Factors in childhood as predictors of asthma in adult life

Do early-life allergic sensitization and respiratory infection interact to increase asthma risk?

OBJECTIVE

The 'two-hit' hypothesis theorizes that early life allergic sensitization and respiratory infection interact to increase asthma risk.

METHODS

We sought to determine in a high allergy risk birth cohort whether interactions between early life allergic sensitization and respiratory infection were associated with increased risk for asthma at ages 6-7 years and 18 years. Allergic sensitization was assessed at 6, 12, and 24 months by skin prick testing to 3 food and 3 aeroallergens. Respiratory infection was defined as reported "cough, rattle, or wheeze" and assessed 4-weekly for 15 months, at 18 months, and age 2 years. Regression analysis was undertaken with parent-reported asthma at age 6-7 years and doctor diagnosed asthma at 18 years as distinct outcomes. Interactions between allergic sensitization and respiratory infection were explored with adjustment made for potential confounders.

RESULTS

Odds of asthma were higher in sensitized compared to nonsensitized children at age 6-7 years (OR = 14.46; 95% CI 3.99-52.4), There was no evidence for interactions between allergic sensitization and early life respiratory infection, with a greater frequency of respiratory infection up to 2 years of age associated with increased odds for asthma at age 6-7 years in both sensitized (OR = 1.13; 95% CI 1.02-1.25, n = 199) and nonsensitized children (OR = 1.31; 1.11-1.53, n = 211) (p interaction = 0.089). At age 18 years, these associations were weaker.

CONCLUSIONS

Our findings do not support 'two-hit' interactions between early life allergic sensitization and respiratory infection on asthma risk. Both early life respiratory infections and allergic sensitization were risk factors and children with either should be monitored closely for development of asthma.

Perimenstrual Asthma and Premenstrual Disorders in Adolescents with Asthma

BACKGROUND

Asthma is a common chronic disease in pediatric patients, and perimenstrual asthma (PMA), refers to the worsening of asthma symptoms during the perimenstrual period, mainly reported in adult women. However, there is limited information regarding the exacerbation of symptoms in the presence of premenstrual disorders (PMDs) in adolescents. The aim of this pilot observational study was to investigate the frequency and potential association of PMA and PMDs in a clinical sample of adolescents with asthma.

PATIENTS AND METHODS

The study included 50 adolescents (aged 12-18 years, mean 16.08 ± 2.35) with asthma and at least 2 years of gynecological age. The participants completed the Asthma Control Test (ACT) to assess asthma control (considered pathological if ACT score < 20) and the modified Premenstrual Symptoms Screening Tool for Adolescents (PSST-A) to evaluate PMDs.

RESULTS

A total of 75.5% of adolescents reported PMA. The prevalence of premenstrual symptoms did not significantly differ between the PMA and no-PMA group. Among the study sample, 38.7% experienced symptoms indicative of moderate/severe premenstrual syndrome, and 8.1% exhibited symptoms of premenstrual dysphoric disorder. Compared with the no-PMA group, patients with PMA showed a significant impairment in daily and home activities (P = .03 and P = .02, respectively) and exhibited a difference in the frequency of asthma symptoms (P < .001) and medication use (P ≤ .01).

CONCLUSION

Perimenstrual worsening of asthma symptoms may be common in adolescents with a severe form of asthma. Prospective data collection through menstrual diaries is necessary to further explore the association between PMA and PMDs. Identifying early risk factors for PMA could facilitate the development of preventive strategies and early interventions for adolescents with asthma.

Longitudinal Asthma Phenotypes from Childhood to Middle-Age: A Population-based Cohort Study

Rationale: Asthma is a heterogeneous condition, and longitudinal phenotyping may provide new insights into the origins and outcomes of the disease. Objectives: We aimed to characterize the longitudinal phenotypes of asthma between the first and sixth decades of life in a population-based cohort study. Methods: Respiratory questionnaires were collected at seven time points in the TAHS (Tasmanian Longitudinal Health Study) when participants were aged 7, 13, 18, 32, 43, 50, and 53 years. Current-asthma and ever-asthma status was determined at each time point, and group-based trajectory modeling was used to characterize distinct longitudinal phenotypes. Linear and logistic regression models were fitted to investigate associations of the longitudinal phenotypes with childhood factors and adult outcomes. Measurements and Main Results: Of 8,583 original participants, 1,506 had reported ever asthma. Five longitudinal asthma phenotypes were identified: early-onset adolescent-remitting (40%), early-onset adult-remitting (11%), early-onset persistent (9%), late-onset remitting (13%), and late-onset persistent (27%). All phenotypes were associated with chronic obstructive pulmonary disease at age 53 years, except for late-onset remitting asthma (odds ratios: early-onset adolescent-remitting, 2.00 [95% confidence interval (CI), 1.13-3.56]; early-onset adult-remitting, 3.61 [95% CI, 1.30-10.02]; early-onset persistent, 8.73 [95% CI, 4.10-18.55]; and late-onset persistent, 6.69 [95% CI, 3.81-11.73]). Late-onset persistent asthma was associated with the greatest comorbidity at age 53 years, with increased risk of mental health disorders and cardiovascular risk factors. Conclusions: Five longitudinal asthma phenotypes were identified between the first and sixth decades of life, including two novel remitting phenotypes. We found differential effects of these phenotypes on risk of chronic obstructive pulmonary disease and nonrespiratory comorbidities in middle age.

Risk of asthma in offspring of asthmatic fathers versus mothers: A population-based study of 21,000 individuals in Denmark

Parental asthma or allergy have been linked to higher risk of asthma in a child; this occurs to a variable extent in different study populations. Moreover, it is debated whether maternal more so than paternal asthma history is a stronger predisposing factor: while in some countries/populations the maternal effect was clearly seen over paternal, in others the parental effects were equivalent, and in a few studies paternal effect dominated. Here we aimed to determine parental asthma and allergy effect in the Danish GEneral SUburban population Study (GESUS). This cross-sectional study has involved 21,362 adults aged 20+ years in the suburbs of Copenhagen. We used a combination of questionnaire approach, history of prescribed asthma medications and pulmonary function testing to determine odds ratios for maternal and paternal (and combined) asthma and allergy linked to asthma in the test subjects. We found that the input of maternal vs. paternal asthma effect was approximately equal (age and sex-adjusted OR 2.46, 95% CI: 2.15-2.81 for asthmatic mothers vs. 2.97, 2.58-3.42 for asthmatic fathers), except for the "ever asthma" age and sex-adjusted odds ratios where paternal allergy seems to have conferred a marginally greater effect (age and sex-adj. OR 1.96 for maternal allergy vs. 2.44 for paternal allergy, p = 0.03). Stratifying for gestational tobacco smoking did not affect the maternal results. We conclude that in the GESUS study parental asthma or allergy were strongly linked to higher asthma risk in offspring, without a prominent maternal or paternal effect.

Factors associated with resolution of childhood asthma by the age of 17: Large cohort analysis

BACKGROUND

Many children with asthma will become asymptomatic during adolescence. In this study, we evaluated factors associated with recovery from asthma by the age of 17.

METHODS

The medical records of 17-year-old conscripts to the Israeli army with asthma were compared with the records of conscripts with rigorously diagnosed resolved asthma. We assessed the association between the following parameters and asthma resolution: body mass index (BMI), recurrent rhinitis, birth season, socioeconomic level, and cognition.

RESULTS

Sixty-eight thousand and ninety conscripts with active asthma were compared to 14,695 with resolved asthma. In univariate analysis, rhinitis, overweight, underweight, higher socioeconomic level, and lower cognitive score were associated with active asthma (p < 0.001 for both sexes), but not the season of birth. In multivariate analysis, only overweight, underweight, rhinitis, and lower cognitive score (p < 0.001 for both sexes) remained significantly associated with persistence of asthma.

CONCLUSIONS

Although association does not prove causation, our finding is another reason to encourage adolescents with asthma to maintain a normal body weight. Prospective interventional studies are needed in order to decide whether changing weight to ensure BMI is within the ideal range and controlling rhinitis increases the odds of resolution of asthma in adolescence.

Predicting the course of asthma from childhood until early adulthood

PURPOSE OF REVIEW

To communicate recent insights about the natural history of childhood asthma, with a focus on prediction of persistence and remission of childhood asthma, up to early adulthood.

RECENT FINDINGS

Lung function around the age of 8-9 years is the strongest predictor: obstructive lung function predicts asthma persistence up to early adulthood, whereas normal lung function predicts remission. The ability to predict asthma remission improves when lung function is combined with blood eosinophil levels and degree of bronchial hyperresponsiveness. Interventions, such as inhaled corticosteroids and immunotherapy do not appear to alter the course of asthma. Epigenetic studies have revealed potential novel biomarkers of asthma remission, such as micro-RNA patterns in blood. Specifically, lower serum levels of mi-R221-5p, which is associated with lower IL-6 release and eosinophilic inflammation, predict remission. Higher levels of blood DNA-methylation of a CpG site in Peroxisomal Biogenesis Factor 11 Beta were associated with asthma remission.

SUMMARY

Lung function, allergic comorbidity and polysensitization in childhood predict the course of asthma. Recent epigenetic studies have provided a better understanding of underlying pathological processes in asthma remission, which may be used to improve prediction or develop novel treatments aimed at altering the course of asthma.

Issues affecting young people with asthma through the transition period to adult care

Asthma is among the most common medical conditions affecting children and young people, with adolescence a recognised period of increased risk, overrepresented in analyses examining recent increasing asthma mortality rates. Asthma may change significantly during this period and management also occurs in the context of patients seeking increased autonomy and self-governance whilst navigating increasing academic and social demands. A number of disease factors can destabilise asthma during adolescence including: increased rates of anaphylaxis, anxiety, depression, obesity, and, in females, an emerging resistance to corticosteroids and the pro-inflammatory effects of oestrogen. Patient factors such as smoking, vaping, poor symptom recognition, treatment non-adherence and variable engagement with health services contribute to difficult to treat asthma. Significant deficiencies in the current approach to transition have been identified by a recent EAACI task force, and subsequent asthma-specific recommendations, published in 2020 provide an important framework moving forward. As with other chronic conditions, effective transition programmes plan ahead, engage with adolescents and their families to identify the patients' management priorities and the current challenges they are experiencing with treatment. Transition needs may vary significantly across asthma patients and for more complex asthma may include dedicated transition clinics involving multidisciplinary care requiring input including, amongst others, allergy and immunology, psychological medicine, respiratory physicians and scientists and nurse specialists. Across different global regions, barriers to treatment may vary but need to be elicited and an individualised approach taken to optimising asthma care which is sustainable within the local adult healthcare system.

Prospective study of disease persistence and lung function trajectories of childhood asthma

BACKGROUND

A proportion of asthmatic children outgrow their disease by adulthood, but there are limited data on predictors for asthma persistence. This prospective study characterized the trajectory of spirometric indices and identified predictors for the persistence of childhood asthma.

METHODS

Chinese asthmatic children aged 6-15 years from pediatric allergy clinic underwent annual visits for ≥5 years and until their adulthood. Pre-bronchodilator spirometry and anti-asthma medications were recorded at baseline and then at least annually. Asthma resolution was defined when patients were free from asthma symptoms and use of anti-asthma drugs for ≥2 years. Logistic regression was used to identify predictors for asthma persistence. Generalized estimating equation was used to analyze longitudinal changes in lung function parameters in relation to asthma persistence.

RESULTS

181 asthmatic children aged [mean (SD)] 10.0 (2.7) years were followed for [mean (SD)] 12.5 (2.8) years. One third of them outgrew asthma during follow-up. Female was 3.36 times more likely to have persistent asthma. Inhaled corticosteroid (ICS) treatment ever and frequent asthma exacerbation (AE) predicted asthma persistence with respective odds ratios of 3.19 (95% confidence interval [CI] 1.44-7.09) and 3.05 (95% CI 1.39-6.68). Persistent asthma was inversely associated with baseline forced expiratory volume in 1-second (FEV₁ %) with an odds ratio of 0.96 (95% CI 0.93-1.00). Throughout follow-up, patients with persistent asthma had generally lower forced expiratory indices than those with asthma resolution. Children with persistent asthma experienced poorer lung function growth.

CONCLUSIONS

Female, ICS ever, and frequent AE predicted persistent asthma. Patients with persistent asthma had lower forced expiratory indices and poorer lung function growth into adulthood.

Revisiting Late-Onset Asthma: Clinical Characteristics and Association with Allergy

The Global Initiative for Asthma (GINA) 2020 defines late-onset asthma (LOA) as one of the clinical phenotypes of asthma wherein patients, particularly women, present with asthma for the first time in adult life, tend to be non-allergic and often require higher doses of inhaled corticosteroids (ICS) or are relatively refractory to corticosteroid treatment. In this review, we examine the published literature improve the understanding of the following aspects of LOA: 1) the age cut-off for its diagnosis; 2) its distinct clinical phenotypes, characteristics and risk factors; and 3) its association with allergic comorbidities and conditions. Overall, our review reveals that clinicians and researchers have used multiple age cut-offs to define LOA, with cut-off ages ranging from >12 years to ≥65 years. LOA has also been classified into several distinct phenotypes, some of which drastically differ in their clinical characteristics, course and prognosis. Although LOA has traditionally been considered non-allergic in nature, our review indicates that it is commonly associated with allergic features and comorbidities. Our findings suggest that there is an urgent need for the development of more clear clinical practice guidelines that can provide more clarity on the definition and other aspects of LOA. In addition, the association of LOA and allergy needs to be re-examined to frame a more optimal treatment strategy for patients with LOA.

Asthma Remission by Age at Diagnosis and Gender in a Population-Based Study

BACKGROUND

Child-onset asthma is known to remit with high probability, but remission in adult-onset asthma is seemingly less frequent. Reports of the association between remission and asthma age of onset up to late adulthood are scarce.

OBJECTIVE

To evaluate the association between asthma remission, age at diagnosis and gender, and assess risk factors of nonremission.

METHODS

In 2016, a random sample of 16,000 subjects aged 20 to 69 years from Helsinki and Western Finland were sent a FinEsS questionnaire. Physician-diagnosed asthma was categorized by age at diagnosis to early- (0-11 years), intermediate- (12-39 years), and late-diagnosed (40-69 years) asthma. Asthma remission was defined by not having had asthma symptoms and not having used asthma medication in the past 12 months.

RESULTS

Totally, 8199 (51.5%) responded, and 879 reported physician-diagnosed asthma. Remission was most common in early-diagnosed (30.2%), followed by intermediate-diagnosed (17.9%), and least common in late-diagnosed asthma (5.0%) (P < .001), and the median times from diagnosis were 27, 18.5, and 10 years, respectively. In males, the corresponding remission rates were 36.7%, 20.0%, and 3.4%, and in females, 20.4%, 16.6%, and 5.9% (gender difference P < .001). In multivariable binary logistic regression analysis, significant risk factors of asthma nonremission were intermediate (odds ratio [OR] = 2.15, 95% confidence interval: 1.37-3.36) and late diagnosis (OR = 11.06, 4.82-25.37) compared with early diagnosis, chronic obstructive pulmonary disease (COPD) (OR = 5.56, 1.26-24.49), allergic rhinitis (OR = 2.28, 1.50-3.46), and family history of asthma (OR = 1.86, 1.22-2.85). Results were similar after excluding COPD.

CONCLUSION

Remission was rare in adults diagnosed with asthma after age 40 years in both genders. Late-diagnosed asthma was the most significant independent risk factor for nonremission.

Do clinical investigations predict long-term wheeze? A follow-up of pediatric respiratory outpatients

INTRODUCTION

The contribution of clinical investigations to prediction of long-term outcomes of children investigated for asthma is unclear.

AIM

We performed a broad range of clinical tests and investigated whether they helped to predict long-term wheeze among children referred for evaluation of possible asthma.

METHODS

We studied children aged 6 to 16 years referred to two Swiss pulmonary outpatient clinics with a history of wheeze, dyspnea, or cough in 2007. The initial assessment included spirometry, fractional exhaled nitric oxide, skin prick tests, and bronchial provocation tests by exercise, methacholine, and mannitol. Respiratory symptoms were assessed with questionnaires at baseline and at follow-up 7 years later. Associations between baseline factors and wheeze at follow-up were investigated by logistic regression.

RESULTS

At baseline, 111 children were examined in 2007. After 7 years, 85 (77%) completed the follow-up questionnaire, among whom 61 (72%) had wheeze at baseline, while at follow-up 39 (46%) reported wheeze. Adjusting for age and sex, the following characteristics predicted wheeze at adolescence: wheeze triggered by pets (odds ratio, 4.2; 95% CI, 1.2-14.8), pollen (2.8, 1.1-7.0), and exercise (3.1, 1.2-8.0). Of the clinical tests, only a positive exercise test (3.2, 1.1-9.7) predicted wheeze at adolescence.

CONCLUSION

Reported exercise-induced wheeze and wheeze triggered by pets or pollen were important predictors of wheeze persistence into adolescence. None of the clinical tests predicted wheeze more strongly than reported symptoms. Clinical tests might be important for asthma diagnosis but medical history is more helpful in predicting prognosis in children referred for asthma.

Genetic Architectures of Childhood- and Adult-Onset Asthma Are Partly Distinct

The extent to which genetic risk factors are shared between childhood-onset (COA) and adult-onset (AOA) asthma has not been estimated. On the basis of data from the UK Biobank study (n = 447,628), we found that the variance in disease liability explained by common variants is higher for COA (onset at ages between 0 and 19 years; h²_g = 25.6%) than for AOA (onset at ages between 20 and 60 years; h²_g = 10.6%). The genetic correlation (r_g) between COA and AOA was 0.67. Variation in age of onset among COA-affected individuals had a low heritability (h²_g = 5%), which we confirmed in independent studies and also among AOA-affected individuals. To identify subtype-specific genetic associations, we performed a genome-wide association study (GWAS) in the UK Biobank for COA (13,962 affected individuals) and a separate GWAS for AOA (26,582 affected individuals) by using a common set of 300,671 controls for both studies. We identified 123 independent associations for COA and 56 for AOA (37 overlapped); of these, 98 and 34, respectively, were reproducible in an independent study (n = 262,767). Collectively, 28 associations were not previously reported. For 96 COA-associated variants, including five variants that represent COA-specific risk factors, the risk allele was more common in COA- than in AOA-affected individuals. Conversely, we identified three variants that are stronger risk factors for AOA. Variants associated with obesity and smoking had a stronger contribution to the risk of AOA than to the risk of COA. Lastly, we identified 109 likely target genes of the associated variants, primarily on the basis of correlated expression quantitative trait loci (up to n = 31,684). GWAS informed by age of onset can identify subtype-specific risk variants, which can help us understand differences in pathophysiology between COA and AOA and so can be informative for drug development.

Transition for Adolescents and Young Adults With Asthma

Asthma is a complex, heterogenous medical condition which is very common in children and adults. The transition process from pediatric to adult health care services can be a challenge for young people with chronic medical conditions. The significant changes in physical and mental health during this time, as well as the many unique developmental and psychosocial challenges that occur during adolescence can complicate and impede transition if not adequately addressed and managed. The transition period can also be a challenging time for health professionals to assess readiness for transition and manage some of the complications which are particularly common during this time, including poor adherence to therapy, smoking, drug use, and emerging mental health conditions. The natural history, presentation, symptoms, and management of asthma is often significantly different when comparing pediatric and adult practice. In addition, management in infants, toddlers, school aged children, and adolescents differs significantly, offering an additional challenge to pediatric physicians managing asthmatic children and young people. Despite these challenges, if the transition process for young people with asthma is planned and performed in a formalized manner, many of these issues can be addressed, allowing the transition to occur smoothly despite changes that may occur in medical and psychosocial domains.

Wheezing phenotypes and risk factors in early life: The ELFE cohort

Objective

Different phenotypes of wheezing have been described to date but not in early life. We aim to describe wheezing phenotypes between the ages of two months and one year, and assess risk factors associated with these wheezing phenotypes in a large birth cohort.

Methods

We studied 18,041 infants from the ELFE (French Longitudinal Study of Children) birth cohort. Parents reported wheezing and respiratory symptoms at two and 12 months, and answered a complete questionnaire (exposure during pregnancy, parental allergy).

Results

Children with no symptoms (controls) accounted for 77.2%, 2.1% had had wheezing at two months but no wheezing at one year (intermittent), 2.4% had persistent wheezing, while 18.3% had incident wheezing at one year. Comparing persistent wheezing to controls showed that having one sibling (ORa = 2.19) or 2 siblings (ORa = 2.23) compared to none, nocturnal cough (OR = 5.2), respiratory distress (OR = 4.1) and excess bronchial secretions (OR = 3.47) at two months, reflux in the child at 2 months (OR = 1.55), maternal history of asthma (OR = 1.46) and maternal smoking during pregnancy (OR = 1.57) were significantly associated with persistent wheezing. These same factors, along with cutaneous rash in the child at 2 months (OR = 1.13) and paternal history of asthma (OR = 1.32) were significantly associated with increased odds of incident wheezing. Having one sibling (ORa = 1.9) compared to none, nocturnal cough at 2 months (OR = 1.76) and excess bronchial secretions at 2 months (OR = 1.65) were significantly associated with persistent compared to intermittent wheezing.

Conclusion

Respiratory symptoms (cough, respiratory distress, and excessive bronchial secretion) were significantly associated with a high risk of persistent wheezing at one year. Smoking exposure during pregnancy was also a risk factor for persistent and incident wheezing.

The Dose-Response Association between Nitrogen Dioxide Exposure and Serum Interleukin-6 Concentrations

Systemic inflammation is an integral part of chronic obstructive pulmonary disease (COPD), and air pollution is associated with cardiorespiratory mortality, yet the interrelationships are not fully defined. We examined associations between nitrogen dioxide (NO₂) exposure (as a marker of traffic-related air pollution) and pro-inflammatory cytokines, and investigated effect modification and mediation by post-bronchodilator airflow obstruction (post-BD-AO) and cardiovascular risk. Data from middle-aged participants in the Tasmanian Longitudinal Health Study (TAHS, n = 1389) were analyzed by multivariable logistic regression, using serum interleukin (IL)-6, IL-8 and tumor necrosis factor-α (TNF-α) as the outcome. Mean annual NO₂ exposure was estimated at residential addresses using a validated satellite-based land-use regression model. Post-BD-AO was defined by post-BD forced expiratory ratio (FEV₁/FVC) < lower limit of normal, and cardiovascular risk by a history of either cerebrovascular or ischaemic heart disease. We found a positive association with increasing serum IL-6 concentration (geometric mean 1.20 (95% CI: 1.1 to 1.3, p = 0.001) per quartile increase in NO₂). This was predominantly a direct relationship, with little evidence for either effect modification or mediation via post-BD-AO, or for the small subgroup who reported cardiovascular events. However, there was some evidence consistent with serum IL-6 being on the causal pathway between NO₂ and cardiovascular risk. These findings raise the possibility that the interplay between air pollution and systemic inflammation may differ between post-BD airflow obstruction and cardiovascular diseases.

Reliably estimating prevalences of atopic children: an epidemiological study in an extensive and representative primary care database

Electronic health records stored in primary care databases might be a valuable source to study the epidemiology of atopic disorders and their impact on health-care systems and costs. However, the prevalence of atopic disorders in such databases varies considerably and needs to be addressed. For this study, all children aged 0–18 years listed in a representative primary care database in the period 2002–2014, with sufficient data quality, were selected. The effects of four different strategies on the prevalences of atopic disorders were examined: (1) the first strategy examined the diagnosis as recorded in the electronic health records, whereas the (2) second used additional requirements (i.e., the patient had at least two relevant consultations and at least two relevant prescriptions). Strategies (3) and (4) assumed the atopic disorders to be chronic based on strategy 1 and 2, respectively. When interested in cases with a higher probability of a clinically relevant disorder, strategy 2 yields a realistic estimation of the prevalence of atopic disorders derived from primary care data. Using this strategy, of the 478,076 included children, 28,946 (6.1%) had eczema, 29,182 (6.1%) had asthma, and 28,064 (5.9%) had allergic rhinitis; only 1251 (0.3%) children had all three atopic disorders. Prevalence rates are highly dependent on the clinical atopic definitions used. The strategy using cases with a higher probability of clinically relevant cases, yields realistic prevalences to establish the impact of atopic disorders on health-care systems. However, studies are needed to solve the problem of identifying atopic disorders that are missed or misclassified.

The prevalence of atopic disorders in children can be more reliably calculated by incorporating clinical information with diagnosis data. Researchers in the Netherlands, led by David Pols from the Erasmus University Medical Center Rotterdam, examined the electronic health records of more than 660,000 children, aged 0 to 18, from a Dutch primary care database to determine the number of cases of atopic eczema, asthma, and allergic rhinitis. They looked for diagnosed children who also had at least two relevant clinical consultations and at least two relevant prescriptions. This strategy helps correct for the problem of overestimation, because it doesnot assume that a child, once diagnosed, will have an atopic disorder for life. However, other methods are still needed to identify cases that are missed or misclassified in the health database.

Environmental Determinants of Bronchial Asthma among Saudi School Children in Southwestern Saudi Arabia

The aim here was to study the possible environmental and dietary determinants of asthma among school-aged children in Southwestern Saudi Arabia. In a cross-sectional study on a representative sample in Najran in Southwestern Saudi Arabia using an Arabic version of the modified ISAAC Phase III, parent-administered questionnaire data were collected. Skin prick tests (SPTs) were performed. The study included 1700 school children, out of them 468 (27.5%) were diagnosed with, cases of bronchial asthma and 20.8% (353) reported a 12-month nocturnal cough (as a proxy of severe asthma). In multivariable analysis, the study identified the following risk factors for having asthma or severe asthma: having dogs in the house, being male, being exposed to dense truck traffic on the street, using wood as a cooking fuel, conducting vigorous exercise, consuming eggs, consuming vegetables, having an allergic sensitization to dog hair, and being exposed to Cladosporium, pigweed, and Bermuda grass. On the other hand, the following food stuffs were found to be protective: seafood, fruit, and dairy products. Comprehensive school educational programs for both children and their parents should be adopted to prevent the use of wood in cooking and heating, to ensure that house pets are properly cared for, and to encourage proper dietary habits. Physicians should be informed of the patterns of allergens in order to improve asthma diagnosis and management.

Strengths, Pitfalls, and Lessons from Longitudinal Childhood Asthma Cohorts of Children Followed Up into Adult Life

Asthma is a common problem worldwide and longitudinal studies of children followed up into adult life enable the assessment of clinical outcomes, examine the pattern of lung function outcomes, and importantly provide insight into aetiology and prognosis for patients with asthma. The aim of this review is to examine the major childhood asthma cohort studies which have continued into adult life, describing the strengths and weaknesses and the lessons that can be learnt regarding pathophysiology and potential future directions for research.

Preterm birth and low birth weight continue to increase the risk of asthma from age 7 to 43

BACKGROUND

Perinatal events can influence the development of asthma in childhood but current evidence is contradictory concerning the effects on life-time asthma risk.

OBJECTIVE

To assess the relationship between birth characteristics and asthma from childhood to adulthood.

METHODOLOGY

All available birth records for the Tasmanian Longitudinal Health Study (TAHS) cohort, born in 1961 were obtained from the Tasmanian State Archives and Tasmanian hospitals. Low birth weight (LBW) was defined as less than 2500 grams. Preterm birth was defined as delivery before 37 weeks' gestation. Small for gestational age (SGA) was defined as a birth weight below the 10^th percentile for a given gestational age. Multivariate logistic and cox regression were used to examine associations between birth characteristics and lifetime risk of current and incident asthma, adjusting for confounders.

RESULTS

The prevalence of LBW was 5.2%, SGA was 13.8% and preterm was 3.3%. LBW (OR = 1.65, 95%CI 1.12,2.44) and preterm birth (OR = 1.81, 95%CI 0.99, 3.31) were both associated with an increased risk of current asthma between the ages of 7 to 43 years. There was no association between SGA and current asthma risk. However, SGA was associated with incident asthma (HR = 1.32, 95%CI 1.00, 1.74), and there was an interaction with sex (p value = 0.08), with males having a greater risk of incident asthma (HR = 1.70, 95%CI 1.16-2.49) than females (HR = 1.04, 95%CI 0.70-1.54).

CONCLUSIONS

Preterm birth and LBW were associated with an increased risk of current asthma into middle-age. These findings are the first to demonstrate the continuing impact of these characteristics on asthma risk into middle-age.

Asthma transition from childhood into adulthood

Asthma is the most prevalent chronic respiratory disease both in children and adults and resembles a complex syndrome rather than a single disease. Different methods have been developed to better characterise distinct asthma phenotypes in childhood and adulthood. In studies of adults, most phenotyping relies on biomaterials from the lower airways; however, this information is missing in paediatric studies because of restricted accessibility. Few patients show symptoms throughout childhood, adolescence, and adulthood. Risk factors for this might be genetics, family history of asthma and atopy, infections early in life, allergic diseases, and lung function deficits. In turn, a large proportion of children with asthma lose their symptoms during school age and adolescence. This improved prognosis, which might also reflect a better treatment response, is associated with being male and with milder and less allergic disease. Importantly, whether clinical remission of symptoms equals the disappearance of underlying pathology is unknown. In fact, airway hyper-responsiveness and airway inflammation might remain despite the absence of overt symptoms. Additionally, a new-onset of asthma symptoms is apparent in adulthood, especially in women and in the case of impaired lung function. However, many patients do not remember childhood symptoms, which might reflect relapse rather than true initiation. Both relapse and adult-onset of asthma symptoms have been associated with allergic disease and sensitisation in addition to airway hyper-responsiveness. Thus, asthma symptoms beginning in adults might have originated in childhood. Equivocally, persistence into, relapse, and new-onset of symptoms in adulthood have all been related to active smoking. However, underlying mechanisms for the associations remain unclear, and future asthma research should therefore integrate standardised molecular approaches in identical ways in both paediatric and adult populations and in longitudinal studies.

Current asthma contributes as much as smoking to chronic bronchitis in middle age: a prospective population-based study

BACKGROUND AND OBJECTIVE

Personal smoking is widely regarded to be the primary cause of chronic bronchitis (CB) in adults, but with limited knowledge of contributions by other factors, including current asthma. We aimed to estimate the independent and relative contributions to adult CB from other potential influences spanning childhood to middle age.

METHODS

The population-based Tasmanian Longitudinal Health Study cohort, people born in 1961, completed respiratory questionnaires and spirometry in 1968 (n=8,583). Thirty-seven years later, in 2004, two-thirds responded to a detailed postal survey (n=5,729), from which the presence of CB was established in middle age. A subsample (n=1,389) underwent postbronchodilator spirometry between 2006 and 2008 for the assessment of chronic airflow limitation, from which nonobstructive and obstructive CB were defined. Multivariable and multinomial logistic regression models were used to estimate relevant associations.

RESULTS

The prevalence of CB in middle age was 6.1% (95% confidence interval [CI]: 5.5, 6.8). Current asthma and/or wheezy breathing in middle age was independently associated with adult CB (odds ratio [OR]: 6.2 [95% CI: 4.6, 8.4]), and this estimate was significantly higher than for current smokers of at least 20 pack-years (OR: 3.0 [95% CI: 2.1, 4.3]). Current asthma and smoking in middle age were similarly associated with obstructive CB, in contrast to the association between allergy and nonobstructive CB. Childhood predictors included allergic history (OR: 1.3 [95% CI: 1.1, 1.7]), current asthma (OR: 1.8 [95% CI: 1.3, 2.7]), "episodic" childhood asthma (OR: 2.3 [95% CI: 1.4, 3.9]), and parental bronchitis symptoms (OR: 2.5 [95% CI: 1.6, 4.1]).

CONCLUSION

The strong independent association between current asthma and CB in middle age suggests that this condition may be even more influential than personal smoking in a general population. The independent associations of childhood allergy and asthma, though not childhood bronchitis, as clinical predictors of adult CB raise the possibility of some of this burden having originated in childhood.

IgE mediates broncho-vascular remodeling after neonatal sensitization in mice

The temporal origins of childhood asthma are incompletely understood. We hypothesize that allergen sensitization which begins in early infancy causes IgE-mediated airway and vascular remodeling, and airway hyper-responsiveness. Mice were sensitized with ovalbumin (OVA) without or with anti-IgE antibody from postnatal day (P) 10 through P42. We studied airway resistance in response to Methacholine (MCh) challenge, bronchoalveolar lavage fluid (BAL) inflammatory cell content, immunohistochemistry for inflammation, alpha-smooth muscle actin (alpha-SMA) and platelet/endothelial cell adhesion molecule (PECAM) proteins, and Western blotting for vascular endothelial growth factor (VEGF) protein. Compared to controls, mice treated with OVA had increased airway resistance (baseline: 192% of control; MCH 12 mg/mL 170% of control; P less than 0.0.5). OVA treatment also increased lung alpha-SMA, VEGF and PECAM compared to controls. Inflammatory cells in the BAL and perivascular and peribronchiolar inflammatory cell infiltrates increased over controls with OVA exposure. These changes were counteracted by anti-IgE treatment. We conclude that mice sensitized in early infancy develop an IgE-mediated hyper-reactive airway disease with airway and vascular remodeling. Preventive approaches in early infancy of at-risk individuals may reduce childhood asthma.

Mother's smoking and complex lung function of offspring in middle age: A cohort study from childhood

BACKGROUND AND OBJECTIVE

Existing evidence that supports maternal smoking to be a potential risk factor for chronic obstructive pulmonary disease (COPD) for adult offspring has barely been mentioned in major guideline documents, suggesting a need for more robust and consistent data. We aimed to examine whether such early life exposure can predispose to COPD in middle age, possibly through its interaction with personal smoking.

METHODS

The fifth-decade follow-up of the Tasmanian Longitudinal Health Study cohort, which was first studied in 1968 (n = 8583), included a 2004 postal survey (n = 5729 responses) and subsequent laboratory attendance (n = 1389) for comprehensive lung function testing between 2006 and 2008. Multivariable linear and logistic regression models included sampling weights.

RESULTS

Post-bronchodilator airflow obstruction (less than fifth percentile) was detected for 9.3% (n = 123) of middle-aged offspring. Its association with heavy maternal smoking (>20 cigarettes/day) during childhood was 2.7-fold higher than for those without exposure (95% confidence interval [1.3, 5.7] P = 0.009). Maternal smoking per se approximately doubled the adverse effect of personal smoking on gas transfer factor (z-score -0.46 [-0.6 to -0.3] vs -0.25 [-0.4 to -0.1], P[interaction] = 0.048) and was paradoxically associated with reduced residual volumes for non-smokers.

CONCLUSIONS

Heavy maternal smoking during childhood appears to predispose to spirometrically defined COPD. The interplay between maternal and personal smoking on gas transfer factor suggests that early life exposure increases an individual's susceptibility to adult smoking exposure. These findings provide further evidence to suggest that maternal smoking might be a risk factor for COPD and reinforce the public health message advocating smoking abstinence.

Childhood asthma and chronic obstructive pulmonary disease: outcomes until the age of 50

PURPOSE OF REVIEW

There has been recent interest in understanding the origins of chronic obstructive pulmonary disease. Epidemiological studies suggest that chronic obstructive pulmonary disease clearly has other causes apart from tobacco smoke.

RECENT FINDINGS

Cross-sectional studies of adult cohorts with chronic obstructive pulmonary disease highlight that childhood asthma is a risk factor. A recent longitudinal childhood cohort study of children from childhood to the age of 50 years describes that children with severe asthma are at increased risk of chronic obstructive pulmonary disease and that the deficit in lung function can be tracked back to early years.

SUMMARY

Children with severe asthma are at increased risk of developing chronic obstructive pulmonary disease.

Predicting asthma outcomes

This review addresses predictors of remission or persistence of wheezing and asthma from early childhood through adulthood. Early childhood wheezing is common, but predicting who will remit or have persistent childhood asthma remains difficult. By adding parental history of asthma and selected infant biomarkers to the history of recurrent wheezing, the Asthma Predictive Index and its subsequent modifications provide better predictions of persistence than simply the observation of recurrent wheeze. Sensitization, especially to multiple allergens, increases the likelihood of development of classic childhood asthma. Remission is more likely in male subjects and those with milder disease (less frequent and less severe symptoms), less atopic sensitization, a lesser degree of airway hyperresponsiveness, and no concomitant allergic disease. Conversely, persistence is linked strongly to allergic sensitization, greater frequency and severity of symptoms, abnormal lung function, and a greater degree of airway hyperresponsiveness. A genetic risk score might predict persistence more accurately than family history. Remission of established adult asthma is substantially less common than remission during childhood and adolescence. Loss of lung function can begin early in life and tracks through childhood and adolescence. Despite therapy which controls symptoms and exacerbations, the outcomes of asthma appear largely resistant to pharmacologic therapy.

Childhood wheezing phenotypes influence asthma, lung function and exhaled nitric oxide fraction in adolescence

The objective of this study was to examine the associations of childhood wheezing phenotypes with asthma, lung function and exhaled nitric oxide fraction (FeNO) in adolescence.In a population-based, prospective cohort study of 6841 children, we used latent class analysis to identify wheezing phenotypes during the first 7 years of life. Physician-diagnosed asthma, spirometry and FeNO were assessed at 14-15 years.Compared with never/infrequent wheeze, intermediate-onset and persistent wheeze were consistently strongest associated with higher risk of asthma (risk ratio (95% CI) 10.9 (8.97-13.16) and 9.13 (7.74-10.77), respectively), lower forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio (mean difference in standard deviation units (SDU) (95% CI) -0.34 (-0.54- -0.14) and -0.50 (-0.62- -0.38), respectively), lower forced expiratory flow at 25-75% of FVC (FEF25-75%) (mean difference in SDU (95% CI) -0.30 (-0.49- -0.10) and -0.42 (-0.54- -0.30), respectively) and increased FEV1 bronchodilator reversibility (mean difference in SDU (95% CI) 0.12 (0.02-0.22) and 0.13 (0.06-0.19), respectively). Prolonged early and persistent wheeze were associated with a decline in FEV1/FVC ratio and FEF25-75% between 8-9 and 14-15 years. Intermediate-onset, late-onset and persistent wheeze were associated with higher FeNO ratios (ratio of geometric means (95% CI) 1.90 (1.59-2.29), 1.57 (1.39-1.77) and 1.37 (1.22-1.53), respectively, compared with never/infrequent wheeze).Early-onset wheezing phenotypes persisting after 18 months of age show the strongest associations with asthma, lower lung function, even worsening from mid-childhood, and higher FeNO levels in adolescence.

Hormonal contraception increases risk of asthma among obese but decreases it among nonobese subjects: a prospective, population-based cohort study

Epidemiological data on asthma suggest a sex difference that varies with age. Hormonal effects have been suggested as a possible explanation for these differences but there is a scarcity of evidence on these relationships. Our objective was to examine the relationship between reproductive factors and asthma risk among females and to examine whether body mass index (BMI) modifies this relationship.

Female participants in the 2004 fifth decade follow-up postal survey of the Tasmanian Longitudinal Health Study formed the study population. Reproductive history and data on hormonal contraceptive (HC) use were collected on 2764 females. Multiple logistic regression was used to assess the association between the reproductive factors and current asthma.

The mean age of participants was 43 years and the prevalence of middle-aged current asthma was 12.8%. Females with very early menarche (≤10 years) had higher odds of middle-aged current asthma (OR 1.91, 95% CI 1.14–3.2). Pregnancy history (number of births and age at first pregnancy) were not associated with current asthma risk at 44 years. Ever having used HCs, years of use and age started using HCs were not individually associated with current asthma risk. However, body mass index significantly modified the relationship between HC use and asthma. We found increasing years of pill use was associated with a significantly increased risk of current asthma in overweight/obese women but a reduced risk in normal weight women (interaction p=0.015).

Hormonal effects from use of HCs and early menarche may contribute to the sex differential in asthma risk. Our findings suggest that in obese women with a history of long-term HC use may be at an increased risk of chronic respiratory disease, and regular monitoring for asthma and asthma symptoms may be recommended.

Overweight or obese women are at increased risk of asthma if they use hormonal contraceptives for extended periodshttp://ow.ly/SwY8p

Age-of-asthma onset as a determinant of different asthma phenotypes in adults: a systematic review and meta-analysis of the literature

Age-of-asthma onset is often used to distinguish different adult asthma phenotypes; however, similarities and differences between early- and late-onset adult asthma have not been summarized to date. Of the 2921 records found, we identified 12 studies comparing early- and late-onset current asthma in adults. Age 12 was most commonly used to delineate the two age-of-onset phenotypes. Adults with early-onset current asthma were more likely to be atopic and had a higher frequency of asthma attacks, whereas adults with late-onset disease were more likely to be female, smokers and had greater levels of spirometrically defined fixed airflow obstruction. The prevalence of severe asthma was similar in both groups, and, in general, there were few phenotypic differences between severe asthmatics regardless of age of onset. Findings for several key characteristics, including lung function, were inconsistent between studies. Overall, there appears to be distinctive phenotypic differences with age of asthma onset. Although early-onset adult asthma is likely more attributable to atopy and potentially genetic factors, late-onset adult asthma appears to be more related to environmental risk factors, and so may be better targeted by preventive strategies. More detailed research is required to better characterize these phenotypes and to clarify potential clinical implications.

Natural progression of childhood asthma symptoms and strong influence of sex and puberty

RATIONALE

Asthma prevalence, onset, remission and relapse, and healthcare use have been intensively studied. However, asthma symptom progression through childhood and adolescence has not been well studied, in part due to the challenges in obtaining consistent and robust long-term follow-up data on a large series of subjects with asthma.

OBJECTIVES

To use the asthma diary symptom data of the Childhood Asthma Management Program placebo group (5 yr, 418 subjects, and total 564,518 records) to establish sex-specific high-resolution time courses of the natural progression of asthma symptoms through childhood and adolescence.

METHODS

We used the asthma diary symptom code as a measure of daily disease severity. Annual records of Tanner stage were used to determine the influence of puberty on severity. A data alignment technique was used to derive 13-year time courses of mean symptoms and mean Tanner stage.

MEASUREMENTS AND MAIN RESULTS

Data analyses showed three age- and sex-related phases of asthma symptom progression: Phase 1 (ages 5 and 6 yr)-greater severity in boys; Phase 2 (ages 7 to 9 yr)-no sex difference in severity; and Phase 3 (age 10-17 yr)-greater severity in girls. The continuous decline of symptoms in both sexes stops abruptly at the onset of puberty.

CONCLUSIONS

The severity of asthma symptoms varies through childhood and adolescence, and patterns differ by sex. Puberty has a strong influence on symptom progression in both sexes. Progression of symptoms is a distinct aspect of asthma epidemiology.

Children hospitalised with bronchiolitis in the first year of life have a lower quality of life nine months later

AIM

Acute bronchiolitis increases the risk of asthma, and reduced quality of life (QoL) is reported in children with asthma and allergy. However, the impact of asthma risk factors on QoL is unclear. This study investigated whether bronchiolitis and common asthma risk factors in infancy had an influence on later QoL.

METHODS

The parents of 209 infants recruited during hospitalisation for bronchiolitis at a mean age of 4 months, and 206 controls responded to the generic Infant Toddler Quality of Life Questionnaire 9 months later. We used robust regression analyses to assess the association between four asthma risk factors, atopic eczema, parental asthma, parental allergic rhinoconjunctivitis and second-hand smoke and QoL in the two groups.

RESULTS

QoL was lower among children with previous bronchiolitis in the overall health and general health domains and lower in six of 13 domains in children with atopic eczema. Compared with no risk factors, children with previous bronchiolitis and three risk factors had lower scores in four domains, and control children with three risk factors had lower scores in three domains.

CONCLUSION

Having acute bronchiolitis, atopic eczema and three asthma risk factors were negatively associated with later QoL in early childhood.

The Respiratory System

This chapter addresses upper airway physiology for the pediatric intensivist, focusing on functions that affect ventilation, with an emphasis on laryngeal physiology and control in breathing. Effective control of breathing ensures that the airway is protected, maintains volume homeostasis, and provides ventilation. Upper airway structures are effectors for all of these functions that affect the entire airway. Nasal functions include air conditioning and protective reflexes that can be exaggerated and involve circulatory changes. Oral cavity and pharyngeal patency enable airflow and feeding, but during sleep pharyngeal closure can result in apnea. Coordination of breathing with sucking and nutritive swallowing alters during development, while nonnutritive swallowing at all ages limits aspiration. Laryngeal functions in breathing include protection of the subglottic airway, active maintenance of its absolute volume, and control of tidal flow patterns. These are vital functions for normal lung growth in fetal life and during rapid adaptations to breathing challenges from birth through adulthood. Active central control of breathing focuses on the coordination of laryngeal and diaphragmatic activities, which adapts according to the integration of central and peripheral inputs. For the intensivist, knowledge of upper airway physiology can be applied to improve respiratory support. In a second part the mechanical properties of the respiratory system as a critical component of the chain of events that result in translation of the output of the respiratory rhythm generator to ventilation are described. A comprehensive understanding of respiratory mechanics is essential to the delivery of optimized and individualized mechanical ventilation. The basic elements of respiratory mechanics will be described and developmental changes in the airways, lungs, and chest wall that impact on measurement of respiratory mechanics with advancing postnatal age are reviewed. This will be follwowed by two sections, the first on respiratory mechanics in various neonatal pathologies and the second in pediatric pathologies. The latter can be classified in three categories. First, restrictive diseases may be of pulmonary origin, such as chronic interstitial lung diseases or acute lung injury/acute respiratory distress syndrome, which are usually associated with reduced lung compliance. Restrictive diseases may also be due to chest wall abnormalities such as obesity or scoliosis (idiopathic or secondary to neuromuscular diseases), which are associated with a reduction in chest wall compliance. Second, obstructive diseases are represented by asthma and wheezing disorders, cystic fibrosis, long term sequelae of neonatal lung disease and bronchiolitis obliterans following hematopoietic stem cell transplantation. Obstructive diseases are defined by a reduced FEV1/VC ratio. Third, neuromuscular diseases, mainly represented by DMD and SMA, are associated with a decrease in vital capacity linked to respiratory muscle weakness that is better detected by PImax, PEmax and SNIP measurements.

Ovalbumin sensitization of guinea pig at birth prevents the ontogenetic decrease in airway smooth muscle responsiveness

Airway smooth muscle (ASM) displays a hyperresponsive phenotype at young age and becomes less responsive in adulthood. We hypothesized that allergic sensitization, which causes ASM hyperresponsiveness and typically occurs early in life, prevents the ontogenetic loss of the ASM hyperresponsive phenotype. We therefore studied whether neonatal allergic sensitization, not followed by later allergen challenges, alters the ontogenesis of ASM properties. We neonatally sensitized guinea pigs to ovalbumin and studied them at 1 week, 3 weeks, and 3 months (adult). A Schultz‐Dale response in isolated tracheal rings confirmed sensitization. The occurrence of inflammation was evaluated in the blood and in the submucosa of large airways. We assessed ASM function in tracheal strips as ability to produce force and shortening. ASM content of vimentin was also studied. A Schultz‐Dale response was observed in all 3‐week or older sensitized animals. A mild inflammatory process was characterized by eosinophilia in the blood and in the airway submucosa. Early life sensitization had no effect on ASM force generation, but prevented the ontogenetic decline of shortening velocity and the increase in resistance to shortening. Vimentin increased with age in control but not in sensitized animals. Allergic sensitization at birth without subsequent allergen exposures is sufficient to prevent normal ASM ontogenesis, inducing persistence to adulthood of an ASM hyperresponsive phenotype.

Airway smooth muscle (ASM) displays a hyperresponsive phenotype at young age and becomes less responsive in adulthood. In this study, we found that allergic sensitization at birth without subsequent allergen exposures is sufficient to prevent normal ASM ontogenesis, inducing persistence to adulthood of an ASM hyperresponsive phenotype.

Association between mental disorders and subsequent adult onset asthma

BACKGROUND AND OBJECTIVES

Associations between asthma and anxiety and mood disorders are well established, but little is known about their temporal sequence. We examined associations between a wide range of DSM-IV mental disorders with adult onset of asthma and whether observed associations remain after mental comorbidity adjustments.

METHODS

During face-to-face household surveys in community-dwelling adults (n = 52,095) of 19 countries, the WHO Composite International Diagnostic Interview retrospectively assessed lifetime prevalence and age at onset of 16 DSM-IV mental disorders. Asthma was assessed by self-report of physician's diagnosis together with age of onset. Survival analyses estimated associations between first onset of mental disorders and subsequent adult onset asthma, without and with comorbidity adjustment.

RESULTS

1860 adult onset (21 years+) asthma cases were identified, representing a total of 2,096,486 person-years of follow up. After adjustment for comorbid mental disorders several mental disorders were associated with subsequent adult asthma onset: bipolar (OR = 1.8; 95%CI 1.3-2.5), panic (OR = 1.4; 95%CI 1.0-2.0), generalized anxiety (OR = 1.3; 95%CI 1.1-1.7), specific phobia (OR = 1.3; 95%CI 1.1-1.6); post-traumatic stress (OR = 1.5; 95%CI 1.1-1.9); binge eating (OR = 1.8; 95%CI 1.2-2.9) and alcohol abuse (OR = 1.5; 95%CI 1.1-2.0). Mental comorbidity linearly increased the association with adult asthma. The association with subsequent asthma was stronger for mental disorders with an early onset (before age 21).

CONCLUSIONS

A wide range of temporally prior mental disorders are significantly associated with subsequent onset of asthma in adulthood. The extent to which asthma can be avoided or improved among those with early mental disorders deserves study.

Asthma incidence, remission, relapse and persistence: a population-based study in southern Taiwan

BACKGROUND

In western countries, late-onset asthmatics are more severe than early-onset asthmatics in clinic-based studies. However, whether asthma occurrence rates were higher in late ages than in younger ages was inconclusive. This information is essentially lacking in Asian population.

METHODS

The participants were schoolchildren's parents recruited from 94 elementary and middle schools in 2004. A cross-sectional self-administered questionnaire was sent through the children to their parents to survey their respiratory health. We investigated typical asthma symptoms occurring at different ages and subsequent remission or relapse after the first asthma event. Person-years of the participants from birth to the time of survey were used as the denominator.

RESULTS

Among the 25,377 participants consisting of 949,807 total person-years, 860 reported ever having asthma. Highest incidences occurred at ages 0-12 and 36-40 years. The incidence of asthma was higher in males before puberty, and higher in females after puberty, with overall incidences 1.00 and 0.77 per 1000 person-years for females and males, respectively. Participants with late-onset asthma (onset age >12 years) comprised a large portion of adult current asthmatics. More than 52% of persistence or relapse was observed in early-onset asthma (onset age ≤12 years). The younger birth cohort had a more prominent later peak of asthma incidence than the older one.

CONCLUSIONS

In Asian population, asthma occurrence showed a U-shape age distribution with a prominent second peak in the thirties. A high proportion of early-onset asthma relapsed and most of late-onset asthma persisted or relapsed in adulthood.

Development of rhinitis may be an indicator for the persistence of childhood asthma

OBJECTIVES

Results of previous studies have established several factors related with the natural course of childhood asthma. The aim of this study is to investigate the prognosis of childhood asthma and to determine possible risk factors for disease persistence.

METHODS

An outpatient cohort with a median (interquartile range) follow-up duration of 19.4 (17.7-21.8) years was re-evaluated. Current clinical remission (CR) was defined as no asthma symptoms and no use of controller medication within the past year.

RESULTS

Out of 115 patients, 78 could be surveyed with questionnaire and 46 patients with a median age of 25.3 (23.9-27.0) years were further investigated with clinical work-up. Nineteen (24.4%) patients were in CR in both visits (adolescence and young adulthood). A further 7 patients (9.0%) who were not in CR at adolescence were in CR at the young adulthood visit. However, 21 patients (26.9%) who were in CR at adolescence were not in CR at the young adulthood visit. Thirty-one patients (39.7%) with persistent symptoms at adolescence were not in CR at young adulthood, either. In multivariate logistic models, the presence of obstructive pattern (forced expiratory volume in 1s (FEV1)/forced vital capacity (FVC) <80% vs. ≥80%) in pulmonary function tests during the adolescence period (odds ratio; [95% confidence interval] (6.71 [1.65-27.29]; p=0.008) and later-onset rhinitis (10.27 [1.18-89.13]; p=0.035) predicted the absence of CR at young adulthood.

CONCLUSION

A substantial number of patients who were in CR during adolescence have re-emerging disease. The presence of obstructive pattern in adolescence and later-onset rhinitis were associated with the absence of CR in young adults with asthma. Awareness of risk factors along with early interventions may provide better results in childhood asthma.

Outcomes of childhood asthma to the age of 50 years

BACKGROUND

In 1964, The Melbourne Asthma Study was established to describe the spectrum and natural history of childhood asthma.

OBJECTIVE

To describe the clinical and lung function outcome of childhood asthma to the age of 50 years.

METHOD

Subjects were invited to complete an interviewer-administered questionnaire, skin prick testing, and measurement of lung function from the age of 7 years to the age of 50 years at 7-year intervals.

RESULTS

Of 458 survivors (from the original 484 subjects at recruitment), 346 subjects (76%) participated, of whom, 197 completed lung function measurement. Asthma remission at the age of 50 years was 64% in those with wheezy bronchitis, 47% for those with persistent asthma, and 15% for those with severe asthma in childhood. Multivariable analysis identified severe asthma in childhood (odds ratio [OR] 11.9 [95% CI, 3.4-41.8]), female sex (OR 2.0 [95% CI, 1.1-3.6]), and childhood hay fever (OR 2.0 [95% CI, 1.0-4.0]) as risk factors for "current asthma" at age 50 years. There was no evidence of a difference in the rate of decline in FEV1 (mL/y, 95% CI) between the severe asthma group (15 mL/y [95% CI, 9-22 mL/y]) and all the other recruitment groups: control (16 mL/y [95% CI, 12-20 mL/y]), mild wheezy bronchitis (14 mL/y [95% CI, 8-19 mL/y]), wheezy bronchitis (16 mL/y [95% CI, 11-20 mL/y]), and persistent asthma (19 mL/y [95% CI, 13-24 mL/y]).

CONCLUSION

The clinical and lung function outcome in adult life is strongly determined by asthma severity in childhood. The reduced lung function seen in adults is established in childhood and does not appear to decline more rapidly in adult years despite continuing symptoms.

The potential to predict the course of childhood asthma

Many children experience pre-school or early childhood wheezing. In a significant proportion symptoms disappear as the child grows, but others have persistent and troublesome asthma which can be life-long. Tools to predict course of disease in young children are a priority for families and clinicians. This review summarizes evidence from several longitudinal population-based birth-cohort studies that have identified risk factors for persistence and remission of childhood asthma. These factors include clinical characteristics, environmental and other exposures, familial factors, biomarkers of allergic inflammation, measurements of lung function and airway responsiveness, and genetic variants. This review also introduces the concept of polygenic risk and genetic risk scores, and describes results from a recent study that suggests promise for the use of genetic information in predicting the course of childhood asthma. We conclude with a discussion of implications and future directions.

Risk factors for persistence of asthma in children: 10-year follow-up

OBJECTIVE

Risk factors related to the outcome of childhood asthma are not yet well established. We aimed to investigate the long-term outcome for children with asthma to determine the risk factors in predicting persistence of disease.

METHODS

Sixty-two children with asthma were evaluated retrospectively at the end of a 10-year follow-up. Patients were asked to complete a questionnaire requesting clinical information, and underwent physical examination, skin prick testing, a pulmonary function test and bronchial provocation testing. Immunologic parameters evaluated were allergen-specific IgE and IgG4 levels, and allergen-induced generation of CD4(+)CD25(+) cells.

RESULTS

Mean age at final assessment was 15.9 ± 3.6 years, and duration of follow-up was 10.30 ± 1.27 years. Fifty percent of patients outgrew their asthma during the 10-year follow-up period. All the non-atopic patients outgrew their disease during the study period, whereas 67% of atopic patients did not. We identified two risk factors independently related to the persistence of symptoms: presence of bronchial hyper-responsiveness and presence of rhinitis. Atopic children who were in remission demonstrated significantly higher allergen-induced CD4(+)CD25(+) T cells compared to healthy controls.

CONCLUSIONS

Atopy, presence of rhinitis, positive and presence of bronchial hyper-reactivity are important risk factors for the persistence of asthma in children. Allergen-induced CD4(+)CD25(+) T cells were higher in the atopic children who outgrew their disease, implicating an immunological mechanism of asthma remission in children.

Relevance of birth cohorts to assessment of asthma persistence

The definition of persistent asthma in longitudinal studies reflects symptoms reported at every assessment with no substantive asymptomatic periods. Early-childhood wheezing may be transient, especially if it is of viral etiology. Longitudinal studies provide greater opportunity to confirm the diagnosis by variability of symptoms, objective measurements, and therapeutic responses. Several clinical phenotypes of childhood asthma have been identified, with general consistency between cohorts. Persistent wheezing is often associated with loss of lung function, which is evident from early-childhood and related to persistent inflammation and airway hyperresponsiveness. Female sex, atopy, airway responsiveness, and personal smoking, but not exposure to environmental tobacco smoke, are risk factors for persistence of childhood asthma into adulthood. The effect of breastfeeding remains controversial, but gene-environment interactions may partly explain outcomes. Understanding the natural history and underlying causes of asthma may lead to development of strategies for primary prevention.

Childhood infections and the risk of asthma: a longitudinal study over 37 years

BACKGROUND

Few studies have examined common childhood infections and adult asthma. We examined associations between childhood infectious diseases, childhood pneumonia, and current, persisting, and incident asthma to middle age.

METHODS

We analyzed data from the Tasmanian Longitudinal Health Study (TAHS). A history of pneumonia was ascertained from their parents when the TAHS participants were 7 years old. Measles, rubella, mumps, chickenpox, diphtheria, and pertussis were identified from school medical records. Associations with current, persisting, or incident asthma were examined using regression techniques.

RESULTS

Greater infectious diseases load was negatively associated with persisting asthma at all ages. Individually, pertussis (adjusted OR [aOR], 0.53; 95% CI, 0.28-1.00) was negatively associated with asthma persisting to age 13 years, chickenpox (aOR, 0.58; 95% CI, 0.38-0.88) was negatively associated with asthma persisting to age 32 years, and rubella was negatively associated with asthma persisting to ages 32 (aOR, 0.61; 95% CI, 0.31-0.96) and 44 years (aOR 0.53; 95% CI, 0.35-0.82). Pertussis was associated with preadolescent incident asthma (adjusted hazard ratio [aHR], 1.80; 95% CI, 1.10-2.96), whereas measles was associated with adolescent incident asthma (aHR, 1.66; 1.06-2.56). Childhood pneumonia was associated with current asthma at ages 7 (aOR, 3.12; 95% CI, 2.61-3.75) and 13 years (aOR, 1.32; 95% CI, 1.00-1.75), an association stronger in those without than those with eczema (aOR, 3.46; 95% CI, 2.83-4.24 vs aOR, 2.08; 95% CI, 1.38-3.12).

CONCLUSIONS

Overall, childhood infectious diseases protected against asthma persisting in later life, but pertussis and measles were associated with new-onset asthma after childhood. Measles and pertussis immunization might lead to a reduction in incident asthma in later life.

The interplay between the effects of lifetime asthma, smoking, and atopy on fixed airflow obstruction in middle age

RATIONALE

The contribution by asthma to the development of fixed airflow obstruction (AO) and the nature of its effect combined with active smoking and atopy remain unclear.

OBJECTIVES

To investigate the prevalence and relative influence of lifetime asthma, active smoking, and atopy on fixed AO in middle age.

METHODS

The population-based Tasmanian Longitudinal Health Study cohort born in 1961 (n = 8,583) and studied with prebronchodilator spirometry in 1968 was retraced (n = 7,312) and resurveyed (n = 5,729 responses) from 2002 to 2005. A sample enriched for asthma and chronic bronchitis underwent a further questionnaire, pre- and post-bronchodilator spirometry (n = 1,389), skin prick testing, lung volumes, and diffusing capacity measurements. Prevalence estimates were reweighted for sampling fractions. Multiple linear and logistic regression were used to assess the relevant associations.

MEASUREMENTS AND MAIN RESULTS

Main effects and interactions between lifetime asthma, active smoking, and atopy as they relate to fixed AO were measured. The prevalence of fixed AO was 6.0% (95% confidence interval [CI], 4.5-7.5%). Its association with early-onset current clinical asthma was equivalent to a 33 pack-year history of smoking (odds ratio, 3.7; 95% CI, 1.5-9.3; P = 0.005), compared with a 24 pack-year history for late-onset current clinical asthma (odds ratio, 2.6; 95% CI, 1.03-6.5; P = 0.042). An interaction (multiplicative effect) was present between asthma and active smoking as it relates to the ratio of post-bronchodilator FEV(1)/FVC, but only among those with atopic sensitization.

CONCLUSIONS

Active smoking and current clinical asthma both contribute substantially to fixed AO in middle age, especially among those with atopy. The interaction between these factors provides another compelling reason for atopic individuals with current asthma who smoke to quit.

Does bronchial hyperresponsiveness in childhood predict active asthma in adolescence?

RATIONALE

Bronchial hyperresponsiveness (BHR) is an important, but not specific, asthma characteristic.

OBJECTIVES

We aimed to assess the predictive value of BHR tested by methacholine and exercise challenge at age 10 years for active asthma 6 years later.

METHODS

From a Norwegian birth cohort, 530 children underwent methacholine challenge and exercise-induced bronchoconstriction (EIB) test (n = 478) at 10 years and structured interview and clinical examination at age 16 years. The methacholine dose causing 20% reduction in FEV(1) (PD(20)) and the reduction in FEV(1) (%) after a standardized treadmill test were used for BHR assessment. Active asthma was defined with at least two criteria positive: doctor's diagnosis of asthma, symptoms of asthma, and/or treatment for asthma in the last year.

MEASUREMENTS AND MAIN RESULTS

PD(20) and EIB at 10 years of age increased the risk of asthma (β = 0.94 [95% confidence interval (CI), 0.92-0.96] per μmol methacholine and β = 1.10 [95% CI, 1.06-1.15] per %, respectively). Separately the tests explained 10 and 7%, respectively, and together 14% of the variation in active asthma 6 years later. The predicted probability for active asthma at the age of 16 years increased with decreasing PD(20) and increasing EIB. The area under the curve (receiver operating characteristic curves) was larger for PD(20) (0.69; 95% CI, 0.62-0.75) than for EIB (0.60; 95% CI, 0.53-0.67).

CONCLUSIONS

BHR at 10 years was a significant but modest predictor of active asthma 6 years later, with methacholine challenge being superior to exercise test.

Different implications of paternal and maternal atopy for perinatal IgE production and asthma development

Asthma is a hereditary disease associated with IgE-mediated reaction. Whether maternal atopy and paternal atopy have different impacts on perinatal IgE production and asthma development remains unclear. This paper reviews and summarizes the effects of maternal and paternal atopy on the developmental aspects of IgE production and asthma. Maternal atopy affects both pre- and postnatal IgE production, whereas paternal atopy mainly affects the latter. Maternally transmitted genes GSTP1 and FceRI-beta are associated with lung function and allergic sensitization, respectively. In IgE production and asthma development, the maternal influence on gene-environment interaction is greater than paternal influence. Maternal, paternal, and/or postnatal environmental modulation of allergic responses have been linked to epigenetic mechanisms, which may be good targets for early prevention of asthma.

Epidemiology of asthma: risk factors for development

This comprehensive review of the recent literature was undertaken to determine the current state of knowledge of the risk factors involved in the development of asthma in order to focus investigations in a proposed new longitudinal birth cohort study. The origins of asthma appear to lie in the prenatal and early postnatal period, and renewed investigations in this period with long-term close follow-up and objective phenotypic characterization will help to unravel the role of the multiple putative environmental factors in the development of asthma. It is only after understanding these effects that one can hope to design rational prevention studies for asthma.

Trends in prevalence of childhood and parental asthma in Merseyside, 1991-2006

BACKGROUND

To determine changes in prevalence of parental and childhood asthma in Merseyside between 1991 and 2006.

METHODS

Four standardized cross-sectional respiratory surveys using a parent-completed questionnaire were completed in 1991 (n = 1171), 1993 (n = 2368) 1998 (n = 1964) and in 2006 (n = 1074) among primary school children attending the same schools in lower socio-economic areas of Merseyside. Main outcome measures were prevalence of doctor diagnosed asthma (DDA) and the symptom triad of cough, wheeze and breathlessness (C+W+B+).

RESULTS

Between 1991 and 1998 prevalence of DDA increased (P < 0.001), but in 2006 this decreased from 29.8 to 19.4% (P < 0.001). Prevalence of C+W+B+ increased from 7.8 to 8.0% by 1998, then decreased to 6.7% in 2006 (P = 0.39). Between 1998 and 2006, childhood hospital admissions for respiratory illness decreased from 11.3 to 9.7% (P = 0.23). During this period paternal asthma prevalence increased from 8.6 to 10.7% (P = 0.001) and maternal asthma from 11.2 to 13.4% (P = 0.09).

CONCLUSIONS

An increase in the prevalence of DDA and asthmatic respiratory symptoms occurred in children prior to 1998, but this had decreased by 2006. Prevalence of parental asthma increased during the same period.

Childhood immunization and atopic disease into middle-age--a prospective cohort study

The association between childhood immunizations and risk of atopic diseases is unclear. No study has examined possible associations between childhood immunizations and such diseases in middle age. The Tasmanian Longitudinal Health Study (TAHS) is a population based cohort study of respiratory disease. The TAHS participants were followed from 7 to 44 yrs of age. Immunizations during childhood were examined for any association with asthma and atopic disease at age 44 yrs. Multivariable regression models were used to estimate relative risks while adjusting for confounders. Cox regression was used to estimate the association between childhood immunizations and asthma developing after the age of 7 yrs. We found no association between any childhood immunization (Diphtheria, Tetanus, Pertussis, Polio, Smallpox) and asthma (ORs ranged from 0.87 to 1.17 p > 0.05), eczema (ORs ranged from 0.99 to 1.07 p > 0.05), food allergy (ORs ranged from 0.97 to 1.11 p > 0.05), or hay fever (ORs ranged from 1.02 to 1.05 p > 0.05) at age 44. Nor did we find any association between childhood immunizations and an increased risk of incident asthma after the age of 7 yrs (Diphtheria HR = 1.06, 95% CI 0.82, 1.36; Tetanus HR = 1.13, 95% CI 0.88, 1.44; Pertussis HR = 1.03, 95% CI 0.81, 1.30; Polio HR = 1.15, 95% CI 0.86, 1.54; Smallpox HR = 1.21, 95% CI 0.99, 1.48; DTP HR = 1.05, 95% CI 0.85, 1.30). Our analysis does not support any association between common childhood immunizations and risk of asthma and atopic disease in middle-age. Our findings should provide reassurance that in terms of life time risk of asthma and atopic disease, childhood immunization is safe.

Predictors of remitting, periodic, and persistent childhood asthma

BACKGROUND

The course of mild to moderate persistent asthma in children is not clearly established.

OBJECTIVE

To determine the rate and predictors for remitting, periodic, and persistent asthma in adolescence.

METHODS

The Childhood Asthma Management Program (CAMP) was a 4.3-year randomized, double-masked, multicenter trial in children with mild to moderate persistent asthma that compared continuous therapy with either budesonide or nedocromil, each to placebo, followed by a 4-year observational follow-up period. Asthma activity during the observation period included remitting (no asthma activity in the last year), persistent (asthma activity in every quarter), and periodic asthma (neither remitting nor persistent).

RESULTS

Asthma was identified as remitting in 6%, periodic in 39%, and persistent in 55% of the 909 participants, with no effect noted from earlier anti-inflammatory treatment during the CAMP trial. Within all 3 asthma activity categories, improvements in airway hyperresponsiveness, eosinophilia, and asthma morbidity were observed over time. Features at entry into CAMP associated with remitting versus persistent asthma were lack of allergen sensitization and exposure to indoor allergens (odds ratio [OR], 3.23; P < .001), milder asthma (OR, 2.01; P = .03), older age (OR, 1.23; P = .01), less airway hyperresponsiveness (higher log methacholine FEV(1) PC(20) (OR, 1.39; P = .03), higher prebronchodilator FEV(1) percent predicted (OR, 1.05; P = .02), and lower forced vital capacity percent predicted (OR, 0.96; P = .04).

CONCLUSION

Remission of asthma in adolescence is infrequent and not affected by 4 years of anti-inflammatory controller therapy. Factors such as sensitization and exposure, low lung function, and airway greater hyperresponsiveness decrease the likelihood of remitting asthma.