Problematic severe asthma in children, not one problem but many: a GA2LEN initiative

Although most children with asthma are easy to treat with low doses of safe medications, many remain symptomatic despite every therapeutic effort. The nomenclature regarding this group is confusing, and studies are difficult to compare due to the proliferation of terms describing poorly defined clinical entities. In this review of severe asthma in children, the term problematic severe asthma is used to describe children with any combination of chronic symptoms, acute severe exacerbations and persistent airflow limitation despite the prescription of multiple therapies. The approach to problematic severe asthma may vary with the age of the child, but, in general, three steps need to be taken in order to separate difficult-to-treat from severe therapy-resistant asthma. First, confirmation that the problem is really due to asthma requires a complete diagnostic re-evaluation. Secondly, the paediatrician needs to systematically exclude comorbidity, as well as personal or family psychosocial disorders. The third step is to re-evaluate medication adherence, inhaler technique and the child's environment. There is a clear need for a common international approach, since there is currently no uniform agreement regarding how best to approach children with problematic severe asthma. An essential first step is proper attention to basic care.

IgE to peanut allergen components: relation to peanut symptoms and pollen sensitization in 8-year-olds

BACKGROUND

Allergen-specific IgE testing is often performed with crude peanut extract, but the results may be difficult to interpret because of cross-reactions between peanut and other plant allergens. The aim was to investigate IgE reactivity to peanut allergen components in children from a birch-rich region in relation to pollen sensitization and peanut symptoms.

METHODS

From a birth cohort, clinical parameters were obtained through questionnaires and IgE antibody levels to peanut and birch pollen were measured. Different peanut/birch sensitization phenotypes were defined among 200 selected children. IgE reactivity to peanut and pollen allergen components was analysed using microarray technique.

RESULTS

Peanut symptoms were reported in 87% of the children with IgE reactivity to any of the peanut allergens Ara h 1, 2 or 3 but not to Ara h 8 (n = 46) vs 17% of children with IgE reactivity to Ara h 8 but not to Ara h 1, 2 or 3 (n = 23), P < 0.001. Furthermore, symptoms were more severe in children with Ara h 1, 2 or 3 reactivity. Children with IgE reactivity both to Ara h 2 and to Ara h 1 or 3 more often reported peanut symptoms than children with IgE only to Ara h 2 (97%vs 70%, P = 0.016), particularly respiratory symptoms (50%vs 9%, P = 0.002).

CONCLUSIONS

IgE analysis to peanut allergen components may be used to distinguish between peanut-sensitized individuals at risk of severe symptoms and those likely to have milder or no symptoms to peanut if sensitized to pollen allergens and their peanut homologue allergens.

Identifying problematic severe asthma in the individual child--does lung function matter?

AIM

Measures of lung function (usually FEV(1) <80% predicted) are used to classify asthma severity in both adults and children, despite evidence that lung function impairment is less pronounced in the paediatric asthma population. The present study assesses the relevance of lung function measurements as discriminators of severe childhood asthma.

METHODS

Fifty-one school-aged children with problematic severe asthma, 37 mild-to-moderate asthmatics and 29 healthy controls underwent a comprehensive clinical work-up. Problematic severe asthma was defined in patients exhibiting poor asthma control despite high-dose inhaled corticosteroid treatment and at least one other asthma controller drug. Mild-to-moderate asthmatic children used low-dose inhaled steroids and reported minimal asthma symptoms.

RESULTS

Baseline FEV(1) values were significantly reduced in children with problematic severe asthma, yet FEV(1) <80% predicted showed a low sensitivity (41%) for discriminating severe vs. mild-to-moderate asthma. Receiver-operated characteristic analysis estimated the optimal cut-off of FEV(1) to be 90% predicted in this population (sensitivity 61%, specificity 83%). Baseline FEV(1)/FVC and FEF(25-75) values were not superior to FEV(1) in discriminating problematic severe asthma, and neither exhaled nitric oxide levels nor bronchial hyperresponsiveness differentiated between the two asthmatic study populations.

CONCLUSION

Spirometric measurements are insensitive discriminators of problematic severe asthma in childhood.

Reported symptoms to peanut between 4 and 8 years among children sensitized to peanut and birch pollen - results from the BAMSE birth cohort

BACKGROUND

Specific IgE tests are sometimes difficult to interpret due to structural similarities between certain food and pollen allergens. This may be the reason why concomitant sensitization to peanut and birch pollen is frequently seen. The aim of this study was to investigate reported symptoms to peanut- and birch pollen in relation to sensitization.

METHODS

The data originate from 1928 children in the BAMSE birth cohort. Background factors and clinical parameters were obtained and the levels of IgE antibodies to peanut and birch pollen measured at 4 and 8 years.

RESULTS

IgE antibodies to peanut were found in 5.5% and 7.4% of the children at 4 and 8 years, respectively. The IgE antibody levels to peanut were higher in children sensitized to peanut but not birch than in children sensitized to peanut and birch among both 4- and 8-year-olds (P = 0.093 and P = 0.003, respectively). Eight-year-olds sensitized to peanut but not birch, more often reported symptoms to peanut than children sensitized to both peanut and birch pollen (76%vs 46%, P = 0.002). The probability of reported symptoms to peanut increased significantly with increasing IgE levels to peanut, especially in 8-year-olds not sensitized to birch.

CONCLUSIONS

Children sensitized to both peanut and birch pollen are less likely to report symptoms to peanut than children sensitized to peanut but not to birch pollen at 8 years. This is likely due to cross reactions between birch pollen and peanut and can explain the high sensitization rate to peanut in areas where birch trees are common.

Paediatrics in Vienna

The aim of this article is to describe the paediatric highlights from the 2009 European Respiratory Society Annual Congress in Vienna, Austria. The best abstracts from the seven groups of the Paediatric Assembly (asthma and allergy, respiratory epidemiology, cystic fibrosis, respiratory physiology, respiratory infections and immunology, neonatology and paediatric intensive care, and bronchology) are presented alongside findings from the current literature.

Sensitization to inhalant allergens between 4 and 8 years of age is a dynamic process: results from the BAMSE birth cohort

BACKGROUND

There is limited knowledge of the development of IgE-antibody levels over time in childhood, with respect to persistency and co-sensitization to specific inhalant allergens.

METHODS

Data from 2033 children participating in the BAMSE birth cohort was used. Background factors and clinical parameters were obtained and IgE antibody (ab) levels to eight common airborne allergens were measured (>or=0.35 kU(A)/L) when the children were 4 and 8 years of age.

RESULTS

Between 4 and 8 years the proportion of children sensitized to any of the inhalant allergens tested increased from 15% to 25%. At 4 years IgE-ab to birch and cat dominated, whereas at the age of 8, there was a considerable increase in the proportion of sensitization to timothy and dog. Except for mites and moulds, IgE-ab levels to all aeroallergens increased significantly between 4 and 8 years among those already sensitized at 4. Transient sensitization to inhalant allergen was uncommon. Furthermore, sensitization to birch pollen at 4 years increased the risk for becoming sensitized to timothy, cat and dog later in life. Such an association was not observed among those sensitized primarily to animal dander.

CONCLUSIONS

There is a prominent process of sensitization at pre-school age to inhalant allergens, and in Northern Europe sensitization to birch pollen early in life seems to be important for this process. Such a process has a probable impact on the development of allergic disease in the growing child.

Higher immunoglobulin E antibody levels to recombinant Fel d 1 in cat-allergic children with asthma compared with rhinoconjunctivitis

BACKGROUND

Current diagnosis of allergy and asthma to cat is confirmed using cat dander extract (CDE). We have previously engineered a recombinant major cat allergen, rFel d 1, with properties identical to the natural molecule.

OBJECTIVE

The aim of the study was to evaluate IgE and IgG4 antibodies to rFel d 1 among sera from cat-allergic children and adults suffering from asthma and/or rhinoconjunctivitis (RC) in populations from Sweden and Austria.

METHODS

Cat-allergic children and adults from Sweden (n=27 and 31, respectively) and Austria (n=41 and 41) with RC and/or asthma were selected. Sera were tested for IgE and IgG4 antibodies to CDE and rFel d 1 by CAP, and IgE to rFel d 1 by ELISA. Healthy subjects and non-cat-allergic patients (n=75) were included as controls.

RESULTS

There was a high correlation between IgE responses to rFel d 1 and CDE among the 140 patients (r(s)=0.85, P<0.001); however, measured levels to rFel d 1 were on average 30% higher (P<0.0001). Ninety-eight percent of patients and none of the controls showed IgE to rFel d 1 and there was a threefold increased risk of asthma for half of the children with the highest IgE levels [odds ratio 3.23; 95% confidence interval (CI), 1.19-8.79] by ELISA. IgE responses to rFel d 1 among children with asthma were higher (median 19.4 kU/L) compared with children with RC (median 6.6 kU/L, P<0.05) and adults with asthma (median 3.0 kU/L, P<0.01). Furthermore, children with asthma displayed higher IgG4 levels than the asthmatic adults.

CONCLUSION

A single recombinant molecule, rFel d 1, is at least as sensitive for in vitro diagnostics of cat allergy as the current extract-based test. Elevated IgE antibody levels to Fel d 1 are suggested to be a risk factor for asthma in cat-allergic children.

Determinants of lung function and airway hyperresponsiveness in asthmatic children

BACKGROUND

Asthma patients exhibit an increased rate of loss of lung function. Determinants to such decline are largely unknown and the modifying effect of steroid therapy is disputed. This cross-sectional study aimed to elucidate factors contributing to such decline and the possible modifying effect of steroid treatment.

METHODS

We analyzed determinants of lung function and airway hyperresponsiveness (AHR) in a Scandinavian study of 2390 subjects from 550 families. Families were selected for the presence of two or more asthmatic children as part of a genetic study, Scandinavian Asthma Genetic Study (SAGA).

RESULTS

The primary analysis studied the association between the lung function and delay of inhaled corticosteroids (ICS) after asthma diagnosis among asthmatic children and young adults with a history of regular ICS treatment (N=919). FEV(1) percent predicted (FEV(1)% pred) was 0.25% lower per year of delay from diagnosis until treatment (p=0.039). This association was significantly greater in allergy skin prick test negative children. There was no significant influence of gender, age at asthma onset, or smoking. In the secondary analysis of the whole population of 2390 asthmatics and non-asthmatics, FEV(1)% pred was inversely related to having asthmatic siblings (-7.9%; p<0.0001), asthma diagnosis (-2.7%; p=0.0007), smoking (-3.5%; p=0.0027), and positive allergy skin prick test (-0.47% per test; p=0.012), while positively related to being of female gender (1.8%; p=0.0029). Risk of AHR was higher by having asthmatic siblings (OR 2.7; p<0.0001), being of female gender (OR 2.0; p<0.0001), and having asthma (OR 2.0; p<0.0001).

CONCLUSIONS

These data suggest that lung function is lower in asthmatics with delayed introduction of ICS therapy, smoking, and positive allergy skin prick test. Lung function is lower and AHR higher in female asthmatics and subjects with asthmatic siblings or established asthma.

Psoriasis in Swedish conscripts: time trend and association with T-helper 2-mediated disorders

BACKGROUND

According to the T-helper (Th)1/Th2 paradigm, it has been argued that Th1-dominated diseases such as psoriasis and Th2-dominated diseases such as asthma and hay fever should be mutually exclusive, as the immune regulatory cells, Th1 and Th2, cross-regulate each other. An increase in asthma and hay fever has occurred in Sweden over the past four to five decades, but the time trend for psoriasis is not clear.

OBJECTIVES

To assess the prevalence of psoriasis in young Swedish men over a period of three decades and the association between psoriasis and allergic disorders.

METHODS

Register study based on data from the Swedish Military Service Conscription Register and the Total Population and the Population and Housing Censuses. Psoriasis, asthma (with and without allergic rhinitis) and allergic rhinitis at conscription were studied in 1 226 193 male conscripts in successive cohorts born between 1952 and 1977.

RESULTS

The prevalence of psoriasis was about 0.5% and it remained stable over three decades. Conscripts with psoriasis and their siblings were less likely to have eczema. The reduced risk of eczema in conscripts with psoriasis was unchanged over time. A reduced risk of allergic rhinitis was also demonstrated in conscripts with psoriasis and their siblings but only in the most recent birth cohort born between 1970 and 1977.

CONCLUSIONS

A strong genetic influence may explain the unchanged prevalence of psoriasis in Swedish conscripts. A genetic predisposition for psoriasis may confer partial protection from eczema and allergic rhinitis. The inverse relationship between allergic rhinitis and psoriasis appeared to be a recent phenomenon.

Immunoglobulin G4-antibodies to rBet v 1 and risk of sensitization and atopic disease in the child

BACKGROUND

In 1993 extremely high levels of birch-pollen were recorded in Stockholm, Sweden. This provided an opportunity to evaluate the effects of aeroallergen exposure (exp.) on the early immune response.

OBJECTIVE

To assess the influence of exp. to birch-pollen during pregnancy and infancy on the allergen-specific IgE- and IgG4-antibody (ab) response and the development of atopic disease in children.

METHODS

A total of 970 children with atopic heredity and born in Stockholm 1992, 1993 or 1994 were investigated at age 4.5-5 years. They were divided into five groups; high-dose exp. at 1 year of age, high-dose exp. at 0-3 months, low-dose exp. at 0-3 months, high-dose exp. during pregnancy and low-dose exp. during pregnancy. The children were examined and skin prick tested with inhalant and food allergens. IgE abs (against birch-pollen and recombinant Bet v 1(rBet v1)) and IgG4 abs (against rBet v 1) were analysed in serum. All children were assembled in one group to assess the effects of different ab responses (IgE/IgG4) on the development of atopic disease.

RESULTS

Children exposed to high doses of birch-pollen during the first 3 months of life more often had detectable levels of IgG4 abs to rBet v 1 than the children in the other groups (P < 0.001), independent of sensitization to birch. Overall, the risk of allergic rhinoconjunctivitis was increased among children sensitized to birch-pollen and appeared more pronounced in children without detectable levels of IgG4 ab to rBet v 1 (Odds ratio 9.4; 95% Confidence interval: 5.5-16.1). IgE sensitization to birch-pollen seemed to have a stronger influence on the development of atopic disease than the IgG4-ab response.

CONCLUSION

Exposure to high doses of inhalant allergens during the early postnatal period is associated with detectable levels of allergen-specific IgG4 ab even at 5 years of age. An immune modulating effect by IgG4 on symptoms of allergic rhinoconjunctivitis is suggested in children sensitized to birch.

Group discussions with parents have long-term positive effects on the management of asthma with good cost-benefit

AIM

To investigate if an intervention with extra information and support in a group setting to parents of preschool children could improve adherence and clinical outcome.

METHODS

This is a controlled, prospective study where the parents of 60 newly diagnosed preschool asthmatic children aged 3 mo-6 y were randomized to either a control group or to an intervention that consisted of four group sessions in close connection with the diagnosis. The basic education on asthma and the written treatment plan were the same in both groups. The outcome measures were questionnaires to the parents and classification of the children according to symptoms and medication. The adherence rate and the burden of asthma were calculated with the help of diaries and weighing of the MDIs used between 12 and 18 mo after inclusion.

RESULTS

The follow-up rate was 85% after 18 mo. The parents' presence in the sessions was around 70%, with no gender difference. The parents' view on adherence issues improved significantly in the intervention group. In the control group, 30% had poor adherence compared to 8% in the intervention group (p=0.015). Both the parents and the paediatricians underestimated the number of children with poor adherence. The children in the intervention group had significantly fewer exacerbation days during the last 6 mo-2.1 compared to 3.9 d/child-although they had lower inhaled steroid doses after 18 mo. An economic calculation showed that the intervention was profitable.

CONCLUSION

This intervention resulted in an improvement in the parents' view on adherence, in the measured adherence rates and in the clinical outcome.

Direct and indirect exposure to pets - risk of sensitization and asthma at 4 years in a birth cohort

INTRODUCTION

There are conflicting data on the association between early exposure to pets and allergic diseases. Bias related to retrospective information on pet ownership has been addressed as a reason for distorted study results.

OBJECTIVE

To elucidate how early exposure to cat and dog relates to IgE-sensitization and asthma in children at 2 and 4 years of age, in a prospective birth-cohort study.

METHODS

Four thousand and eighty-nine families with children born 1994-1996 in predefined areas of Stockholm answered questionnaires on environmental factors and symptoms of allergic disease at birth, one, two and four years of age. Dust samples collected from the mothers' beds at birth were analysed for Fel d 1 and Can f 1 in a subgroup of the cohort. Blood samples taken at four years from 2614 children were analysed for allergen-specific IgE to common airborne allergens. Risk associations were calculated with a multiple logistic regression model, with adjustment for potential confounders.

RESULTS

A correlation was seen between allergen levels and reported exposure to cat and dog. Exposure to cat seemed to increase the risk of cat sensitization, OR (odds ratio) 1.44 (95% confidence interval 1.03-2.01), whereas dog exposure did not have any effect on dog sensitization, OR 1.16 (0.79-1.72). Dog ownership was related to a reduced risk of sensitization to other airborne allergens, OR 0.36 (0.15-0.83), and a similar tendency was seen for cat ownership OR 0.63 (0.37-1.07). Early dog ownership seemed to be associated with a lower risk of asthma, OR 0.50 (0.24-1.03), with no corresponding effect after cat ownership, OR 0.88 (0.56-1.38).

CONCLUSION

Early exposure to cat seems to increase the risk of sensitization to cat but not of asthma at 4 years of age. Dog ownership, on the other hand, appears to be associated with lowered risk of sensitization to airborne allergens and asthma. Both aetiological relationships and selection effects have to be considered in the interpretation of these findings.

Exposure to high doses of birch pollen during pregnancy, and risk of sensitization and atopic disease in the child

BACKGROUND

The role of maternal allergen exposure during pregnancy in sensitization and development of atopic disease in the child remains controversial. In the spring of 1993, extremely high levels of birch pollen were recorded in Stockholm, Sweden. In 1994, the corresponding pollen levels were low. The aim of this study was to assess the influence of exposure during pregnancy to high/low doses of birch pollen on the risk of sensitization and development of atopic disease in children. In addition, a comparison was made with children exposed to birch pollen in early infancy.

METHODS

Three hundred and eighty-seven children with atopic heredity, born in Stockholm in July-October 1993 or 1994 (mothers exposed during pregnancy), were investigated at age 4.5 years. The children were clinically examined and were skin prick tested (SPT) with inhalant and food allergens. IgE antibodies (RAST) against birch pollen and recombinant birch pollen allergen (rBet v 1) were analysed in serum. A comparison was made with a similar group of children exposed during the same incident, but in the first 3 months of life, in 1993.

RESULTS

The children of mothers high-dose exposed during pregnancy in 1993 tended to be more sensitized (SPT > or = 3 mm) to birch pollen than the children with low-dose exposure during the corresponding period in 1994 (7.6 and 4.6%, respectively, OR: 1.7; 95% CI: 0.7-4.1). A similar but weak tendency was seen for positive RAST analyses (> or =0.35 kU/l) against birch pollen and rBet v 1. Children of mothers high-dose exposed during pregnancy were significantly less sensitized to birch pollen than the children high-dose exposed in early infancy (17.9%, OR: 0.4; 95% CI: 0.2-0.7). There was an overall trend towards a slightly increased prevalence of bronchial asthma, allergic rhinoconjunctivitis and atopic dermatitis in the group with mothers high-dose exposed during pregnancy, compared to those with low exposure.

CONCLUSION

Exposure of the mother during pregnancy to high levels of birch pollen resulted in a tendency towards increased risk of sensitization to the same allergen and symptoms of atopic disease in children with atopic heredity. Furthermore, our data indicate that exposure of the mother during pregnancy to inhalant allergens is less likely to result in sensitization in the child than exposure of the child in early infancy.

Increased eosinophil transmigration after nasal allergen challenge in children with allergic asthma and rhinitis

BACKGROUND

Eotaxin and interleukin-5 together provide the signal essential for eosinophil transmigration to airway tissue in allergic reactions. However, it is not known whether peripheral blood eosinophils (PBE) possess an increased transmigration capacity in vitro after allergen challenge in vivo before they leave the circulation. We aimed to determine whether PBE in cat-sensitized children have increased spontaneous and/or eotaxin-induced transmigration capacity in vitro, and to what extent allergen challenge alters this feature.

METHODS

Fourteen cat-allergic children and four healthy controls underwent nasal challenge with cat-allergen. Blood samples were drawn prechallenge and at 2 h and 24 h postchallenge. We analyzed the in vitro transmigration of PBE, with and without eotaxin as a chemoattractant. We used a transmigration assay with fibronectin-coated membranes. Eosinophil cationic protein (ECP) and PBE counts were run in parallel.

RESULTS

The spontaneous transmigration capacity of eosinophils in vitro was significantly higher at 2 h after allergen challenge (P < 0.01 vs. prechallenge) and returned to prechallenge levels at 24 h postchallenge (P < 0.02 vs. 2 h postchallenge). Addition of eotaxin further augmented the increased transmigration. In concordance, no accompanying changes were measured in the levels of eosinophils in blood or ECP in serum. Furthermore no spontaneous or eotaxin-induced eosinophil transmigration was detected in healthy controls.

CONCLUSION

PBE possess increased spontaneous (and eotaxin-induced) capacity to transmigrate as early as 2 h after allergen challenge in allergic children, without accompanying signs of eosinophil activation in terms of increased PBE count or ECP level. This is probably due to the increased stage of activation of the eosinophil, often referred to as "priming".

Down-regulated IL-5 receptor expression on peripheral blood eosinophils from budesonide-treated children with asthma

BACKGROUND

The expression and function of cytokine receptors on peripheral blood eosinophils (PBE) from healthy and asthmatic children are poorly characterized.

METHODS

The PBE count and expression of IL-5 receptor (R) and GM-CSFR positive PBE was analyzed in nonsteroid-treated asthmatic children (n = 13), budesonide-treated asthmatic children (n = 24) and healthy children (n = 16) by flow cytometry. Alterations in intracellular EG2-epitope expression were used to measure the in vitro responsiveness of PBE to recombinant IL-5 and GM-CSF.

RESULTS

The PBE count was increased (P < 0.05) in both asthmatic groups, independent of treatment, as compared to healthy children. The IL-5R expression on PBE, as well as the in vitro responsiveness of PBE to recombinant IL-5, was reduced (P < 0.05), in budesonide-treated asthmatic children compared to nonsteroid-treated asthmatic children and healthy children. The proportion of GM-CSFR positive PBE and in vitro responsiveness of PBE to recombinant GM-CSF were not different between the groups. In vitro treatment with budesonide did not down-regulate the proportion of IL-5R positive PBE.

CONCLUSIONS

Budesonide-treatment of asthmatic children induces a selectively reduced IL-5R expression on PBE, concomitant with a reduced in vitro responsiveness of PBE to IL-5. We suggest that this budesonide-related down-regulation of the IL-5R might be a mechanism by which steroid treatment inhibits the action of IL-5 on eosinophil accumulation and activation in vivo.

[Can asthma deaths in young people be predicted and prevented?]

In spite of increased asthma prevalence, the mortality in the disease has decreased during the last two decades in Sweden and in some other countries. However, in the age group 15-24 years an increased death rate was noted at the end of the 1980s. Therefore we started a prospective study from 1994 with the aim of trying to analyse the precipitating factors of all deaths in the ages 1-34 years in which the death certificate alleged asthma or anaphylaxis as the main or contributing cause of death. We conducted a confidential telephone enquiry of the next of kin of the deceased using a modified questionnaire developed by the British Thoracic Association. When available, patient records and post mortem protocols were obtained.

RESULTS

The mortality in asthma in the ages 1-34 years has decreased from around 5 per million/year to 0.5/million/year over the period 1987-1998. The main preventable factors found in this analysis are undertreatment, non-compliance, psychosocial factors including alcohol/drug abuse, food allergy and inhalation allergy. Lacking awareness of the risks and underestimation of the severity of the asthma both by the physician and the patient seem to be dominating factors.

Eosinophil markers in blood, serum, and urine for monitoring the clinical course in childhood asthma: impact of budesonide treatment and withdrawal

BACKGROUND

Markers of airway inflammation are needed for prediction of asthma deterioration and evaluation of disease severity. Few studies have focused on the dynamics of airway inflammation as reflected by the activity of the eosinophils and their proteins after withdrawal of inhaled corticosteroids.

OBJECTIVE

Our goal was to investigate the effect of withdrawal of inhaled budesonide on eosinophil count in blood and eosinophil proteins in serum and urine and to relate the levels of these markers to the risk of symptoms of asthma, increased bronchial hyperresponsiveness, and deterioration of lung function.

METHODS

Thirty-three children were randomly selected to continue or discontinue use of inhaled budesonide in a double-blind, placebo-controlled study. They were followed up for 4 months with regular analysis of blood, serum, and urine samples; lung function; and methacholine challenges. Eosinophil activity markers were analyzed. Age-matched healthy children provided reference data for all parameters measured.

RESULTS

The eosinophil number in blood and eosinophil protein levels in serum (serum eosinophil cationic protein [ECP] and serum eosinophil peroxidase [EPO]) increased significantly in the withdrawal group, and the difference between the groups was significant (P =.02 for all). Twenty-nine percent of the children in the withdrawal group remained symptom free. This subgroup had eosinophil counts at baseline below 350/microL, a serum ECP level below 15 microg/L, and a serum EPO level below 25 microg/L, each of which was related to a low risk of exacerbation (relative risk = 0.37, 0.48, and 0.37 respectively; P <.05 for all). All eosinophil markers were lower in the healthy children than in the symptom-free children with asthma.

CONCLUSION

Our data indicate that eosinophil count and/or ECP and EPO levels can be used to estimate the short-term risk of deterioration and the need for corticosteroid treatment in cases of mild and moderate allergic asthma.

Worsening of asthma in children allergic to cats, after indirect exposure to cat at school

Exposure to cat allergen at school might exacerbate symptoms in asthmatic children with cat allergy. To study this, we identified 410 children, 6-12 yr of age, who were being treated for asthma (inhaled steroids and beta-agonists), were allergic to cats, and had no cat at home. Peak expiratory flow (PEF), asthma symptoms, medication, fever and/or sore throat, and contact with furred pets were recorded twice daily during the last week of summer holidays and the second and third weeks of school. The number of cat owners in each class was recorded. Ninety-two children with asthma reported no contact with furred pets. Among these, children who attended classes with > 18% (median value) cat owners reported significantly decreased PEF, more days with asthma symptoms, and increased use of medication after school started. Those in classes with < or = 18% cat owners reported no change. Children in classes with many cat owners ran a 9-fold increased risk of exacerbated asthma after school start compared with children in classes with few cat owners, after adjusting for age, sex, and fever and/or sore throat. Thus, asthma symptoms, PEF, and the use of asthma medication in children with cat allergy may be affected by indirect cat exposure at school.

Ethnicity, childhood environment and atopic disorder

BACKGROUND

The International Study of Asthma and Allergies in Childhood (ISAAC) has demonstrated large differences in the prevalence of atopic disorders in children between different regions in the world. Populations with a higher standard of living and a more westernized lifestyle tend to have higher rates of atopy and asthma. Many hypotheses regarding environmental causes of atopic disorder focus on the early childhood environment.

OBJECTIVE

To study the influence of ethnicity and country of birth for the prevalence of atopic disorders.

METHODS

The prevalence of atopic disorders in Swedish residents born in Turkey and Chile, who settled in Sweden as adults in the 1980s, was compared with their own Swedish-born children and a sample of Swedish-born parents and their children in interview data from the Survey of Living Conditions in 1996. The study group included 1734 adults 27-60 years of age and their 2964 children aged 3-15.

RESULTS

The Chilean-born parents and their children had the highest risk for allergic asthma; adjusted odds ratios (ORs) 2.2 (1.2-4.0) and 2.7 (1.6-4.5), respectively, and allergic rhino-conjunctivitis; OR 1.6 (1.1-3) and 1.6 (1.1-2.5) in both groups, when compared with the Swedish-born parents and their children. The Turkish-born parents and their children had the lowest risk for allergic rhino-conjunctivitis; both groups had OR 0.6 (0. 4-0.9) and the children in this group also had the lowest risk for eczema; OR; 0.4 (0.3-0.7). The risk for all atopic disorders was lower in the Turkish group compared with the Chileans.

CONCLUSION

This study demonstrates that ethnicity is an important determinant of atopic disorder independent of the external childhood environment. The value of international comparisons of environment and risk for atopic disorders can be questioned until more is known about factors related to ethnicity, such as genetic susceptibility and diet, for the development of atopy.

Vernal keratoconjunctivitis in a Stockholm ophthalmic centre--epidemiological, functional, and immunologic investigations

PURPOSE

To classify a cohort of 62 patients with vernal keratoconjunctivitis (VKC) in immunologic, functional, and epidemiological terms.

METHODS

A retrospective chart review was conducted to establish the patients' ethnic origin and to ascertain the results of standard in vitro and in vivo testing for atopic allergy. The latter data were compared with tear Phadiatop, an allergy screening test, in 31 subjects. Further subgroup analyses included methacholine bronchial provocations, serum screening for chlamydial antibodies and epidemiological calculations of the observed prevalence of VKC in the Stockholm area in 1994.

RESULTS

Thirty-seven subjects (59.7%) were sensitised to common allergens. No additional allergic subjects were diagnosed with the tear Phadiatop test. The serology for ocular chlamydial disease was negative. Only 6 out of 17 subjects displayed bronchial reactivity to methacholine of whom 4 had a history of asthma. VKC was clearly more common in individuals with an Asian and African origin.

CONCLUSIONS

Sensitivity to allergens is a strong determinant for the disease but in a large proportion of the subjects this immunologic abnormality is absent. The varying prevalence of the condition in different ethnic groups indicates a genetic predisposing factor.