Office-based exhaled nitric oxide measurement in children 4 years of age and older

Fractional Exhaled Nitric Oxide for the Diagnosis of Childhood Asthma: a Systematic Review and Meta-analysis

The gold standard for diagnosing asthma in children is based on clinical history of respiratory symptoms, physical examination, and respiratory function testing. Recent advances indicate that a non-invasive measure of airway inflammation, fractional exhaled nitric oxide (FeNO), provides objective data for use in asthma diagnosis. However, the diagnostic performance of FeNO in children with asthma has not been clearly defined. This systematic review and meta-analysis aimed to evaluate the diagnostic accuracy of FeNO in the clinical determination of asthma in children. Databases of PubMed, the Cochrane Library, EMBASE, MEDION, and Web of Science were searched for relevant articles through March 31, 2016. A bivariate model was used for pooling estimates of sensitivity, specificity, diagnostic odds ratio (DOR), and area under the summary receiver operating curves (SROC) as the main diagnostic measures. In total, eight studies met the inclusion criteria, which included 2933 subjects. The pooled estimates of sensitivity, specificity, and DOR for the detection of asthma in children were 0.79 [95 % confidence interval (CI), 0.64-0.89], 0.81 (95 % CI, 0.66-0.90), and 16.52 (95 % CI, 7.64-35.71). The SROC was 0.87 (95 % CI, 0.84-0.90). In brief, FeNO achieves a moderate diagnostic performance in the detection of asthma in children.

[Correlation of fractional exhaled nitric oxide in the upper and lower airways with the level of asthma control]

OBJECTIVE

To study the clinical value of combined measurement of fractional exhaled nitric oxide (FeNO) and nasal fractional exhaled nitric oxide (FnNO) and its correlation with the level of asthma control.

METHODS

A total of 120 children who were diagnosed with asthma from January to June, 2018 and were in the chronic persistent stage were enrolled as subjects. The childhood asthma control test (C-ACT) was performed for all the 120 children. According to the C-ACT score, these children were divided into 4 groups: complete control group with a C-ACT score of >23, partial control group with a C-ACT score of 20-23, and uncontrolled group with a C-ACT score of ≤19 (n=40 each). According to the presence or absence of allergic rhinitis, they were divided into 2 groups: non-rhinitis group with 55 children and rhinitis group with 65 children. A total of 40 children who underwent physical examination during the same period of time were enrolled as the control group. FeNO and FnNO levels were measured for all the 120 children.

RESULTS

The uncontrolled group had the highest level of FeNO, followed by the partial control group and the complete control group (P<0.05). The uncontrolled and partial control groups had a significantly higher level of FeNO than the control group (P<0.05). The uncontrolled and partial control groups had a significantly higher level of FnNO than the complete control and control groups (P<0.05). The rhinitis group had significantly higher FeNO and FnNO levels than the non-rhinitis group (P<0.05).

CONCLUSIONS

FeNO can be used to assess the level of asthma control in children, and its combination with FnNO may be useful for the evaluation of the degree of inflammation in the upper and lower airways and provide a basis for the combined treatment of the upper and lower airways.

An independent relation of atopic dermatitis to exercise-induced wheezing in asthmatic children

BACKGROUND

Atopic dermatitis (AD) and exercise-induced asthma (EIA) are common in asthmatic children, and exercise is the most common trigger other than infection for acute onset asthma attack in children. We examined whether AD is related to exercise-induced wheezing (EIW), some proxy for EIA.

METHODS

Japanese version of the International Study of Asthma and Allergies in Childhood questionnaires were used. For 12,405 asthmatic school children, AD was defined as itchy rash coming and going for at least 6 months at any time in the last 12 months with affecting places of flexural parts of body, and severity of AD was rated according to frequency of being kept awake at night with the itch as follows: never in the past 12 months, less than one night per week and one or more nights per week.

RESULTS

Adjusted for frequency of asthma attack, odds ratios (OR) of children with current AD as compared to those without AD for having EIW were 1.32 (95% confidence interval = 1.15-1.52), 1.35 (1.14-1.68) and 1.10 (0.92-1.31) for primary school, junior high school and high school children, respectively. EIW was more likely observed in accordance with increasing severity of AD in the primary school children with ORs of 1.12, 1.59 and 1.54 (p for trend < 0.01), and in the junior high school ones with ORs of 1.18, 1.31, 2.03 (<0.01), respectively.

CONCLUSIONS

AD may be possibly related to EIW. Further studies investigating effect of AD treatment on EIW may be required.

Measurement of FeNO with a portable, electrochemical analyzer using a 6-second exhalation time in 7-10-year-old children with asthma: comparison to a 10-second exhalation

Objective: Fractional exhaled nitric oxide (FeNO) is a valuable tool for assessing Th2 inflammation in children with asthma. Exhalation times of 6 and 10 s meet the current recommendations for assessing FeNO. The 6-s exhalation provides an alternative for 7-10 year olds not able to complete the 10-s exhalation. Methods: We performed a sub-analysis on data from 7-10-year-old children who participated in a previous study which evaluated the agreement of the 6 and 10-s exhalation times in 6-10 year olds with asthma. Agreement between observed FeNO results obtained by both modes was assessed by weighted Deming regression analysis and Bland-Altman plots. Repeatability was also assessed. Results: Repeatability and agreement of the 6 and 10-s exhalations was demonstrated in 7-10 year olds with two measurements in each mode. Mean observed FeNO measurements were 33.59 ppb (SD = 25.804) for 6 s and 32.46 ppb (SD = 25.302) for 10-s exhalation. Paired differences were centered close to 0 ppb (median = 0.50). Conclusions: Children aged 7-10 years can successfully perform FeNO measurements using a portable, electrochemical FeNO analyzer. Measurements from the 6 and 10-s exhalations were repeatable and consistent with a high degree of agreement between one another. Thus, in young children successful FeNO measurements can be obtained in either the 6-s or 10-s mode, providing physicians valuable information on airway inflammation to aid in the diagnosis and treatment of asthma.

[Clinical significance of fractional exhaled nitric oxide combined with in vitro allergen test in identifying children at a high risk of asthma among those with recurrent wheezing]

OBJECTIVE

To investigate the clinical value of combined determination of in vitro allergens and fractional exhaled nitric oxide (FeNO) in indentifying children at a high risk of asthma among those with recurrent wheezing.

METHODS

A total of 148 children with recurrent wheezing (0.5-6 years old) were enrolled as study subjects, and 80 healthy children who underwent physical examination were enrolled as the control group. Pharmacia UniCAP immunoassay analyzer was used to measure specific immunoglobulin E (sIgE). Nano Coulomb Nitric Oxide Analyzer was used to measure FeNO. The asthma predictive index (API) was evaluated.

RESULTS

The recurrent wheezing group had a significantly higher proportion of children with positive sIgE than the control group [68.9% (102/148) vs 11.3% (9/80); P<0.05]. The recurrent wheezing group also had significantly higher levels and positive rate of FeNO than the control group (P<0.05). The overall positive rate of API in children with wheezing was 32.4%, and the API-positive children had a significantly higher FeNO value than the API-negative children (51±6 ppb vs 13±5 ppb; P<0.05). The detection rate of API was 40.2% (41/102) in positive-sIgE children and 50.1% (38/73) in FeNO-positive children, and there was no significant difference between these two groups. The children with positive sIgE and FeNO had a significantly higher detection rate of API (81.4%) than those with positive sIgE or FeNO (P<0.05).

CONCLUSIONS

Combined determination of FeNO and in vitro allergens is more sensitive in detecting children at a high risk of asthma than FeNO or in vitro allergens determination alone and provides a good method for early identification, diagnosis, and intervention of asthma in children.

[Application of pulmonary function and fractional exhaled nitric oxide tests in the standardized management of bronchial asthma in children]

OBJECTIVE

To investigate the changes of pulmonary function and fractional exhaled nitric oxide (FeNO) in the standardized treatment of bronchial asthma in children.

METHODS

A total of 254 children who were newly diagnosed with acute exacerbation of bronchial asthma were selected as asthma group, and they were divided into two subgroups: asthma with concurrent rhinitis and asthma without concurrent rhinitis. All patients received the standardized management and treatment for one year. The pulmonary function parameters included forced expiratory volume in one second (FEV1), peak expiratory flow (PEF), maximal mid-expiratory flow (MMEF), and mid-expiratory flow at 25%, 50%, and 75% of vital capacity (MEF25, MEF50, and MEF75). The FeNO levels were measured before treatment and at 3, 6, 9, and 12 months after treatment. Another 62 healthy children were selected as the control group, and the pulmonary function and FeNO levels were measured only once.

RESULTS

During one year of standardized treatment, FEV1, PEF, MMEF, MEF25, MEF50, and MEF75 gradually increased, and FeNO levels gradually decreased (P<0.05). Indicators of large airway function, such as FEV1 and PEF, almost returned to normal after 6 months of treatment; indicators of small airway function, such as MMEF, MEF25, MEF50, and MEF75 almost returned to normal after 9 months of treatment; there were no significant differences in the above indices between the asthma group and the control group after one year of treatment (P>0.05). However, the asthma group had a significantly higher FeNO levels than the control group after one year of treatment (P<0.05). The asthmatic patients with concurrent rhinitis had significantly higher FeNO levels than those without concurrent rhinitis before treatment and 3 months after treatment (P<0.05). Before treatment, there was a significant negative correlation between FeNO levels and pulmonary function parameters (P<0.05).

CONCLUSIONS

With the standardized treatment of bronchial asthma in children, pulmonary function parameters gradually increase and FeNO levels gradually decrease. The recovery of large airway function occurs earlier than the recovery of small airway function. Furthermore, the effect of rhinitis on airway responsiveness should be noted.

Clinical Tools to Assess Asthma Control in Children

Asthma affects an estimated 7 million children and causes significant health care and disease burden. The most recent iteration of the National Heart, Lung and Blood Institute asthma guidelines, the Expert Panel Report 3, emphasizes the assessment and monitoring of asthma control in the management of asthma. Asthma control refers to the degree to which the manifestations of asthma are minimized by therapeutic interventions and the goals of therapy are met. Although assessment of asthma severity is used to guide initiation of therapy, monitoring of asthma control helps determine whether therapy should be maintained or adjusted. The nuances of estimation of asthma control include understanding concepts of current impairment and future risk and incorporating their measurement into clinical practice. Impairment is assessed on the basis of frequency and intensity of symptoms, variations in lung function, and limitations of daily activities. "Risk" refers to the likelihood of exacerbations, progressive loss of lung function, or adverse effects from medications. Currently available ambulatory tools to measure asthma control range are subjective measures, such as patient-reported composite asthma control score instruments or objective measures of lung function, airway hyperreactivity, and biomarkers. Because asthma control exhibits short- and long-term variability, health care providers need to be vigilant regarding the fluctuations in the factors that can create discordance between subjective and objective assessment of asthma control. Familiarity with the properties, application, and relative value of these measures will enable health care providers to choose the optimal set of measures that will adhere to national standards of care and ensure delivery of high-quality care customized to their patients.

[Research progress in relationship between fractional exhaled nitric oxide and asthma in children]

Bronchial asthma is a heterogeneous disease that is characterized by airway hyperresponsiveness and chronic inflammation. It is often accompanied by reversible airflow obstruction. Current laboratory testing methods for the diagnosis of asthma in children mainly include lung ventilation function test. Due to the non-cooperation of children, it is very challenging to conduct lung ventilation function test for preschoolers. Lung function testing is an instantaneous indicator, which is influenced by the children's understanding ability and mental factors. In addition, it could not assess the severity of airway inflammation. Fractional exhaled nitric oxide (FeNO) is a noninvasive, simple, and objective indicator of airway inflammation and has gradually gained increased use in children in recent years. This review article introduces the source of FeNO, the reference value of FeNO in laboratory testing, and the progress in the application of FeNO in the diagnosis, prediction, and treatment of asthma in children of various ages.

Measurement of exhaled nitric oxide concentration in asthma: a systematic review and economic evaluation of NIOX MINO, NIOX VERO and NObreath

BACKGROUND

High fractions of exhaled nitric oxide (FeNO) in the breath of patients with symptoms of asthma are correlated with high levels of eosinophils and indicate that a patient is likely to respond to inhaled corticosteroids. This may have a role in the diagnosis and management of asthma.

OBJECTIVE

To assess the diagnostic accuracy, clinical effectiveness and cost-effectiveness of the hand-held electrochemical devices NIOX MINO(®) (Aerocrine, Solna, Sweden), NIOX VERO(®) (Aerocrine) and NObreath(®) (Bedfont Scientific, Maidstone, UK) for the diagnosis and management of asthma.

DATA SOURCES

Systematic searches were carried out between March 2013 and April 2013 from database inception. Databases searched included MEDLINE, EMBASE, the Cochrane Database of Systematic Reviews, the Database of Abstracts of Reviews of Effects, Science Citation Index Expanded and Conference Proceedings Citation Index - Science. Trial registers such as ClinicalTrials.gov and the metaRegister of Controlled Trials were also searched in March 2013. All searches were updated in September 2013.

REVIEW METHODS

A rapid review was conducted to assess the equivalence of hand-held and chemiluminescent FeNO monitors. Systematic reviews of diagnostic accuracy and management efficacy were conducted. A systematic review of economic analyses was also conducted and two de novo health economic models were developed. All three reviews were undertaken according to robust high-quality methodology.

RESULTS

The rapid review (27 studies) found varying levels of agreement between monitors (Bland-Altman 95% limits of agreement up to ±10 parts per billion), with better agreement at lower FeNO values. Correlation was good (generally r > 0.9). The diagnostic accuracy review identified 22 studies in adults (all ages) and four in children. No studies used NObreath or NIOX VERO and seven used NIOX MINO. Estimates of diagnostic accuracy varied widely. FeNO used in combination with another test altered diagnostic accuracy only slightly. High levels of heterogeneity precluded meta-analysis. Limited observations included that FeNO may be more reliable and useful as a rule-in than as a rule-out test; lower cut-off values in children and in smokers may be appropriate; and FeNO may be less reliable in the elderly. The management review identified five randomised controlled trials in adults, one in pregnant asthmatics and seven in children. Despite clinical heterogeneity, exacerbation rates were lower in all studies but not generally statistically significantly so. Effects on inhaled corticosteroid (ICS) use were inconsistent, possibly because of differences in management protocols, differential effectiveness in adults and children and differences in population severity. One UK diagnostic model and one management model were identified. Aerocrine also submitted diagnostic and management models. All had significant limitations including short time horizons and the selective use of efficacy evidence. The de novo diagnostic model suggested that the expected difference in quality-adjusted life-year (QALY) gains between diagnostic options is likely to be very small. Airway hyper-responsiveness by methacholine challenge test is expected to produce the greatest QALY gain but with an expected incremental cost-effectiveness ratio (ICER) compared with FeNO (NObreath) in combination with bronchodilator reversibility of £1.125M per QALY gained. All remaining options are expected to be dominated. The de novo management model indicates that the ICER of guidelines plus FeNO monitoring using NObreath compared with guidelines alone in children is expected to be approximately £45,200 per QALY gained. Within the adult subgroup, FeNO monitoring using NObreath compared with guidelines alone is expected to have an ICER of approximately £2100 per QALY gained. The results are particularly sensitive to assumptions regarding changes in ICS use over time, the number of nurse visits for FeNO monitoring and duration of effect.

CONCLUSIONS

Limitations of the evidence base impose considerable uncertainty on all analyses. Equivalence of devices was assumed but not assured. Evidence for diagnosis is difficult to interpret in the context of inserting FeNO monitoring into a diagnostic pathway. Evidence for management is also inconclusive, but largely consistent with FeNO monitoring resulting in fewer exacerbations, with a small or zero reduction in ICS use in adults and a possible increased ICS use in children or patients with more severe asthma. It is unclear which specific management protocol is likely to be most effective. The economic analysis indicates that FeNO monitoring could have value in diagnostic and management settings. The diagnostic model indicates that FeNO monitoring plus bronchodilator reversibility dominates many other diagnostic tests. FeNO-guided management has the potential to be cost-effective, although this is largely dependent on the duration of effect. The conclusions drawn from both models require strong technical value judgements with respect to several aspects of the decision problem in which little or no empirical evidence exists. There are many potential directions for further work, including investigations into which management protocol is best and long-term follow-up in both diagnosis and management studies.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013004149.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

An Overview of Fractional Exhaled Nitric Oxide and Children with Asthma

Asthma is the most common pediatric chronic disease and is characterized by lung inflammation. Fractional exhaled nitric oxide (FeNO) is thought to reflect the presence of eosinophilic airway inflammation, and is an easy, non-invasive test that has held promise in providing additional objective data. However, not all studies have shown a clinical benefit in the use of FeNO to guide management of asthma in children. This review will describe the results of the most recent studies examining the use of FeNO in the diagnosis and treatment of asthma in infants, preschool-aged children and in school-aged children. It will aid the clinician in providing a clinical context in which FeNO may be most useful in treating pediatric asthma.

Fraction of exhaled nitric oxide in healthy Chilean schoolchildren aged 8-15 years

BACKGROUND

The fraction of exhaled nitric oxide (FENO) measured using portable devices is increasingly used in the clinical setting to assess asthmatic children. However, there is little and variable information on the reference values obtained using these devices in healthy children from different populations.

METHODS

190 healthy non-smoker children (8-15 years old) were randomly selected from public schools participating in this study. The objective was to determine FENO reference values for healthy Chilean schoolchildren. Healthy individuals were identified by medical interview and parent questionnaire on the use of asthma medications, and current and past symptoms of asthma, rhinoconjunctivitis and eczema. FENO was measured at schools using a portable device with electrochemical sensor (NIO MINOX). Reference values of FENO were expressed as geometric mean and upper limit of the 95% reference interval (right-sided). The relationship of FENO with gender, age, height, body mass, and other factors was assessed by multiple regression, and the difference between groups was contrasted by ANOVA.

RESULTS

The FENO geometric mean was 15.4ppb with a 95% reference interval upper limit (right-sided), of 27.4ppb (90%CI 25.6-29.2). The 5th and 95th percentiles were 9.0ppb and 28.0ppb, respectively. Height was the only factor significantly associated to FENO (p=0.022). There was no significant difference in mean FENO regarding age, gender, weight, parent reported rhinoconjunctivitis and eczema.

CONCLUSION

This study suggests that FENO values higher than 27ppb are likely to be abnormal and would reflect airway inflammation in children as those in the present study.

Challenges and limitations of testing efficacy of aerosol device delivery in young children

An increasing number of medical conditions are chronically or acutely managed with some form of aerosolized therapy. Due to the benefit of directly administering medications to the intended site of action, there is great interest in evaluating treatments for aerosol use. One of the major challenges in selecting and testing new drug-device combinations in children is the uncertainty regarding the appropriate outcome measure to choose. In studies involving adult patients, typically exacerbations of disease or airflow obstruction are assessed as endpoints in drug trials or device assessment. However, in young children, choosing endpoints to assess efficacy is difficult due to the potential lack of sensitive, noninvasive endpoints that are easily performed across sites. In this review, we discuss the challenges and limitations of selecting clinical endpoints for drug-device trials in the youngest population, with a focus on novel emerging technologies. This article provides an overview of preschool and infant pulmonary function testing, multiple-breath washout, imaging techniques including computed tomography and magnetic resonance imaging, flexible bronchoscopy in children, mucociliary clearance scans, and exhaled breath condensate.