Asthma and allergy among schoolchildren in a mountainous, dry, non-polluted area in Norway

Sensitization pattern of inhalant allergens in children with asthma who are living different altitudes in Turkey

Variability in children's allergic sensitization has been detected not only among different countries but also among cities within the same nation but yet different climatic areas. The aim of this study was to investigate the sensitization pattern of asthmatic children who lived in different altitude areas: the two largest Turkish cities, Istanbul (sea level) and Erzurum (high altitude). Five hundred and twelve asthmatic children (6-15 years old) from Istanbul (western Turkey, at sea level) and 609 from Erzurum (eastern Turkey, at an altitude of 1800 m) were included in the study. All participants underwent skin testing with common inhalant allergens, spirometry, total IgE level, and clinical examination. The positive sensitization ratio to aeroallergens in children with asthma living at sea level was statistically higher than that in children living in the high altitude group [p = 0.001, OR (odds ratio) 4.9 (confidence interval (CI) 3.67-6.459)]. However, pollen sensitization in asthmatic children living in high altitudes was significantly higher than that in children living at sea level [p = 0.00, OR 2.6 (CI 1.79-3.87)]. Children with asthma who live at high altitudes are characterized by higher pollen but lower mite sensitization rates than those living at sea level in Turkey. Different climatic conditions and altitudes may affect aeroallergen sensitization in children with asthma.

Innate affairs of allergens

Activation of receptors of the innate immune system is a critical step in the initiation of immune responses. It has been shown that dominant allergens have properties that could allow them to interact with toll-like and C-type lectin receptors to favour Th2-biased responses and many bind lipids and glycans that could associate with ligands to mimic pathogen-associated microbial patterns. In accord with the proposed allergen-specific innate interactions it has been shown that the immune responses to different allergens and antigens from the same source are not necessarily coordinately regulated.

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.

Skin sensitization in school children in northern and southern Norway

It has been suggested that environmental exposures and living conditions can explain some of the worldwide variation in atopic disorders. Norway has large environmental contrasts within the country. We compared skin prick sensitization rates among school children living in the southern subarctic and in the northern arctic part of Norway. Approximately one quarter of the children were sensitized, mostly against pollen and animal dander, while mite and mould sensitization seemed to be a minor problem. Sensitization rates and profiles were similar in the north and south despite differences in living conditions and environmental exposures.

Living at high altitude and risk of hospitalisation for atopic asthma in children: results from a large prospective birth-cohort study

BACKGROUND

Asthma is among the most common chronic diseases in childhood and is steadily increasing in prevalence. Better characterisation of factors that determine the risk of hospitalisation for atopic asthma in childhood may help design prevention programmes and improve our understanding of disease pathobiology. This study will focus on the altitude of residence.

METHODS

This is an ongoing prospective birth-cohort study that enrolled all live-born infants in the Tyrol. Between 1994 and 1999, baseline data were collected for 33 808 infants. From 2000 to 2005, all children hospitalised for atopic asthma at the age of > or =6 years (n = 305) were identified by a careful search of hospital databases. Disease status was ascertained from the typical medical history, a thorough examination and proof of atopy.

RESULTS

Living at higher altitude was associated with an enhanced risk of hospitalisation for atopic asthma (multivariate RRs (95% confidence interval 2.08 (1.45 to 2.98) and 1.49 (1.05 to 2.11) for a comparison between altitude categories > or =1200 m and 900-1199 m versus <900 m; p<0.001). This finding applied equally to hospital admissions in spring, summer, autumn and winter. When altitude of residence was analysed as a continuous variable, the risk for asthma hospitalisation increased by 7% for each 100-m increase in altitude (p = 0.013).

CONCLUSIONS

This large prospective study shows a significant association between the risk of hospitalisation for atopic asthma and altitude of residence between 450 and 1800 m. The underlying mechanisms remain to be elucidated, but it is tempting to speculate about a role for altitude characteristics such as the decline in outdoor temperature and air humidity and increase in ozone levels, which may trigger airway hyper-responsiveness and attenuate lung function.

Cardiopulmonary exercise testing in children and adolescents with asthma who report symptoms of exercise-induced bronchoconstriction

Patients with asthma often report symptoms of exercise-induced bronchoconstriction. We performed cardiopulmonary exercise testing to establish the cause of exercise limitation in patients with asthma, under treatment, who reported symptoms of exercise-induced bronchoconstriction. Ten of the 42 patients meeting criteria for inclusion in our study (24%) developed exercise-induced bronchoconstriction. Exercise limitation without exercise-induced bronchoconstriction was found in both obese and non-obese patients, suggesting that poor fitness is a problem independent of body habitus. Including cardiopulmonary exercise testing in the management of children with suspected exercise-induced bronchoconstriction would provide a better understanding of the etiology of their symptoms and facilitate more appropriate treatment.

Asthma in every fifth child in Oslo, Norway: a 10-year follow up of a birth cohort study

BACKGROUND

The western world's increase in childhood asthma is suggested to level off. We aimed to investigate asthma prevalence in 10-year-old children within the prospective birth cohort Environment and Childhood Asthma (ECA) Study in Oslo established in 1992/1993.

SUBJECTS AND METHODS

Six hundred and sixteen (77%) of 803 children (mean age 10.9 +/- 0.9 (SD) years) with lung function measurements at birth were reinvestigated at age 10 years. At birth they corresponded to the entire birth cohort (n = 3754) regarding gender, socio-demographic factors, parental allergic diseases, pet keeping and maternal smoking. Results from structured parental interview, spirometry, and skin prick test for inhalant and food allergens are presented. Asthma definition required minimum two positive criteria, (i) doctor's diagnosis of asthma, (ii) wheeze and/or chest tightness, (iii) use of anti-asthmatic treatment. Current asthma required asthma definition plus either (ii) and/or (iii) in the last 12 months, and/or > or = 10% fall in forced expired volume in 1 s after treadmill running.

RESULTS

Lifetime prevalence of asthma was 20.2%; current asthma 11.1%, doctor diagnosis of asthma 16.1% and wheezes ever 30.3%. Allergic sensitization (29.3% overall) was more common among children with current (56.3%) compared to asymptomatic (last 12 months) (26.0%) or no asthma (27.6%) (P < 0.001). Boys more often than girls had current asthma (14.4 vs 7.1%, P = 0.004), wheeze ever (36.9 vs 22.5%, P = 0.002) and allergic sensitization (36.2 vs 22.1%, respectively, P < 0.001).

CONCLUSION

Childhood asthma apparently continues to increase in Oslo, having affected every fifth 10-year-old child.

The prognosis of bronchial asthma in childhood in Hungary: a long-term follow-up

The aim of this study was to determine the prognosis of bronchial asthma in childhood in Hungary. One hundred and forty five adults (96 men and 49 women) with a clinical history of childhood bronchial asthma were examined at the age of 28 years or above (mean age 37.6, SD 5.9 years). The patients completed questionnaires concerning their asthmatic and accompanying allergic symptoms in childhood, at the age of 18 and at present. They were all prick-tested with 12 inhalant allergens. The results showed that 42.8% of the patients had become symptom-free, but 57.2% still had intermittent or persisting asthmatic symptoms in adulthood. More patients had intermittent day-time (59%) and night-time (67%) asthmatic symptoms than persistent symptoms (41% and 33%). Accompanying allergic diseases (rhinitis, conjunctivitis, dermal and gastrointestinal diseases, and drug andfood allergies) in childhood did not definitely affect the prognosis of the bronchial asthma. The proportion of females with allergic diseases increased, and among patients with skin diseases it was significantly higher than the proportion of affected males. At the age of 18, allergic rhinitis was more frequent than in childhood. The frequencies of other allergic disorders did not change significantly. In the patients with asthmatic symptoms, molds and cat-hair allergies were more frequent than in the symptom-free group. The long-term prognosis of bronchial asthma in childhood in Hungary is relatively good, but fewer than half of the patients became symptom-free. The complaints of most of the patients were mild, but one in seven of all the adults suffered from moderate or serious bronchial asthma. Household allergens may contribute to the persistence of asthmatic symptoms.

The influence of altitude in bronchial asthma

BACKGROUND

Some asthmatic children living in mountain areas experience significant improvement in daily symptoms and in the degree of bronchial obstruction. The aim of this study is to investigate the effect of altitude on the prevalence and morbidity of childhood bronchial asthma.

METHODS

A questionnaire regarding the history and symptoms of asthma was distributed to 874 children aged 6-12 years, to be completed by their parents with the help of their pediatrician. A total of 583 children lived at sea level, 180 at an altitude between 501 and 800 meters, and 111 at an altitude between 801 and 1,200 meters. All children with recurrent cough, shortness of breath, wheezing, and a history of bronchial asthma were considered to have bronchial asthma.

RESULTS

The prevalence of childhood bronchial asthma in the mountains (800-1,200 meters) was twice as low as that at sea level (15.8% of children) (p <0.01). Parental smoking was more frequent in children who lived at sea level than in the mountains. Additionally, consumption of fish and oranges was more frequent at sea level. Children with asthma who lived in the mountains were absent fewer days from school per year (0.2) and had fewer nights with dyspnea per year (0.5) than asthmatic children who lived at sea level (1.6 days and 25 nights, respectively).

CONCLUSIONS

Bronchial asthma in children who live at high altitudes is characterized by low prevalence and low morbidity.

Eosinophil cationic protein (ECP) in school children living in a mountainous area of Norway: a population-based study of ECP as a tool for diagnosing asthma in children with reference values

BACKGROUND

Most previous studies on eosinophil cationic protein (ECP) have been performed on carefully selected groups of asthmatic patients. Few studies based upon population cohorts have been reported. The primary objective of the present study was to assess the usefulness of serum eosinophil cationic protein (s-ECP) in the diagnosis of asthma in schoolchildren and determine reference values based on measurements in healthy children.

METHODS

The population consisted of 216 schoolchildren (aged 7-16 years) who in a previous questionnaire had reported asthma or asthma-like symptoms and a control group. The questionnaire study comprised the entire population of schoolchildren in Upper Hallingdal. After clinical assessment, blood samples, and skin prick tests, these subjects were then reclassified into four groups: atopic and nonatopic asthmatic and nonasthmatics. S-ECP was assessed in relation to atopy, asthma severity, allergen exposure, and sex.

RESULTS

The asthma group (n = 105) had significantly higher mean s-ECP level than the nonasthma group (n = 111) (13.3 vs 8.3 microg/l, P < 0.001), with no significant difference between atopic asthmatics and atopic nonasthmatics. Mean s-ECP levels in children with mild, moderate, or severe asthma were 12.1, 18.5, and 12.2 microg/l, respectively. The children with animal dander allergy demonstrated higher levels of s-ECP than children without this allergy (12.9 vs 9.1 microg/l, P = 0.001). The upper reference limit (determined as the 95th percentile in healthy children) of 19.1 microg/l, showed low sensitivity (24%) and high specificity (93%) for the diagnosis of asthma. The positive and negative likelihood ratios for the asthma diagnosis were found to be 3.2 and 0.83, respectively.

CONCLUSIONS

The highest s-ECP values were found among children with moderate asthma. Animal dander allergy resulted in elevated s-ECP. However, mean values were still below the reference value of 19.1 microg/l, and the sensitivity was low, suggesting that s-ECP is not a useful parameter for diagnosing asthma in population-based studies.