Atopic disease and exhaled nitric oxide in an unselected population of young adults

Effect of dupilumab on asthma and aeroallergen sensitization in pediatric atopic dermatitis patients: Results of the BioDay registry

BACKGROUND

Atopic dermatitis (AD) is frequently associated with asthma and allergic rhinitis (AR). Dupilumab is an effective treatment for pediatric AD, although the effect on atopic comorbidities in pediatric AD patients is limited.

OBJECTIVE

To investigate the prevalence of asthma and AR in pediatric AD patients starting dupilumab treatment and to evaluate the effect of dupilumab on these comorbidities.

METHODS

This study included pediatric AD patients (aged 3-17 years) treated with dupilumab between 2019 and 2023. Patients were screened at baseline by a pulmonologist for the presence of asthma and AR. Screening included evaluation of medical history and current symptoms, spirometry (including Forced Expiratory Volume in 1 s (FEV1)), Fractional exhaled Nitric Oxide (FeNO), and measurement of aeroallergen-specific IgE levels. In patients diagnosed with comorbid asthma and/or AR, measurements were repeated at weeks 16 and 52. Spirometry measurements, FeNO, and aeroallergen-specific IgE levels during treatment were analyzed using a covariance pattern model.

RESULTS

Eighty-four patients were included. Asthma was diagnosed in 50 patients (59.5%) and AR in 72 patients (85.7%). Baseline FeNO levels were elevated in both patients with (29.0 ppb (95% CI 22.0-54.0)) and without asthma (26.0 ppb (95% CI 22.0-30.0)). During treatment, FeNO levels decreased (p < .001) and FEV1 scores increased (p < .001) in patients with asthma. In patients with asthma and/or AR, all aeroallergen-specific IgE levels decreased between 61.3% and 89.1% at 52 weeks of treatment.

CONCLUSION

One year of dupilumab treatment, primarily indicated for AD, resulted in a significant improvement in comorbid asthma and a profound decrease in aeroallergen-specific IgE levels in patients with asthma and/or AR.

Screening Accuracy of FeNO Measurement for Childhood Asthma in a Community Setting

(1) Background: The exhaled fractional nitric oxide is a well-recognized biomarker used in clinical settings for controlling and managing asthma. Less is known about the value of Fractional Exhaled Nitric Oxide (FeNO) measurement in epidemiological studies on childhood asthma, although available evidence suggests that an increased FeNO is associated with an increased risk of asthma. (2) Aim: The aim of the study was to assess FeNO accuracy in the identification of children with asthma, participants in a population-based respiratory survey. (3) Material and methods: The cross-sectional study included 449 children, 224 (49.9%) boys and 225 (50.1%) girls aged 6−10 years. The FeNO was measured in 449 children; Spirometry tests were completed with 441 children, but technically acceptable spirometry was done in 350. All participants fulfilled the questionnaire (ISAAC) for assessment of the status of their respiratory system on which diagnosis was based on. FeNO and Spirometry were performed according to ERS/ATS recommendations. (4) Results: The FeNO was significantly higher in asthmatic children (n = 22): 27.3 ± 21.3 ppb; with allergic rhinitis (n = 106): 9.9 ± 21.6 ppb, with atopic dermatitis (n = 67) 20.8 ± 25.0 ppb, with an asthmatic tendency (n = 27): 19.8 ± 16.0 ppb in comparison to children without any respiratory/atopy symptoms. The highest diagnostic odds ratio and area under the curve were found in any treated asthma or asthma without any atopic symptoms in relation to FeNO cutoff > 35 ppb; DOR 4.85 and 8.37; AUC 0.615 and 0.795, respectively. The adjustment for spirometry parameters did not improve the diagnostic accuracy of FeNO. In each FeNO cutoff, there were more false positive than true positive subjects. (5) Conclusions. The best diagnostic accuracy of FeNO was for isolated asthma without any atopy against children without any coexisting respiratory or allergic disease. The sensitivity and specificity did not reach the required values for a good screening tool; therefore, it should not be used in epidemiological settings.

The association between serum apolipoprotein B and fractional exhaled nitric oxide in bronchial asthma patients

Background

Asthma and lipid metabolism are associated with systemic inflammation. However, the studies about the relationship between lipid profile, fractional exhaled nitric acid (FeNO) and pulmonary function test (PFT) results are currently lacking.

Methods

We enrolled asthma patients who had serum lipid profiles including apolipoprotein levels from March 1, 2019 to December 31, 2019. We classified the asthma patients into two groups according to the diagnosis method: (I) patients who were diagnosed based on clinical symptoms/signs and PFT results and (II) patients diagnosed with clinical symptoms/signs. Clinical characteristics including age, underlying diseases, smoking status, allergy test results and treatment agents were compared between the two groups. The associations between blood cholesterol levels including apolipoprotein and pulmonary functions were analyzed. Moreover, patients were divided into two groups according to the median value of apolipoprotein B (Apo B), and lung function test results were compared between the patients who had high and low Apo B levels.

Results

Among the 167 patients, 93 (55.7%) were PFT-proven asthma patients. In PFT-proven asthma patients, the levels of total cholesterol (TC) (r =0.37, P=0.03), low-density lipoprotein (LDL) (r =0.46, P=0.01) and Apo B (r =0.38, P=0.02) showed a significant correlation with FeNO, which had no statistical significance in physician-diagnosed asthma group. In multivariate regression analysis, log (FeNO) showed a significant correlation with Apo B (P<0.01) after adjustment for presence of PFT-proven asthma (P=0.01) and current smoking (P=0.01). Patients with high Apo B levels had a lower post-bronchodilator (BD) forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) ratio (69.8 vs. 74.9, P=0.02) and lower post-BD FEV1 (%) (77.5 vs. 85.0, P=0.04) compared with those showing low Apo B levels.

Conclusions

The levels of Apo B and FeNO had positive correlations and high Apo B levels were associated with severe airflow obstruction and low FEV1 (%). Apo B could reflect the uncontrolled status of bronchial asthma and poor lung function.

Contributions of asthma, rhinitis and IgE to exhaled nitric oxide in adolescents

Exhaled nitric oxide fraction (F_eNO) is an indicator of allergic airway inflammation. However, it is unknown how asthma, allergic rhinitis (AR) and allergic sensitisation relate to F_eNO, particularly among adolescents and in overlapping conditions. We sought to determine the associations between asthma, AR, and aeroallergen immunoglobulin (Ig)E and F_eNO in adolescents.

We measured F_eNO among 929 adolescents (aged 11–16 years) in Project Viva, an unselected prebirth cohort in Massachusetts, USA. We defined asthma as ever asthma physician diagnosis plus wheezing in the past year or taking asthma medications in the past month, AR as a physician diagnosis of hay fever or AR, and aeroallergen IgE as any IgE >0.35 IU·mL⁻¹ among 592 participants who provided blood samples. We examined associations of asthma, AR and IgE with percent difference in F_eNO in linear regression models adjusted for sex, race/ethnicity, age and height, maternal education and smoking during pregnancy, and household/neighbourhood demographics.

Asthma (14%) was associated with 97% higher F_eNO (95% CI 70–128%), AR (21%) with 45% higher F_eNO (95% CI 28–65%), and aeroallergen IgE (58%) with 102% higher F_eNO (95% CI 80–126%) compared to those without each condition, respectively. In the absence of asthma or AR, aeroallergen IgE was associated with 75% higher F_eNO (95% CI 52–101), while asthma and AR were not associated with F_eNO in the absence of IgE.

The link between asthma and AR with F_eNO is limited to those with IgE-mediated phenotypes. F_eNO may be elevated in those with allergic sensitisation alone, even in the absence of asthma or AR.

While asthma, allergic rhinitis (AR) and allergic sensitisation are associated with higher F_ENO, asthma and AR in the absence of aeroallergen IgE are not associated with F_ENO. When elevated in asthma or AR, F_ENO suggests allergic sensitisation.https://bit.ly/3bGgr0r

Fractional Exhaled Nitric Oxide Values in Indigenous Australians 3 to 16 Years of Age

BACKGROUND

Fractional exhaled nitric oxide (Feno) levels can identify eosinophilic asthma phenotypes. We aimed to determine Feno values of healthy Aboriginal and/or Torres Strait Islander (Indigenous) Australians, differences between these Indigenous ethnic groups, and appropriateness of published cutoff values.

METHODS

We measured Feno levels in 1,036 Indigenous Australians (3-16 years of age). Participants were classified into healthy (ie, no asthma or atopy history) or asthmatic and/or atopic groups.

RESULTS

Median Feno values and distribution did not differ between Indigenous ethnicities. For healthy participants < 12 years of age (n = 390), 7.2% of our cohort fell into the inflammatory zone of the American Thoracic Society (ATS), National Institute for Health and Care Excellence (NICE), and British Thoracic Society (BTS)/Scottish Intercollegiate Guidelines Network (SIGN) guidelines (cutoff 35 parts per billion [ppb]), but only 3.8% fell into this category when using the Global Initiative for Asthma (GINA) guidelines (50 ppb). Similarly, when using the NICE and BTS/SIGN guidelines (40 ppb) for participants 12 to 16 years of age (n = 213), more healthy participants fell into the inflammatory zone compared with the ATS and GINA guidelines (50 ppb) (9.9% vs 4.7%, respectively).

CONCLUSIONS

Feno values for healthy Indigenous Australians children (3-16 years of age) are likely higher than published white-based values. The GINA recommended cutoff value (> 50 ppb) appears the most appropriate for identifying healthy Indigenous children but requires confirmation from a larger study.

School-aged asthma children with high fractional exhaled nitric oxide levels and lung dysfunction are at high risk of prolonged lung dysfunction

Background

Long-term management of bronchial asthma based on the fractional exhaled nitric oxide (FeNO) value alone is not conclusive yet. Therefore, we combined FeNO testing and spirometry, a commonly used test in routine practice, to evaluate acute exacerbation and respiratory function in children with bronchial asthma.

Objective

We combined FeNO testing and spirometry, commonly used in routine practice, to evaluate acute exacerbations and respiratory function in children with bronchial asthma.

Methods

Subjects were school aged children 7 years and older with bronchial asthma who underwent FeNO testing in January 2015 to May 2016. We evaluated the changes in the frequency of acute exacerbations and respiratory function in the 30 subsequent months. Subjects were divided into 2 groups: those with initial FeNO levels ≥ 21 parts per billion (ppb) (high FeNO) and < 20 ppb (normal FeNO) groups.

Results

There were 48 children (33 boys) in the high FeNO group and 68 children (46 boys) in the normal FeNO group. Spirometry was conducted on 83 children (72%) prior to the initial FeNO test, revealing no difference in the ratio of detecting lung dysfunction between the 2 groups. The observation period was 25.8 ± 0.7 and 24.7 ± 0.6 months for the high and normal FeNO groups, respectively. The children in the high FeNO group with lung dysfunction in the initial FeNO test continued to exhibit lung dysfunction at the test at 30 months. In the normal FeNO group, even if lung dysfunction was observed at the initial FeNO, it improved within the 20-month point, and the improvement was maintained thereafter.

Conclusion

Children with bronchial asthma with high FeNO levels and lung dysfunction are at a higher risk of prolonged lung dysfunction.

A pathophysiological approach for FeNO: A biomarker for asthma

The present review is focused on literature concerning the relevance of fractional exhaled nitric oxide (FeNO) in clinical practice from a pathophysiological point of view. There is increasing evidence that asthma is a heterogeneous pathological condition characterised by different phenotypes/endotypes related to specific biomarkers, including FeNO, helpful to predict therapeutic response in selected asthmatic populations. Nowadays FeNO, a non-invasive biomarker, appears to be useful to foresee asthma developing, to recognise specific asthma phenotypes, like the eosinophilic, to ameliorate asthma diagnosis and management in selected populations and to predict standard corticosteroid and biologic therapy efficacy. In addition, FeNO assessment may also be useful in patients with allergic rhinitis in order to detect the potential involvement of eosinophilic bronchial inflammation in "case finding" subjects at risk of asthma diagnosis. Therefore, it is possible to hypothesise a future with an appropriate use of FeNO by physicians dealing with worrisome clinical issues in specific asthma phenotypes.

Exhaled nitric oxide measures allergy not symptoms in children with allergic rhinitis in primary care: a prospective cross-sectional and longitudinal cohort study

Background:

Allergic rhinitis (AR) and asthma are both inflammatory diseases and are often associated. Relationships between fractional exhaled nitric oxide (FeNO) and asthma, atopy, and quality of life have been shown.

Aims:

This study aimed to determine whether FeNO in children with AR (n=158) or combined AR and asthma (n=93) was associated with clinical symptoms, house dust mite (HDM)-specific IgE, and rhinitis-specific quality of life, both cross-sectionally and longitudinally.

Methods:

Children with AR aged 6–18 years (n=251) in primary care were assessed for FeNO, nasal symptom scores, asthma symptom scores, quality of life, and HDM-specific IgE at baseline and 2 years later.

Results:

We found similarly elevated FeNO in children with only AR and in those with combined AR and asthma. No correlations were found between FeNO and nasal or asthma symptoms and rhinitis-related quality of life. Longitudinal correlations were strongest for HDM-specific IgE (r=0.91, p<0.0001).

Conclusions:

FeNO was similar in a selected group of children with AR with and without asthma in primary care and was unrelated to symptoms or quality of life in both groups. FeNO is unlikely to be a useful biomarker of the clinical severity of upper or lower airway disease in primary care.

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.

Assessment of fractionated exhaled nitric oxide as a biomarker for the treatment of eosinophilic esophagitis

Diagnosis of eosinophilic esophagitis (EoE) and determination of response to therapy is based on histological assessment of the esophagus, which requires upper endoscopy. In children, in whom a dietary approach is commonly used, multiple endoscopies are needed, because foods are eliminated and then gradually reintroduced. Ideally, noninvasive methods could supplement or replace upper endoscopy to facilitate management. Fractionated exhaled nitric oxide (FeNO) has been proposed as a useful measure for monitoring disease activity in studies of patients with eosinophil-predominant asthma and in other atopic disorders. Thus, we evaluated whether FeNO levels could be a useful biomarker to assess the response to therapy in EoE patients. This study was designed to determine whether there is a change in FeNO levels during treatment with topical corticosteroids and whether changes correlated with clinical response. This was a prospective, multicenter study that enrolled nonasthmatic patients with established EoE. FeNO levels and symptom scores were measured at baseline, biweekly during 6-week swallowed fluticasone treatment, and 4 weeks posttreatment. Twelve patients completed the trial. We found a statistically significant difference between median pre- and posttreatment FeNO levels [20.3 ppb (16.0 -29.0 ppb) vs 17.6 ppb (11.7 -27.3 ppb), [corrected] p=0.009]. However, neither the pretreatment FeNO level, a change of FeNO level after 2 weeks of treatment, nor the FeNO level at the end of treatment confidently predicted a clinical or histological response. Although our findings suggest nitric oxide possibly has a physiological role in EoE, our observations do not support a role of FeNo determination for management of EoE.

Fractional exhaled nitric oxide measurements in rhinitis and asthma in children

Exaled nitric oxide (FeNO) is considered a good noninvasive marker to assess airway inflammation in asthma and allergic rhinitis. In asthma, exhaled NO is very useful to verify adherence to therapy, and to predict upcoming asthma exacerbations. It has been also proposed that adjusting anti-inflammatory drugs guided by the monitoring of exhaled NO, could improve overall asthma control. Other studies showed increased FeNO levels in subjects with allergic rhinitis.

Allergen exposure modifies the relation of sensitization to fraction of exhaled nitric oxide levels in children at risk for allergy and asthma

BACKGROUND

Studies on airway inflammation, measured as fraction of exhaled nitric oxide (FENO), have focused on its relation to control of asthma, but the contribution of allergen exposure to the increase in FENO levels is unknown.

OBJECTIVE

We evaluated (1) whether FENO levels were increased in children with allergic sensitization or asthma; (2) whether specific allergen exposure increased FENO levels in sensitized, but not unsensitized, children; and (3) whether sedentary behavior increased FENO levels independent of allergen exposures.

METHODS

At age 12 years, in a birth cohort of children with a parental history of allergy or asthma, we measured bed dust allergen (dust mite, cat, and cockroach) by means of ELISA, specific allergic sensitization primarily based on specific IgE levels, and respiratory disease (current asthma, rhinitis, and wheeze) and hours of television viewing/video game playing by means of questionnaire. Children performed spirometric maneuvers before and after bronchodilator responses and had FENO levels measured by using electrochemical detection methods (NIOX MINO).

RESULTS

FENO levels were increased in children with current asthma (32.2 ppb), wheeze (27.0 ppb), or rhinitis (23.2 ppb) compared with subjects without these respective symptoms/diagnoses (16.4-16.6 ppb, P < .005 for all comparisons). Allergic sensitization to indoor allergens (cat, dog, and dust mite) predicted higher FENO levels and explained one third of the variability in FENO levels. FENO levels were highest in children both sensitized and exposed to dust mite. Greater than 10 hours of weekday television viewing was associated with a 0.64-log increase in FENO levels after controlling for indoor allergen exposure, body mass index, and allergic sensitization.

CONCLUSION

Allergen exposures and sedentary behavior (television viewing/video game playing) might increase airway inflammation, which was measured as the FENO.

Exhaled nitric oxide discriminates children with and without allergic sensitization in a population-based study

BACKGROUND

Fraction of exhaled nitric oxide (FeNO) as a biomarker of airway inflammation in children warrants better clarification.

OBJECTIVE

To identify the determinants of FeNO in children and assess the validity of FeNO as a discriminative tool for asthma, rhinitis or allergic sensitization in a population setting.

METHODS

Children aged 5-18 years (N=1717) were evaluated using online FeNO measurements, questionnaires, anthropometric measurements, pulmonary function tests and total and specific serum IgE.

RESULTS

FeNO levels were age-dependent, with an average increase of 7.4% per year of age. It decreased with increasing body mass index (BMI), estimated at 1.5% decrease per kg/m(2) . Children with allergic sensitization had elevated FeNO independent of allergic symptoms. In the combined analyses of asthma, rhinitis and allergic sensitization, elevated FeNO levels were confined mainly to children having allergic sensitization. After adjusting for allergic sensitization, a significant association between rhinitis and FeNO remained, but no such association was seen with asthma. The sensitivity, specificity, and positive (PPV) and negative predictive values (NPV) of FeNO at the optimum cut-off of 28 p.p.b. for diagnosing asthma were 64.3%, 69.9%, 8.8%, and 97.7%, respectively (area under the ROC curve [AUC] 0.67), and were slightly better for diagnosing allergic asthma: 70.0%, 70.4%, 9.0%, 98.3%, respectively (AUC 0.71). FeNO had modest accuracy in discriminating rhinitis with an AUC value of 0.70, and performed better in discriminating allergic rhinitis (AUC 0.78). FeNO was a robust discriminator of allergic sensitization independent of symptoms at a cut-off of 15.4 p.p.b. (AUC 0.80; sensitivity 72.2%; specificity 71.2%; PPV 76.9%; NPV 65.8%).

CONCLUSION AND CLINICAL RELEVANCE

FeNO measurement discriminates children with and without allergic sensitization independent of allergic symptoms. On the other hand, low FeNO levels in children may help exclude allergic asthma but high levels may be caused by allergic sensitization, older age, rhinitis, and lower BMI, in addition to asthma.

Factors attributable to the level of exhaled nitric oxide in asthmatic children

Background

Asthma is a heterogeneous disease with variable symptoms especially in children. Exhaled nitric oxide (FeNO) has proved to be a marker of inflammation in the airways and has become a substantial part of clinical management of asthmatic children due to its potential to predict possible exacerbation and adjust the dose of inhalant corticosteroids.

Objectives

We analyzed potential factors that contribute to the variability of nitric oxide in various clinical and laboratory conditions.

Materials and methods

Study population consisted of 222 asthmatic children and 27 healthy control subjects. All children underwent a panel of tests: fractioned exhaled nitric oxide, exhaled carbon monoxide, asthma control test scoring, blood sampling, skin prick tests, and basic spirometry.

Results

FeNO and other investigated parameters widely changed according to clinical or laboratory characteristics of the tested children. Asthmatics showed increased levels of FeNO, exhaled carbon monoxide, total serum IgE, and higher eosinophilia. Boys had higher FeNO levels than girls. We found a significant positive correlation between FeNO levels and the percentage of blood eosinophils, %predicted of forced vital capacity, total serum IgE levels, and increasing age.

Conclusions

Various phenotypes of children's asthma are characterized by specific pattern of the results of clinical and laboratory tests. FeNO correlates with total serum IgE, blood eosinophilia, age, and some spirometric parameters with different strength. Therefore, the coexistence of atopy, concomitant allergic rhinitis/rhinoconjunctivitis, and some other parameters should be considered in critical evaluation of FeNO in the management of asthmatic children.

Importance of allergic rhinitis management in achieving asthma control: ARIA update

Asthma continues to be a major burden for the health and healthcare of people worldwide. The recent updates of the Global Initiative for Asthma and the National Heart, Lung and Blood Institute asthma guidelines stress the need for achieving and monitoring asthma 'control', emphasizing the importance of identifying, assessing and treating comorbid conditions. Allergic rhinitis (AR) is a major comorbid condition in people with asthma and is related to inflammation of the upper portions of the airway. Recognizing and treating AR has been shown to improve asthma control, specifically by decreasing rates of asthma attacks or asthma exacerbations. In 2008, updated Allergic Rhinitis in Asthma (ARIA) guidelines were published. The updated version of the guidelines has a familiar look, with classification systems and care algorithms that are similar to those presented in other asthma guidelines. The new ARIA guidelines make one major change that should affect the care of adults and children with asthma: everyone with asthma should be assessed for AR. In addition, AR should be considered a risk factor for asthma, and all children and adults with AR, especially persistent AR, should be assessed for asthma, including testing lung function for reversible obstruction whenever feasible. Treatment for AR follows a similar format to that for asthma, including symptom management, treatment of chronic inflammation, identification and management of triggers, including allergens, and ongoing education for self-management. Pharmacotherapies that address both asthma and AR include corticosteroids (intranasal and inhaled), leukotriene receptor antagonists, immunomodulation or immunotherapy. Too often, pharmacotherapy is not supplemented by the necessary education and evaluation related to allergen, trigger identification and management.

Utility of exhaled nitric oxide in the diagnosis and management of asthma

PURPOSE OF REVIEW

The fraction of nitric oxide in exhaled air (FeNO) is elevated in the presence of airway inflammation, and it may be a useful biomarker in asthma. The purpose of the present review is to highlight the current literature investigating the use of exhaled nitric oxide in the diagnosis and management of asthma.

RECENT FINDINGS

The measurement of exhaled nitric oxide has been studied in normal populations and in asthmatics. FeNO appears to be a useful screening tool for asthma, although nondisease factors may confound the interpretation of an elevated FeNO level. Clinical trials investigating the use of FeNO measurements in predicting asthma exacerbation and tailoring maintenance therapy have had varying success. Further studies incorporating individualized FeNO profiles into treatment algorithms are needed.

SUMMARY

FeNO shows promise as a tool in the diagnosis and treatment of asthma. However, further studies are needed to address outstanding questions about its exact role in guiding asthma management.

Comparison of eNO and histamine hyperresponsiveness in diagnosing asthma in new referrals

The mainstay of the diagnosis of asthma is the presence of reversible airway obstruction. Exhaled NO levels are increased in asthma, in close relationship with the amount of airway inflammation, and may be used for monitoring the disease and adjusting therapy. In this study we investigated the role of eNO as a diagnostic for asthma, compared with the FEV1-reversibility and the PC20 (20% decrease of the FEV1 in the bronchial histamine provocation test), in two independent centers, on an unselected population. ENO measurements were performed with chemoluminesence technique in one center and with an electrochemical device in the other. Only after correction for so-called nuisance factors (allergy, use of inhaled steroids, recent infection, smoking, sex and the use of nitrate food) the eNO appeared as a diagnostic with equal power as the FEV1-reversibility and the PC20. Therefore, screening for asthma in our study population, with the eNO measurement, is a simple, fast and safe strategy.

Fractional exhaled nitric oxide measurements are most closely associated with allergic sensitization in school-age children

BACKGROUND

Factors affecting fractional exhaled nitric oxide (FeNO) in early childhood are incompletely understood.

OBJECTIVE

To examine the relationships between FeNO and allergic sensitization, total IgE, atopic dermatitis, rhinitis, asthma, and lung function (spirometry) in children.

METHODS

Children at high risk of asthma and other allergic diseases because of parental history were enrolled at birth and followed prospectively. FeNO was measured by an online technique at ages 6 and 8 years. Relationships among FeNO, various atopic characteristics, and asthma were evaluated.

RESULTS

Reproducible FeNO measurements were obtained in 64% (135/210) of 6-year-old and 93% (180/194) of 8-year-old children. There was seasonal variability in FeNO. Children with aeroallergen sensitization at ages 6 and 8 years had increased levels of FeNO compared with those not sensitized (geometric mean; 6 years, 10.9 vs 6.7 parts per billion [ppb], P < .0001; 8 years, 14.6 vs 7.1 ppb, P < .0001). FeNO was higher in children with asthma than in those without asthma at 8 years but not 6 years of age (6 years, 9.2 vs 8.3 ppb, P = .48; 8 years, 11.5 vs 9.2 ppb, P = .03). At 8 years of age, this difference was no longer significant in a multivariate model that included aeroallergen sensitization (P = .33). There were no correlations between FeNO and spirometric indices at 6 or 8 years of age.

CONCLUSION

These findings underscore the importance of evaluating allergen sensitization status when FeNO is used as a potential biomarker in the diagnosis and/or monitoring of atopic diseases, particularly asthma.

Exhaled nitric oxide in a population-based study of southern California schoolchildren

Background

Determinants of exhaled nitric oxide (FeNO) need to be understood better to maximize the value of FeNO measurement in clinical practice and research. Our aim was to identify significant predictors of FeNO in an initial cross-sectional survey of southern California schoolchildren, part of a larger longitudinal study of asthma incidence.

Methods

During one school year, we measured FeNO at 100 ml/sec flow, using a validated offline technique, in 2568 children of age 7–10 yr. We estimated online (50 ml/sec flow) FeNO using a prediction equation from a separate smaller study with adjustment for offline measurement artifacts, and analyzed its relationship to clinical and demographic characteristics.

Results

FeNO was lognormally distributed with geometric means ranging from 11 ppb in children without atopy or asthma to 16 ppb in children with allergic asthma. Although effects of atopy and asthma were highly significant, ranges of FeNO for children with and without those conditions overlapped substantially. FeNO was significantly higher in subjects aged > 9, compared to younger subjects. Asian-American boys showed significantly higher FeNO than children of all other sex/ethnic groups; Hispanics and African-Americans of both sexes averaged slightly higher than non-Hispanic whites. Increasing height-for-age had no significant effect, but increasing weight-for-height was associated with decreasing FeNO.

Conclusion

FeNO measured offline is a useful biomarker for airway inflammation in large population-based studies. Further investigation of age, ethnicity, body-size, and genetic influences is needed, since they may contribute to substantial variation in FeNO.

Differences in exhaled nitric oxide in atopic children

BACKGROUND

Exhaled nitric oxide (FeNO) has been introduced in the diagnosis and control of asthma. Atopy related diseases are a common comorbidity in asthma, but in these cases the FeNO values and their relevance have not been clearly defined. In this study we compared the differences in FeNO levels in various atopic conditions.

METHODS

A prospective study was performed comparing online FeNO in six groups of patients (non-atopic control, asymptomatic atopic, non-active rhinitis, active rhinitis, asthma, asthma with rhinitis).

RESULTS

90 children (15 per group) assisted in an outpatient hospital clinic were enrolled. FeNO levels (ppb) were: 7.9 (non-atopic control), 19 (asymptomatic atopic), 16.6 (non-active rhinitis), 26.3 (active rhinitis), 31 (asthma), and 35 (asthma and rhinitis). All groups presented higher levels of FeNO than the non-atopic control group (P < 0.001). Both asthma groups had higher levels than the rest of the groups (P < 0.05), except for the active rhinitis group. Dispersion of FeNO levels was wide in the study sample. No correlation was found between FeNO and FEV(1). A weak correlation was seen with age (r = 0.28)

CONCLUSIONS

Atopy, rhinitis and its exacerbations can be confounders in the interpretation of FeNO levels in asthmatic children.

Comparing 6 and 10 sec exhalation time in exhaled nitric oxide measurements in children

Standard exhalation time for Fractional exhaled Nitric Oxide (FeNO) measurements is 10 sec but this is difficult for young children. Recommended exhalation time for children is 6 sec, but this was never substantiated in literature. We aimed to investigate the agreement between FeNO values measured with exhalation times of 6 and 10 sec and the preference of children for either method. The study population comprised children aged 5-17 years visiting the Pediatric Pulmonology outpatient clinic. FeNO values, measured during 6 (FeNO-6) and 10 (FeNO-10) sec (random order) using the single-breath online (SBOL) technique, were compared. Preferences for exhalation times were related to FVC values. Ninety-eight children (mean age 10.6 years) were included. Median FeNO-6 (15.2 ppb) and FeNO-10 (13.6 ppb) did not differ significantly (P = 0.259). Mean difference between FeNO-6 and FeNO-10 was -0.3 ppb, limits of agreement ranging from -5.8 ppb to +5.3 ppb. Sixty percent of children with a Forced Vital Capacity (FVC) less than 3 L preferred the FeNO-6 method. We found good agreement between FeNO-6 and FeNO-10, so they can be used interchangeably. An exhalation time of 6 sec was preferred by the majority of subjects with a FVC below 3 L.