that high airway LIGHT expression may be a feature of asthma with PAL associated with specific expression patterns of inflammatory molecules.

METHODS

This hypothesis was tested in 16 patients with asthma on inhaled corticosteroid treatment. Induced sputum was collected, the expression of LIGHT and 3-nitrotyrosine (NT), which reflects the footprint of reactive nitrogen species content, was measured using immunohistochemical staining, and the inflammatory molecules in the sputum supernatant were analyzed using a magnetic bead array.

RESULTS

LIGHT staining in the cells had a significantly higher intensity in participants with PAL than in participants without PAL (47.9 × 10⁴/ml vs. 5.4 × 10⁴/ml; p < 0.05). The array analysis indicated that IL-8, IL-19, matrix metalloproteinase 2, and osteopontin, were associated with high LIGHT immunoreactivity. The fractionation of 3-NT-positive cells was positively correlated with that of LIGHT-positive cells (r = 0.57, p < 0.05) and the TGF-β1 level (r = 0.61, p < 0.05). LIGHT- and 3-NT-positive cells showed significant positive correlation with the differential cell counts of neutrophils, macrophages, and eosinophils in the induced sputum. Intense immunoreactivities of LIGHT (r = -0.54, p < 0.05) and 3-NT (r = -0.42, p = 0.1) were negatively associated with decreased forced expiratory volume in 1/forced vital capacity ratio.

CONCLUSIONS

The findings suggest that LIGHT is a key component in the association between airway inflammation and airflow limitation in patients with asthma, and its expression may be persistently correlated with the abundance of inflammatory cells and inflammatory and profibrogenic radical/molecules.

Comparison of fractional exhaled nitric oxide in asthmatics with and without allergic rhinitis

PURPOSE OF THE STUDY

The aim of this study was to measure the concentration of FeNO in asthmatics with and without allergic rhinitis (AR) and to determine usefulness of the test in the assessment of asthma control in the Polish population. The next objective of this study was to estimate the cut-off point of FeNO which might be a good indicator of uncontrolled asthma.

MATERIALS AND METHODS

The measurements were taken using the Hyp'Air FeNO in 303 adult patients with asthma, AR, comorbid AR and asthma, and non-diseased volunteers.

RESULTS

FeNO level in healthy adults was similar to the FeNO concentration in AR as well as controlled asthmatic patients without and with AR. Patients with partly controlled and uncontrolled asthma with and without AR had higher FeNO (>60 ppb) levels when compared to adults with controlled disease. The optimal cut-off point of FeNO > 46 ppb and FeNO > 33 ppb was estimated for identification of uncontrolled asthmatics without and with AR, respectively.

CONCLUSION

In conclusion, we found a significant correlation between the FeNO concentration and the level of asthma symptom control in asthmatic patients with and without AR.

Japanese guidelines for adult asthma 2020

Bronchial asthma is characterized by chronic airway inflammation, which manifests clinically as variable airway narrowing (wheezes and dyspnea) and cough. Long-standing asthma may induce airway remodeling and become intractable. The prevalence of asthma has increased; however, the number of patients who die from it has decreased (1.3 per 100,000 patients in 2018). The goal of asthma treatment is to control symptoms and prevent future risks. A good partnership between physicians and patients is indispensable for effective treatment. Long-term management with therapeutic agents and the elimination of the triggers and risk factors of asthma are fundamental to its treatment. Asthma is managed by four steps of pharmacotherapy, ranging from mild to intensive treatments, depending on the severity of disease; each step includes an appropriate daily dose of an inhaled corticosteroid, which may vary from low to high. Long-acting β₂-agonists, leukotriene receptor antagonists, sustained-release theophylline, and long-acting muscarinic antagonists are recommended as add-on drugs, while anti-immunoglobulin E antibodies and other biologics, and oral steroids are reserved for very severe and persistent asthma related to allergic reactions. Bronchial thermoplasty has recently been developed for severe, persistent asthma, but its long-term efficacy is not known. Inhaled β₂-agonists, aminophylline, corticosteroids, adrenaline, oxygen therapy, and other approaches are used as needed during acute exacerbations, by selecting treatment steps for asthma based on the severity of the exacerbations. Allergic rhinitis, eosinophilic chronic rhinosinusitis, eosinophilic otitis, chronic obstructive pulmonary disease, aspirin-exacerbated respiratory disease, and pregnancy are also important conditions to be considered in asthma therapy.

Airway inflammation and lung function recovery after lobectomy in patients with primary lung cancer

OBJECTIVE

Fractional exhaled nitric oxide (FeNO), which represents airway inflammation, is an indicator of postoperative complication after lung surgery. However, its effects in the late postoperative period are unknown. The aim of this prospective study was to clarify the impact of FeNO on postoperative lung function in patients with lung cancer.

METHODS

We measured preoperative FeNO using NIOX VERO® in patients with primary lung cancer. Patients were divided into two groups according to their potential airway inflammatory status: preoperative FeNO levels below 25 ppb (N group) and above 25 ppb (H group). They were evaluated by spirometry at 3 and 6 months after surgery during follow-up. The relationship between postoperative lung function and preoperative FeNO was evaluated.

RESULTS

Between September 2017 and March 2019, 61 participants were enrolled. All of them underwent lobectomy as a curative surgery. There were no significant background variables between the two groups. Postoperative vital capacity (VC) and forced expiratory volume in 1 s (FEV1) in the H group achieved less predictive values than those in the N group, which were not significant. The postoperative VC and FEV1 from 3 to 6 months in the H group were significantly increased as compared to those in the N group (p < 0.001).

CONCLUSIONS

Preoperative FeNO is a predictor of delayed lung function recovery 3 months after lobectomy in lung cancer patients. The impact had extended to VC and FEV1. Although this impact is temporary, early postoperative intervention is expected to reduce the adverse effect.

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.

Relationships among bronchodilator reversibility, the fraction of exhaled nitric oxide, and the parameters of the forced oscillation technique in adult asthma treated with inhaled corticosteroids and long-acting β2 agonists combination

In bronchial asthma, both airway inflammation and reversible airway narrowing require assessment and treatment. These two pathologies are treated primarily with inhaled corticosteroids (ICS) and long-acting β2 agonists (LABA), respectively. Therefore, ICS-LABA combinations are widely used to treat asthma. Airway inflammation and reversible airway narrowing are assessed primarily with fraction of exhaled nitric oxide (FENO) and bronchodilator reversibility (BDR). The forced oscillation technique (FOT) has recently attracted attention as a method for assessing obstructive respiratory disturbance. However, little is known about the relationships among these assessments. Therefore, we investigated the relationships among BDR, FENO, and FOT during ICS-LABA combination therapy. The subjects comprised 87 patients (25 men and 62 women) with asthma undergoing ICS/LABA combination therapy from July to September 2017. We applied the FENO test, FOT, and BDR testing without the patients stopping their therapy. The rates of change in FEV₁ (ΔFEV₁%) was correlated with FENO (r = 0.278). Among the FOT parameters, X5 (r = -0.263), Fres (r = 0.292), and AX (r = 0.245) were significantly correlated with ΔFEV₁%. FENO, Fres and %FEV₁ at baseline in these stable asthmatics were significantly assosiated with ΔFEV₁% independently of the effects of age, atopy and body mass index (BMI). These results suggest that FENO and the results of respiratory function testing and FOT reflect different aspects of asthma and should be combined and comprehensively evaluated.

Histopathological Type of Lung Cancer and Underlying Driver Mutations in Patients with Chronic Obstructive Pulmonary Disease (COPD) versus Patients with Asthma and COPD Overlap: A Single-Center Retrospective Study

OBJECTIVES

Chronic obstructive pulmonary disease (COPD) increases the risk of lung cancer. The relationships between COPD and Asthma COPD Overlap (ACO), and between the histopathological types of lung cancer and driver mutations remain unclear and need further study. The aim of this retrospective study was to examine the relationships between the histopathological type, frequency of epidermal growth factor receptor (EGFR) driver mutations, and anaplastic lymphoma receptor tyrosine kinase (ALK) rearrangements in the lung cancers of patients with COPD and ACO.

MATERIALS AND METHODS

Patients with pure COPD (n=198) or ACO (n=318) who were admitted to our hospital were reviewed retrospectively.

RESULTS

Lung cancers were identified in 43 (21.7%) patients with pure COPD and 54 (17.0%) patients with ACO. The following lung cancers types were observed: patients with pure COPD had 19 (44.2%) adenocarcinomas, 13 (30.2%) squamous cell lung carcinomas (SCC), 8 (18.6%) small cell lung carcinomas (SCLC); patients with ACO had 23 (42.6%) adenocarcinomas, 23 (42.6%) SCC, 2 (3.70%) SCLC. SCLC was significantly more prevalent in patients with pure COPD (p<0.05) than in those with ACO. Differences between the numbers of other histological types of lung cancer and the numbers of driver mutations in the 2 groups of patients were not significant.

CONCLUSION

The differences in the rate of lung cancer and prevalence of EGFR driver mutations between the patients with pure COPD and those with ACO were not significant.

Impact of sinus surgery on type 2 airway and systemic inflammation in asthma

Objective: Asthma is frequently associated with chronic rhinosinusitis with nasal polyps (CRSwNP). Although endoscopic sinus surgery (ESS) improves asthma control in CRSwNP patients with asthma, the mechanism that underlies the response to surgical treatment is still unclear. We evaluated the relevance of changes in asthma control and changes in airway/systemic inflammation in eosinophilic CRSwNP patients with not well controlled asthma who underwent ESS.Methods: We prospectively assessed changes in the asthma control questionnaire (ACQ) score, blood eosinophil counts (B-Eos), forced expiratory volume in 1 s (FEV₁), and fraction of exhaled nitric oxide (FeNO) levels at 1-week before and 8 and 52 weeks after ESS.Results: Twenty-five subjects were analyzed. The ACQ score, B-Eos, and FeNO decreased, and FEV₁ increased significantly after ESS. In the period from baseline to 52 weeks after ESS, changes in ACQ were significantly correlated with the changes in blood eosinophil counts (r = 0.58, p<.01) and FeNO (r = 0.45, p<.05). Ten subjects (40%) showed consistently improved asthma control at 52-weeks after ESS. In the remaining subjects, although the ACQ score temporarily improved at 8-weeks after ESS, but eventually deteriorated at 52-weeks. Higher levels of total immunoglobulin E were associated with long-term improved asthma control after ESS.Conclusions: In eosinophilic CRSwNP patients with asthma, sinus surgery impacts asthma control through the suppression of airway/systemic type 2 inflammation. The present study reinforced the common pathophysiology of type 2 inflammation between the upper and lower airways.

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.

Phenotype classification using the combination of lung sound analysis and fractional exhaled nitric oxide for evaluating asthma treatment

BACKGROUND

We report the utility of combining lung sound analysis and fractional exhaled nitric oxide (FeNO) for phenotype classification of airway inflammation in patients with bronchial asthma. We investigated the usefulness of the combination of the expiration-to-inspiration sound power ratio in the mid-frequency range (E/I MF) of 200-400 Hz and FeNO for comprehensively classifying disease type and evaluating asthma treatment.

METHODS

A total of 233 patients with bronchial asthma were included. The cutoff values of FeNO and E/I MF were set to 38 ppb and 0.36, respectively, according to a previous study. The patients were divided into 4 subgroups based on the FeNO and E/I MF cutoff values. Respiratory function, the percentages of sputum eosinophils and neutrophils, and patient background characteristics were compared among groups.

RESULTS

Respiratory function was well controlled in the FeNO low/E/I MF low group (good control). Sputum neutrophil was higher and FEV₁,%pred was lower in the FeNO low/E/I MF high group (poor control). History of childhood asthma and atopic asthma were associated with the FeNO high/E/I MF low group (insufficient control). The FeNO high/E/I MF high group corresponded to a longer disease duration, increased blood or sputum eosinophils, and lower FEV₁/FVC (poor control).

CONCLUSIONS

The combination of FeNO and E/I MF assessed by lung sound analysis allows the condition of airway narrowing and the degree of airway inflammation to be assessed in patients with asthma and is useful for evaluating bronchial asthma treatments.

Role of Regulatory T cells in Airway Inflammation in Asthma

Asthma is an allergic disease characterized by chronic airway inflammation, airway hyperresponsiveness (AHR), reversibility and remodeling. Inhaled corticosteroids (ICS) are effective in many patients with asthma. However, ICS are a controlling, but not but curative treatment, and there are still many patients with refractory and difficult-to-treat asthma. The evaluation of airway inflammation by induced sputum, non-specific AHR by methacholine, and asthmatic reactions by specific allergen challenge techniques are useful not only to investigate the pathogenesis of asthma but also to help develop new drugs for asthma management. Interactions between inflammation and regulation, such as between regulatory T cells (Tregs), and AHR were investigated using these techniques. The phenotypes are Tregs characterized by expression of the forkhead box P3 (Foxp3) and cytotoxic T-lymphocyte antigen 4 (CTLA4), which are potent mediators of dominant self-tolerance. Foxp3 and CTLA4 interact with each other. In patients with mild asthma, airway Tregs were decreased and airway eosinophilic inflammation was activated with accelerated AHR. Human asthmatic attack models by allergen challenge demonstrated that airway Tregs were decreased from the baseline with late asthmatic response (LAR) in patients with dual-responder asthma, and there was a significant correlation between change in airway Tregs and LAR. Airway Tregs were increased with escalation of interleukin-10 by ICS. The investigation of Tregs may lead to new strategies for management of asthma and other allergic diseases.

Does Ethnicity Influence Fractional Exhaled Nitric Oxide in Healthy Individuals?: A Systematic Review

BACKGROUND

Fractional exhaled nitric oxide (Feno) is used clinically as a biomarker of eosinophilic airway inflammation. Awareness of the factors influencing Feno values is important for valid clinical interpretation.

METHODS

We undertook a systematic review of PubMed, Cochrane Library, Scopus, and Web of Science databases and reference lists of included articles to evaluate whether ethnicity influences Feno values, and to determine if this influence affects clinical interpretation according to current guidelines. We included all studies that performed online Feno measurements on at least 25 healthy, non-Caucasian individuals, and examined the effect of ethnicity on Feno.

RESULTS

From 62 potential studies, 12 studies were included. One study recruited only children (< 12 years of age), six studies recruited children and/or adolescents, four studies recruited adults only, and a single study involved children, adolescents, and adults. In total, 16 different ethnic populations representing 11 ethnicities were studied. Ethnicity was considered a significant influencing factor in 10 of the included studies. We found the geometric mean Feno to be above the normal healthy range in two studies. We also identified five studies in which at least 5% of participants had Feno results above the age-specific inflammatory ranges.

CONCLUSIONS

Ethnicity influences Feno values, and for some ethnic groups this influence likely affects clinical interpretation according to current guidelines. There is a need to establish healthy Feno reference ranges for specific ethnic groups to improve clinical application.

Both exhaled nitric oxide and blood eosinophil count were associated with mild allergic asthma only in non-smokers

BACKGROUND

The fractional exhaled nitric oxide (FENO) and the blood eosinophil count (B-eos) are markers of eosinophilic inflammation used in the diagnosis and management of asthma. The relationships between smoking cigarette and both FENO and B-eos are complex and raise questions about the association between these markers and asthma in smokers.

OBJECTIVE

To determine the relationships between both FENO and B-eos on one hand and asthma and atopy on the other, according to smoking status.

METHODS

FENO and B-eos were measured in, respectively, 1579 and 1496 of the 1607 middle-aged adults randomly selected from the general population in the cross-sectional ELISABET survey. Allergic asthma was defined as asthma (a self-report of physician-diagnosed asthma, and wheezing in the previous 12 months or the use of asthma medications) with atopy (allergic rhinitis or hayfever in the previous 12 months, or a previous positive prick test or allergen desensitization therapy). Non-allergic asthma was defined as asthma without atopy.

RESULTS

The analysis included 812 (51.4%) never, 473 (30%) former and 294 (18.6%) current smokers. A total of 490 (32%) participants were atopic, 80 (5.1%) had allergic asthma, and 31 (2%) had non-allergic asthma. Only 16.2% (18/111) of asthmatics were treated with glucocorticoid inhalants, suggesting that among them a majority of participants had mild asthma. A positive interaction between smoking status and allergic asthma was observed in multivariate models explaining FENO (P = 0.003) and B-eos (P = 0.001). Thus, compared to those without allergic asthma, participants with allergic asthma had higher FENO values (+ 63.4%, 95% CI = [39; 92]) and higher B-eos (+ 63.2% [38.2; 92.7]) in never and former smokers, but not in current smokers. Lastly, an analysis of receiver-operating characteristic curves showed that each of the two markers was able to discriminate moderately allergic asthma but only in non-smokers.

CONCLUSIONS & CLINICAL RELEVANCE

FENO and B-eos were associated with the presence of mild allergic asthma only in non-smokers, not in current smokers. These findings raise questions about the clinical value of FENO and B-eos in smokers.

Determinants of Incomplete Asthma Control in Patients with Allergic Rhinitis and Asthma

BACKGROUND

Characterizing associations between the upper and lower airways is important for asthma management.

OBJECTIVES

This study aimed to assess the determinants of incomplete asthma control in patients with allergic rhinitis (AR) and asthma.

METHODS

Multiple factors including age, sex, atopy, smoking history, medication use, Asthma Control Questionnaire (ACQ) score, FEV₁, fraction of exhaled nitric oxide (Feno), and rhinitis questionnaire score were examined. AR was defined by rhinitis symptoms and the sensitization to inhaled allergens. ACQ was used to dichotomize the subjects into the incompletely controlled group (ACQ score ≥0.75) and the well-controlled group. The factors that contribute to incomplete asthma control were assessed by a multivariate analysis.

RESULTS

A total of 260 patients with AR and asthma were enrolled and 108 patients (42%) were classified as incomplete asthma control. The incompletely controlled group was older (P < .05), and had more airflow limitation, more airway inflammation, and more severe rhinitis symptoms (all P < .001). In contrast, the well-controlled group was more likely to be taking nasal corticosteroids (NCSs) (P < .01). In a multivariate model adjusted by age, asthma treatment, airflow limitation, and Feno, persistence and severity of rhinitis (odds ratio [OR], 2.57; 95% CI, 1.41-4.70, and OR, 2.00; 95% CI, 1.10-3.65) and nonuse of NCSs (OR, 3.83; 95% CI, 1.50-9.81) were independently associated with incomplete asthma control.

CONCLUSIONS

The persistence and severity of AR and the use of NCSs were associated with the level of asthma control in patients with AR and asthma. Further studies are required to determine whether appropriate treatment of rhinitis would improve asthma control.

Normal values of nasal NO and exhaled NO in young Chinese people aged 9 - 22 years

Objective

To assess the normal levels of nasal nitric oxide (NNO) and fractional exhaled nitric oxide (FENO) in healthy Chinese young people, and to determine whether the obtained values were associated with age, sex, height, weight, BMI (body mass index) or BSA (body surface area).

Methods

One hundred and twenty healthy people were selected from a total of 436 Chinese young people based on their answers to a questionnaire. An electrochemical analyzer (NIOX MINO system) was used to measure NNO and FENO. The relationship between NNO, FENO and age, sex, height, weight, BMI, BSA was analyzed using SPSS software.

Results

The values of NNO were normal distributed (mean 273.5 ppb; SD 112.3). The values of FENO were non-normally (Skewed) distributed (median: 14.00 ppb; interquartile range: 7.00 ppb). The obtained NNO values were independent of age, sex, height, weight, BMI and BSA, but were positively correlated to lnFENO (FENO log base e); lnFENO values were also independent of age, height, weight, BMI and BSA, but correlated with NNO and sex.

Conclusions

NNO values positively correlate with lnFENO in healthy people and the levels of each may be predicted by the other. The results of this study are expected to serve as a reference for future studies in China.

Pharmacological effects of lysozyme on COPD and bronchial asthma with sputum: A randomized, placebo-controlled, small cohort, cross-over study

BACKGROUND

Mucolytic agents are often used in Japan to ease excessive mucus production in patients with chronic obstructive pulmonary disease (COPD) or bronchial asthma (BA); the treatment ameliorates dyspnea and improves quality of life (QOL).

AIM

Efficacy and safety of lysozyme hydrochloride (LYS), an oral mucolytic enzyme preparation, for patients with COPD or BA were investigated.

PATIENTS AND METHODS

This study was a placebo-controlled, double-blind, randomized, cross-over design. Twenty-four patients with COPD and twenty-four patients with BA were enrolled. LYS or placebo was administered for 28 days in each treatment period, with a 28-day washout between the first and second treatment periods. The results of spirometry, impulse oscillometry system (IOS) examination, fractional exhaled nitric oxide (FeNO) measurement, as well as the changes in the subjective symptoms, were evaluated after the treatment period.

RESULTS

On spirometry, airway function (FEV1) improved in patients with COPD after administration of LYS (LYS vs placebo: 0.08 L vs 0.029 L, p = 0.030). Similar trends were also found in %FEV1 in COPD patients. On IOS examination, resistance of the respiratory system at 5 Hz levels was significantly improved only in patients with COPD (LYS vs placebo: -0.455 cm H2O/L/s vs 0.095 cmH2O/L/s, p = 0.012). Similar trends were found in terms of the resistance of the respiratory system at 20 Hz, and of the reactance area. In the COPD assessment test, subjective symptoms also significantly improved in patients with COPD during the LYS treatment period (improvement rates-LYS vs. placebo: 69.6% vs. 39.1%; p = 0.022). A similar effect of LYS was not seen in BA patients.

CONCLUSION

LYS, a mucolytic agent, has capability to improve the function of peripheral airways in patients with COPD, which leads to improvements of the patients' symptoms and QOL.

Fractional exhaled nitric oxide levels as a predictor of long-term prognoses in patients with mild asthma

BACKGROUND

There is a growing belief that patients with bronchial asthma (BA) should be provided an individualized and optimized treatment plan. We aimed to clarify the predictors of long-term prognoses in patients with mild BA.

METHODS

We conducted a retrospective study of consecutive patients who were newly diagnosed with mild BA at Iwate Medical University from 2011 to 2013, focusing on achievement of full asthma control based on the Asthma Control Test as an indicator of prognosis. Predictors were identified on the basis of a chart review.

RESULTS

Among 71 patients with mild BA, 37 patients completed regular clinic visits for 1 year. Nineteen (51.4%) of these patients achieved full asthma control. Current smoking and the fractional exhaled nitric oxide (FeNO) level at the first patient visit were identified by multivariate logistic regression as possible predictors of the discontinuation of clinic visits and achievement of full asthma control, respectively. Low FeNO levels at the first clinic visit yielded a receiver operating characteristic-area under the curve of 0.860 (95% confidence interval [CI]=0.774-0.975) for the achievement of full asthma control. Using an FeNO cut-off level of 34 parts per billion yielded a sensitivity of 76.5% (95% CI=59.5-88.2%) and specificity of 73.7% (95% CI=58.5-84.2%).

CONCLUSION

Our preliminary results suggested that patients with newly diagnosed mild BA who display higher FeNO levels at their first clinic visits should be appropriately educated during early visits to receive optimal treatment and complete regular clinic visits.

Biomarker-based detection of asthma-COPD overlap syndrome in COPD populations

Asthma-chronic obstructive pulmonary disease (COPD) overlap syndrome (ACOS) was proposed by the science committees of both Global Initiative for Asthma (GINA) and Global Initiative for Chronic Obstructive Lung Disease (GOLD). However, the definition of ACOS has remained unclear all over the world, and the prevalence rate of ACOS is basically dependent on the patient's symptoms or the physician's opinion, based on questionnaire testing. In the current case report, we investigated the prevalence rate of COPD patients with high levels of fractional exhaled nitric oxide (FENO) or immunoglobulin E (IgE) as candidate markers of ACOS in COPD, as a multicenter, cross-sectional study. Outpatients with COPD were enrolled from Tohoku University Hospital, Sendai, Japan, and five hospitals (Tohoku University Hospital, Sendai, Japan; NTT East Tohoku Hospital, Sendai, Japan; Wakayama Medical University Hospital, Kimiidera, Japan; Hiraka General Hospital, Yokote, Japan; Iwate Prefectural Isawa Hospital, Oshu, Japan) with pulmonary physicians from March 1, 2013 to February 28, 2014. When they were estimated using 35 ppb as the cutoff value of FENO, the prevalence rate of ACOS was 16.3% in COPD. When estimated by both FENO and IgE, the high-FENO/high-IgE group was 7.8% in COPD. To the best of our knowledge, this study is the first to detect the prevalence rate of ACOS in COPD populations by using objective biomarkers. The results from the current study should be useful to identify the subgroup requiring early intervention by inhaled corticosteroids/long-acting beta agonist combination in COPD in order to improve the long-term management for ACOS.

Fraction of exhaled nitric oxide in healthy elderly Tunisian subjects

INTRODUCTION

Exhaled-fraction-of-nitric-oxide (Fe_NO) norms are absent in healthy elderly North-African subjects.

OBJECTIVES

i) to identify Fe_NO influencing factors of elderly Tunisians older 50 years and more; ii) to assess the applicability of some published Fe_NO norms for elderly in local population; iii) to set-up Fe_NO norms and to prospectively evaluate their validity in two elderly validation-groups (healthy and asthmatic subjects).

METHODS

A convenience sample of healthy and asthmatic elderly Tunisians was recruited. Subjects responded to a medical questionnaire and then Fe_NO levels were measured by an online method (Medisoft, Sorinnes (Dinant), Belgium). Clinical, anthropometric and spirometric data were collected. Three groups of subjects were identified: group I (healthy-elderly; n = 100, 57 females); group II (healthy-validation; n = 17, 4 females) and group III (asthmatic-validation; n = 10, 9 females). ANOVA was performed to compare the three groups' data.

RESULTS

No significant factor, among those evaluated, influenced Tunisian elderly Fe_NO values. The available published Fe_NO norms did not reliably predict Fe_NO in Tunisian elderly population. The mean ± SD (minimum-maximum) of Fe_NO (ppb) for group I was 14 ± 6 (3-34). For Tunisian people, each elderly Fe_NO value higher than 34 ppb will be considered as abnormal. There was no statistical significant difference between Fe_NO (ppb) mean values of group I and groups II (15 ± 8) or III (18 ± 13). No subject of group II had a Fe_NO value higher than 34 ppb. Thirty percent of group III subjects had a Fe_NO value higher than 34 ppb.

CONCLUSION

In practice, Fe_NO value of more than 34 ppb is considered abnormal in elderly Tunisian population.

Fractional exhaled nitric oxide (FeNO) among office workers in an academic institution, Malaysia--associations with asthma, allergies and office environment

OBJECTIVE

There are few studies on fractional exhaled nitric oxide (FeNO) and respiratory symptoms among adults in tropical areas. The aim was to study associations between FeNO and selected personal factors, respiratory symptoms, allergies, office characteristics and indoor office exposures among office workers (n = 460) from a university in Malaysia.

METHODS

Information on health was collected by a questionnaire, skin prick test and FeNO measurement. Temperature, relative air humidity, carbon monoxide and carbon dioxide were measured in the offices. Settled dust was vacuumed in the offices and analyzed for endotoxin, (1,3)-β-glucan and house dust mites allergens, namely Dermatophagoides pteronyssinus (Der p 1) and Dermatophagoides farinae (Der f 1). Two-level linear mixed models and multiple logistic regression were used to analyze the associations.

RESULTS

One-fourth (25.9%) of the office workers had elevated FeNO level (≥ 25 ppb) and 61.5% had HDM, cat, seafood or pollen allergy. Male gender (p < 0.001), current smoking (p = 0.037), height (p < 0.001) and atopy (p < 0.001) were associated with FeNO. The amount of vacuumed dust was associated with FeNO among atopic subjects (p = 0.009). Asthma and rhinitis symptoms were associated with FeNO (p < 0.05), especially among atopic subjects. In particular, a combination of atopy and elevated FeNO were associated with doctor-diagnosed asthma (p < 0.001), rhinitis (p < 0.001) and airway symptoms last 12 months (p < 0.001).

CONCLUSION

Gender, smoking, height and atopy are important risk factors for elevated FeNO levels. A combination of allergy testing and FeNO measurement could be useful in respiratory illness epidemiology studies and patient investigations in tropical areas.

Effect of a smoking ban on respiratory health in nonsmoking hospitality workers: a prospective cohort study

OBJECTIVE

The aim of this study was to examine the effect of a smoking ban on lung function, fractional exhaled nitric oxide, and respiratory symptoms in nonsmoking hospitality workers.

METHODS

Secondhand smoke exposure at the workplace, spirometry, and fractional exhaled nitric oxide were measured in 92 nonsmoking hospitality workers before as well as twice after a smoking ban.

RESULTS

At baseline, secondhand smoke-exposed hospitality workers had lung function values significantly below the population average. After the smoking ban, the covariate-adjusted odds ratio for cough was 0.59 (95% confidence interval, 0.36 to 0.93) and for chronic bronchitis 0.75 (95% confidence interval, 0.55 to 1.02) compared with the preban period.

CONCLUSIONS

The below-average lung function before the smoking ban indicates chronic damages from long-term exposure. Respiratory symptoms such as cough decreased within 12 months after the ban.

Progression of Irreversible Airflow Limitation in Asthma: Correlation with Severe Exacerbations

BACKGROUND

Severe exacerbations of asthma are periods of excess functional and pathological changes in the airways that have been proposed to induce airway remodeling.

OBJECTIVE

The objective of this study was to explore whether severe exacerbations are correlated with the decline in post-bronchodilator forced expiratory volume in 1 second (FEV1) and loss of bronchodilator reversibility (BDR).

METHODS

We examined the changes in FEV1 and BDR in 140 nonsmoking patients with well-controlled asthma at baseline and correlated these changes with the frequency of severe asthma exacerbations.

RESULTS

A 3-year follow-up assessment was completed in 128 patients. A total of 28 (21.9%) patients experienced at least 1 severe exacerbation with a mean rate of 0.16 year(-1). The exacerbation rate was significantly correlated with an annual rate of decline in FEV1 (ρ = 0.49, P < .0001). Both patients with 1 exacerbation and those with 2 or more exacerbations had greater declines in FEV1 than patients with no exacerbations (no exacerbation, 13.6 mL/year; 1 exacerbation, 41.3 mL/year; 2 or more exacerbations, 58.3 mL/year; P < .01 and P < .0001, respectively). The changes in BDR from baseline to the end of the study in patients who did or did not experience an exacerbation were -1.2% and 0.1%, respectively (P < .0005). The changes in BDR were significantly correlated with the annual rates of change in FEV1 (r = 0.40, P < .0001).

CONCLUSION

The occurrence of severe exacerbations of asthma is correlated with the progression of irreversible airflow limitation over time. This suggests that asthma exacerbations could have the long-term adverse consequences of structural and functional changes in the airways.

Japanese Guideline for Adult Asthma 2014

Adult bronchial asthma (hereinafter, asthma) is characterized by chronic airway inflammation, reversible airway narrowing, and airway hyperresponsiveness. Long-standing asthma induces airway remodeling to cause intractable asthma. The number of patients with asthma has increased, and that of patients who die from asthma has decreased (1.5 per 100,000 patients in 2012). The aim of asthma treatment is to enable patients with asthma to lead a normal life without any symptoms. A good relationship between physicians and patients is indispensable for appropriate treatment. Long-term management with antiasthmatic agents and elimination of the causes and risk factors of asthma are fundamental to its treatment. Four steps in pharmacotherapy differentiate between mild and intensive treatments; each step includes an appropriate daily dose of an inhaled corticosteroid, varying from low to high. Long-acting 02-agonists, leukotriene receptor antagonists, and sustained-release theophylline are recommended as concomitant drugs, while anti-immunoglobulin E antibody therapy has been recently developed for the most severe and persistent asthma involving allergic reactions. Inhaled 02-agonists, aminophylline, corticosteroids, adrenaline, oxygen therapy, and others are used as needed in acute exacerbations by choosing treatment steps for asthma exacerbations depending on the severity of attacks. Allergic rhinitis, chronic obstructive pulmonary disease, aspirin-induced asthma, pregnancy, asthma in athletes, and coughvariant asthma are also important issues that need to be considered.

Fractional exhaled nitric oxide in healthy Tibetans at high altitude

Background

Fractional exhaled NO (FENO) is a marker of airway inflammation. For successful use of this marker it is important to have reference ranges from different healthy populations. The aim of this study was to establish these in healthy Tibetan adults who had always lived at high altitude on the Qinghai-Tibet Plateau.

Materia/Methods

The study included 145 healthy Tibetan subjects, aged 18 to 75 years, who were non-smokers. FENO was measured at a flow rate of 50 mL/s using a chemiluminescence analyzer. Residential altitude was classified as: Grade 1 (3678–3800 m), Grade 2 (3800–4200 m), or Grade 3 (>4200 m). Correlations between subject characteristics (age, sex, height, and weight), altitude, and FENO were investigated.

Results

The geometric mean FENO (95% CI) was 15.4 (7.0, 35.0) parts per billion (ppb). The 95% upper limit of the log-transformed data was 33.0 ppb, which was slightly lower than that for Han Chinese, and much lower than in the Northwest Han population. Mean FENO values were higher in males (16.8 ppb) than females (14.3 ppb) and inversely related to altitude. Multiple linear regression analysis showed that FENO was predicted by the equation Ln (FENO)=[2.844+0.161 × sex (1 for male; 0 for female) −0.111 × altitude grade]. The residual standard deviation (SD) was 0.048, and the explanatory value was 7%.

Conclusions

The upper limit of FENO in healthy Tibetan adults is 33 ppb. This value can be predicted on the basis of sex and altitude.

Fraction of exhaled nitric oxide (FeNO ) norms in healthy Tunisian adults

Aims. To establish Fe_NO norms for healthy Tunisian adults aged 18–60 years and to prospectively assess their reliability. Methods. This was a cross-sectional analytical study. A convenience sample of healthy Tunisian adults was recruited. Subjects responded to a medical questionnaire, and then Fe_NO levels were measured by an online method (Medisoft, Sorinnes (Dinant), Belgium). Clinical, anthropometric, and plethysmographic data were collected. All analyses were performed on natural logarithm values of Fe_NO. Results. 257 adults (145 males) were retained. The proposed reference equation to predict Fe_NO value is lnFe_NO (ppb) = 3.47−0.56× height (m). After the predicted Fe_NO value for a given adult was computed, the upper limit of normal could be obtained by adding 0.60 ppb. The mean ± SD (minimum-maximum) of Fe_NO (ppb) for the total sample was 13.54 ± 4.87 (5.00–26.00). For Tunisian and Arab adults of any age and height, any Fe_NO value greater than 26.00 ppb may be considered abnormal. Finally, in an additional group of adults prospectively assessed, we found no adult with a Fe_NO higher than 26.00 ppb. Conclusion. The present Fe_NO norms enrich the global repository of Fe_NO norms that the clinician can use to choose the most appropriate norms.

Changes in forced expiratory volume in 1 second over time in patients with controlled asthma at baseline

BACKGROUND

A predominant feature of asthma is an accelerated rate of decline in forced expiratory volume in 1 s (FEV1), but data on the variability and factors associated with this change in patients with controlled asthma are largely unknown.

METHODS

140 patients with controlled asthma were enrolled based on the Global Initiative for Asthma guidelines. We examined the data of a prospective analysis of the association between asthma control and change in FEV1 over time.

RESULTS

A 3-year follow-up assessment was completed in 128 patients. The mean rate of change in FEV1 was a decline of 22.2 mL yr(-1), with significant variation in the levels of change. The between patient standard deviation for the rate of decline was 34.1 mL yr(-1). We next classified the subjects of less than the 25th percentile as rapid decliners, and greater than the 25th percentile as non-rapid decliners. The decrease in the Asthma Control Test score over a 3-year period was higher for rapid decliners than that for non-rapid decliners (p < 0.001). The rapid decliner was more likely to be older, to have higher levels of FeNO, and to have had severe exacerbations during the study. Patients with severe exacerbations had a greater annual decline in FEV1 compared to patients with no exacerbations (-13.6 vs. -53.2 mL yr(-1), p < 0.0001).

CONCLUSIONS

Among patients with controlled asthma at baseline, the rate of change in FEV1 is highly variable. Severe exacerbations are strongly associated with a rapid loss of lung function.

Ongoing allergic rhinitis impairs asthma control by enhancing the lower airway inflammation

BACKGROUND

The relationship between allergic rhinitis and asthma is well accepted; however, little is known about the mechanism that underlies the interactions between the upper and lower airways.

OBJECTIVE

To investigate the symptomatic and inflammatory linkages between allergic rhinitis and asthma in patients with atopy.

METHODS

We enrolled 520 patients with asthma who were taking inhaled corticosteroids, and examined them by using the Asthma Control Questionnaire, spirometry, exhaled nitric oxide fraction (FENO), visual analog scale for nasal symptoms, allergic rhinitis questionnaire, and serum specific IgE (study 1). The symptomatic and inflammatory marker responses to nasal corticosteroids in patients with incompletely controlled asthma (Asthma Control Questionnaire > 0.75) and moderate-to-severe persistent allergic rhinitis were also observed (study 2).

RESULTS

A total of 348 patients (66.9%) had atopy and allergic rhinitis. There was a striking difference in the proportion of patients with incomplete asthma control, depending on the presence as well as the activity of rhinitis (no rhinitis, 11.0%; mild intermittent, 20.4%; moderate-to-severe intermittent, 44.6%; mild persistent, 53.1%; moderate-to-severe persistent, 65.7%). The FENO levels were increased with the activity of rhinitis, and the nasal visual analog scale was positively correlated with the FENO levels (r = 0.31; P < .0001). The additive treatment with nasal corticosteroids improved the nasal visual analog scale, Asthma Control Questionnaire, and FENO levels, and the changes in these variables were correlated with each other in all parameters (all P < .001).

CONCLUSION

This observational study of patients with atopy indicates that the ongoing allergic rhinitis is related to worsening of asthma by enhancing the lower airway inflammation.

Stratifying a risk for an increased variation of airway caliber among the clinically stable asthma

BACKGROUND

Recently, correlations of peak expiratory flow (PEF) variation have been shown to facilitate the prediction of later asthma symptoms and exacerbations. However, it has not been fully examined whether or not any patient characteristics are associated with the residual airway lability in treated asthmatics. The objective of this study is to examine a predictive marker for increased variation of PEF in patients with clinically stable asthma.

METHODS

We studied 297 asthmatic patients who were monitored for PEF twice a day. Asthma Control Questionnaire (ACQ), spirometry, and exhaled nitric oxide fraction (FENO) were measured. After the assessment of baseline values, PEF measuring was continued and associations between these clinical markers and later variation of PEF over a week (Min%Max) were investigated.

RESULTS

17.5% of the subjects showed increased PEF variability (Min%Max < 80%). ACQ, forced expiratory volume in 1 s % of predicted (%FEV1), and FENO were identified as independent predictors of Min%Max < 80%. An ACQ ≥ 0.4 yielded 96% sensitivity and 59% specificity, a %FEV1 ≤ 85% yielded 62% sensitivity and 89% specificity, and a FENO ≥ 40 ppb yielded 75% sensitivity and 90% specificity for identifying the subjects with high variability in PEF. When we combine %FEV1 ≤ 85% and FENO ≥ 40 ppb, this index showed the highest specificity (98%) for increased PEF variability.

CONCLUSIONS

These results indicate that ACQ, %FEV1 and FENO can stratify the risk for increased variation in airway caliber among patients with stable asthma. This may help identify subjects in whom further monitoring of lung function fluctuations is indicated.

Predictors for identifying the efficacy of systemic steroids on sustained exhaled nitric oxide elevation in severe asthma

BACKGROUND

Some patients with asthma have high levels of exhaled nitric oxide fraction (FENO) despite inhaled corticosteroids (ICS) therapy. Early studies suggested that this might be explained by the presence of heterogeneous airway inflammation. We aimed to assess the predictors for identifying the efficacy of systemic corticosteroids on residual FENO elevations in severe asthma.

METHODS

Twenty severe asthmatics with persistent FENO elevation (≥40ppb) despite maintenance therapy including high-daily-dose ICS were enrolled. Asthma Control Questionnaire (ACQ), lung function, blood eosinophils, and FENO were assessed before and after 14 days treatment with 0.5mg/kg oral prednisolone/day.

RESULTS

ACQ, blood eosinophils, FENO level, FVC, FEV1, FEV1/FVC ratio and the slope of the single nitrogen washout curve (ΔN2) were significantly improved by treatment with prednisolone. 70% of the subjects showed ≥20% reductions in the FENO levels. The reduction in FENO levels was significantly correlated with the improvements in ACQ (p < 0.0001), FVC (p < 0.01), FEV1 (p < 0.0001), and ΔN2 (p < 0.05). Among the measurements at baseline, the FENO levels and blood eosinophil numbers were identified as significant predictors of ≥20% reductions in the FENO levels by systemic steroid therapy.

CONCLUSIONS

Systemic corticosteroids could suppress the residual FENO elevations in more than half of the patients with severe asthma and the reduction in FENO levels was associated with improvements in asthma control and airflow limitation. The FENO levels and blood eosinophil numbers were the predictors of improved residual airway inflammation by systemic steroid therapy in severe asthma.

Normal values and thresholds for the clinical interpretation of exhaled nitric oxide levels in the US general population: results from the National Health and Nutrition Examination Survey 2007-2010

BACKGROUND

Elevated fractional excretion of exhaled nitric oxide (FENO) reflects airway inflammation, but few studies have established its normal values. This study aims to establish the normal values and thresholds for the clinical interpretation of FENO in the US general population.

METHODS

Thirteen thousand two hundred seventy-five subjects aged 6 to 80 years sampled for the National Health and Nutrition Examination Survey (NHANES) 2007-2010 underwent interviews, physical examination, and FENO analysis at 50 mL/s using an online chemiluminescence device according to American Thoracic Society/European Respiratory Society guidelines. After excluding subjects with self-reported asthma and subjects with wheeze in the prior 12 months, prediction equations for the natural logarithm (ln) of FENO were constructed using age, sex, ethnicity, height, BMI, active/passive smoke exposure, and hay fever episodes as covariates.

RESULTS

The fifth to 95th percentile values of FENO were 3.5 to 36.5 parts per billion (ppb) for children < 12 years of age and 3.5 to 39 ppb for subjects 12 to 80 years of age. Using multiple linear regression, prediction equations explained only 10.3% to 15.7% of the variation in the general population. In the general population, 39% to 45% had ln(FENO) levels > 2 SD of the predicted means. When applied to the general population inclusive of subjects who reported asthma but who did not have attacks within the past year, nearly identical results were obtained.

CONCLUSIONS

Assuming 95% of the healthy US general population had no clinically significant airway inflammation as assessed by FENO, values exceeding the 95th percentiles indicated abnormality and a high risk of airway inflammation. A large variation of normal FENO values existed in the general population, which was poorly predicted by multiple linear regression models.

Persistent elevation of exhaled nitric oxide and modification of corticosteroid therapy in asthma

BACKGROUND

Persistent airway inflammation, detected by fractional exhaled nitric oxide (FENO), is occasionally observed in asthmatic patients, even in those treated with inhaled corticosteroids (ICS). However, improvement in residual airway inflammation and pulmonary function through modification of corticosteroid therapy has not been proven.

METHODS

Thirteen asthmatic patients whose FENO levels were over 40 parts per billion (ppb), despite dry-powder ICS therapy, were enrolled. A 3-step change in steroid treatment was undertaken until FENO was less than 40ppb. In the first step, the powder formula was changed to an ultra-fine particle compound as an equipotent ICS dose. In the second step, the ICS dose was doubled. In the third step, oral corticosteroids were added. We measured pulmonary function and FENO and alveolar NO concentrations (CAlvNO).

RESULTS

Doubling the ICS dose and changing the ICS formula significantly improved FVC (p<0.001), FEV1 (p<0.05), the slope of the single nitrogen washout curve (dN2) (p<0.01), FENO (p<0.001), and CAlvNO (p<0.05), relative to baseline. The reductions in FENO were significantly associated with the improvement in airflow limitation assessed by dN2 (r=0.73, p=0.007). The remaining FENO elevation, even after doubling the ICS dose, did not decrease after oral corticosteroid administration.

CONCLUSIONS

These results suggest that modification of ICS therapy can suppress residual FENO elevation, and that reduction in FENO levels is associated with improvement in airflow limitation. However, steroid-resistance mechanisms may exist in some asthmatic patients with sustained FENO elevations.

Gender and age affect the levels of exhaled nitric oxide in healthy children

Asthma is a chronic inflammatory disorder of the lung and diagnosis is difficult in children. The measurement of fractional exhaled nitric oxide (FeNO) may be useful in the diagnosis and monitoring of treatments. A number of factors affect FeNO levels and their influence varies across countries and regions. This study included 300 healthy students, aged from 6 to 14 years, who participated voluntarily. A comprehensive medical survey was used and measurements of FeNO levels and spirometric parameters were recorded in Shenyang, China. We observed that the median FeNO was 11 ppb (range, 8–16 ppb) in children from the northern areas of China. For males, the median level was 13 ppb (range, 9–18 ppb) and the median level was 10 ppb (range, 8–14 ppb) for females. There was a significant difference between males and females (P= 0.007) and age was correlated with FeNO (R²= 0.6554), while weight, height, body mass index (BMI), forced vital capacity (FVC), forced expiratory volume (FEV1), FEV1/FVC and peak expiratory flow (PEF) had no correlation with FeNO. In conclusion, the median FeNO is 11 ppb (range, 8–16 ppb) in male and female healthy children from northern areas of China and is affected by gender and age.

Difference in time-course of improvement in asthma control measures between budesonide and budesonide/formoterol

Combinations of inhaled corticosteroids (ICS) and inhaled long-acting beta(2)-agonists (LABA) have become widely used for the initiation of maintenance treatment for asthma. However, it has not been fully elucidated whether ICS/LABA alters the time-course of different control outcome measures in steroid-naive patients with asthma compared to the treatment with ICS alone. We compared the time-response in Asthma Control Questionnaire (ACQ), forced expiratory volume in 1 s (FEV1), exhaled nitric oxide fraction (FE(NO)), and airway responsiveness to methacholine (PD(200)) between budesonide (BUD) and budesonide/formoterol (BUD/FM). BUD/FM therapy significantly improved the ACQ score at week 2 and week 4 (p < 0.01 and p < 0.05), and increased FEV1 and the methacholine threshold at week 8 and week 24 (all p < 0.05) compared to BUD alone. A logistic function model showed that the BUD/FM combination significantly improved ACQ, FEV1, FE(NO) and PD(200) at a faster rate than BUD over 24 weeks (p < 0.001 for ACQ, FEV1, PD(200), and p < 0.05 for FE(NO), z-test). A significant variance in the time-response was also found in the outcomes of the two treatment groups (FE(NO) and ACQ > FEV1 and PD(200), p < 0.001, z-test). The present study provides evidence that ICS/LABA combination therapy results in a more rapid improvement in asthma symptoms, lung function, and airway inflammation compared to ICS monotherapy in steroid-naive patients with asthma.

Associated demographics of persistent exhaled nitric oxide elevation in treated asthmatics

BACKGROUND

The fraction of exhaled nitric oxide (FENO) is reduced by anti-inflammatory treatment in asthma. However, the FENO level is also regulated by individual demographics and there is considerable variation among clinically stable patients.

OBJECTIVE

We hypothesized that some demographics may be responsible for persistent FENO elevation despite inhaled corticosteroids (ICS) therapy in asthma.

METHODS

This was a prospective observational study. We initially screened 250 stable asthmatics and determined the FENO cut-off point for identifying poorly controlled asthma defined by one of the following criteria: Asthma control test <20, or forced expiratory volume in one-second % of predicted <80%, or peak expiratory flow variability <80% (Study 1). After 12-weeks, 229 patients who maintained high or low FENO were selected and the independent factors which might contribute to a high FENO were examined (Study 2).

RESULTS

A FENO level >39.5 p.p.b. yielded 67% sensitivity and 76% specificity for identifying the patients with poorly controlled asthma. The persistent high FENO group (≥ 40 p.p.b.) was more likely to be ex-smokers, to show evidence of atopy (positive specific IgE, higher serum IgE and blood eosinophils), and to have allergic comorbidities. Especially, past smoking history, blood eosinophils, and chronic rhinosinusitis were identified to be independent predictors of high FENO. Neither the dose of ICS nor other medication use showed any difference between the groups.

CONCLUSIONS AND CLINICAL RELEVANCE

These results suggested that past smoking history, blood eosinophilia, and chronic rhinosinusitis are involved in the persistent airway inflammation detected by FENO. Although their relative contributions on FENO values should be further quantified, clarification of the features of the subjects with high FENO might provide clues for adjustment of the treatment approach in asthma.

Prevalence of asthma symptoms based on the European Community Respiratory Health Survey questionnaire and FENO in university students: gender differences in symptoms and FENO

BACKGROUND

The fractional concentration of nitric oxide in exhaled air (FENO) is used as a biomarker of eosinophilic airway inflammation. FENO is increased in patients with asthma. The relationship between subjective asthma symptoms and airway inflammation is an important issue. We expected that the subjective asthma symptoms in women might be different from those in men. Therefore, we investigated the gender differences of asthma symptoms and FENO in a survey of asthma prevalence in university students.

METHODS

The information about asthma symptoms was obtained from answers to the European Community Respiratory Health Survey (ECRHS) questionnaire, and FENO was measured by an offline method in 640 students who were informed of this study and consented to participate.

RESULTS

The prevalence of asthma symptoms on the basis of data obtained from 584 students (266 men and 318 women), ranging in age from 18 to 24 years, was analyzed. Wheeze, chest tightness, an attack of shortness of breath, or an attack of cough within the last year was observed in 13.2% of 584 students. When 38.0 ppb was used as the cut-off value of FENO to make the diagnosis of asthma, the sensitivity was 86.8% and the specificity was 74.0%. FENO was ≥ 38.0 ppb in 32.7% of students. FENO was higher in men than in women. The prevalence of asthma symptoms estimated by considering FENO was 7.2%; the prevalence was greater in men (9.4%) than women (5.3%). A FENO ≥ 38.0 ppb was common in students who reported wheeze, but not in students, especially women, who reported cough attacks.

CONCLUSIONS

The prevalence of asthma symptoms in university students age 18 to 24 years in Japan was estimated to be 7.2% on the basis of FENO levels as well as subjective symptoms. Gender differences were observed in both FENO levels and asthma symptoms reflecting the presence of eosinophilic airway inflammation.

TRIAL REGISTRATION NUMBER

UMIN000003244.

Exhaled nitric oxide cutoff values for asthma diagnosis according to rhinitis and smoking status in Japanese subjects

BACKGROUND

Measurement of the exhaled nitric oxide fraction (FE(NO)) has been proposed as a useful diagnostic test for asthma. However, most of the data concerning the FE(NO) cutoff values for the diagnosis of asthma have not yet examined using standard procedures. Furthermore, there is no detailed study that investigated the cutoff values that takes into account patient factors that influence the FE(NO) levels.

METHODS

FE(NO) was measured in 142 steroid-naive asthmatics and 224 control subjects using an online electrochemical nitric oxide analyzer in accordance with the current guidelines. Subjects without respiratory symptoms and normal spirometric parameters were included in the control group. Asthma was diagnosed on the basis of the presence of significant airway reversibility and/or airway hyperresponsiveness during clinical follow up 6 months after FE(NO) measurements.

RESULTS

FE(NO) was significantly higher in asthmatic patients compared with control subjects (p < 0.01). Based on all study subjects, the receiver operating characteristic curves indicated that the cutoff value of FE(NO) 22 parts per billion (ppb) was associated with the highest combination of sensitivity (90.8%) and specificity (83.9%). Multivariate analysis showed allergic rhinitis, current smoking, and asthma were significant factors influencing the FE(NO) levels. The cutoff values of FE(NO) to discriminate asthma from non-asthma ranged from 18 to 28 ppb depending on rhinitis and smoking status.

CONCLUSIONS

The cutoff values presented may be useful for the interpretation of FE(NO) values in the clinical practice.

Improvement of Airflow Limitation by Fluticasone Propionate/Salmeterol in Chronic Obstructive Pulmonary Disease: What is the Specific Marker?

Backgrounds: Inhaled corticosteroids (ICS)/inhaled long-acting beta₂-agonists (LABA) combination drugs are widely used for the long-term management of chronic obstructive pulmonary disease (COPD). However, COPD is a heterogeneous condition and treatment with ICS is associated with a higher risk of pneumonia. The identification of a specific marker for predicting the efficacy of ICS/LABA on pulmonary function would be useful in the treatment of COPD. Methods: Fourteen COPD patients receiving tiotropium therapy participated consecutively. The relationship between the baseline exhaled nitric oxide (FE_NO) levels as well as serum markers and changes in pulmonary function by fluticasone propionate (FP)/salmeterol (SAL) were analyzed. Results: FP/SAL therapy significantly improved forced vital capacity, forced expiratory volume in 1 s (FEV₁), and the third phase slope of the single nitrogen washout curve (ΔN₂) as well as the FE_NO level. The baseline FE_NO levels and positive specific IgE (atopy+) were significantly associated with airway obstructive changes assessed by FEV₁ and ΔN₂. A baseline FE_NO level >35 ppb yielded 80.0% sensitivity and 66.7% specificity for identifying the subjects with significant improvement in FEV₁ (greater than 200 mL). An atopy+ yielded 60.0% sensitivity and 88.9% specificity for an improvement in FEV₁. When combined with FE_NO > 35 ppb and atopy+, it showed 40% sensitivity and 100.0% specificity for FEV₁ improvement. Alternatively, COPD subjects with FE_NO ≤ 35 ppb and atopy− did not show significant improvement in FEV₁. Conclusion: Combining FE_NO and specific IgE may be a useful marker for predicting the response to ICS/LABA on airflow limitation in COPD.