Role of atopy in the natural history of wheeze and bronchial hyper-responsiveness in childhood

The role of atopy in the development of asthma has become increasingly recognised. We have been prospectively following a birth cohort of children of atopic parents to document the development of atopic disease. Our aim in this study was to document the natural history of BHR and wheeze at 10 years of age and to relate this to atopy. We reviewed 47 of our original cohort of 79 infants at 10 years of age and documented their clinical history of atopic disease and performed allergen skin prick tests and BHR to histamine. Thirty-three (70%) children wheezed at some time during their 10 years of life, with 13 commencing in infancy. Twenty-two children (47%) had current wheeze at 10 years of age. Wheeze in infancy was a poor predictor (RR 1.23, Cl₉₅ 0.66–2.23) of current wheeze while wheeze commencing after infancy was a good predictor (RR 2.89, Cl₉₅ 1.45–5.2). In contrast both atopy in infancy (RR 2.94, Cl₉₅ 1.92–4.53) and current atopy (RR 3.58, Cl₉₅ 1.43–9.03) were strong predictors of current wheeze. Analysis of BHR confirmed the importance of atopy in predicting its occurrence and severity. Sensitisation to D. pteronyssinus appeared to be the strongest predictor of both current wheeze and BHR. These observations confirm the importance of atopy in predicting outcome in children with asthma and suggest that wheezing in infancy and wheezing in later childhood may have different pathogenetic mechanisms.     

Wheezing in school children is not always asthma

Our objective was to study whether children with reported asthma differed from children with wheeze but without asthma, and from children with neither asthma nor wheeze, regarding lung function, bronchial hyper‐responsiveness (BHR) using methacholine inhalation, exercise‐induced bronchoconstriction (EIB), and skin prick test (SPT) reactivity. School children (n=2188), enrolled in a survey of asthma, were classified into three mutually exclusive groups by parental report of: asthma, wheeze, and no asthma/no wheeze. A random sample of 80 children in each group was tested (n=240). Among asthmatics, 68% (95% confidence interval (CI), 57–79) had a BHR (measured as PD₂₀ forced expiratory volume in 1 s (FEV₁) ≤ 8.16 μmol using methacholine) compared to 31% (CI 20–42%) and 30% (CI 19–40%) in the wheeze and no asthma/no wheeze groups. The dose–response slope (DRS) confirmed the PD₂₀ data and distinguished equally between groups. EIB (≥10% fall in FEV₁) was more frequent (40%, CI 29–52%) among asthmatics than among children with wheeze (12%, CI 4–19%) and no asthma/no wheeze (7%, CI 1–13%). The prevalence of at least one positive SPT was twice as high in the asthma group (58%, 47–69%) than in the wheeze (27%, CI 16–37%) and the no asthma/no wheeze (25%, 15–35%) groups. These results indicate that children with asthma differ from children with wheeze and children with no asthma/no wheeze regarding lung function, BHR, EIB, and SPT reactivity. Children with wheeze are more similar to children with no asthma/no wheeze with respect to these parameters.     

Prevalence of bronchial hyperreactivity asd etermined by several methods among Estonian schoolchildren

There is a lack of established criteria to identify asthma and bronchial hyerreactivity (BHR) in epidemiological studies, although both conditions appear to bear some relationship to atopy, at least in children. Recent studies indicate a low prevalence of atopy in former Socialist countries in Europe, yet the prevalence of BHR has been reported to be high. We have analysed the relationship between the outcome of various lung function tests, atopy and clinical symptoms of bronchial asthma in an epidemiological survey of Estonian 10-12 year old schoolchildren. Metacholine provocation test (four steps with the cumulative doses 100, 300, 700 and 1100uμg), exercise challenge test and PEF-variability over two weeks were done in 806 children in Tallinn (coastal, industrialised city) and 774 children in Tartu (inland, uniersity town). A positive response to the metacholine challenge test was recorded in 19% in Tallinn and in 32% in Tartu (p < 0.001). A similar tendency was observed for a more than 15% decrease of FEV¹ in the exercise challenge test, i. e. 6% in Tallinn and 18% in Tartu. There was only a weak relationship between BHR, as defined by either a positive metacholine challenge and/or exercise test, diagnosed asthma and reported wheezing. Thus, 47% of the wheezing children and 30% of the children with asthma had negative test results. Only 17% of the children with a positive metacholine challenge were atopic, as defined by at least one positive skin prick test. In conclusion, none of the methods employed to assess bronchial hyperre-sponsiveness were very useful for the identification of wheezing and asthmatic children in this epidemiological study. In contrast to the results of studies in Western Europe, most children with bronchial hyperreactivity in Estonia are not atopic.     

Review Article Towards a better understanding of childhood asthma

Objective: To explore the ways asthma may be defined in childhood and consider the current evidence to support these possible definitions.
Methodology The relationship of symptoms, atopy, bronchial hyperresponsiveness (BHR) and airway inflammation in defining childhood asthma is reviewed.
Results While none of the four proposed methods of defining asthma can stand alone as the 'gold standard], in childhood asthma, all four, namely clinical symptoms, atopy, BHR and airway inflammation, are intimately related. The degree of atopy and BHR, and the presence of airway inflammation, should be viewed as significant risk factors for persistent wheezing in childhood.
Conclusion At present the clinical diagnosis of asthma in childhood remains largely based on symptoms but it is likely that, with further research, the group of children who are now labelled as having asthma will be subdivided into different subgroups with implications for both treatment and outcome.     

Hypertonic saline challenge tests in the diagnosis of bronchial hyperresponsiveness and asthma in children

The hypertonic saline challenge test is the recommended method to assess bronchial hyperresponsiveness in the International Study of Asthma and Allergies in Childhood (ISAAC). The sensitivity of this procedure to assess asthma symptoms, however, has been reported to vary among study centers. The purpose of our study was to evaluate the value of this provocation test in an epidemiological survey in children, and to relate the degree of bronchial hyperresponsiveness to the severity of asthma symptoms. All 11–13‐year‐old children from 16 randomly selected schools in Linköping, Sweden received a questionnaire regarding respiratory symptoms and allergic disease. Skin prick tests with eight inhalant allergens were performed. In addition, all children with wheeze over the past 12 months (current wheeze) and a random sample of children without current wheeze were invited to perform hypertonic saline provocation tests. A complete data set was available for 170 children, including 50 with and 120 without current wheeze. Bronchial hyperresponsiveness (BHR) was defined as at least 15% decline in FEV₁. The degree of BHR was represented by the response/dose ratio, i.e. the fall in FEV₁ divided by total dose of inhaled saline. The severity of asthma symptoms was classified by the number of wheezing episodes over the past 12 months. ‘Asthma ever’ was defined by a combination of symptoms in the questionnaires. Children with ‘asthma ever’ and current wheeze were considered as having current asthma. Current atopic asthma was defined as current asthma with at least one positive skin prick test. The sensitivity of the procedure to detect ‘asthma ever’, current asthma and current atopic asthma was 62, 61 and 83%, and the specificity 83, 81 and 60%, respectively. The positive challenge rate was 52, 34, 13 and 7% among current wheezers, previous wheezers, non‐wheezers with a history of allergy and healthy children. The degree of bronchial hyperresponsiveness increased with the number of wheezing episodes. Thus, the median and range of the response/dose ratio were 4.8%/ml (2.1–14.8), 2.6%/ml (0.7–8.6) and 1.3%/ml (0.8–2.7), respectively, for children with ≥ 4 episodes, 1–3 episodes and no wheezing episodes over the past 12 months (p<0.001). In conclusion, hypertonic saline provocation test is useful as a tool to detect asthma in epidemiological studies in children. The degree of bronchial hyperresponsiveness, as represented by the response/dose ratio, reflects the severity of asthma symptoms.     

The outcome after severe bronchiolitis is related to gender and virus

The association between bronchiolitis in the first year of life and subsequent asthma, atopy, airway obstruction and bronchial hyper-responsiveness (BHR) is unsettled. Genetic predispositions, pre-morbid lung function, environmental interactions and altered immunological responses are risk factors that have been studied. The aim of this study was to assess lung function, BHR and the occurrence of asthma and atopy 11 yr after hospitalization for bronchiolitis in the first year of life, particularly focusing on the role of gender and virus involved. The study included 121 of 131 (92%) children hospitalized for bronchiolitis, 90 (74%) respiratory syncytial virus (RSV)-positive children and 141 children in an age-matched and unselected control group. At follow-up, current asthma was more common after RSV-negative bronchiolitis compared to controls (35.5% vs. 9.2%; p < 0.001), but not after RSV bronchiolitis (15.6%; p = 0.144). Higher BHR and an obstructive lung function pattern were observed after bronchiolitis, the latter most prominent after RSV-negative bronchiolitis. Higher BHR was confined to boys, but present in both the RSV-positive and RSV-negative groups (p = 0.007 and 0.003, respectively). Asthma after bronchiolitis was not associated with atopy. Atopy was similarly distributed between the RSV-positive and RSV-negative bronchiolitis groups and the control group. This study has shown that gender and type of virus are important factors to consider when addressing later development of asthma, BHR and lung function after hospitalization for bronchiolitis in early life.     

ISAAC-based asthma and atopic symptoms among Ha Noi school children

Childhood asthma and atopy prevalence patterns in the developing world are only beginning to be defined. No such information exists for Vietnam. Estimates would assist in anticipating health service needs as well as add to the growing database on global patterns of atopy. To estimate the prevalence of atopic symptoms in school children in Ha Noi, Vietnam, a cross-sectional survey was conducted of children aged 5- to 11-years-old in two schools using the parent self-administered International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. The response rate was 66.4% (969 responses). The overall prevalence of selected symptoms were: 'ever wheezed' 24.9%, 'wheezed in past 12 months' 14.9%, 'ever had asthma' 12.1%, 'doctor-diagnosed asthma' 13.9%, 'ever experienced allergic rhinitis (AR) symptoms' 34.9%, 'AR-conjunctivitis symptoms in past 12 months' 10.7%, 'ever had hay fever' 7.8%, 'doctor-diagnosed hay fever' 11.2%, 'ever had eczema' 3.3% and 'doctor-diagnosed eczema' 3.2%. Kappa statistics demonstrated high within symptom category consistency for 'ever had asthma/doctor-diagnosed asthma' (0.728) and 'ever had eczema/doctor-diagnosed eczema' (0.906). Age and gender adjusted odds ratios (OR) were also consistently significant across wheeze and allergic rhinitis symptom categories [highest OR = 10.10 (95% CI 6.23–16.35) between allergic rhinoconjunctivitis and wheeze in past 12 months]. There is a high prevalence of ISAAC-based symptoms in school children in Ha Noi, Vietnam, often above global averages. The high level of association between atopic symptoms suggests some degree of reliability and validity. Childhood atopy symptom prevalence in Vietnam is more similar to that in developed countries rather than developing countries.     

Bronchial hyper-responsiveness in selective IgA deficiency

Secretory IgA in mucosal secretions has a broad protective function. The insufficient protection provided by the respiratory mucosa in children with selective IgA deficiency (sIgAD) might facilitate the development of bronchial hyper-responsiveness (BHR) and consequently asthma symptoms. This study was conducted to clarify the prevalence of BHR in sIgAD children and the relationship with atopic status. A cohort of 20 children (group A) aged 6.4-20.1 yr (median: 12.6) with sIgAD (serum IgA <6 mg/dl) were evaluated for BHR using inhaled hypertonic saline test as well as for atopy by skin prick testing (SPT) to eight common aero-allergens. Seventy other children with normal levels of serum IgA, but sensitized to aero-allergens (group B) and 102 with normal IgA and negative SPTs (group C) were also evaluated. Baseline spirometry demonstrated that forced vital capacity (FVC) values in group A were significantly lower than in C. Forced expiratory volume in 1 s values were similar in all groups, but impairment of the forced expiratory flow over the middle half of the FVC was detected in group B. The prevalence of BHR was similar among group A (30.0%) and group B (35.7%) (p = 0.79) but they differed from group C (5.9%) (p = 0.005). An association between BHR and reported current (p = 0.001) but not lifetime asthma symptoms among group A was also observed. There was no association between atopy and BHR in group A but only to mites' sensitization (p = 0.03). In conclusion, these results indicate that sIgAD constitutes a risk factor for development of BHR but it appears to be related to sensitization to mites.     

Airway infections in infancy and the presence of allergy and asthma in school age children.

AIM: To investigate the association between a history of otitis media and respiratory tract infections in infancy and allergic sensitisation and asthma in school age children of atopic and non-atopic parents. METHODS: Based on a survey of 4585 schoolchildren, three groups of children aged 6-16 years were selected, of whom 502 were eligible with complete data: (1) diagnosed asthma (n = 166); (2) wheeze within past 12 months (n = 155); and (3) no asthma/no wheeze (n = 181). This study population was further analyzed by subgroups of children with or without parental atopy. Main outcome measures were allergic sensitisation verified by skin prick test and asthma. RESULTS: Children of atopic parents had a reduced risk of developing allergic sensitisation in school age if they had a combined history of both otitis media and lower respiratory tract infections during infancy (adjusted odds ratio (aOR) 0.13, 95% CI 0.03 to 0.50) or a history of otitis media (aOR 0.31, 95% CI 0.12 to 0.83). A history of lower respiratory tract infections in infancy increased the risk of asthma in children of non-atopic parents (aOR 4.21, 95% CI 1.68 to 10.57). CONCLUSION: In the present study population, a history of otitis media in infancy seems to be negatively associated with allergic sensitisation in school age children of atopic parents, whereas a history of lower respiratory tract infections was positively associated with asthma in children of non-atopic parents.     

Associations between respiratory symptoms,bronchial response to methacholine,and atopy in two age groups of schoolchildren.

Data on respiratory symptoms were obtained on 2503 schoolchildren aged 7 and 11 in Southampton by means of a self administered parental questionnaire. Children were classified into seven symptom groups from which 330 were tested for bronchial responsiveness to less than or equal to 6.4 mumol methacholine and skin tested for the presence of atopy. The symptoms of wheeze, cough, and shortness of breath were all significantly associated both with each other and bronchial responsiveness to methacholine but only wheeze was associated with atopy. The association of wheeze with both bronchial responsiveness to methacholine and atopy remained highly significant when controlling for the symptoms of cough and shortness of breath. Neither cough nor shortness of breath, however, were significantly related to bronchial responsiveness to methacholine when controlling for the symptom of wheeze. This study therefore calls into question the epidemiological relevance of these two symptoms as diagnostic features of asthma, particularly in the absence of wheeze, although they may be useful indicators of morbidity. Wheeze was not related to bronchial responsiveness to methacholine in the absence of atopy or to atopy in the absence of bronchial responsiveness to methacholine but was strongly related to the combination of the two phenomena. The presence of these three characteristics could therefore indicate a discrete disease entity. The decrease in the prevalence of cough between 7 and 11 years appeared to be mirrored by a similar decrease in the prevalence of wheeze when the symptom was not associated with the combination of bronchial responsiveness to methacholine and atopy. On the basis of these findings and those of others we suggest that the latter group may represent children with a separate disease entity(ies) or with residual symptoms secondary to acute viral or other infections of the lower respiratory tract.     

Airway infections in infancy and the presence of allergy and asthma in school age children

Aim: To investigate the association between a history of otitis media and respiratory tract infections in infancy and allergic sensitisation and asthma in school age children of atopic and non-atopic parents. Methods: Based on a survey of 4585 schoolchildren, three groups of children aged 6–16 years were selected, of whom 502 were eligible with complete data: (1) diagnosed asthma (n = 166); (2) wheeze within past 12 months (n = 155); and (3) no asthma/no wheeze (n = 181). This study population was further analyzed by subgroups of children with or without parental atopy. Main outcome measures were allergic sensitisation verified by skin prick test and asthma. Results: Children of atopic parents had a reduced risk of developing allergic sensitisation in school age if they had a combined history of both otitis media and lower respiratory tract infections during infancy (adjusted odds ratio (aOR) 0.13, 95% CI 0.03 to 0.50) or a history of otitis media (aOR 0.31, 95% CI 0.12 to 0.83). A history of lower respiratory tract infections in infancy increased the risk of asthma in children of non-atopic parents (aOR 4.21, 95% CI 1.68 to 10.57). Conclusion: In the present study population, a history of otitis media in infancy seems to be negatively associated with allergic sensitisation in school age children of atopic parents, whereas a history of lower respiratory tract infections was positively associated with asthma in children of non-atopic parents.     

Airway reactivity in parents of infants and young children with recurrent wheeze: a case-control study.

Increased airway reactivity has been found in family members of school age children and adults with asthma. As the relation between recurrent wheeze in infancy and bronchial reactivity is not yet clear, it was decided to test bronchial reactivity to methacholine in both parents of 50 preschool age children with recurrent wheeze and in 200 population based controls matched for sex, age, smoking habits, and atopy. Wheezy children fulfilled the following criteria: first attack of wheezing before the age of 2 years, at least four wheezing episodes triggered by a respiratory infection, negative skin prick tests, and no symptoms related to allergy. Four parents and five controls did not undergo the methacholine challenge because their forced expiratory volume in one second was < 80% of the predicted value. Methacholine reactivity was not significantly different in parents and controls. In summary, an increased bronchial responsiveness was not found in parents of infants and young children with recurrent wheeze triggered by infection.     

Diet, wheeze, and atopy in school children in Menorca, Spain

Epidemiological studies have shown inverse associations of asthma symptoms with fish, vegetable, and fruit intake. We evaluated the association between several dietary factors with wheeze and atopy among children in Menorca, a Spanish Mediterranean island. A cross-sectional analysis was performed on 460 children at age 6.5 yr. Parents completed a questionnaire on the child's respiratory and allergic symptoms, and a 96-item food frequency questionnaire. Children underwent skin prick tests with six common aeroallergens. The average daily intake was relatively high for fruits (177 g) and fish (54 g), and moderate for vegetables (59 g). A high consumption (>40 g/day) of fruity vegetables (tomatoes, eggplants, cucumber, green beans, zucchini) was found to have beneficial effect on current wheeze [odds ratio (OR), 0.38; 95% confidence interval (CI), 0.15-0.95, p < 0.05], and atopic wheeze with a significant decreasing trend when intake was increased (OR, 0.19; 95% CI, 0.04-0.95, p for trend = 0.04). No other fruits or vegetables were significantly associated with wheeze or atopy prevalence. An inverse association was found between a fish intake > or =60 g/day and atopy (OR, 0.43; 95% CI, 0.21-0.90, p < 0.05). The associations remained significant after adjustment for energy intake and maternal diet during pregnancy. Our results support a potential protective effect of fruity vegetables and fish intake during childhood on wheeze and atopy respectively.     

Epidemiologic characteristics of rhinitis in Turkish Children: the International Study of Asthma and Allergies in Childhood (ISAAC) phase 2

Rhinitis is a common problem with important comorbidities. In order to search the association between rhinitis, allergic phenotypes and other risk factors in Turkish children, a parental questionnaire about allergic diseases and risk factors, and skin prick test (SPT) with 13 inhalant allergens were performed in a population-based sample of 2774 children aged 9-11 yr. Bronchoprovocation testing with hypertonic saline (HS)and total IgE analysis were limited to a subsample of 350 children. Rhinitis was defined as a problem with sneezing, rhinorrhea, or nasal congestion when the child did not have a viral respiratory infection. The prevalences of ever rhinitis, current (last 12 months) rhinitis (CR), and ever hay fever were 36.3%, 30.6%, and 8.3%, respectively. SPT positivity rate was 20.4% among children with CR. Current wheezing and flexural dermatitis were significantly associated with CR. CR significantly increased the risk of asthma among both atopic and non-atopic subjects [odds ratio (OR), 3.98; 95% CI, 1.81-8.76; and OR, 2.79; 95% CI, 1.82-4.26, respectively]. The association between CR and bronchial hyperreactivity (BHR) was not significant. The multiple logistic regression analysis revealed family atopy (OR=2.25, 95% CI=1.79-2.83, p<0.001), current indoor heating with gas stove (OR=1.78, 95% CI=1.18-2.64, p=0.006) and dampness/molds at home during the first year of life (OR=1.70, 95% CI=1.25-2.31, p=0.001) as significant risk factors for CR. Turkish school children showed a high prevalence of rhinitis with a preponderance of non-atopics. The highly significant association between rhinitis and asthma independent of atopic sensitization emphasize the importance of non-atopic forms of rhinitis.     

Bronchial responsiveness to methacholine and adenosine 5'-monophosphate (AMP) in young children with post-infectious bronchiolitis obliterans

Aim: Bronchial hyperresponsiveness (BHR) is a characteristic feature of asthma, but it is also frequently demonstrated by children and adults with chronic obstructive lung diseases. BHR is usually measured by bronchial challenges using direct or indirect stimuli. The aim of this study was to compare these two types of bronchial challenge in young children with post-infectious bronchiolitis obliterans (BO). Methods: Methacholine and adenosine 5'-monophosphate (AMP) bronchial challenges were performed on preschool children with post-infectious BO (n=18), those with asthma (n=23) and in controls (n=20), using a modified auscultation method. The endpoint was defined as the appearance of wheezing and/or oxygen desaturation. Results: A positive response to methacholine (an endpoint concentration ≤8 mg/ml) was observed in 88.9% (16/18) of the patients with post-infectious BO, but a positive response to AMP (an endpoint concentration ≤200 mg/ml) was observed in only 22.2% (4/18). All patients with asthma responded positively to methacholine, and most (21/23, 91.3%) of them also responded positively to AMP. The majority of the controls were insensitive to both challenges.

Conclusion: BHR to methacholine is a frequent, but by no means universal, finding in young children with post-infectious BO, but is usually not accompanied by BHR to AMP.     

Early rapid weight gain and current overweight in relation to asthma in adolescents born with very low birth weight

Early catch-up growth and subsequent overweight are suggested to be associated with later cardiovascular diseases and later type II diabetes. However, the impact of early catch-up growth and childhood overweight on the development of asthma has been less studied, particularly in children born with very low birth weight (VLBW). A birth cohort of 74 VLBW children (birth weight < or = 1500 g) was followed from birth and investigated on asthma at 12 yr of age. Early rapid weight gain was in one way defined as an increase of weight > or =1 standard deviation score (SDS) at 6 months of corrected postnatal age. Current overweight was defined by body mass index (BMI) exceeding 21.2 and 21.7 kg/m(2), respectively, for boys and girls at 12 yr of age. Current asthma was diagnosed by a pediatrician, according to asthma ever in combination with a positive response to hypertonic saline bronchial provocation test and/or wheeze at physical examination at 12 yr old. Being overweight at 12 yr of age was associated with an increased risk for current asthma in the VLBW children [crude odds ratio (OR): 5.5, 95% confidence interval (CI): 1.3-22.2]. After adjustment for early weight gain and neonatal risk, the OR of overweight increased nearly three times (adjusted OR: 15.3, 95% CI: 2.5-90.6). Early rapid weight gain seemed to be inversely associated with current asthma (adjusted OR: 0.49 for an increase of weight equal to 1 SDS, 95% CI: 0.23-1.02, p = 0.06). In addition, early rapid weight gain was inversely associated with the magnitude of bronchial responsiveness at 12 yr (coefficient -1.15, p < 0.01). There was a strong and positive association between overweight and asthma at 12 yr of age in the VLBW children. This strong association had been reduced by early rapid weight gain, possibly via the reduction of bronchial responsiveness.     

High prevalence of atopy, but not of asthma, among children in an industrialized area in North Italy: The role of familial and environmental factors – a population-based study

The prevalence of atopy and asthma, and their association with familial and environmental factors were investigated among 13- to 14-yr-old children living in Brescia, an industrialized town in North Italy. All the 1450 children attending primary school in the town were invited to participate, and 967 of them (66.7%, 493 males) provided a valid questionnaire filled in by their parents at home. We used a modified version of the questionnaire adopted in the Italian Study of Respiratory Disorders in Childhood and Environment, which is an extended version of the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. Six hundred and twenty-eight subjects underwent skin prick test (SPT), and 308 of them (49%) were positive for at least one of the 12 allergen extracts commonly employed. Ninety-nine children (10.2%) had a physician's diagnosis of asthma - 12.4% of the males and 8.0% of the females (p = 0.03). The prevalence of wheezing in the past 12 months was 6.2%. Atopy was found in 76.8% of the subjects with, and in 45.6% of those without physician's diagnosis of asthma (p < 0.001). Analysis by multiple logistic regression showed an inverse association between physician-diagnosed asthma and female sex (odds ratio, OR = 0.5); presence of relatives in the bedroom in initial years of life (OR = 0.6); attending day care (OR = 0.4) and infant school (OR = 0.4); a positive association with parental history of wheezing (OR = 2.5) and asthma (OR = 3.8); and the child's history of asthmatic bronchitis (OR = 31.9) and atopic eczema (OR = 3.8) in the first 2 yr of life. The strength of the associations did not change when restricting the analysis to atopic asthma. In conclusion, atopy and clinical asthma among 13- to 14-yr-old adolescents are significantly associated with some familial and environmental factors, providing further support for the hygiene hypothesis. Prevalence of atopy, but not of asthma, is high in this industrialized area. The strong association found between atopy and clinical asthma suggests that atopy may play a role in causing asthma in genetically predisposed children only.     

Bronchial hyper-responsiveness and atopy in urban, peri-urban and rural South African children

Twenty years ago, the prevalence of atopic sensitization and bronchial hyper‐responsiveness (BHR) in Xhosa children in a rural location in South Africa was very low. The aim of this study was to document the current prevalence of these two indices by comparing traditional rural Xhosa children, recently urbanized Xhosa children and established city white children, and to consider factors that may account for the observed increase in all of these groups. One thousand four hundred and fifty‐seven school children aged 10–14 years from the rural Transkei, from a recently urbanized peri‐urban area and from urban Cape Town areas were studied using a questionnaire. Four hundred and eighteen children had histamine challenges, and 492 tests for atopy were also conducted. As determined by bronchial challenge with histamine, 17% of rural and 34.4% of recently urbanized Xhosa children had increased BHR, a marked increase from the 0.03% and 3.17% prevalence of increased BHR previously found using the exercise challenge. The prevalence of increased BHR in white urban children was 33%. Sensitization to one or more aero‐allergens, as indicated by CAP RAST tests, was present in 36.6% of the rural Xhosa children with normal BHR and in 62.5% of those with increased BHR, a striking increase from that of previous studies. Atopic sensitization to one or more aero‐allergens, as indicated by a skin prick test (SPT), was found in 42.3% of the recently urbanized Xhosa children and 45% of urbanized white children. We have also documented sensitization to house dust mites in the rural Xhosa children for the first time. Passive cigarette smoking was not identified as a risk factor for increased BHR or atopy. Wood smoke in the indoor environment did not play a role in the rural Xhosa children's BHR. Ascaris infection does not appear to play any modifying role in the development of increased BHR in the rural or urban children. We have found that increases in BHR in the rural and recently urbanized Xhosa children develop independently of increases in atopy. Our results challenge the ‘hygiene’ hypothesis as a complete explanation for the recent dramatic worldwide increases in allergic diseases.     

High body mass index, asthma and allergy in Swedish schoolchildren participating in the International Study of Asthma and Allergies in Childhood: Phase II

AIM: To assess the relationship between high body mass index (BMI) and asthma and atopic manifestations in 12-y-old children. METHODS: The relationship between high BMI and asthma symptoms was studied in 457 sixth-grade children, with (n = 161) and without (n = 296) current wheeze. High BMI was defined as > or = 75th percentile of gender-specific BMI reference values for Swedish children at 12 y of age; overweight as a subgroup of high BMI was defined as > or = 95th percentile. Children with a BMI < 75th percentile served as controls. Questionnaires were used to assess asthmatic and allergic symptoms, and bronchial hyperresponsiveness was assessed by hypertonic saline provocation tests. RESULTS: Current wheeze was associated with high BMI after adjustment for confounding factors (adjusted OR 1.7, 95% CI 1.0-2.5) and overweight had an even more pronounced effect (adjusted OR 1.9, 95% CI 1.0-3.6). In addition, asthma severity was associated with high BMI, as evaluated by the number of wheezing episodes during the previous 12 mo among the wheezing children (adjusted OR 2.0, 95% CI 1.0-4.0). There was also an association between high BMI and the presence of eczema in wheezing children (adjusted OR 2.2, 95% CI 1.0-4.6). However, high BMI was not significantly associated with hay fever, positive skin prick tests or bronchial hyperresponsiveness. CONCLUSION: The study confirms and extends a previously observed relationship between BMI and the presence of wheezing and asthma.     

Bronchial asthma and wheeze in a desert country

A cross-sectional, population-based study was conducted among school children (3300), aged 7–12 years, in the Kingdom of Saudi Arabia, during the period January, 1988–February, 1990. The aim of the study was to investigate the association between asthma, allergic rhinitis, wheeze and eczema among Saudi school children. The relationship between pet-ownership and respiratory allergy was also studied. Detailed information was collected about wheeze and asthma in 3041 children and history of asthma and allergic rhinitis in their parents. The population sample had a high prevalence rate of diagnosed asthma (6.8%), history of wheeze (10.5%), allergic rhinitis (17.9%), and eczema (10.8%). Allergic rhinitis was the most frequently seen respiratory illness when compared to other respiratory symptoms. The prevalence rate of asthma, allergic rhinitis and eczema among parents reflected the same pattern as that seen in the children. Prevalence rate for asthma in children with pets is twice that of children without pets (OR:2.4; 95%, Cl:1.8–3.1). The odds of having chronic cough (OR:3.9; 95%, Cl:2.8–5.2), chronic wheeze (OR:4.2; 95%, 3.3–5.4), allergic rhinitis (OR:8.0; 95% Cl:6.3–10.3) and eczema (OR:2.8:95 Cl:2.1–3.7) was higher in children with pets than in children without pets. The present study revealed that petownership was associated with increased respiratory symptoms.