Longitudinal study of grass pollen exposure, symptoms, and exhaled nitric oxide in childhood seasonal allergic asthma

Acute exposure to pollen and airway inflammation in adolescents

INTRODUCTION

Pollen exposure is known to exacerbate allergic asthma and allergic rhinitis symptoms, yet few studies have investigated if exposure to pollen affects lung function or airway inflammation in healthy children.

METHODS

We evaluated the extent to which higher pollen exposure was associated with differences in airway inflammation and lung function among 490 early adolescent participants (mean age of 12.9 years) in Project Viva, a prebirth cohort based in Massachusetts. We obtained regional daily total pollen counts, including tree, grass, and weed pollen, from a Rotorod pollen counter. We evaluated associations of 3- and 7-day moving averages of pollen with fractional exhaled nitric oxide (FeNO) and lung function using linear regression models and evaluated the linearity of associations with penalized splines. We tested if associations of pollen with FeNO and lung function were modified by current asthma diagnosis, history of allergic rhinitis, aeroallergen sensitivity, temperature, precipitation, and air pollution.

RESULTS

Three- and 7-day median pollen concentrations were 19.0 grains/m3 (IQR: 73.4) and 20.9 grains/m3 (IQR: 89.7). In main models, higher concentrations of total pollen over the preceding 3 and 7 days were associated with a 4.6% (95% CI: 0.1,9.2) and 7.4% (95% CI: 0.9,14.3) higher FeNO per IQR of pollen, respectively. We did not find associations of pollen with lung function in main models. Asthma, allergic rhinitis, precipitation, and air pollution (nitrogen dioxide and ozone) modified associations of pollen with lung function (Pinteraction < 0.1), while temperature, sex, and aeroallergen sensitization did not.

CONCLUSION

Short-term exposure to pollen was associated with higher FeNO in early adolescents, even in the absence of allergic sensitization and asthma.

Residential greenspace and lung function decline over 20 years in a prospective cohort: The ECRHS study

BACKGROUND

The few studies that have examined associations between greenspace and lung function in adulthood have yielded conflicting results and none have examined whether the rate of lung function decline is affected.

OBJECTIVE

We explored the association between residential greenspace and change in lung function over 20 years in 5559 adults from 22 centers in 11 countries participating in the population-based, international European Community Respiratory Health Survey.

METHODS

Forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) were measured by spirometry when participants were approximately 35 (1990-1994), 44 (1999-2003), and 55 (2010-2014) years old. Greenness was assessed as the mean Normalized Difference Vegetation Index (NDVI) in 500 m, 300 m, and 100 m circular buffers around the residential addresses at the time of lung function measurement. Green spaces were defined as the presence of agricultural, natural, or urban green spaces in a circular 300 m buffer. Associations of these greenspace parameters with the rate of lung function change were assessed using adjusted linear mixed effects regression models with random intercepts for subjects nested within centers. Sensitivity analyses considered air pollution exposures.

RESULTS

A 0.2-increase (average interquartile range) in NDVI in the 500 m buffer was consistently associated with a faster decline in FVC (-1.25 mL/year [95% confidence interval: -2.18 to -0.33]). These associations were especially pronounced in females and those living in areas with low PM10 levels. We found no consistent associations with FEV1 and the FEV1/FVC ratio. Residing near forests or urban green spaces was associated with a faster decline in FEV1, while agricultural land and forests were related to a greater decline in FVC.

CONCLUSIONS

More residential greenspace was not associated with better lung function in middle-aged European adults. Instead, we observed slight but consistent declines in lung function parameters. The potentially detrimental association requires verification in future studies.

Is short-term exposure to grass pollen adversely associated with lung function and airway inflammation in the community?

BACKGROUND

The association between grass pollen exposure and early markers of asthma exacerbations such as lung function changes and increase in airway inflammation is limited. We investigated the associations between short-term grass pollen exposure and lung function and airway inflammation in a community-based sample, and whether any such associations were modified by current asthma, current hay fever, pollen sensitization, age, and other environmental factors.

METHODS

Cross-sectional and short-term analyses of data from the Melbourne Atopy Cohort Study (MACS) participants (n = 936). Lung function was assessed using spirometry. Airway inflammation was assessed by fractional exhaled nitric oxide (FeNO) and exhaled breath condensate pH and nitrogen oxides (NOx). Daily pollen counts were collected using a volumetric spore trap. The associations were examined by linear regression.

RESULTS

Higher ambient levels of grass pollen 2 days before (lag 2) were associated with lower mid-forced expiratory flow (FEF_25%-75% ) and FEV₁ /FVC ratio (Coef. [95% CI] = -119 [-226, -11] mL/s and -1.0 [-3.0, -0.03] %, respectively) and also 3 days before (lag 3). Increased levels of grass pollen a day before (lag 1) were associated with increased FeNO (4.35 [-0.1, 8.7] ppb) and also at lag 2. Adverse associations between pollen and multiple outcomes were greater in adults with current asthma, hay fever, and pollen sensitization.

CONCLUSION

Grass pollen exposure was associated with eosinophilic airway inflammation 1-2 days after exposure and airway obstruction 2-3 days after exposure. Adults and individuals with asthma, hay fever, and pollen sensitization may be at higher risk.

Association of early life and acute pollen exposure with lung function and exhaled nitric oxide (FeNO). A prospective study up to adolescence in the GINIplus and LISA cohort

BACKGROUND

Pollen exposure has both acute and chronic detrimental effects on allergic asthma, but little is known about its wider effects on respiratory health. This is increasingly important knowledge as ambient pollen levels are changing with the changing global climate.

OBJECTIVE

To assess associations of pollen exposure with lung function and fractional exhaled nitric oxide (FeNO) at age 15 in two prospective German birth cohorts, GINIplus and LISA.

METHODS

Background city-specific pollen exposure was measured in infancy (during the first three months of life), and contemporary (on the day of and 7 days prior to lung function measurement). Greenness levels within circular buffers (100-3000 m) around the birth and 15-year home addresses were calculated using the satellite-derived Normalized Difference Vegetation Index. Regression models were used to assess the associations of grass and birch pollen with lung function and FeNO, and the modifying effects of residential greenness were explored.

RESULTS

Cumulative early life exposure to grass pollen was associated with reduced lung function in adolescence (FEV₁: -4.9 mL 95%CI: -9.2, -0.6 and FVC: -5.2 mL 95%CI: -9.8, -0.5 per doubling of pollen count). Acute grass pollen exposure was associated with increased airway inflammation in all children, with higher FeNO increases in children living in green areas. In contrast acute birch pollen exposure was associated with reduced lung function only in children sensitised to birch allergens.

CONCLUSION

This study provides suggestive evidence that early pollen exposure has a negative effect on later lung function, which is in turn influenced by acute pollen exposures.

Intranasal levels of lead as an exacerbation factor for allergic rhinitis in humans and mice

BACKGROUND

Air pollutants are suspected to affect pathological conditions of allergic rhinitis (AR).

OBJECTIVES

After detecting Pb (375 μg/kg) in Japanese cedar pollen, the effects of intranasal exposure to Pb on symptoms of AR were investigated.

METHODS

Pollen counts, subjective symptoms, and Pb levels in nasal epithelial lining fluid (ELF) were investigated in 44 patients with Japanese cedar pollinosis and 57 controls from preseason to season. Effects of intranasal exposure to Pb on symptoms were confirmed by using a mouse model of AR.

RESULTS

Pb levels in ELF from patients were >40% higher than those in ELF from control subjects during the pollen season but not before the pollen season. Pb level in ELF was positively associated with pollen counts for the latest 4 days before visiting a hospital as well as scores of subjective symptoms. Intranasal exposure to Pb exacerbated symptoms in allergic mice, suggesting Pb as an exacerbation factor. Pb levels in ELF and nasal mucosa in Pb-exposed allergic mice were higher than those in Pb-exposed nonallergic mice, despite intranasally challenging the same amount of Pb. Because the increased Pb level in the nasal mucosa of Pb-exposed allergic mice was decreased after washing the nasal cavity, Pb on the surface of but not inside the nasal mucosa may have been a source of increased Pb level in ELF of allergic mice.

CONCLUSIONS

Increased nasal Pb level partially derived from pollen could exacerbate subjective symptoms of AR, indicating Pb as a novel hazardous air pollutant for AR.

Association between lung function of school age children and short-term exposure to air pollution and pollen: the PARIS cohort

BACKGROUND

Daily levels of ambient air pollution and pollen may affect lung function but have rarely been studied together. We investigated short-term exposure to pollen and air pollution in relation to lung function in school-age children from a French population-based birth cohort.

METHODS

This study included 1063 children from the PARIS (Pollution and Asthma Risk: an Infant Study) cohort whose lung function and FeNO measurements were performed at age 8 years old. Exposure data were collected up to 4 days before testing. We estimated daily total pollen concentration, daily allergenic risk indices for nine pollen taxa, as well as daily concentrations of three air pollutants (particulate matter less than 10 µm (PM₁₀), nitrogen dioxide (NO₂), ozone (O₃)). Children with similar pollen and air pollution exposure were grouped using multidimensional longitudinal cluster analysis. Associations between clusters of pollen and air pollution exposure and respiratory indices (FEV₁, FVC, FeNO) were studied using multivariable linear and logistic regression models adjusted for potential confounders.

RESULTS

Four clusters of exposure were identified: no pollen and low air pollution (Cluster 1), grass pollen (Cluster 2), PM₁₀ (Cluster 3) and birch/plane-tree pollen with high total pollen count (Cluster 4). Compared with children in Cluster 1, children in Cluster 2 had significantly lower FEV₁ and FVC levels, and children from Cluster 3 had higher FeNO levels. For FEV₁ and FVC, the associations appeared stronger in children with current asthma. Additional analysis suggested a joint effect of grass pollen and air pollution on lung function.

CONCLUSION

Daily ambient chemical and biological air quality could adversely influence lung function in children.

Annual Fractional Exhaled Nitric Oxide Measurements and Exacerbations in Severe Asthma

Purpose

Fractional exhaled nitric oxide (FENO) reflects eosinophilic inflammation of the airways. However, the significance of longitudinal assessment of FENO, including its variability, in the clinical course of severe asthma remains unclear. The aim of this study is to examine the association between long-term changes in FENO and the development of exacerbations in severe asthma.

Patients and Methods

Among the severe asthma patients enrolled in the Hokkaido Severe Asthma Cohort Study, 100 patients with severe asthma who completed a 3-year follow-up in which FENO was measured annually were included. According to the FENO level at baseline, 1 year, and 2 years, the patients were classified into three groups: the sustained high group (≥50 ppb at all three visits), the sustained low group (<25 ppb at all three visits), and the intermediate group (other). Subjects in the intermediate group were further classified into two groups based on the median value of the coefficient of variation (CV) of FENO during the 3 years (high CV and low CV intermediate groups).

Results

The sustained high group experienced shorter exacerbation-free survival and more frequent exacerbations than the sustained low group (median number of exacerbation events, 3 vs 0, p = 0.01). In the intermediate group, the high CV group experienced shorter exacerbation-free survival than the low CV group, and the CV of FENO was an independent contributing factor to the development of exacerbations.

Conclusion

Persistence of FENO above 50 ppb over the years as well as the presence of large variations in FENO levels was associated with the development of exacerbations in patients with severe asthma.

Tree pollen exposure is associated with reduced lung function in children

BACKGROUND

Allergic disease is a recognized global epidemic and a significant cause of ill health and poor quality of life. The prevalence of pollen allergy is high throughout the world, and pollen exposure itself plays a role in emergency department presentations and hospitalizations for asthma. Lung function and airway inflammation are important measures of asthma activity and control.

OBJECTIVE

To examine associations between exposure to multiple pollen types and lung function and markers of airway inflammation at 8 and 14 years of age, and to explore potential modification by residential greenness.

METHODS

A cohort of high-risk children living in Sydney, Australia had spirometry and fractional exhaled nitric oxide (FeNO) measured at 8 and 14 years of age. Ambient pollen concentration on the day of lung function measurement and up to three days prior was used as the exposure measure. Residential greenness was derived from satellite imagery. We modelled the association between six pollen types and lung function and FeNO. We also assessed modifying effects of residential greenness.

RESULTS

Casuarina, cypress and Pinus pollen in the air the day before measurement and 3 days prior respectively, were associated with reduced lung function in 8-year-olds. The pollen exposures were associated with decreases in FEV₁ and FVC; however, the FEV₁ /FVC ratio was not affected. Effect modification by greenness was not observed due to loss of power.

CONCLUSIONS & CLINICAL RELEVANCE

Airborne tree pollen of cypress, Casuarina and Pinus and not grass in some regions may be detrimental to childhood lung function.

What is a clinically meaningful change in exhaled nitric oxide for children with asthma?

INTRODUCTION

Fractional exhaled nitric oxide (F_E NO) may be a useful objective measurement to guide asthma treatment. What remains uncertain is what change in F_E NO is clinically significant.

METHODS

An individual patient data analysis was performed using data from seven randomized clinical trials which used F_E NO to guide asthma treatment. The absolute and percentage intra-subject change in F_E NO measurements over "stable" and also "unstable" 3-month periods were described.

RESULTS

Data were available in 1112 randomized controlled trial participants and ≥1 stable period was present for 665 individuals. The interquartile range (IQR) and limits of agreement (LoA) for change in absolute F_E NO among individuals whose initial F_E NO was <50 parts per billion (ppb) were -7 to +9 ppb and -43 to +50 ppb, and for those with initial F_E NO ≥50 ppb IQR was -29 to +17 ppb and LoA was -80 to +76 ppb. For percentage change in F_E NO, the IQR and LoA for individuals whose initial F_E NO was <50 ppb were -33% to +51% and -157% to +215%, and for those with initial F_E NO ≥50 ppb were -33% to +35% and -159% to +192%. The variation in F_E NO values for a stable period was similar irrespective of whether it was followed by a stable or unstable period.

CONCLUSIONS

Over a 3-month period where F_E NO is initially <50 ppb, a rise of <10 ppb or of <50% (based on IQR) is unlikely to be related to asthma. When F_E NO is initially ≥50 ppb an percentage change of <50% (based on IQR) is unlikely to be asthma-related.

Short-term exposure to pollen and the risk of allergic and asthmatic manifestations: a systematic review and meta-analysis

BACKGROUND

Several studies have assessed effects of short-term exposure to pollen on allergic and asthmatic manifestations. The evidence is inconclusive, and no meta-analysis has been published.

OBJECTIVE

To synthesise the evidence on the relations between short-term pollen exposure and the risk of allergic and asthmatic manifestations.

METHODS

We performed a systematic literature search of PubMed and Scopus databases up to the end of August 2018. In addition, we reviewed the reference lists of relevant articles. Two authors independently evaluated the eligible articles and extracted relevant information in a structured form. We calculated summary effect estimates (EE) based on the study-specific ORs and regression coefficients (β) by applying both fixed-effects and random-effects models.

RESULTS

26 studies met the a priori eligibility criteria, and 12 of them provided sufficient information for the meta-analysis. The summary EE related to 10 grains per m³ increase in pollen exposure showed an 1% increase (EE 1.01, 95% CI 1.00 to 1.02) in the risk of lower respiratory symptoms and a 2% increase (EE 1.02, 95% CI 1.01 to 1.03) in the risk of any allergic or asthmatic symptom. Correspondingly, the risk of upper respiratory symptoms and ocular symptoms increased 7% (EE 1.07, 95% CI 1.04 to 1.09) and 11% (EE 1.11, 95% CI 1.05 to 1.17), respectively, in relation to such pollen exposure. Short-term exposure to pollen did not show any significant effect on daily lung function levels.

CONCLUSION

Our results provide new evidence that short-term pollen exposure significantly increases the risks of allergic and asthmatic symptoms.

Reducing Asthma Attacks in Children using Exhaled Nitric Oxide as a biomarker to inform treatment strategy: a randomised trial (RAACENO)

Background

Childhood asthma is a common condition. Currently there is no validated objective test which can be used to guide asthma treatment in children. This study tests the hypothesis that the addition of fractional exhaled nitric oxide (F_ENO) monitoring in addition to standard care reduces the number of exacerbations (or attacks) in children with asthma.

Methods

This is a multi-centre, randomised controlled study. Children will be included of age 6–16 years who have a diagnosis of asthma, currently use inhaled corticosteroids (ICSs) and have had an exacerbation in the previous 12 months. Exclusion criteria include being unable to provide F_ENO measurement at baseline assessment, having another chronic respiratory condition and being currently treated with maintenance oral steroids. Participants will be recruited in both primary and secondary care settings and will be randomised to either receive asthma treatment guided by F_ENO plus symptoms (F_ENO group) or asthma treatment guided by symptoms only (standard care group). Within the F_ENO group, different treatment decisions will be made dependent on changes in F_ENO. Participants will attend assessments 3, 6, 9 and 12 months post randomisation. The primary outcome is asthma exacerbation requiring prescription and/or use of an oral corticosteroid over 12 months as recorded by the participant/parent or in general practitioner records. Secondary outcomes include time to first attack, number of attacks, asthma control score and quality of life. Adherence to ICS treatment is objectively measured by an electronic logging device. Participants are invited to participate in a “phenotyping” assessment where skin prick reactivity and bronchodilator response are determined and a saliva sample is collected for DNA extraction. Qualitative interviews will be held with participants and research nurses. A health economic evaluation will take place.

Discussion

This study will evaluate whether F_ENO can provide an objective index to guide and stratify asthma treatment in children.

Trial registration

ISRCTN, ISRCTN67875351. Registered on 12 April 2017. Prospectively registered.

Pollen exposure at birth and adolescent lung function, and modification by residential greenness

BACKGROUND

Exposure to high levels of pollen in infancy is a risk factor for allergic respiratory diseases in later childhood, but effects on lung function are not fully understood. We aim to examine associations between grass pollen exposure in the first months of life and lung function at 12 and 18 years, and explore potential modification.

METHODS

Using the Melbourne Atopy Cohort Study, a birth cohort of children with a family history of allergic diseases, we modeled the association between cumulative grass pollen exposure up to 3 months after birth, on FEV₁ , FVC, and FEV₁ /FVC ratio at 12 and 18 years. We also assessed modifying effects of residential greenness levels (derived from satellite imagery), asthma, and early life sensitization to ryegrass.

RESULTS

Grass pollen exposure in the first 7 days was associated with a reduction in FEV₁ (-15.5 mL; 95% CI: -27.6, -3.3 per doubling of pollen count) and FVC (-20.8 mL; -35.4, -6.1) at 12 years, but not at 18 years. Increase in cumulative grass pollen exposure up to 3 months was negatively associated with FVC at 12 and 18. Exposure to high residential greenness modified the association at 18 years.

CONCLUSION

Early exposure to grass pollen was associated with decreased lung function in children and adolescents. Targeted interventions for pollen avoidance strategies that take into account local topography could be implemented alongside other clinical interventions such as immunotherapy.

Exhaled nitric oxide monitoring does not reduce exacerbation frequency or inhaled corticosteroid dose in paediatric asthma: a randomised controlled trial

INTRODUCTION

Inhaled corticosteroid therapy (ICS) for asthma is currently modified according to symptoms and lung function. Fractional exhaled nitric oxide (FENO) has been demonstrated to be a non-invasive marker of eosinophilic inflammation. Studies of FENO-driven asthma management show variable success. Objectives: This study aimed to evaluate whether monitoring FENO can improve outpatient management of children with moderate to severe asthma using a pragmatic design.

METHODS

Children aged 6–17 years with moderate to severe asthma were recruited. Their asthma was stabilised before randomisation to FENO-driven therapy or to a standard management group where therapy was driven by conventional markers of asthma control. ICS or long-acting bronchodilator therapies were altered according to FENO levels in combination with reported symptoms in the FENO group. Participants were assessed 2 monthly for 12 months. ICS dose and exacerbation frequency change were compared between groups in an intention to treat analysis.

RESULTS

Ninety children were randomised. No difference was found between the two groups in either change in corticosteroid dose or exacerbation frequency. Results were similar in a planned secondary analysis of atopic asthmatics.

CONCLUSION

FENO-guided ICS titration does not appear to reduce corticosteroid usage or exacerbation frequency in paediatric outpatients with moderate to severe asthma. This may reflect limitations in FENO-driven management algorithms, as there are now concerns that FENO levels relate to atopy as much as they relate to asthma control.

Exposure to grass pollen--but not birch pollen--affects lung function in Swedish children

Allergic response to pollen is increasing worldwide, leading to high medical and social costs. However, the effect of pollen exposure on lung function has rarely been investigated. Over 1800 children in the Swedish birth cohort BAMSE were lung‐function‐ and IgE‐tested at the age of 8 and 16 years old. Daily concentrations for 9 pollen types together with measurements for ozone, NO₂, PM₁₀, PM_2.5 were estimated for the index day as well as up to 6 days before the testing. Exposure to grass pollen during the preceding day was associated with a reduced forced expiratory volume in 8‐yr‐olds; −32.4 ml; 95% CI: −50.6 to −14.2, for an increase in three pollen counts/m³. Associations appeared stronger in children sensitized to pollen allergens. As the grass species flower late in the pollen season, the allergy care routines might be weakened during this period. Therefore, allergy information may need to be updated to increase awareness among grass pollen‐sensitized individuals.

Exhaled nitric oxide and the management of childhood asthma--yet another promising biomarker "has been" or a misunderstood gem

Childhood asthma is a common chronic condition. Approximately five percent of all children in western countries are prescribed treatment with inhaled corticosteroids (ICS) to prevent asthma symptoms. Current guidelines advocate titrating ICS dose to symptoms but this approach is not without problem, e.g. how to discern asthmatic from non-asthmatic symptoms? And when to reduce ICS dose? This review describes the strengths and weaknesses of fractional exhaled nitric oxide (FENO) as an objective index for individualising asthma control in children. Epidemiological and mechanistic evidence suggest that FENO should be a promising biomarker for eosinophilic airway inflammation (a hall mark for asthma) but somewhat surprisingly, clinical trials in children have not consistently found benefit from adding FENO to a symptom-based approach to ICS treatment in children. There are a number of reasons why FENO has apparently failed to translate from promising biomarker to clinically useful tool, and one reason may be a lack of understanding of what merits a significant intrasubject change in FENO. This review describes the rise and apparent fall of FENO as biomarker for asthma and then focuses on more recent evidence which suggest that FENO may prove to have a role in the management of childhood asthma, and in particular preventing exacerbations.

Pollen count and exhaled nitric oxide levels in a seasonal allergic rhinitis patient

The subject was a 52-year-old man with Japanese cedar pollinosis, which developed between February and May. He had no history of asthma and was an ex-smoker. He underwent fractional exhaled nitric oxide (FeNO) measurements twice a week from 2010 to 2012. The pollen counts in 2010 were the lowest during the last decade, and the FeNO level was less than 30 ppb for the whole year. In contrast, the mean pollen count in 2011 was very high and the patient’s FeNO level rose to more than 100 ppb. The mean pollen count in 2012 was comparable with that of 2010; however, high counts were detected in April and May, and the FeNO level rose to 70 ppb during the latter stages of the pollen season. These results indicate that pollen counts should be taken into consideration during the interpretation of FeNO data in asthma or allergic rhinitis.

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.

Longitudinal measurements of exhaled nitric oxide in children-what is a significant change in FE(NO) ?

BACKGROUND

The principle aim of this study was to describe the variability of exhaled nitric oxide (FE(NO)) concentrations over 10 months in children with and without asthma.

METHODS

FE(NO) was measured on six occasions at 2-month intervals in a community-based cohort of children with and without asthma.

RESULTS

There were 178 children recruited, 47 had asthma, mean age 9.6 yr. A total of 851 FE(NO) measurements were made. The change in FE(NO) values was positively associated with the initial FE(NO) concentration (p < 0.001) and duration between paired measurements (p = 0.016) but not asthma diagnosis; there was an interaction between initial FE(NO) and duration between measurements. As an approximate rule-of-thumb, a child's FE(NO) may rise by up to 100% of their current FE(NO) over 2 and 4 months, independent of asthma.

CONCLUSIONS

Both the baseline FE(NO) and interval between repeated FE(NO) measurements are relevant to FE(NO) values, independent of asthma. These findings may be useful to clinical interpretation of FE(NO) results in children.

Grass pollen allergy in children and adolescents-symptoms, health related quality of life and the value of pollen prognosis

INTRODUCTION

An association between pollen count (Poaceae) and symptoms is well known, but to a lesser degree the importance of priming and lag effects. Also, threshold levels for changes in symptom severity need to be validated. The present study aims to investigate the relationship between pollen counts, symptoms and health related quality of life (HRQL), and to validate thresholds levels, useful in public pollen warnings.

MATERIAL AND METHODS

Children aged 7-18 with grass pollen allergy filled out a symptom diary during the pollen season for nose, eyes and lung symptoms, as well as a HRQL questionnaire every week. Pollen counts were monitored using a volumetric spore trap.

RESULTS

89 (91%) of the included 98 children completed the study. There was a clear association between pollen count, symptom severity and HRQL during the whole pollen season, but no difference in this respect between early and late pollen season. There was a lag effect of 1-3 days after pollen exposure except for lung symptoms. We found only two threshold levels, at 30 and 80 pollen grains/m(3) for the total symptom score, not three as is used today. The nose and eyes reacted to low doses, but for the lung symptoms, symptom strength did hardly change until 50 pollen grains/m(3).

CONCLUSION

Grass pollen has an effect on symptoms and HRQL, lasting up to 5 days after exposure. Symptoms from the lungs appear to have higher threshold levels than the eyes and the nose. Overall symptom severity does not appear to change during the course of season. Threshold levels need to be revised. We suggest a traffic light model for public pollen warnings directed to children, where green signifies "no problem", yellow signifies "can be problems, especially if you are highly sensitive" and red signifies "alert - take action".

Seasonal Changes in Endotoxin Exposure and Its Relationship to Exhaled Nitric Oxide and Exhaled Breath Condensate pH Levels in Atopic and Healthy Children

Endotoxin, a component of the cell walls of gram-negative bacteria, is a contaminant in organic dusts (house dust) and aerosols. In humans, small amounts of endotoxin may cause a local inflammatory response. Exhaled nitric oxide (eNO) levels, an inflammation indicator, are associated with the pH values of exhaled breath condensate (EBC). This study evaluated seasonal changes on indoor endotoxin concentrations in homes and the relationships between endotoxin exposure and eNO/EBC pH levels for healthy children and children with allergy-related respiratory diseases. In total, 34 children with allergy-related respiratory diseases and 24 healthy children were enrolled. Indoor air quality measurements and dust sample analysis for endotoxin were conducted once each season inside 58 surveyed homes. The eNO, EBC pH levels, and pulmonary function of the children were also determined. The highest endotoxin concentrations were on kitchen floors of homes of children with allergy-related respiratory diseases and healthy children, and on bedroom floors of homes of asthmatic children and healthy children. Seasonal changes existed in endotoxin concentrations in dust samples from homes of children with allergic rhinitis, with or without asthma, and in EBC pH values among healthy children and those with allergy-related respiratory diseases. Strong relationships existed between endotoxin exposure and EBC pH values in children with allergic rhinitis.

Fractioned exhaled nitric oxide (FE(NO)) is not a sufficiently reliable test for monitoring asthma in pregnancy

It has been reported that fractioned exhaled nitric oxide (FENO) can be used for monitoring airway inflammation and for asthma management but conclusions drawn by different researchers are controversial. The aim of our study was to evaluate the clinical usefulness of FENO assessment for monitoring asthma during pregnancy. We monitored 72 pregnant asthmatics aged 18-38years (Me=29 years) who underwent monthly investigations including: the level of asthma control according to GINA (Global Initiative for Asthma), the occurrence of exacerbations, ACT (Asthma Control Test), as well as FENO and spirometry measurements. In 50 women, during all visits, asthma was well-controlled. In the remaining 22 women, asthma was periodically uncontrolled. FENO measured at the beginning of the study did not show significant correlation with retrospectively evaluated asthma severity (r=0.07; p=0.97). An analysis of data collected during all 254 visits showed that FENO correlated significantly but weakly with ACT scores (r=0.25; p=0.0004) and FEV1 (r=0.21; p=0.0014). FENO at consecutive visits in women with well-controlled asthma (N=50) showed large variability expressed by median coefficient of variation (CV)=32.0% (Min 2.4%, Max 121.9%). This concerned both: atopic and nonatopic groups (35.5%; and 26.7%, respectively). Large FENO variability (35.5%) was also found in a subgroup of women (N=11) with ACT=25 constantly throughout the study. FENO measured at visits when women temporarily lost control of asthma (N=22; 38 visits), showed an increasing tendency (64.2 ppb; 9.5 ppb-188.3 ppb), but did not differ significantly (p=0.13) from measurements taken at visits during which asthma was well-controlled (27.6 ppb; 6.2 ppb-103.4 ppb). The comparison of FENO in consecutive months of pregnancy in women who had well-controlled asthma did not show significant differences in FENO values during the time of observation. The assessment of asthma during pregnancy by means of monitoring FENO is of limited practical value due to this parameter's considerable intrasubject variability, regardless of the degree of asthma control.

Exhaled nitric oxide in symptomatic children at preschool age predicts later asthma

BACKGROUND

Prediction of asthma in young children with respiratory symptoms is hampered by the lack of objective measures applicable in clinical routine. In this prospective study in a preschool children cohort, we assessed whether the fraction of exhaled nitric oxide (FeNO), a biomarker of airway inflammation, is associated with asthma at school age.

METHODS

At baseline, IgE and eosinophils were measured in the blood, and FeNO was measured offline in 391 children aged 3-47 months with lower airway symptoms. We developed an asthma predictive index (API) including high FeNO as major criterion. At follow-up, primary outcome was physician-diagnosed asthma based on standardized interviews in those children reaching school age (n = 166).

RESULTS

FeNO was significantly elevated in those children with later asthma (68/166) as compared to children not developing asthma. Median (IQR) FeNO was 10.5 (6.6-17.2) vs. 7.4 (5.3-10.3) ppb. Per 5 ppb FeNO increase, the odds ratio (95% CI) for asthma increased by 2.44 (1.61-3.70) without changing when adjusting for confounders. Using the new API, children scored at risk had 58.0% probability for later asthma, whereas the negative predictive value was 78.2%, which was comparable to the classical API.

CONCLUSIONS

In this cohort of high-risk preschool children, elevated FeNO is associated with increased risk for school-age asthma. The new API including FeNO identifies children at risk of later asthma comparably to the classical API, but does not require blood sampling.

Clinical application of exhaled nitric oxide measurement in pediatric lung diseases

Fractional exhaled nitric oxide (FeNO) is a non invasive method for assessing the inflammatory status of children with airway disease. Different ways to measure FeNO levels are currently available. The possibility of measuring FeNO levels in an office setting even in young children, and the commercial availability of portable devices, support the routine use of FeNO determination in the daily pediatric practice. Although many confounding factors may affect its measurement, FeNO is now widely used in the management of children with asthma, and seems to provide significantly higher diagnostic accuracy than lung function or bronchial challenge tests. The role of FeNO in airway infection (e.g. viral bronchiolitis and common acquired pneumonia), in bronchiectasis, or in cases with diffuse lung disease is less clear. This review focuses on the most recent advances and the current clinical applications of FeNO measurement in pediatric lung disease.

Pollen starch granules in bronchial inflammation

BACKGROUND

Pollen grains with a diameter of more than 10 μm preferentially deposit in the upper airways. Their contribution to lower airway inflammation is unclear. One hypothesis is that lower airway inflammation is mainly caused by allergen containing pollen starch granules, which are released from the pollen grains and can easily enter the peripheral airways because of their smaller size.

OBJECTIVE

To investigate the differential effect of pollen grains and pollen starch granules on nasal symptoms and lower airway inflammation.

METHODS

In a 2-period crossover design, 30 patients with allergic rhinitis and mild intermittent asthma underwent 2 allergen challenges on consecutive days in an environmental challenge chamber with either a mixture of pollen grains plus starch granules or starch granules only. End points were the total nasal symptom score (TNSS), nasal secretion weight, nasal flow, spirometry, and exhaled nitric oxide (eNO).

RESULTS

The presence of pollen grains had a significant and considerable effect on increase in TNSS and secretion weight and on decrease in nasal flow. Starch granules alone only had minimal effects on nasal symptoms. Challenges with starch granules significantly increased eNO. Pollen had no effect on eNO.

CONCLUSION

Pollen grains cause nasal symptoms but do not augment lower airway inflammation, whereas starch granules trigger lower airway inflammation but hardly induce nasal symptoms.

Exhaled nitric oxide in pediatrics: what is new for practice purposes and clinical research in children?

Fractional exhaled NO (FeNO) is universally considered an indirect marker of eosinophilic airways inflammation, playing an important role in the physiopathology of childhood asthma. Advances in technology and standardization have allowed a wider use of FeNO in clinical practice in children from the age of four years. FeNO measurements add a new dimension to the traditional clinical tools (symptoms scores, lung function tests) in the assessment of asthma. To date a number of studies have suggested a possible use of FeNO in early identification of exacerbation risk and in inhaled corticosteroids titration. The aim of this paper is to address practical issues of interest to paediatric clinicians who are attempting to use FeNO measurements as an adjunctive tool in the diagnosis and management of childhood airway diseases.

Exhaled nitric oxide is associated with allergic inflammation in children

Exhaled nitric oxide (eNO) has been proposed as a noninvasive marker of airway inflammation in asthma. In asthmatic patients, exhaled NO levels have been shown to relate with other markers of eosinophilic recruitment, which are detected in blood, sputum, bronchoalveolar lavage fluid and bronchial biopsy samples. The purpose of this study was to assess the possible relationship between eNO and allergic inflammation or sensitization in childhood asthma and allergic rhinitis. Subjects consisted of 118 asthmatic children, 79 patients with allergic rhinitis, and 74 controls. Their age ranged from 6 to 15 yr old. eNO level, peripheral blood eosinophil count, eosinophil cationic protein (ECP), serum total IgE level and specific IgE levels were measured. Methacholine challenge test and allergic skin prick test for common allergens were performed in all subjects. Atopic group (n = 206, 44.48 ± 30.45 ppb) had higher eNO values than non-atopic group (n = 65, 20.54 ± 16.57 ppb, P < 0.001). eNO level was significantly higher in patients with asthma (42.84 ± 31.92 ppb) and in those with allergic rhinitis (43.59 ± 29.84 ppb) than in healthy controls (27.01 ± 21.34 ppb, P < 0.001) but there was no difference between asthma and allergic rhinitis group. eNO also had significant positive correlations with Dermatophagoides pteronyssinus IgE level (r = 0.348, P < 0.001), Dermatophagoides farinae IgE level (r = 0.376, P < 0.001), and the number of positive allergens in skin prick test (r = 0.329, P = 0.001). eNO had significant positive correlations with peripheral blood eosinophil count (r = 0.356, P < 0.001), serum total IgE level (r = 0.221, P < 0.001), and ECP (r = 0.436, P < 0.001). This study reveals that eNO level is associated with allergic inflammation and the degree of allergic sensitization.

Seven-days-ahead forecasting of childhood asthma admissions using artificial neural networks in Athens, Greece

Artificial Neural Network (ANN) models were developed and applied in order to predict the total weekly number of Childhood Asthma Admission (CAA) at the greater Athens area (GAA) in Greece. Hourly meteorological data from the National Observatory of Athens and ambient air pollution data from seven different areas within the GAA for the period 2001-2004 were used. Asthma admissions for the same period were obtained from hospital registries of the three main Children's Hospitals of Athens. Three different ANN models were developed and trained in order to forecast the CAA for the subgroups of 0-4, 5-14-year olds, and for the whole study population. The results of this work have shown that ANNs could give an adequate forecast of the total weekly number of CAA in relation to the bioclimatic and air pollution conditions. The forecasted numbers are in very good agreement with the observed real total weekly numbers of CAA.

Fluctuation phenotyping based on daily fraction of exhaled nitric oxide values in asthmatic children

BACKGROUND

Fraction of exhaled nitric oxide (Feno), a marker of airway inflammation, has been proposed to be useful for asthma management, but conclusions are inconsistent. This might be due to the failure of mean statistics to characterize individual variability in Feno values, which is possibly a better indicator of asthma control than single measurements.

OBJECTIVE

We characterized fractal fluctuations in daily Feno values over time and the relationship between Feno values and symptom scores. We investigated whether these are associated with asthma severity, control, and exacerbation risk.

METHODS

Daily Feno values and symptom scores over 192 days in 41 atopic asthmatic children from the Childhood Asthma Respiratory Inflammatory Status Monitoring study were analyzed. Two methods of time-series analysis were used: detrended fluctuation analysis to quantify fractal patterns in fluctuations in daily Feno values (α value) and cross-correlation to quantify the strength of the relationship between daily Feno values and symptom scores. The associations of α values and cross-correlation with markers of asthma severity and control were assessed by means of regression analysis.

RESULTS

Daily fluctuations in Feno values exhibited fractal-type long-range correlations. Those subjects receiving higher doses of inhaled corticosteroids at study entry had a significantly lower α value, corresponding to more random fluctuations in Feno values in those with greater inhaled corticosteroid need. The cross-correlation between Feno values and symptom scores was significantly higher in those subjects who had exacerbations.

CONCLUSIONS

Fluctuation in Feno values and their cross-correlation to symptom scores contains information on asthma severity and control. Methods that quantify the complexity of asthma over time might assist in identifying asthmatic subjects with concordance between eosinophilic inflammation and symptoms and thus increased exacerbation risk.

Associations of Fraction of Exhaled Nitric Oxide with Beta Agonist Use in Children with Asthma

The fraction of exhaled nitric oxide (FeNO), a measure of airway inflammation, is a potential noninvasive tool to guide asthma management in children. It remains unclear, however, if FeNO adds any information beyond clinical assessment of asthma control. We evaluated the associations of FeNO level with short acting beta agonist use and compared it with other clinical asthma assessments. We examined a prospective cohort study of 225 tobacco-smoke-exposed children aged 6-12 years with doctor-diagnosed asthma, including measures of FeNO, reported days of short acting beta agonist use, and unscheduled asthma visits. FeNO was analyzed in relation to current and future (3 months later) short acting beta agonist use. Mean FeNO at baseline, 6, and 12 months was 15.5, 15.7, and 16.8 ppb. In multivariable analyses, higher FeNO level was associated with increased short acting beta agonist use but only among children who were not on inhaled corticosteroids. Among those not on an inhaled steroid, there was a 12% increase in current and 15% increase in future days of short acting beta agonist use for every 10 ppb increase in FeNO level. FeNO levels remained associated with current short acting beta agonist use even after adjusting for unscheduled asthma visits. FeNO levels remained associated with future short acting beta agonist use even after adjusting for current short acting beta agonist use or unscheduled asthma visits. We conclude that FeNO levels are associated with short acting beta agonist use but only among children who are not on an inhaled corticosteroid.

Outdoor particulate matter and childhood asthma admissions in Athens, Greece: a time-series study

BACKGROUND

Particulate matter with diameter less than 10 micrometers (PM10) that originates from anthropogenic activities and natural sources may settle in the bronchi and cause adverse effects possibly via oxidative stress in susceptible individuals, such as asthmatic children. This study aimed to investigate the effect of outdoor PM10 concentrations on childhood asthma admissions (CAA) in Athens, Greece.

METHODS

Daily counts of CAA from the three Children's Hospitals within the greater Athens' area were obtained from the hospital records during a four-year period (2001-2004, n = 3602 children). Mean daily PM10 concentrations recorded by the air pollution-monitoring network of the greater Athens area were also collected. The relationship between CAA and PM10 concentrations was investigated using the Generalized Linear Models with Poisson distribution and logistic analysis.

RESULTS

There was a statistically significant (95% CL) relationship between CAA and mean daily PM10 concentrations on the day of exposure (+3.8% for 10 microg/m3 increase in PM10 concentrations), while a 1-day lag (+3.4% for 10 microg/m3 increase in PM10 concentrations) and a 4-day lag (+4.3% for 10 microg/m3 increase in PM10 concentrations) were observed for older asthmatic children (5-14 year-old). High mean daily PM10 concentration (the highest 10%; >65.69 microg/m3) doubled the risk of asthma exacerbations even in younger asthmatic children (0-4 year-old).

CONCLUSIONS

Our results provide evidence of the adverse effect of PM10 on the rates of paediatric asthma exacerbations and hospital admissions. A four-day lag effect between PM10 peak exposure and asthma admissions was also observed in the older age group.

FeNO as a Marker of Airways Inflammation: The Possible Implications in Childhood Asthma Management

The aim of this study was to verify FeNO usefulness, as a marker of bronchial inflammation, in the assessment of therapeutic management of childhood asthma. We performed a prospective 1-year randomized clinical trial evaluating two groups of 32 children with allergic asthma: "GINA group", in which therapy was assessed only by GINA guidelines and "FeNO group", who followed a therapeutic program assessed also on FeNO measurements. Asthma Severity score (ASs), Asthma Exacerbation Frequency (AEf), and Asthma Therapy score (ATs) were evaluated at the start of the study (T1), 6 months (T2), and 1 year after (T3). ASs and AEf significantly decreased only in the FeNO group at times T2 and T3 (p[T1-T2] = 0.0001, and p[T1-T3] = 0.01; p[T1-T2] = 0.0001; and p[T1-T3] < 0.0001, resp.). After six months of follow-up, we found a significant increase of patients under inhaled corticosteroid and/or antileukotrienes in the GINA group compared to the FeNO group (P = .02). Our data show that FeNO measurements, might be a very useful additional parameter for management of asthma, which is able to avoid unnecessary inhaled corticosteroid and antileukotrienes therapies, however, mantaining a treatment sufficient to obtain a meaningful improvement of asthma.

Influence of atopy and asthma on exhaled nitric oxide in an unselected birth cohort study

BACKGROUND

Asthma is considered to be associated with elevated levels of exhaled nitric oxide (FeNO). The nature of this relationship and how it is influenced by atopy are still not resolved.

METHODS

The Isle of Wight birth cohort (N=1456) was reassessed at 18 years of age. Participants able to attend the research centre were assessed by questionnaires, skin prick testing and FeNO in order to explore the interrelationship between asthma, atopy and FeNO.

RESULTS

Atopy was significantly associated with higher levels of FeNO. However, the level of FeNO for non-atopic asthmatic participants was no different to the non-atopic no-asthma group. The highest levels of FeNO were seen in subjects with both atopy and asthma. In addition, FeNO was positively associated with increasing atopic burden as evidenced by increasing FeNO with increasing skin prick testing positivity, and with increasing severity of atopic asthma as evidenced by the number of attacks of wheezing. FeNO and current inhaled corticosteroid use were not significantly associated.

CONCLUSIONS

FeNO behaves as a biomarker of atopy and the "allergic asthma" phenotype rather than asthma itself. This may explain why FeNO-guided asthma treatment outcomes have proved to be of limited success where atopic status has not been considered and accounted for.

Are exhaled nitric oxide measurements using the portable NIOX MINO repeatable?

Background

Exhaled nitric oxide is a non-invasive marker of airway inflammation and a portable analyser, the NIOX MINO (Aerocrine AB, Solna, Sweden), is now available. This study aimed to assess the reproducibility of the NIOX MINO measurements across age, sex and lung function for both absolute and categorical exhaled nitric oxide values in two distinct groups of children and teenagers.

Methods

Paired exhaled nitric oxide readings were obtained from 494 teenagers, aged 16-18 years, enrolled in an unselected birth cohort and 65 young people, aged 6-17 years, with asthma enrolled in an interventional asthma management study.

Results

The birth cohort participants showed a high degree of variability between first and second exhaled nitric oxide readings (mean intra-participant difference 1.37 ppb, 95% limits of agreement -7.61 to 10.34 ppb), although there was very close agreement when values were categorised as low, normal, intermediate or high (kappa = 0.907, p < 0.001). Similar findings were seen in subgroup analyses by sex, lung function and asthma status. Similar findings were seen in the interventional study participants.

Conclusions

The reproducibility of exhaled nitric oxide is poor for absolute values but acceptable when values are categorised as low, normal, intermediate or high in children and teenagers. One measurement is therefore sufficient when using categorical exhaled nitric oxide values to direct asthma management but a mean of at least two measurements is required for absolute values.

Indoor environmental risk factors and seasonal variation of childhood asthma

Seasonality of asthma may result from varying exposures. This cross-sectional study was designed to examine the relationship between indoor environmental factors and seasonal childhood asthma. Study subjects were participants from the International Study of Asthma and Allergies in Childhood (ISAAC) in 2004, a population-based surveillance, which included school children aged 6-15 yr in south Taiwan. Cases included 1725 children who experienced asthma symptoms in the past 12 months and the references consisted of 19,646 children who reportedly have no asthma history. By using a moving average and principal component analysis, asthmatic children were grouped into four asthma subtypes: winter, spring, summer/fall, and perennial. Multivariate logistic regression was used to evaluate the effect of indoor environmental factors on seasonality of childhood asthma. For all asthma prevalence, a peak occurred in the winter and a nadir appeared in summer. Contributing factors of asthma for children, regardless of seasonality, included younger age, parental atopy, maternal smoking during pregnancy, breast feeding, and perceived air pollution. After adjusted for salient risk factors, water damage was significantly associated with all subtypes of asthma. Presence of cockroaches was related to the summer/fall asthma (adjusted odds ratio [aOR] = 1.65, 95% confidence interval [CI] = 1.12-2.55). Visible mold on the walls was associated with an increased occurrence of winter and spring asthma (aOR = 1.53, 95% CI = 1.26-1.85 and aOR = 1.34, 95% CI = 1.10-1.62, respectively). Passive smoking was shown to be related to spring and summer/fall asthma. Water damage is a possible risk for childhood asthma year-round. Cockroaches and visible mold on the walls may play essential roles for seasonality of childhood asthma in Taiwan. Plausible mechanisms and allergic effects should be further determined. Elimination of these allergens is necessary to help prevent the development of asthma.

Exhaled nitric oxide in evaluation of young adults with chronic cough

BACKGROUND

Bronchial asthma (A) is frequently diagnosed in patients with chronic cough. The study was conducted to determine whether an evaluation of fractional exhaled nitric oxide (FeNO) concentration can be used as a screening test for asthma in young adults with chronic cough (CCP).

METHODS

The study was performed on 540 (mean age 26.5; range 18-45 years), nonsmoking young CCP. All patients had resting spirometry within normal limits and no abnormalities on chest radiographs. Skin prick tests with common aeroallergens, bronchial provocation challenge with histamine, and evaluation of FeNO concentration were performed in all patients. One hundred healthy, nonsmoking, nonatopic subjects were used as control subjects (HC).

RESULTS

Asthma (A) was diagnosed in 178 CCP (32.96%). Other frequent diagnoses included rhinitis/sinusitis (R) and gastroesophageal reflux (GERD). The median FeNO concentration in A (86 ppb; 95% CI 72 to 94,5 ppb) was significantly greater than in R (37 ppb; 95% CI 35,6 to 42,9 ppb; p < 0.0001), GERD (14,8 ppb; 95%CI 13.3 to 16.2 ppb; p < 0.0001), or in HC (13 ppb; 95%CI 11 to 15 ppb; p < 0.0001). Significant correlation was found between log(FeNO) and bronchial reactivity expressed as log(PC20) (r = -0.529; 95%CI -0.616 to -0.429; p < 0.0001), but even stronger correlation was demonstrated between log(FeNO) and peripheral blood eosinophilia (r = 0.757; 95%CI 0.717 to 0.792). Receiver Operator Characteristic (ROC) curve analysis revealed that CCP can be screened for A by measuring FeNO concentration. Using 40 ppb as a cut-off value for the FeNO concentration, the specificity 82.6% and sensitivity 88.3% can be achieved.

CONCLUSION

In clinical practice, assessment of FeNO concentration can be used as a screening test for asthma in young adults who have chronic cough.

Environmental exposures, nitric oxide synthase genes, and exhaled nitric oxide in asthmatic children

Exhaled nitric oxide (FeNO), a measure of airway inflammation, is being explored as a tool to guide asthma management in children. Investigators have identified associations of genetic polymorphisms in nitric oxide synthase genes (NOS1 and NOS3) with FeNO levels; however, none have explored whether these polymorphisms modify the relationship of environmental exposures with FeNO. The objective of this project was to evaluate the association of NOS polymorphisms and environmental exposures with FeNO levels among children with asthma. We conducted a 12-month prospective cohort study of 225 tobacco-smoke exposed children (6-12 years) with doctor-diagnosed asthma. We assessed environmental exposures (tobacco, indoor allergens, & airborne particulates), polymorphisms in NOS1 (an intronic AAT tandem repeat) and NOS3 (G894T), and FeNO levels. There was no association of NOS1 or NOS3 polymorphisms with FeNO levels. There were no significant interactions of environmental exposures and the NOS1 polymorphism with FeNO levels. In contrast, there was an interaction of the NOS3 polymorphism and airborne nicotine concentration with FeNO levels (P = 0.01). Among GG genotype individuals, nicotine exposure did not affect FeNO levels; however, among individuals with at least one T allele, higher nicotine exposure was associated with lower FeNO levels (approximately 5 ppb decrease from the lowest to the highest quartile). We conclude that genetic differences may explain some of the conflicting results in studies of the effects of tobacco smoke exposure on FeNO levels and may make FeNO interpretation difficult for a subset of children with asthma.

Complexity of chronic asthma and chronic obstructive pulmonary disease: implications for risk assessment, and disease progression and control

Although assessment of asthma control is important to guide treatment, it is difficult since the temporal pattern and risk of exacerbations are often unpredictable. In this Review, we summarise the classic methods to assess control with unidimensional and multidimensional approaches. Next, we show how ideas from the science of complexity can explain the seemingly unpredictable nature of bronchial asthma and emphysema, with implications for chronic obstructive pulmonary disease. We show that fluctuation analysis, a method used in statistical physics, can be used to gain insight into asthma as a dynamic disease of the respiratory system, viewed as a set of interacting subsystems (eg, inflammatory, immunological, and mechanical). The basis of the fluctuation analysis methods is the quantification of the long-term temporal history of lung function parameters. We summarise how this analysis can be used to assess the risk of future asthma episodes, with implications for asthma severity and control both in children and adults.

Seasonal changes in platelet activity in pollen-induced seasonal allergic rhinitis and asthma

BACKGROUND

Previously we reported that patients sensitized to pollen-allergens who had seasonal allergic rhinitis and seasonal asthma may show increased plasma levels of platelet activation markers during grass pollen season.

OBJECTIVE

To find out whether the pattern of platelet activity measured by plasma PF-4 level in the same group of patients changed off-season compared with the pollen season as well as in comparison with healthy control subjects.

METHODS

Off-pollen season, plasma PF-4 level was determined by enzyme-linked immunosorbent assay (ELISA) in 16 grass pollen allergic patients who had seasonal allergic rhinitis and seasonal asthmatic symptoms (none of them had any history of allergic diseases outside the season) and in 29 healthy nonatopic subjects.

RESULTS

Plasma PF-4 level in the patients off-pollen season was significantly lower as compared with the season and did not differ significantly as compared to the healthy subjects.

CONCLUSIONS

This observation taken along with our previous results indicates that patients with seasonal allergic rhinitis and asthma symptoms may have an increased circulating platelet activation, yet this phenomenon disappears in the asymptomatic period of the disease. This might indicate that platelet activation within the systemic circulation is an important factor in the development of seasonal allergic airway inflammation.

Exhaled nitric oxide decreases in association with attendance at an asthma summer cAMP

Attendance at a summer asthma camp has been associated with improved outcomes in children with asthma. We hypothesized that one mechanism involved in improved asthma outcomes is reduction in airway inflammation. To investigate this, we measured the fractional concentration of exhaled nitric oxide (FeNO), lung function (forced expiratory volume in 1 sec, FEV(1)) and asthma control (Juniper Asthma Control Questionnaire, ACQ) from children at the beginning and end of a 1-week asthma summer camp. We also obtained a symptoms-only ACQ at 1 and 6 months after the end of camp. We enrolled 10 girls, 17 boys, mean (+/- SD) age = 9.6 +/- 1.3 years. At baseline, FeNO (ppb), median (25-75 IQR) = 11.4 (7.2-21.3); ACQ = 0.86 (0.43-1.21); FEV(1) (%pred, mean +/- SD) = 87 +/- 10. At the end of camp, FeNO = 6.2 (4.4-8.4), a change of -45%, p < 0.0001; ACQ = 0.71 (0.43-1.14), a fall of 14%, p = 0.72; and mean FEV(1)% predicted remained unchanged. There were no significant changes in the follow-up symptoms-only ACQ at 1 and 6 months. We conclude that airway inflammation, as measured by FeNO, improved during 1 week of asthma camp, but there were no significant changes in lung function or asthma control. Since no child had a change in anti-inflammatory therapy during camp, these findings suggest that airway inflammation was reduced because of improved adherence to therapy and/or reduced exposure to pro-inflammatory stimuli in the home environment. The finding of reduced inflammation following attendance at an asthma summer camp should motivate the child, the parents and the clinician to focus their efforts on improving adherence to therapy and reducing exposures at home.

The value of FeNO measurement in asthma management: the motion for Yes, it's NO--or, the wrong end of the Stick!

The utility of measurements of exhaled nitric oxide (FeNO) will likely depend on context, being most helpful in moderate and severe asthma, rather than mild asthmatics and community based studies. Atopy on its own is a cause of elevation in FeNO. Adult and paediatric studies have clearly established that measurement of some aspect of airway inflammation is part of state of the art management of asthma, but it is as yet unclear which of several techniques is most useful. The relationship between FeNO and sputum eosinophils is relatively loose, but this does not preclude it being a useful test in clinical practice. In fact, there are only poor correlations between sputum, proximal mucosal, and distal eosinophils, and the importance of these different compartments is unclear. A low FeNO in the setting of supposedly poorly controlled asthma should cast doubt on the diagnosis. We certainly cannot treat an isolated elevation in FeNO, which may be due to a simple viral cold, or constitutional. If FeNO is elevated, particularly if asthma is uncontrolled, it suggests an imbalance between anti-inflammatory therapy and pro-inflammatory environmental influences. Inadequate anti-inflammatory therapy may be due to the prescribed dose being too low; the drug delivery device not being used correctly; or the medication not being taken. Adverse pro-inflammatory environmental influences driving up FeNO include IgE and non-IgE mediated allergen sensitivity in the home, and even in the child's school. Novel technology allows home monitoring of FeNO, but the role of these devices is less clear. Although more data is needed properly to define the role of FeNO measurements in clinical practice, there is sufficient data already published to conclude that 'inflammometry' is an important part of asthma management at the more severe end of the spectrum, and that FeNO measurements are probably the most useful at the moment.

Seasonal variation and environmental predictors of exhaled nitric oxide in children with asthma

The fraction of exhaled nitric oxide (FeNO), a measure of airway inflammation, shows promise as a noninvasive tool to guide asthma management, but there is a paucity of longitudinal data about seasonal variation and environmental predictors of FeNO in children. The objective of this project was to evaluate how environmental factors affect FeNO concentrations over a 12-month study period among children with doctor diagnosed asthma. We conducted a prospective cohort study of 225 tobacco-smoke exposed children age 6-12 years with doctor-diagnosed asthma including measures of FeNO, medication use, settled indoor allergens (dust mite, cat, dog, and cockroach), and tobacco smoke exposure. Baseline geometric mean FeNO was 12.4 ppb (range 1.9-60.9 ppb). In multivariable analyses, higher baseline FeNO levels, atopy, and fall season were associated with increased FeNO levels, measured 6 and 12 months after study initiation, whereas inhaled steroid use, summer season, and increasing nicotine exposure were associated with lower FeNO levels. In secondary analyses of allergen sensitization, only sensitization to dust mite and cat were associated with increased FeNO levels. Our data demonstrate that FeNO levels over a year long period reflected baseline FeNO levels, allergen sensitization, season, and inhaled steroid use in children with asthma. These results indicate that FeNO levels are responsive to common environmental triggers as well as therapy for asthma in children. Clinicians and researchers may need to consider an individual's baseline FeNO levels to manage children with asthma.

Exhaled nitric oxide in the diagnosis and management of asthma

PURPOSE OF REVIEW

Gaseous nitric oxide is present in our exhaled breath and may be a biomarker for asthma. The purpose of the present paper is to review recent studies that have explored the potential of exhaled nitric oxide as a biomarker for asthma diagnosis and treatment.

RECENT FINDINGS

The upper limit of exhaled nitric oxide has been described in several populations, using a standard methodology. Measurements of exhaled nitric oxide have good specificity but relatively poor sensitivity for diagnosing asthma. The inter- and intra-subject variability of exhaled nitric oxide values in asthmatics remains uncertain. Clinical trials have used exhaled nitric oxide to guide steroid treatment in asthmatics with varied success. The greatest success is in studies where inhaled corticosteroids are reduced and/or withdrawn in stable asthmatics. These pioneering clinical trials have given insight into how exhaled nitric oxide might be a useful index of control of eosinophilic airway inflammation.

SUMMARY

Measurements of exhaled nitric oxide have the potential to be useful in the management of allergic asthma and the answers to a number of important questions are awaited.

The effect of weather variability on pediatric asthma admissions in Athens, Greece

The aim of this study was to determine whether there is any association between weather variability and asthma admissions among children in Athens, Greece. Medical data were obtained from hospital registries of the three main Children's Hospitals in Athens during the 1978-2000 period; children were classified into two age groups: 0-4 and 5-14 years. The application of Generalized Linear Models with Poisson distribution revealed a significant relationship among asthma hospitalizations and the investigated parameters, especially for the children aged 0-4 years. Our findings showed that Hospital admissions for childhood asthma in Athens, Greece, is negatively correlated with discomfort index, air temperature and absolute humidity whereas there is a positive correlation with cooling power, relative humidity and wind speed.

Nasobronchial interaction mechanisms in allergic airways disease

PURPOSE OF REVIEW

During the past few decades, the incidence of sensitization to inhaled allergens as well as allergic airways disease has grown steadily. Genetic and environmental factors are recognized as etiologic factors in the development of allergic airway disease, with allergic rhinitis often preceding the development of asthma. Allergic rhinitis is considered a risk factor for the development of asthma, and almost all allergic asthmatic patients have rhinitis. Insight into the risk factors responsible for allergic airways disease and the interaction between the involved organs results in a better diagnostic and therapeutic approach in global airway allergy syndrome.

RECENT FINDINGS

Recent studies have shown that local tissue factors, such as microbial stimuli and systemic inflammatory mechanisms, play a role in the clinical expression of the allergic airway syndrome. In addition, impaired nasal function affects the lower airways of asthmatic patients via different pathways. To date, most human and animal data point towards a systemic pathway linking the upper and lower airways, involving both bloodstream and bone marrow. Recent clinical trials and current guidelines underline the importance of an integrated treatment strategy involving both ends of the respiratory tract.

SUMMARY

This review provides an overview of recent epidemiological and immunopathologic evidence concerning the link between upper and lower airways in allergic disease and its therapeutic implications.

Exhaled nitric oxide in childhood asthma: a review

As an 'inflammometer', the fraction of nitric oxide in exhaled air (Fe(NO)) is increasingly used in the management of paediatric asthma. Fe(NO) provides us with valuable, additional information regarding the nature of underlying airway inflammation, and complements lung function testing and measurement of airway hyper-reactivity. This review focuses on clinical applications of Fe(NO) in paediatric asthma. First, Fe(NO) provides us with a practical tool to aid in the diagnosis of asthma and distinguish patients who will benefit from inhaled corticosteroids from those who will not. Second, Fe(NO) is helpful in predicting exacerbations, and predicting successful steroid reduction or withdrawal. In atopic asthmatic children Fe(NO) is beneficial in adjusting steroid doses, discerning those patients who require additional therapy from those whose medication dose could feasibly be reduced. In pre-school children Fe(NO) may be of help in the differential diagnosis of respiratory symptoms, and may potentially allow for better targeting and monitoring of anti-inflammatory treatment.

Exhaled nitric oxide daily evaluation is effective in monitoring exposure to relevant allergens in asthmatic children

BACKGROUND

Though asthma is an airway inflammatory disease, the assessment of treatment efficacy is mainly based on symptom monitoring and the evaluation of lung function parameters. This study was aimed to evaluate the feasibility of exhaled nitric oxide monitoring in allergic asthmatic children who were exposed to relevant allergens in their homes.

METHODS

Twenty-two children allergic to mites underwent twice-daily fractional exhaled nitric oxide (FeNO) therapy using a portable device (NIOX MINO; Aerocrine AB; Stockholm, Sweden) and peak expiratory flow (PEF) measurements before, during, and after periods of natural exposure to mite allergens. The children were admitted to the study if they had lived in a mite-free environment for 3 months. They were observed in this environment for 10 days and then were moved to a site with natural mite exposure at sea level for 19 days. Finally, they were relocated to the mite-free environment for a period of 6 days for follow-up measurements.

RESULTS

Significant differences were seen between the mite-free baseline FeNO level (26.4 parts per billion [ppb]; range, 19.3 to 36.2 ppb) and FeNO levels measured during natural mite exposure (37.3 ppb; 27.3 to 51 ppb) and after natural mite exposure (34.9 natural mite exposure; 25.2 to 48.2 ppb). Six children reported asthma symptoms during the mite exposure, and an increase in FeNO was observed in each case (p<0.031); PEF values showed no significant differences, whether between the different environments or between different periods.

CONCLUSIONS

These data give further evidence for a possible role of frequent determinations of FeNO in order to promptly assess changes in the level of airway inflammation in asthmatic children.