The clinical expression of asthma in schoolchildren has changed between 1996 and 2006

Is asthma in children still increasing? 20-year prevalence trends in northern Sweden

BACKGROUND

In the present study, we describe prevalence trends of asthma and investigate the association with asthma symptoms, use of asthma medication, and asthma severity among 8-year-old children in Norrbotten, Sweden in 1996, 2006, and 2017.

METHODS

Within the Obstructive Lung Disease in Northern Sweden (OLIN) studies, three pediatric cohorts were recruited in 1996, 2006, and 2017 respectively. Identical methods were used; all children in first and second grade (median age 8 years) in three municipalities were invited to a parental questionnaire survey, completed by n = 3430 in 1996 (97% participation), n = 2585 in 2006 (96%), and n = 2785 in 2017 (91%). The questionnaire included questions about respiratory symptoms and diagnosis, treatment, and severity of asthma.

RESULTS

The prevalence of wheezing was stable during the study, 10.1% in 1996; 10.8% in 2006; and 10.3% in 2017, p = .621, while physician-diagnosed asthma increased: 5.7%, 7.4%, and 12.2%, p < .001. The use of asthma medication in the last 12 months increased: 7.1%, 8.7%, and 11.5%, p < .001. Among children diagnosed with asthma, the prevalence of asthma symptoms, the impact on daily life, and severe asthma decreased, while the use of inhaled corticosteroids increased from 1996 until 2017.

CONCLUSION

The prevalence of wheezing was stable among 8-year-old in this area from 1996 to 2017, while the prevalence of physician-diagnosed asthma doubled but without an increase in asthma morbidity. The increase of physician-diagnosed asthma without a coincident increase in asthma morbidity can partly be explained by more and earlier diagnosis among those with mild asthma.

Decreasing prevalence of atopic dermatitis in Swedish schoolchildren: three repeated population-based surveys

BACKGROUND

The prevalence of atopic dermatitis (AD) has increased over several decades and now affects about one-fifth of all children in high-income countries (HICs). While the increase continues in lower-income countries, the prevalence of AD might have reached a plateau in HICs.

OBJECTIVES

To investigate trends in the prevalence of AD and atopic comorbidity in schoolchildren in Sweden.

METHODS

The study population consisted of three cohorts of children (median age 8 years) in Norrbotten, Sweden, for 1996 (n = 3430), 2006 (n = 2585) and 2017 (n = 2785). An identical questionnaire that included questions from the International Study of Asthma and Allergies in Childhood (ISAAC) protocol was used in all three cohorts. Trends in AD prevalence were estimated, as well as trends in atopic comorbidity. AD prevalence was estimated both according to the ISAAC definition of AD and by adding the reported diagnosis by a physician (D-AD).

RESULTS

The prevalence of AD decreased in the last decade, from 22.8% (1996) and 21.3% (2006) to 16.3% (2017; P < 0.001). The prevalence of D-AD was lower, but the same pattern of decrease was seen, from 9.3% (1996) and 9.4% (2006) to 5.7% (2017; P < 0.001). In all three cohorts, AD was more common among girls than boys (18.9% vs. 13.8% in 2017; P < 0.001). Children from the mountain inlands had a higher prevalence of AD than children from coastal cities (22.0% vs. 15.1% in 2017; P < 0.001). In comparing D-AD, there were no significant differences between the sexes or between inland or coastal living. Concomitant asthma increased over the years from 12.2% (1996) to 15.8% (2006) to 23.0% (2017; P < 0.001). Concomitant allergic rhinitis and allergic sensitization increased from 1996 (15.0% and 27.5%) to 2006 (24.7% and 49.5%) but then levelled off until 2017 (21.0% and 46.7%).

CONCLUSIONS

The prevalence of AD among schoolchildren in Sweden decreased over the study period, whereas atopic comorbidity among children with AD increased. Although a decrease was seen, AD is still common and the increase in atopic comorbidity among children with AD, especially the increase in asthma, is concerning.

Prevalence and risk factors for allergic sensitization: 3 cross-sectional studies among schoolchildren from 1996 to 2017

Background

The prevalence of allergic sensitization and allergic diseases has increased for decades in Northern Europe, but recent studies are lacking.

Objective

We sought to study the prevalence trends of allergic sensitization, associated risk factors, and the association with asthma and allergic rhinitis (AR) among children in Northern Sweden.

Methods

Three cohorts of children aged 7 to 8 years participated in a skin prick test (SPT) with 10 airborne allergens in 1996, 2006, and 2017, with 2148, 1693, and 1762 participants tested, respectively, representing 87% to 90% of schoolchildren in the catchment communities. Adjusted Poisson regression was used to identify risk factors for allergic sensitization and the association with asthma and AR.

Results

The prevalence of any positive SPT response increased from 21% in 1996 to 30% in 2006 and remained at 30% in 2017 (P < .001). Sensitization to cat was the most common for all the years. The risk factor pattern for a positive SPT response was similar in all examinations, with positive and significant associations with a family history of allergy (risk ratio, 1.4-1.5) and negative and significant associations with having a cat at home (risk ratio, 0.7-0.8). The prevalence of physician-diagnosed asthma increased, but the association with allergic sensitization weakened. The opposite trends were found for AR-decreasing prevalence and strengthened association with allergic sensitization.

Conclusions

The prevalence of allergic sensitization increased from 1996 to 2006 but plateaued in the next decade, whereas the risk factor pattern remained stable. The diverging trends of associations between allergic sensitization and asthma and AR suggest secular trends in the clinical management of allergic diseases.

Patient Delay, Lead Times, and Adherence to Diagnostic Guidelines in Children and Adolescents With Idiopathic Intracranial Hypertension

AIMS

In a cohort of 45 children and adolescents diagnosed with idiopathic intracranial hypertension (IIH), our main aims were to investigate patient delay, lead time to final diagnosis, and adherence to current diagnostic guidelines.

METHODS

This population-based, retrospective, single-center cohort study was performed at Uppsala University Children's Hospital, Sweden, a tertiary referral center for children and adolescents with rare and/or complicated neurologic disease. Patient data were retrieved from the local registries for patients filling the following criteria: age (0-17.99 yr), study period (2000-2020), and International Classification of Diseases code G93.2 (IIH). Medical records from pediatric, neuropediatric, ophthalmology, and neurosurgery departments were scrutinized. All included patients met the Friedman criteria.

RESULTS

Fifty-one percent of the patients sought medical advice within 1 month of symptom debut, 23% were seen within 1 to three months, and 26% after three months. A final diagnosis of IIH was reached within 48 hours in 60%, within two weeks in 80%, and within four weeks in 89% of patients. Visual fields, color vision, and complete ancillary laboratory investigations to exclude secondary etiologies were performed in 62%, 47%, and 59% of patients, respectively.

CONCLUSION

The clinical presentation of IIH in children and adolescents may range from acute fulminant symptoms, to a more insidious or even chronic presentation with long-term headache. Although a majority of patients received a correct and prompt diagnosis, lead time to final diagnosis and adherence to diagnostic care guidelines might be improved. A higher awareness and knowledge of the condition may achieve this.

Perimenstrual Asthma in Adolescents: A Shared Condition in Pediatric and Gynecological Endocrinology

Asthma is a frequent medical condition in adolescence. The worsening of the most common symptoms perimenstrually is defined as perimenstrual asthma (PMA). The cause of PMA remains unclear, but a role for hormonal milieu is plausible. Data on PMA in adolescents are limited, and its management is not fully established. We aimed to discuss the PMA phenomenon in young females from pathophysiology to preventive strategies, focusing on the relationship with the hormonal pattern. The fluctuation of estrogens at ovulation and before menstruation and the progesterone secretion during the luteal phase and its subsequent withdrawal seem to be the culprits, because the deterioration of asthma is cyclical during the luteal phase and/or during the first days of the menstrual cycle. Conventional asthma therapies are not always effective for PMA. Preventive strategies may include innovative hormonal contraception. Even a possible beneficial effect of other hormonal treatments, including estrogens, progestogens, and androgens, as well as leukotriene receptor antagonists and explorative approach using microbial-directed therapy, is considered. The underlying mechanisms, through which sex-hormone fluctuations influence asthma symptoms, represent a challenge in the clinical management of such a distressing condition. Further studies focused on young females are mandatory to promote adolescent health.

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.

Parental questionnaires provided reliable data on childhood asthma compared with national registers

BACKGROUND

Much of our knowledge of childhood asthma comes from questionnaire-based studies. Our main aim was to assess the agreement between parental-reported data at 12 years of age and data from two national Swedish registers.

METHODS

Data were obtained from the prospective, longitudinal, population-based Children of Western Sweden cohort, which focused on children born in 2003. The parents answered questionnaires at six months and one, four, eight and 12 years of age. Personal identity numbers linked 3634 children to the Swedish Prescribed Drug Register (SPDR) and the National Patient Register (NPR).

RESULTS

At 12 years of age, there was substantial overall agreement between the asthma medication reported by the parents in the questionnaire and the SPDR for any asthma medication (94.8%, kappa 0.71) and maintenance treatment (95.3%, kappa 0.68). In contrast, the agreement between the outpatient asthma diagnoses in the NPR and the questionnaire-based asthma was 30.5% and it was 32.8% between the NPR and the dispensed asthma medication in the SPDR. Hospitalization was rare for obstructive diseases after early childhood, and 38.2% of the 12-year-old children only received a short-acting beta agonist, with no maintenance treatment.

CONCLUSION

There was good agreement between the questionnaire-based data on asthma medication and the national drug register, but the National Patient Register provided incomplete information on asthma diagnoses, probably because it did not include primary care diagnoses. The results show that well-constructed parental questionnaires can provide reliable data on childhood asthma.

Adolescent girls with asthma have worse asthma control and health-related quality of life than boys-A population based study

BACKGROUND

Population-based studies investigating health-related quality of life (HRQoL) among asthmatic adolescents are rare. Further, among subjects with asthma, HRQoL may be affected by asthma control and severity.

AIM

To investigate HRQoL in relation to asthma control and asthma severity among adolescents.

METHOD

As a part of the population-based OLIN pediatric study, 266 adolescents with current asthma (14-15 yr) were identified. N = 247 completed the DISABKIDS HRQoL asthma module, including the domains impact and worry. The Asthma Control Test (ACT) was used and a disease severity score was calculated based on symptoms and medicine use.

RESULTS

The prevalence of current asthma was 11%. Well-controlled asthma was reported by 15% of the adolescents, and 53% had partly controlled asthma. The prevalence of uncontrolled asthma was significantly higher among girls than boys (38% vs 25%), and girls also reported lower HRQoL scores. There was a fairly strong correlation between the ACT and DISABKIDS scores. Independent risk factors for low HRQoL impact (a score <67) were female sex (OR 4.66, 95%CI 1.82-9.54) and decreased ACT scores (1.38, 1.18-1.62). Risk factors for low HRQoL worry (a score <70) were female sex (3.33, 1.41-7.86), decreased ACT scores (1.35, 1.16-1.57), severe asthma (6.23, 1.46-16.50), and having current eczema (2.68, 1.00-7.24).

CONCLUSION

Only a minority of the asthmatic adolescents reported well-controlled asthma, and poor asthma control and female sex were risk factors for low HRQoL. Our results demonstrate that evaluation of asthma control is of great importance for asthma management.

Asthma in adolescence affects daily life and school attendance - Two cross-sectional population-based studies 10 years apart

Aim

The aim of this study was to study the impact of asthma on daily life, school absenteeism and physical education. In addition, to describe asthma triggers at school.

Design

Two cross‐sectional population‐based studies ten years apart.

Method

Within the OLIN‐studies, in 2003 (n = 3,327) and in 2013 (n = 2,345) adolescents (14–15 years) answered an expanded ISAAC questionnaire. Of these, 8% and 11%, respectively with current asthma participated in this study.

Results

Between the years 2003–2013, the proportion of adolescents reporting that asthma interfered with daily life had increased, in 2013, girls were significantly more affected than boys. The proportion reporting a worsening of asthma at school had decreased, but it was still over a quarter. The proportion of absenteeism from school and from physical education was at the same level both years. Asthma triggers were described to be poor air quality, poorly cleaned environment, allergens, strong fragrance, rebuilding projects, physical education and stress.

Asthma in adolescence: Is there any news?

Asthma is a chronic disease that has a significant impact quality of life, which is particularly important in adolescence. We will discuss aspects of epidemiology, the clinical spectrum, diagnostics, and management of asthma in adolescence. In particular, we will highlight the psychological implications of having asthma during this developmental period. Data published in the past 10 years, since we last reviewed the subject, will be the main focus of this paper. The care of the teenager with asthma should take into account the rapid physical, emotional, cognitive, and social changes that occur during normal adolescence. The diagnostic process may be more difficult since teenagers tend to deny their illness. Thus, both under-diagnosis and under-assessment of asthma severity may lead to under-treatment and potentially avoidable morbidity and even mortality. Conversely, teenagers may be often misdiagnosed as having asthma or their asthma severity may be overestimated leading to inappropriate and sometimes excessive treatment. Educational programs, environmental avoidance measures, proper use of medications along with a skilled approach, and a caring attitude of health providers are all very important for successful management. Pediatr Pulmonol. 2017;52:129-138. © 2016 Wiley Periodicals, Inc.

The allergic march comprises the coexistence of related patterns of allergic disease not just the progressive development of one disease

Aim

This study explored the development and comorbidity of allergic diseases by analysing the relationship between allergic manifestations in infancy and at the age of 8.

Methods

We included 5654 children born in Sweden in 2003 in a longitudinal study. Parents answered postal questionnaires when the children were six months and one, four‐and‐a‐half and eight years of age.

Results

The response rate at eight years was 4051 (71.6%), and we analysed 3382 children with complete data. The number of manifestations in infancy increased the risk of allergic disease at eight years of age: 72% of children with one early manifestation were symptom free at 8, compared to 45% with two or more manifestations. Similar manifestations occurred in infancy and at the age of 8, for example recurrent wheeze increased the risk of doctor‐diagnosed asthma by an adjusted odds ratio of 6.5. Eczema and food allergy independently increased the risk of all four allergic manifestations at eight years.

Conclusion

Allergic disease at the age of 8 was related to the number of allergic manifestations in infancy. Manifestations were similar at both ages, suggesting an allergic march with the coexistence of disease patterns rather than the progressive development of one disease.

Swimming pool attendance is related to asthma among atopic school children: a population-based study

BACKGROUND

By-products of water disinfectants have been suggested to cause asthma, especially in atopic children. However, studies on indoor swimming pool attendance and asthma in children have presented conflicting results. The present study examined the relationship between indoor swimming pool attendance and asthma among sensitized and non-sensitized children aged 11-12 years.

METHODS

An extended ISAAC questionnaire was sent to the families of all children attending fifth or sixth grade, aged 11-12 years, in two municipalities in Northern Sweden in 2010. A total of 1866 participated (96% of those invited) in the questionnaire study and 1652 (89%) also participated in skin prick testing for 10 standard airborne allergens. Asthma was defined as physician-diagnosed asthma in combination with wheeze or use of asthma medication in the last 12 months. Current swimming pool attendance was reported as ≥ 1/week or <1/week. Logistic regression models were used for data analysis.

RESULTS

The prevalence of current asthma was 8.9% (10.0% of boys; 7.9% of girls) and 14% had attended indoor pools ≥ 1/week. Children currently attending swimming pools ≥ 1/week had an increased risk of current asthma. Stratified analyses for allergic sensitization adjusted for sex, parental smoking, parental asthma, and damp housing, showed a statistically significant association for current asthma only among sensitized subjects (OR 95% CI 1.90 1.09-3.32). No association was found between current pool attendance and wheeze, sensitization, rhinitis or eczema.

CONCLUSIONS

The present study supports the proposed link between indoor swimming pool attendance and asthma in sensitized children.

Trends in the prevalence of asthma, rhinitis, and eczema in 15 year old adolescents over an 8 year period

BACKGROUND

Trends in prevalence of asthma and allergic diseases are still controversial, and rarely studied among adolescents at midpoint of puberty.

METHODS

In 2000, a questionnaire was mailed to adolescents (n = 18,158) attending 9th grade at school and living in Västra Götaland County, Sweden. Eight years later, the same questionnaire was mailed to adolescents (n = 21,651), using identical inclusion criteria as previously. Altogether, 10,837 adolescents completed the questionnaire in 2000 and 11,754 in 2008. Differences in prevalence of physician diagnosed asthma, asthma symptoms, rhinitis, and eczema between the periods were analyzed by Chi-square test. Multiple logistic regression models were performed to test for trends in prevalence of these diseases, adjusting for potential confounders.

RESULTS

Physician diagnosed asthma and lifetime and current rhinitis were increased in 2008, while wheeze decreased (p < 0.05). Taking sex, foreign descent, body mass index, and parents' education into account, the prevalence of physician diagnosed asthma (OR 1.3 [95% CI 1.2-1.4]) and lifetime (1.7 [1.6-1.8]) and current rhinitis (1.5 [1.4-1.6]) had increased. Eczema had decreased (0.9 [0.8-0.98]). These trends were consistent in boys and girls, but more prominent in those with obesity. In physician diagnosed asthmatics, there was no change in wheeze, asthma symptoms, or asthma medication.

CONCLUSIONS

The prevalence of physician diagnosed asthma has increased over the last decade, maybe due to combinations of changes in diagnostics and increased general awareness, rather than a real increase. Results showed an increase in rhinitis and a decrease in eczema. Obesity seems to have a modifying effect, which calls for further investigation.

Asthma Heredity, Cord Blood IgE and Asthma-Related Symptoms and Medication in Adulthood: A Long-Term Follow-Up in a Swedish Birth Cohort

Cord blood IgE has previously been studied as a possible predictor of asthma and allergic diseases. Results from different studies have been contradictory, and most have focused on high-risk infants and early infancy. Few studies have followed their study population into adulthood. This study assessed whether cord blood IgE levels and a family history of asthma were associated with, and could predict, asthma medication and allergy-related respiratory symptoms in adults. A follow-up was carried out in a Swedish birth cohort comprising 1,701 consecutively born children. In all, 1,661 individuals could be linked to the Swedish Prescribed Drug Register and the Medical Birth Register, and 1,227 responded to a postal questionnaire. Cord blood IgE and family history of asthma were correlated with reported respiratory symptoms and dispensed asthma medication at 32-34 years. Elevated cord blood IgE was associated with a two- to threefold increased risk of pollen-induced respiratory symptoms and dispensed anti-inflammatory asthma medication. Similarly, a family history of asthma was associated with an increased risk of pollen-induced respiratory symptoms and anti-inflammatory medication. However, only 8% of the individuals with elevated cord blood IgE or a family history of asthma in infancy could be linked to current dispensation of anti-inflammatory asthma medication at follow-up. In all, 49 out of 60 individuals with dispensed anti-inflammatory asthma medication at 32-34 years of age had not been reported having asthma at previous check-ups of the cohort during childhood. Among those, only 5% with elevated cord blood IgE and 6% with a family history of asthma in infancy could be linked to current dispensation of anti-inflammatory asthma medication as adults. Elevated cord blood IgE and a positive family history of asthma were associated with reported respiratory symptoms and dispensed asthma medication in adulthood, but their predictive power was poor in this long-time follow-up.

Allergic airway diseases in childhood - marching from epidemiology to novel concepts of prevention

In the past years, a wide range of epidemiological, clinical, and experimental studies have produced remarkable advances in the field of respiratory allergies in childhood. By the recent investigations on epidemiological trends, risk factors, and prevention of asthma and allergic rhinitis, various exiting concepts have been challenged, and novel innovative approaches have been developed. Pediatric Allergy and Immunology (PAI), with a number of highly relevant contributions between 2010 and 2012, has become an important forum in this area. The prevalence of asthma in some developed countries may have reached a plateau, while in developing countries, where the prevalence was previously low, allergic diseases are still on the increase. A wide array of risk and protective factors, including hygiene, infections, outdoor and indoor air pollution, allergen exposure, breast-feeding practices, nutrition, and obesity, play a multifaceted role in shaping the observed worldwide trends of respiratory allergies. Under the guidance of recent research, prediction and prevention strategies in the clinical practice are progressively changing, the focus moving away from avoidance of allergen exposure and toward tolerance induction.

High basophil allergen sensitivity (CD-sens) is associated with severe allergic asthma in children

Children with problematic severe asthma (PA) have persistent symptoms and/or severe exacerbations despite treatment with several drugs. Classification of asthma severity is currently based on level of treatment and assessment of asthma control, but objective biomarkers of asthma severity are needed. To investigate the clinical relevance of basophil allergen threshold sensitivity (CD-sens) as a measure of allergen sensitivity in a well-characterized cohort of children with different manifestations of persistent allergic asthma. Cat-allergic children (6-18 yr) with problematic severe asthma (n = 11) according to GINA were compared with eleven age-matched children with controlled, but persistent asthma (CA). The protocol included standardized questionnaires, asthma control test (ACT), spirometry, methacholine challenges, measurement of FE(NO,) IgE, cat IgE and IgG antibodies, and analysis of CD-sens (CD63-expression) by flow cytometry. The 11 cat-allergic children with PA had a significantly lower ACT score (p < 0.001), reduced FEV(1) (p = 0.04), and increased numbers of blood eosinophils (p = 0.03) compared with the 11 children with CA. The former exhibited a higher CD-sens to cat (p = 0.02). No significant differences were detected with respect to FE(NO) (p = 0.17), IgE (p = 0.84), cat IgE (p = 0.12), and the major cat-allergen rFel d 1 (p = 0.30). CD-sens significantly correlated with ACT (p = 0.002, r = -0.63) and FE(NO) (p = 0.01, r = 0.55). No significant differences between PA and CA were found regarding IgG antibodies to rFel d 1. Cat-allergic children with problematic severe asthma have higher sensitivity to cat allergen, as measured by CD-sens, compared with children with controlled asthma. This suggests that CD-sens could be used as an additional marker for identifying children with the most severe allergic asthma.

Allergic diseases and respiratory symptoms in urban and rural children in Grodno Region (Belarus)

BACKGROUND

Because of the unknown frequency of asthma and other common allergic diseases in children living in Belarus, we conducted a population-based respiratory health survey. The objective of the study was to estimate the prevalence of allergic diseases and major allergic symptoms in children of the Grodno Region (Western Belarus) and to examine their familial and environmental correlates.

METHODS

The cross-sectional study was conducted in 2010 and included 2606 urban and 2422 rural children aged 6-16 years. Physician-diagnosed respiratory diseases and symptoms were ascertained using the ISAAC questionnaire completed by the parents. Both family and environmental factors were examined for their association with respiratory health outcomes including asthma and spastic bronchitis. Descriptive statistics and multiple logistic regression analysis were used to test associations.

RESULTS

The prevalence of asthma, atopic eczema and allergic rhinitis was 1.39%, 10.25%, and 3.84%, respectively. Spastic bronchitis was reported for 6.74% of children. Chronic respiratory symptoms occurring in the past 12 months and suggestive of asthma included chest wheeze (9.71%) attacks of dyspnea at rest (1.77%), symptoms of hay fever (2.45%) attacks of sneezing and nasal congestion without a cold (6.78%), and recurrent itchy rash (13.48%). All diseases except for asthma and spastic bronchitis as well as symptoms of hay fever, congested nose and itchy rash were more frequent in urban than in rural children (p < 0.05). Results of multivariate logistic analysis confirmed associations (p < 0.05) between asthma and parental asthma (OR = 4.82) and dampness in home (OR = 2.12) after adjustment for age, gender and place of residence. Spastic bronchitis in children who did not have a concurrent diagnosis of asthma was related (p < 0.05) to parental asthma (OR = 2.18), dampness in the home (OR = 1.68) and less use of coal-based heating (OR = 0.64). Allergic rhinitis and atopic eczema were associated (p < 0.05) with parental asthma (OR = 5.07 and OR = 1.91, respectively), dampness (OR = 2.33 and OR = 1.51, respectively), lower parental education (OR = 0.74 and OR = 0.68, respectively) and household density (OR = 0.84 and OR = 0.92), respectively.

CONCLUSIONS

The findings show a low prevalence of allergic diseases and symptoms in children of Western Belarus, following similar East-West gradients described in the literature. All allergic disorders except asthma were less frequent in the rural population. A very low prevalence of childhood asthma and the possibility of underdiagosis of the disease in the surveyed population deserve further investigation.

Conventional epidemiology underestimates the incidence of asthma and wheeze-a longitudinal population-based study among teenagers

Background

Because of shifts in the gender ratio and incidence and remission rates of asthma during the teen ages, the methodology of incidence studies among teenagers is important, i.e. if the time intervals between surveys are too long, the incident cases might not be properly identified. The aim was to study the impact of study design on the incidence rates of asthma and wheeze during the teen ages.

Methods

In a study about asthma and allergic diseases within the OLIN studies (Obstructive Lung Disease in northern Sweden), a cohort of school children (n = 3,430) was followed annually by questionnaire from age 8 yrs. In the endpoint survey (age 18 yrs) 2,582 (75% of original responders) participated. Incident cases from age 12-18 yrs were identified by two methods: annual questionnaire reports (AR) and baseline-endpoint surveys only (BE).

Results

The cumulative incidence of asthma and wheeze was significantly higher based on AR compared to BE. Compared to the incidence rates based on all the annual surveys, the calculated average annual rates based on BE were in general lower both among the boys and among the girls. There were no differences between boys and girls in incidence rates of asthma or wheeze during the early teen years. However, from the age of 15 years, the annual incidence rates were significantly or borderline significantly higher among girls than boys. At onset, the additional cases of current asthma identified by AR had significantly less severe asthma than those identified in BE (p < 0.02).

Conclusion

the size of the incidence of asthma and wheeze during the teen ages was influenced by study design. By using the conventional prospective study design with longer follow-up time, the incidence was underestimated.

Pregnancy exposures and risk of childhood asthma admission in a population birth cohort

BACKGROUND

There is increasing interest in the potential for in utero exposures to affect the risk of asthma. We used population data to explore the associations between perinatal conditions and the risk of hospital admission with asthma between the 2nd and 5th birthday.

METHODS

The study population was 240,511 singleton infants born during 2001-2003. Birth records and longitudinally linked hospital admissions were used to identify asthma admissions and to model potential risk factors.

RESULTS

A total of 7245 children (3.0%) had one or more childhood admissions with asthma. In utero infectious exposures associated with childhood asthma were maternal antenatal admission with a urinary tract infection (UTI) [adjusted odds ratio (aOR) = 1.49, 95% confidence interval (1.23-1.79)] and pre-term pre-labor rupture of membranes (PROM) [aOR = 1.23 (1.04-1.45)]. There was no evidence that gestational age at time of first antenatal UTI admission (<28, ≥ 28 wks) affected the risk of asthma (homogeneity test p = 0.6). Pre-term birth was a risk factor for asthma admission, with the risk decreasing by 5.3% with each extra week of gestation. Autumn and winter conceptions were associated with an increased risk of childhood asthma admission: winter aOR = 1.15 (1.08-1.23), autumn aOR = 1.09 (1.02-1.16).

CONCLUSIONS

As in utero exposure to both UTI and PROM carry an increased risk of childhood asthma admission, this suggests that the immune system response generally is the relevant factor rather than a specific organism. The season-associated risk is consistent with early pregnancy exposures such as the winter flu season or low vitamin D.

Heavy vehicle traffic is related to wheeze among schoolchildren: a population-based study in an area with low traffic flows

BACKGROUND

An association between traffic air pollution and respiratory symptoms among children has been reported. However, the effects of traffic air pollution on asthma and wheeze have been very sparsely studied in areas with low traffic intensity in cold climate with poor dispersion. We evaluated the impact of vehicle traffic on childhood asthma and wheeze by objective exposure assessment.

METHODS

As a part of the Obstructive Lung Disease in Northern Sweden (OLIN) studies, a questionnaire was sent to the families of all children attending first or second grade in Luleå (72,000 inhabitants) in Northern Sweden in 2006. The age of the children was 7-8 years and the participation rate was 98% (n = 1357). Skin prick tests were performed in 1224 (89%) children. The home addresses were given geographical coordinates and traffic counts were obtained from the local traffic authorities. A proximity model of average daily traffic and average daily heavy vehicle traffic within 200 meters from each participant's home address was used. The associations between traffic exposure and asthma and wheeze, respectively, were analysed in an adjusted multiple logistic regression model.

RESULTS

Exposure to high traffic flows was uncommon in the study area; only 15% of the children lived within 200 meters from a road with a traffic flow of ≥8000 vehicles per day. Living closer than 200 meters from a road with ≥500 heavy vehicles daily was associated with current wheeze, odds ratio 1.7 (confidence interval 1.0-2.7). A dose-response relation was indicated. An increased risk of asthma was also seen, however not significant, odds ratio 1.5 (confidence interval 0.8-2.9). Stratified analyses revealed that the effect of traffic exposure was restricted to the non-sensitized phenotype of asthma and wheeze. The agreement between self-reported traffic exposure and objective measurements of exposure was moderate.

CONCLUSIONS

This study showed that already at low levels of exposure, vehicle traffic is related to an increased risk of wheeze among children. Thus, the global burden of traffic air pollution may be underestimated.

Preterm birth and inhaled corticosteroid use in 6- to 19-year-olds: a Swedish national cohort study

OBJECTIVE

Preterm birth is associated with respiratory morbidity later in life, including asthma. Previous studies have mainly focused on asthma in early childhood in children born extremely preterm. In this study, we examined the risk of asthma in a national cohort of schoolchildren grouped according to degree of immaturity expressed as completed gestational weeks at birth.

METHODS

This was a register study in a Swedish national cohort of 1 100 826 children 6 to 19 years old. Retrieval of at least 1 prescription of inhaled corticosteroids (ICS) during 2006 was used as the main indicator for asthma. Logistic regression was used to test hypotheses, with adjustment for multiple socioeconomic and perinatal indicators.

RESULTS

Degree of immaturity, expressed as completed gestational weeks at birth, had an inverse dose-response relationship with ICS use. Compared with children born between 39 and 41 weeks' gestation, the odds ratio for ICS use increased with the degree of prematurity, from 1.10 (95% confidence interval: 1.08-1.13) for children born in weeks 37 to 38, to 2.28 (95% confidence interval: 1.96-2.64) for children born in weeks 23 to 28, after adjustment for confounders. The increase in ICS use with decreasing gestational age at delivery was similar in boys and girls, and declined with older age.

CONCLUSION

Preterm birth increased the risk of ICS use in these 6- to 19-year-olds by degree of immaturity, from extremely preterm to early term birth.