Early childhood risk factors for sensitization at school age

Food and Aeroallergen Sensitization in IgE -Mediated Asthma in Egypt

Purpose:

Identifying the distribution of allergens is valuable to the effective diagnosis and treatment of allergic disease. So, our aim is to explore the sensitization of food and aeroallergens in Egyptian patients with atopic asthma.

Methods:

Cross-sectional study recruited 268 Egyptian patients with atopic asthma. Asthmatic patients were assessed by the enzyme allegro sorbent test (EAST) method for specific IgE to a panel of 19 common regional inhaled allergens and 15 food allergens.

Results and Discussion:

One hundred percent of the patients were sensitive to at least one allergen. Allergy to food allergens only was 2.9%; inhaled allergens only were 26.2% and both were70.9%. Fungi (62%) were the most frequent sensitizing aeroallergen amongst our asthmatic patients, followed by the pollen allergens (42.5%) and house dust mites (HDMs) (26%). Cows’ milk (30.5%) was the most frequent sensitizing food amongst our asthmatic patients, followed by eggs (22.4%) and fish (21.6%). Mono-sensitized patients accounted for 6.7% of all cases, while polysensitized was 93.3%. Moderate and severe asthma showed a significantly higher frequency of polysensitization compared to mild asthma.

Conclusion:

Fungi and cow's milk are the chief sensitizing allergens in Egyptian patients with atopic asthma. This study represents the first report of sensitization in atopic adult asthma using a large extract panel in Upper Egypt.

Allergic sensitisation in early childhood: Patterns and related factors in PARIS birth cohort

BACKGROUND

Allergic sensitisation is poorly documented in infants. This study aims to provide new insights into allergic sensitisation patterns and related factors in infancy.

METHODS

This study concerns 1860 infants involved in the Pollution and Asthma Risk: an Infant Study (PARIS) population-based birth cohort who had a standardised health examination when 18 months old, from 2004 to 2008. Sensitisation was assessed by measurements of serum specific IgE to 12 food and 4 inhalant allergens and defined by IgE≥0.35kU_A/L. Information regarding lifestyle and environment were obtained from questionnaires prospectively administered.

RESULTS

Prevalence of allergic sensitisation to any allergen, to food allergens, and to aeroallergens was 13.8%, 12.3%, and 2.3%, respectively. Multiple sensitisation (to at least two allergens) concerned 6.2% of toddlers. Intrinsic factors such as male gender, family history of allergy, and high birth weight increased the risk of food allergen sensitisation and multiple sensitisation. Caesarean section was also positively associated with multiple sensitisation. Day-care attendance was negatively related to food allergen, aeroallergen, and multiple sensitisation. A cat entering the baby's room in early life was strongly associated with aeroallergen sensitisation (ORa 3.21, 95%CI: 1.29-8.01). An introduction of meat in infant's diet after 6 months of age was negatively related to food allergen sensitisation (ORa 0.46, 95%CI: 0.24-0.91).

CONCLUSION

Our results suggest that intrinsic factors and indicators of exposure to microorganisms such as caesarean section and day-care attendance may be associated with inhalant as well as food allergen sensitisation in infancy. For example, male gender, family history of allergy, high birth weight, and caesarean section could be positively related whereas day-care attendance could be negatively related to both aeroallergen and food allergen sensitisation. Conversely, early life exposure to inhalant allergens or food allergens may be specifically linked to either aeroallergen sensitisation or food allergen sensitisation, respectively.

Environmental tobacco smoke exposure and risk of allergic sensitisation in children: a systematic review and meta-analysis

BACKGROUND

Environmental tobacco smoke (ETS) exposure in children is linked with the development of allergic asthma. However, its influence on allergic sensitisation in children has not been conclusively determined.

OBJECTIVE

To systematically review existing evidence of ETS exposure's impact on markers of allergic sensitisation in children.

METHODS

CENTRAL, MEDLINE and EMBASE databases were searched. Included studies assessed following markers of atopic sensitisation: total immunoglobulin E (tIgE) concentrations, at least one specific IgE (sIgE+), and positive skin-prick tests (SPTs+) in ETS-exposed and non-exposed children.

RESULTS

8 studies on the influence of ETS on tIgE concentration (2603 patients), 6 studies on ETS and sIgE+ (9230 participants) and 14 papers on ETS and SPT (14 150 patients) met our inclusion criteria. ETS was shown to raise tIgE concentrations by 27.7 IU/mL (95% CI 7.8 to 47.7; I(2)=58%; results based on 3 studies) and to increase the risk of atopic sensitisation, as assessed by sIgE+ (OR=1.12, 95%CI 1.00 to 1.25; I(2)=54%; results based on 4 studies) and SPT+ (OR=1.15; 95% CI 1.04 to 1.28; I(2)=0%; results based on 10 studies). In a subgroup analysis, this effect was most pronounced in children <7 years (preschoolers) by OR=1.20; (95% CI 1.05 to 1.38) and OR=1.30 (95% CI 1.05 to 1.61), (for sIgE+ and SPT+, respectively).

CONCLUSIONS

Current analysis supports an association between ETS exposure in early childhood and the increased risk of allergic sensitisation. Subgroup meta-analyses demonstrate that younger children suffer the most from detrimental immunomodulating effects of ETS exposure. This study underscores ETS as an important but avoidable risk factor for the development of allergic disease in children.

Perinatal Risk Factors for Hay Fever — A Study Among 2550 Finnish Twin Families

Previous studies have suggested that perinatal factors influence the risk for asthma but population studies on perinatal factors and risk for hay fever are few. We studied the effect of perinatal factors on the risk for hay fever among adolescent twins by a questionnaire study involving five consecutive nation-wide birth cohorts of 16-year-old twins and their parents. The risk for parent-reported, doctor-diagnosed hay fever in the adolescents associated with several perinatal characteristics was assessed with logistic regression analysis among individuals and by a discordant pair analysis. In the univariate analysis of the birth factors, the risk for hay fever increased with increasing birth weight (p for trend = 0.048, OR for those ≥ 3000g 1.35, 95% CI 0.91–2.02 compared to those < 2000g) and gestational age (p for trend = 0.04, OR for those born after 40 weeks of gestation 2.24, 95% CI 1.03–4.86, compared to those born before 33 weeks of gestation) and was lower in those subjects hospitalised in the neonatal period (OR 0.74, 95% CI 0.58–0.93). Because of significant interactions between parental hay fever status and birth factors (ponderal index, p = 0.03 and maternal age p = 0.04), stratified analysis were performed. The positive association between birth weight and hay fever was most obvious among adolescents with no parental history of hay fever (p for trend = 0.03). Similar, though not significant, trends were found with other birth factors among these families, whereas no such trend was found among adolescents with parental hay fever, suggesting that gestational maturity increases the risk for hay fever in the absence of genetic predisposition. However, of the perinatal factors only neonatal hospitalisation (OR 0.75, 95% CI 0.59–0.96) remained a significant risk factor for the development of hay fever, when adjusted for non-perinatal factors.

Preterm birth reduces the incidence of atopy in adulthood

BACKGROUND

Immunologic pathways are primed in early life. Preterm birth can influence this process and thereby affect whether a person will have atopy later in life. Previous studies on the effects of preterm birth on atopy in adulthood have been inconclusive and limited to children or subjects born moderately preterm.

OBJECTIVE

Our aim was to compare the incidence of atopy among young adults who were born preterm and at very low birth weight (≤ 1500 g) with that of term-born young adults (control subjects).

METHODS

The study comprised 166 adults who were born preterm and at very low birth weight and 172 control subjects, all of whom were from the Helsinki Study of Very Low Birth Weight Adults. We assessed atopic predisposition at ages 18 to 27 years using skin prick tests for 6 common aeroallergens and measurements of serum concentrations of total IgE and 3 types of allergen-specific (cat, birch, and timothy) IgE. We asked the subjects whether they had been given a diagnosis of asthma or allergic rhinitis or had atopic eczema and analyzed data by using logistic or linear regression, adjusting for potential confounding factors.

RESULTS

The risk for having at least 1 positive reaction on a skin prick test was reduced (adjusted odds ratio, 0.43; 95% CI, 0.23-0.79, P = .007), and the concentration of cat-specific IgE was less (25% less; 95% CI, 43% to 2.3% less; P = .033) in sera from very-low-birth-weight subjects compared with that seen in sera from control subjects. Within the very-low-birth-weight group, those born at an earlier gestational age were less likely to have positive skin prick test reactions (adjusted odds ratio for 1 week, 0.82; 95% CI, 0.68-0.98, P = .029) and less likely to have high levels of allergen-specific IgE. Cumulative incidences of atopic disease were similar between adults of very low birth weight and control subjects.

CONCLUSIONS

Young adults born prematurely and at very low birth weight have a lower incidence of atopy than adults who were born full term. This finding supports the hypothesis that the risk for atopy is determined during early stages of development.

Glutamine-enriched enteral nutrition in very low birthweight infants and allergic and infectious diseases at 6 years of age

In a previous randomised controlled trial, we found that glutamine-enriched enteral nutrition in 102 very low birthweight (VLBW) infants decreased both the incidence of serious infections in the neonatal period and the risk of atopic dermatitis during the first year of life. We hypothesised that glutamine-enriched enteral nutrition in VLBW infants in the neonatal period influences the risk of allergic and infectious disease at 6 years of age. Eighty-eight of the 102 infants were eligible for the follow-up study (13 died, 1 chromosomal abnormality). Doctor-diagnosed allergic and infectious diseases were assessed by means of validated questionnaires. The association between glutamine-enriched enteral nutrition in the neonatal period and allergic and infectious diseases at 6 years of age was based on univariable and multivariable logistic regression analyses. Seventy-six of the 89 (85%) infants participated, 38 in the original glutamine-supplemented group and 38 in the control group. After adjustment, we found a decreased risk of atopic dermatitis in the glutamine-supplemented group: adjusted odds ratio (aOR) 0.23 [95% CI 0.06, 0.95]. No association between glutamine supplementation and hay fever, recurrent wheeze and asthma was found. A decreased risk of gastrointestinal tract infections was found in the glutamine-supplemented group (aOR) 0.10 [95% CI 0.01, 0.93], but there was no association with upper respiratory, lower respiratory or urinary tract infections. We concluded that glutamine-enriched enteral nutrition in the neonatal period in VLBW infants decreased the risk of atopic dermatitis and gastrointestinal tract infections at 6 years of age.

Aeroallergen sensitization rates in military children with rhinitis symptoms

BACKGROUND

Childhood sensitization rates for many aeroallergens are underreported.

OBJECTIVES

To examine aeroallergen sensitization rates in military children undergoing skin testing for rhinitis and investigate the timing of atopic development for perennial and seasonal allergens.

METHODS

A skin testing database was retrospectively analyzed. Children 18 years and younger referred for rhinitis underwent skin prick testing to either a screening panel of 8 tests or a standard panel of 51 allergens.

RESULTS

A total of 209 patients underwent skin testing to the 8-test panel. Of these patients, 35.4% had at least 1 positive result. Atopy increased with age, from 6.3% in those younger than 1 year to 58.8% in those 5 years old. The most common allergens were mold mix (16.3%), cat (13.2%), dust mite mix (11.4%), tree mix (9.4%), and grass mix (9.4%). Only 4.0% were sensitized to seasonal aeroallergens before the age of 3 years. A total of 345 children underwent testing to a 51-allergen panel. A total of 80.3% had at least 1 positive test result, and the average number of positive test results was 11.4. Both the percentage of atopy and the average number of positive skin test results increased with age. The most common allergens were grasses, Alternaria, and cottonwood. Thirty-two of 51 allergens were positive in 20% or more children. Rates for many underreported allergens are presented.

CONCLUSIONS

In children, aeroallergen sensitization rates are high and increase with age. Perennial allergens predominate up to the age of 3 years. Rates for many underreported allergens are presented. Although performed in a military population, these results should be applicable to many practices.

Maternal testosterone in pregnancy and atopic outcomes in childhood

BACKGROUND

In mice, androgens downregulate Th2 cytokine responses, but whether androgen levels during pregnancy might influence the development of allergy in the offspring has not been studied.

METHODS

In the Avon Longitudinal Study of Parents and Children (ALSPAC), a population-based birth cohort of 14 541 pregnancies, we related maternal blood total testosterone during pregnancy, measured in a subset of the cohort, to allergic outcomes in the offspring, including asthma, hayfever, eczema (n=543) and wheezing (n=532) at 69-81 months, and atopy (positive skin prick test to Dermatophagoides pteronyssinus, cat or grass, n=386) and blood total immunoglobulin E (IgE; n=314) at 7 years. We used logistic and linear regression to analyse binary outcomes and log-transformed IgE, respectively, controlling for potential confounders.

RESULTS

Maternal testosterone was negatively associated with total IgE in boys [adjusted geometric mean ratio (GMR), per doubling of testosterone, 0.33 (0.20-0.55), P=0.000038 (n=168)], but not in girls [GMR 1.04 (0.53-2.06), P=0.91 (n=146)], P-value interaction 0.0086. The effect in boys was even stronger in the absence of maternal atopic disease. Testosterone was not associated with skin test positivity or atopic disease in either sex.

CONCLUSIONS

Higher testosterone levels in pregnancy are associated with lower IgE production in boys.

Air pollution: a threat to the health of our children

BACKGROUND/METHODS

Current air pollution levels pose a threat to the health of children starting from conception. The scientific evidence is presented for mortality, morbidity, and sub-clinical effects. The first section deals with exposure data, the following sections with the evidence of health effects from epidemiology and toxicology leading to recommendations.

RESULTS

Improved air quality reduces the number of infants' deaths as well as disease and pain.

CONCLUSIONS

Medical doctors have a responsibility to know the facts and to advise their patients. Doctors when visiting their patients' homes should be aware of the possibly grave impact of the indoor environment for the respiratory health of their patients. They should recognize and advise the parents on problems associated with environmental tobacco smoke, poor ventilation, mould growth, and maintenance of heating installations. With regard to outdoor air pollution, doctors could serve as role models and also advise their patients and parents on environmentally friendly behaviour. Such behaviour not only calls for personal commitment but also for the right infrastructure to be provided (e.g. public transport, district heating). Doctors should be proactive in the community and in their country as advocates for a healthier environment for our children.

Perinatal characteristics and obstetric complications as risk factors for asthma, allergy and eczema at the age of 6 years

BACKGROUND

Considerable effort has been put into identifying early determinants for atopic disorders. Many studies have evaluated the role of fetal development and obstetric complications. However, the results are not unequivocal.

STUDY OBJECTIVE

To assess the relationship between perinatal characteristics and obstetric complications, and the presence of reported current asthma, allergy and eczema at the age of 6 years in the framework of a previously conducted study.

METHOD

Seven hundred families in the Netherlands with index children born in 1988-1990 were retrospectively selected. Data were extracted from the Municipal Health Service's records of health examinations of these children and their siblings. These examinations were carried out at the age of 6 years. The records contained data on reported atopic disorders and perinatal characteristics.

RESULTS

Gestational age was inversely related to the risk of asthma (P for trend: 0.03). Children with low birth weight tended to have a lower risk of any allergy, albeit not significant (P=0.07). However, no link was found between neonatal head circumference and atopic disorders. The ratio of neonatal head circumference to birth weight was positively associated with the risk of atopic disorders, especially with the risk of asthma (odds ratio (OR)=1.87; 95% confidence interval (CI(95%))=[1.11, 3.15]). Vacuum extraction was a risk factor for allergy (OR=1.84, CI(95%)=[1.03, 3.28]), but not for asthma. Induced labour was positively associated with the risk of inhalant allergy (OR=2.22, CI(95%)=[1.09, 4.51]) and, to a lesser extent, asthma (OR=1.72, CI(95%)=[0.95, 3.10]). For caesarean section and forcipal extraction there were no such relationships.

CONCLUSIONS

Prematurity is a risk factor for asthma reported at 6 years. A high ratio of head circumference to birth weight is a risk factor for any atopic disorder. Vacuum extraction was associated with a higher risk of allergy, and induced labour is a risk factor for inhalant allergy. All results should be viewed with the possibility of residual confounding.

High-dose allergen exposure leads to tolerance

Reports of decreased sensitization to cat allergen (Fel d 1) among individuals living with a cat or subjects exposed to high-dose cat allergen may be explained by the development of a form of high-dose tolerance resulting from natural exposure to an inhalant allergen. Although the epidemiological data regarding the relationship between exposure and sensitization to Fel d 1 are conflicting, the ability for high-dose Fel d 1 to induce a characteristic nonallergic immune response with a distinctive serum antibody profile has been established. Definition of this modified T-helper (Th)2 response to cat allergen, coupled with the renewed interest in regulatory T cells within the immunology field, has provided an avenue for exploring the mechanism by which IgE antibody-mediated responses are controlled. There is mounting evidence to suggest that the modified Th2 response is a variation of the allergic response and that the modified Th2-allergic axis is influenced by allergen dose and genetics. This article discusses putative immune mechanisms of tolerance within the context of an allergen-specific system. The relevance of high-dose allergen exposure and alternate factors such as endotoxin to the development of tolerance is considered. Fel d 1 exhibits unique molecular and immunological characteristics that may contribute to its tolerogenic properties. Major T-cell epitopes of Fel d 1 that preferentially induce regulatory factors have been defined. Furthermore, high-titer IgE antibody responses associated with atopic dermatitis are characterized by a defect in the T-cell repertoire that is specific to these epitopes. Identification of Fel d 1 epitopes that induce interleukin-10 may provide new targets for treatment.

Sex differences in asthma, atopy, and airway hyperresponsiveness in a university population

BACKGROUND

A male predominance in atopy, a preadolescent male predominance in asthma, and a female predominance in airway hyperresponsiveness (AHR) have been previously documented, mostly in separate populations.

OBJECTIVE

We examined gender differences in a single population of 500 randomly selected university students from a previous publication which addressed sensitivity and specificity of histamine bronchoprovocation (Cockcroft et al. J Allergy Clin Immunol. 1992;89:23-30).

METHODS

In these 500 subjects (age 21.8 +/- 1.5 years) we assessed gender differences in asthma, atopy, and AHR. We compared our findings with those in the literature from a PUBMED search using the keywords gender, asthma, atopy, AHR, and bronchial reactivity.

RESULTS

A diagnosis of asthma made by another physician was seen in 31, a male-to-female ratio of 2.9:1 (P = 0.004). Our definition of asthma increased the total to 52 and reduced the male-to-female ratio to 1.2:1. Atopy was seen in 190, male-to-female ratio of 1.5:1 (P = 0.001). Borderline to mild AHR had a female predominance with a male-to-female ratio of 1:1.5 (P = 0.02), whereas moderate AHR had a marked predominance with a male-to-female ratio of 7:1 (P = 0.03).

CONCLUSIONS

In our population, the associations among gender and asthma, atopy, and AHR were similar to those seen in the literature with the exception of males having more severe AHR. This may be the one factor contributing to the higher prevalence of asthma (including previous doctor-diagnosed asthma in our population) in boys and young men.

Natural history of asthma

For some children, asthma is a disease whose symptoms seem to remit with time. Numerous children, however, develop disease that is persistent throughout their lifetimes and is associated with more severe symptoms, increased airway reactivity, and loss of lung function. These children typically have a family history of asthma and demonstrate increased airways reactivity and atopy in childhood. A clearer picture of the natural history of asthma in the developing child has been derived from the results of several longitudinal studies. Although some questions have been clarified, several questions still remain. Now that the incidence and severity of asthma seem to be increasing, children born in the last 10 years may experience more severe disease or a different pathophysiology than those born 30 to 40 years ago. New cohort studies are needed to assess this possibility. Additional investigations into the genetics of asthma causation will help elucidate the different phenotypic expressions of this complex disease. Once these different phenotypic groups can be identified early in life, further studies can be performed to explore the impact of therapeutic intervention on the severity of asthma symptoms and loss of lung function.

Methodologic aspects of the quantification of skin prick test responses: the EGEA study

BACKGROUND

The expression of responses of allergy skin prick tests is not standardized. Usual definitions of atopy are not quantitative.

OBJECTIVE

We sought to perform a biometric analysis of responses to various allergens to propose synthetic, quantitative indices independent of the heterogeneity of responses to various allergens.

METHODS

Adults (N = 1286) from the Epidemiological Study on the Genetics and Environment of Asthma, Bronchial Hyperresponsiveness, and Atopy (EGEA) were included in the analysis. The first step, conducted for 678 subjects with at least 1 wheal >0, was to perform a standardization of wheal diameters to obtain comparable figures for 10 allergens through use of the means of the squares of wheal size as a scaling factor. The second step was a factor analysis of the standardized responses conducted not only for all subjects but also separately for asthmatic case and nonasthmatic control subjects. Finally, the strength of the link between various dichotomous and quantitative scores was assessed with multiRAST, total IgE, and asthma. Analyzed quantitative scores were based on the number of positive responses and on the nonstandardized and standardized sizes of the wheals.

RESULTS

The standardization was efficient. Among asthmatic subjects but not other subjects, factor analysis evidenced a pattern with 3 factors, corresponding to outdoor, indoor, and mold allergens. The link study showed that all scores performed very similarly.

CONCLUSION

The number of positive tests is a quantitative score with valid biometric properties. It should be used more widely in clinical settings and in epidemiology to assess the severity of atopy.

Pets in the home and the development of pet allergy in adulthood. The Copenhagen Allergy Study

BACKGROUND

The aim of the study was to investigate the association between exposure to cat and dog in the home and the development (incidence) of IgE sensitization to cat and dog.

METHODS

Participants in a population-based study of 15-69-year-olds in 1990 were invited to a follow-up in 1998. Serum IgE antibodies against common inhalant allergens was assessed in 734 subjects (participation rate 69.0%) on two occasions 8 years apart. Information about current or previous keeping of cats and dogs in the home was obtained in a questionnaire at baseline.

RESULTS

A cat in the home currently was significantly associated with the development of IgE sentisization to cat (adjusted odds ratio 8.4, 95% confidence interval (CI) 1.7-42.7). Moreover, an atopic predisposition in terms of IgE sensitization to allergens other than cat at baseline was an independent risk factor for the development of IgE sensitization to cat. A dog in the home was not significantly associated with the development of IgE sensitization to dog.

CONCLUSIONS

In this adult population, exposure to a cat in the home increased the risk of developing IgE sensitization to cat. More prospective data are needed on this issue.

School education and allergic sensitization in adults

BACKGROUND

There is evidence of an association between socioeconomic status (SES) and atopy mainly from studies in children which investigated atopic diseases and parental SES. We determined the association of allergic sensitization, as measured by skin prick test (SPT) and allergen-specific IgE (RAST), and SES in a population-based study in adults.

METHODS

Within a population-based, nested, case-control study, a standardized interview was performed and allergic sensitization to common aeroallergens was determined by SPT and RAST.

RESULTS

A total of 1537 adults (50.4% female, age: median 50.0, range 28-78 years) were investigated, half of whom (50.2%) exhibited at least one positive RAST result according to the study design. SPT reactivity was 37.3% in this group and was estimated to be 26.1% in the representative study base of 4178 adults. Within increasing categories of school graduation (none; after 8, 10, 13, and >13 years), the prevalence of SPT (20.5%, 31.3%, 44.0%, 44.2%, 48.1%; P trend <0.0001) and RAST reactivity (35.0%, 48.0%, 52.3%, 48.4%, 58.4%; P trend=0.004) increased continuously. Similar results were obtained when testing this association on the level of single allergens. After control for age, sex, and parental history of atopic diseases, all but the first odds ratios for SPT remained significant (first category=reference, 2.06, 3.21, 3.88, 3.96). The same model for RAST reactivity revealed a similar result with effect estimate for the last category being significant (first category=reference, 1.89, 2.08, 2.10, 2.81).

CONCLUSIONS

Allergic sensitization (SPT and RAST) to common aeroallergens in adults follows a significant and linear association with school education.

Why are allergies increasing?

The incidence of atopic allergy is increasing in certain 'Western' countries but this remains unexplained. Various hypotheses with differing amounts of evidence and/or relevance have been assessed, including increased awareness of the diseases, improved diagnostics, genetic susceptibility, psycho-social influences, allergen exposure, decreased immune-system stimulation, underlying disease, anti-allergic therapy and pollution.

Variação na prevalência de asma e atopia em um grupo de escolares de Porto Alegre, Rio Grande do Sul

Introdução: Considerável aumento na prevalência da asma e da atopia vem sendo mundialmente observado ao longo das últimas décadas, porém, em nosso país, os dados epidemiológicos ainda são insuficientes. Objetivo: Este estudo foi realizado a fim de determinar a prevalência de asma e atopia em um grupo de escolares e comparar tais dados com outros dois levantamentos previamente realizados em Porto Alegre, Rio Grande do Sul. Métodos: A prevalência de asma foi identificada através de um questionário aplicado a 855 alunos de cinco escolas de Porto Alegre. Foram considerados atópicos aqueles escolares que, submetidos a testes cutâneos, apresentaram pelo menos uma reação cutânea positiva. Assinatura do termo de consentimento pós-informação de um dos pais foi exigida para a realização dos testes cutâneos. Resultados: Foi identificada prevalência de 42,5% de asma cumulativa e 22% de asma ativa, com predominância nas meninas. Atopia foi identificada em 50,1% da amostra. Tais resultados foram significativamente superiores aos 6,7% (1980) e 16% (1989) de asma cumulativa, 10,9% (1989) de asma ativa e 15,8% (1980) de atopia encontrados nos dois estudos previamente realizados. Conclusões: Altas prevalências de asma e atopia foram identificadas em nossos estudantes. Futuros estudos deverão ser realizados a fim de elucidar o fenômeno aqui demonstrado.

Sensitization to common allergens and its association with allergic disorders at age 4 years: a whole population birth cohort study

BACKGROUND

Atopy is defined as the genetic propensity to develop immunoglobulin E antibodies in response to exposure to allergens and assessed by skin prick test responses to common allergens. Although it is generally agreed that atopy is an important risk factor for allergic diseases such as asthma, rhinitis, and eczema, the extent to which atopy accounts for these diseases is controversial.

OBJECTIVE

We aim to describe the prevalence of sensitization to common allergens and investigate the degree of association of atopy (as defined by positive skin prick test to 1 or more common allergens) to asthma, rhinitis, and eczema in a birth cohort at the age of 4 years.

METHODS

A birth cohort of 1456 children was recruited over a 14-month period (1989-1990). These children have been seen previously at 1 and 2 years of age. At 4 years, 1218 children were reviewed and an interview was administered or postal questionnaire was completed for the presence of allergic diseases (asthma, rhinitis, and eczema). Additionally, in 981 children, skin prick tests with a battery of 12 common allergens were performed. Allergens were house dust mite (Dermatophagoides pteronyssimus), grass pollen mix, cat, dog, Alternaria alternata, Cladosporium herbarum, cow's milk, hen's egg, soya, cod, wheat, and peanut. A mean wheal diameter of at least 3 mm greater than the negative control was taken as positive. This analysis is confined to the 981 (67% of the original population) who also had skin prick tests to the standard battery. chi(2) tests were used to test the univariate association between each allergic disease and positive skin test. Multiple logistic regression analysis was performed to obtain the adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the independent effect of sensitization to each allergen on allergic disease, adjusting for the effect of sensitization to other allergens. To ascertain how much of allergic disease is attributable to atopy, we estimated the population-attributable risk. This was calculated with the formula: P(R - 1) where R is the OR for the allergic disease under consideration and P is the proportion of atopy in children with that disease.

RESULTS

Children who were skin prick-tested at 4 years were similar in most characteristics to the rest of the population, except that they had a higher prevalence of allergic disease. Allergic disorders (asthma, rhinitis, and eczema) were present in 276 (28.1%) of 981. One hundred ninety-two (19.6%) children were atopic (positive reaction to 1 or more allergens). Sensitization to inhalant allergens was relatively common (19.2%) as compared with food allergens (3.5%). House dust mite (11.9%), grass pollen (7.8%), and cat (5.8%) were the most common positive reactions. A test to the 4 most common allergens (house dust mite, grass pollen, cat, and A alternata) could detect 94% of the atopic children. Sensitization to the 4 most common allergens was strongly associated with the presence of allergic disorders. There was a graded effect with the potent allergens, such as house dust mite, having the greatest impact. For example, 50% of children sensitized to house dust mite had asthma as opposed to 44% sensitized to cat, 42% sensitized to grass pollen, and 32% sensitized to A alternata. Overall, 68.4% of children sensitized to house dust mite had asthma, eczema, and/or rhinitis. The respective figures for grass pollen, cat, and A alternata were 64.9%, 66.7%, and 57.4%. The proportion of children sensitized to cat was not higher in households with cat ownership (households with cats: 5.1% [19/374]; households without cats: 6.2% [36/580]; not significant [NS]). Similarly, no difference was seen in sensitization to dog in households with and without dogs (households with dogs: 1.8% [5/282]; households without dogs: 2.8% [19/673]; NS). Boys were atopic more often than girls at this age (male: 112 of 497 [22.5%] vs female: 80 of 484 [16.5%]; OR: 1.47, 95% CI: 1.07-2.02). Male preponderance was observed with most allergens, but this was statistically significant only for house dust mite (male: 75/497 [15.1%] vs female: 42/484 [8.7%]; OR: 1.87; CI: 1.25-2.79) and grass pollen (male: 51/497 [10.3%] vs female: 26/484 [5.4%]; OR: 2.01; CI: 1.23-3.29). An independent effect of allergen sensitization on asthma was observed only with house dust mite with an OR of 8.07 (CI: 4.60-14.14). The highest independent risk for rhinitis was sensitization to grass pollen (OR: 5.02; CI: 2.21-11.41), and for eczema, sensitization to peanut (OR: 4.65; CI: 1.02-21.34). The majority of children (98/192) were sensitized to >1 allergen. A graded effect was observed with the risk of allergic disease in the child increasing with the number of positive skin prick test reactions. This effect was consistent throughout the spectrum of allergic diseases (asthma, eczema, and rhinitis). (ABSTRACT TRUNCATED)

Influence of early and current environmental exposure factors on sensitization and outcome of asthma in pre-school children

BACKGROUND

Exposure to furred pets in early life has been considered to increase the risk of allergic sensitization and consequent development of asthma later in children. However, recently, it has been suggested that early exposure to pets prevents sensitization. The aim of this study was to evaluate the importance of early exposure to pets and other environmental risk factors in asthmatic children.

METHODS

This is a follow-up study after 2 years of a previously investigated group of 193 asthmatic children, aged 1-4 years. The study was completed by 181 children, who were clinically examined; serum IgE antibodies were also measured and a questionnaire was answered.

RESULTS

Children with reported exposure to cats during the first 2 years of life were more likely to have developed sensitization to cat by 4 years of age than unexposed children. High levels of cat allergen (Fel d 1> or =8 microg/g dust) were associated with an increased risk of sensitization to cat and, in combination with tobacco smoke, also with the development of more severe asthma.

CONCLUSION

In young asthmatic children, early exposure to cat and tobacco smoke increased the risk of allergic sensitization and further development of more severe asthma later in childhood.

Exposure to pets and atopy-related diseases in the first 4 years of life

BACKGROUND

It is still unclear how early-life exposure to pets is related to children's risk of developing atopy-related diseases. We estimated associations between early-life exposure to pets and atopy-related diseases at 0-4 years of life in a cohort of Norwegian children.

METHODS

A population-based cohort of 2531 children born in Oslo, Norway, was followed from birth to the age of 4 years. Information on early-life exposure to pets, a number of possible confounders, and atopy-related diseases was mainly collected by questionnaire.

RESULTS

In logistic regression analysis adjusting for potential confounders, the odds ratio for being exposed to pets in early life (reference category: not exposed) was, for bronchial obstruction at 0-2 years of life, 1.2 (95% confidence interval 0.9, 1.8); for asthma at the age of 4 years, 0.7 (0.5, 1.1); for allergic rhinitis at the age of 4 years, 0.6 (0.4, 1.0); and for atopic eczema at 0-6 months of life, 0.7 (0.5, 0.9).

CONCLUSIONS

The results indicate that early-life exposure to pets or lifestyle factors associated with exposure to pets reduce the risk of developing atopy-related diseases in early childhood. However, these findings might also be explained by selection for keeping pets.

Allergy markers in respiratory epidemiology

Assessing allergy by measurement of serum immunoglobulin (Ig) E antibodies is fast and safe to perform. Serum antibodies can preferably be assessed in patients with dermatitis and in those who regularly use antihistamines and other pharmacological agents that reduce skin sensitivity. Skin tests represent the easiest tool to obtain quick and reliable information for the diagnosis of respiratory allergic diseases. It is the technique more widely used, specific and reasonably sensitive for most applications as a marker of atopy. Measurement of serum IgE antibodies and skin-prick testing may give complimentary information and can be applied in clinical and epidemiological settings. Peripheral blood eosinophilia is less used, but is important in clinical practice to demonstrate the allergic aetiology of disease, to monitor its clinical course and to address the choice of therapy. In epidemiology, hypereosinophilia seems to reflect an inflammatory reaction in the airways, which may be linked to obstructive airflow limitation.

Prematurity at birth reduces the long-term risk of atopy

BACKGROUND

Antigen exposure in early life has long-lasting effects on atopic sensitization. Thus the predisposition to atopy of children born preterm can be assumed to differ from that of children born at term.

OBJECTIVE

The aim of this study was to evaluate the association between premature birth and atopy.

METHODS

At an outpatient clinic, we examined 2 groups of 10-year-old children, 72 who were born preterm (birth weight < 1500 g) and 65 who were born at term (birth weight > 2500 g). The atopy data were collected with a questionnaire, by performing skin prick testing, and by measuring the serum total IgE level, 3 allergen-specific IgE levels, the eosinophil cationic protein level, and the blood eosinophil level. The data on perinatal and neonatal events affecting the preterm children were collected from the hospital records.

RESULTS

By the age of 10 years, the children born preterm had significantly less atopy than the children born at term: 15% versus 31% of children in the 2 groups were defined as having had obvious atopy (P = .03, odds ratio 0.41, 95% CI 0.18-0.93). The mean value of total IgE level was significantly higher in the term group, 74 kU/L versus 41 kU/L (P = .02). By skin prick testing, the children born at term had positive reactions 2 to 3 times more often; 37% versus 17% of children in the groups had at least 1 positive reaction (P = .007).

CONCLUSION

Our data show that prematurity at birth is linked with a decreased long-term risk of atopic sensitization.

Does allergy in parents depend on allergy in their children? Recall bias in parental questioning of atopic diseases. Multicenter Allergy Study Group

BACKGROUND

A positive atopic family history has proved to be one important risk factor for the development of atopic diseases in offspring. However, many epidemiologists are concerned about the accuracy and reliability of data because responses to questionnaires can be biased for many reasons.

OBJECTIVE

The study investigated whether responses of parents questioned about their atopic diseases change depending on the development of atopic symptoms in their children.

METHODS

During a prospective birth cohort study on atopy in children (the Multicenter Allergy Study) parents filled out questionnaires twice within 2 years about their atopic diseases. Differences between the 2 responses were examined by log-linear and logistic regression models depending on the diagnosed atopy status of the study children.

RESULTS

Mothers tended to report more atopic diseases in the second questioning than in the first, indicating a nondifferential misclassification. Fathers were influenced by the development of atopic diseases in their children: they reported significantly more atopic diseases if the child developed atopic illness with atopic dermatitis.

CONCLUSION

In parental questioning about atopic diseases, a recall bias must be considered for the association of atopic family history and atopy in children. Especially in case-control and cross-sectional studies, such misclassifications can result in biased estimates of prognosis and risk factors.

Age-dependent tendency to become sensitized to other classes of aeroallergens in atopic asthmatic children

BACKGROUND

Several longitudinal studies report that allergic sensitization increases with age from childhood to adulthood.

OBJECTIVE

To evaluate whether an age-dependent tendency to become sensitized to new classes of allergens is present in atopic children, we studied retrospectively the changes in allergic sensitization in 165 asthmatic patients, monosensitized (ie, sensitized to only one class of allergens) in the first survey.

METHODS

All the children (18 months to 8 years at enrollment), attended our outpatient clinics twice, at time intervals ranging from 2 to 10 years. On each visit, sensitization to house dust mites, pollens, animal danders, and molds was determined by skin prick test.

RESULTS

We found that 43.6% (n = 72) of the patients became polysensitized on the second survey. According to age on first survey, the patients were further divided into two age groups: (1) group 1 = 18 months to < 5 years old (n = 98) and (2) group 2 = 5 to 8 years (n = 67). The transition from monosensitization to polysensitization observed in the entire population was present in both groups: 47 (47.9%) of the 98 children in group 1 and 25 (37.3%) of the 67 children in group 2 showed to be sensitized to more classes of allergens, as compared with first survey. Both in the whole population and in the two age subgroups, the changes in the frequency of monosensitization between the two evaluations were time-dependent (P < .05, each Chi(2)). Finally, to investigate whether monosensitization to a specific class of allergens could favor the development of polysensitization, we evaluated the frequency of polysensitization in the second survey in patients originally monosensitized to house dust mites or to pollens. We found that of the 130 patients originally monosensitized to house dust mites, 59 became polysensitized (45.4%), while of the 28 patients originally monosensitized to pollens, 9 became polysensitized (32.1%) (P > . 1). Similar results were obtained when patients were divided into age groups.

CONCLUSION

These data demonstrate that (1) monosensitized children are likely to become polysensitized and (2) house dust mite sensitization and, at a lower degree, pollen sensitization, apparently seem to play a "triggering" role in the development of polysensitization, since a high proportion of children originally monosensitized to house dust mites or to pollens became polysensitized.

Genetic linkage of HLA-class II locus to mite-specific IgE immune responsiveness

BACKGROUND

IgE response to common inhalant allergens seems to be the major determinant of the development of atopic rhinitis and asthma but it has been difficult to demonstrate genetic control of the IgE response.

OBJECTIVE

To investigate genetic linkage between specific IgE reactions to purified aero-allergens (grass, birch, cat, mite) and the HLA-class II locus.

METHODS

DNA-based HLA-class II typing was performed for determination of DRB1, DQB1 and DPB1 alleles. Linkage was studied by the affected sibpair method and the extended transmission disequilibrium test in 100 children from 40 nuclear families selected from a homogeneous population in south-western Germany.

RESULTS

Significant linkage of mite-specific IgE response to HLA-DPB (P = 0.00001), HLA-DRB (0.02) and HLA-DQB (P = 0.001) was revealed by sibpair analysis of MHC class II alleles and confirmed by the extended transmission disequilibrium test for HLA-DRB (P = 0.01) and HLA-DPB (P = 0.04). No consistent significant linkage between the HLA-class II locus and IgE response to grass pollen, birch pollen, and cat dander could be demonstrated.

CONCLUSION

The findings are consistent with the existence of one or more genes in the HLA-class II region modifying the IgE immune response to common environmental allergens.

Natural course of sensitization to food and inhalant allergens during the first 6 years of life

BACKGROUND

Specific IgE antibody responses to alimentary and environmental allergens are one of the hallmarks of atopic diseases. The knowledge of the time course of allergic sensitization during early life may facilitate measures for preventive interventions.

OBJECTIVE

In a prospective birth cohort study (the Multicenter Allergy Study [MAS]) we investigated annual incidence and prevalence rates of sensitization to food and inhalant allergens during the first 6 years of life.

METHODS

For 216 children of a prospective birth cohort (MAS), a complete follow-up of specific IgE measurements to 9 food and inhalant allergens was available at 1, 2, 3, 5, and 6 years of age. On the basis of these measurements, sensitization rates were estimated for the reference population of 4082 children by weighted analysis.

RESULTS

Annual incidence rates of sensitization to food allergens decreased from 10% at 1 year of age to 3% at the 6 years of age. Incidences of sensitization to inhalant allergen, however, increased with age (from 1.5% at 1 year to 8% at 6 years). Point prevalences of allergic sensitization to at least 1 of the 9 tested allergens increased from 11% at 1 year up to 30% at 6 years. This increase was due to markedly increasing sensitization rates to inhalant allergens (1.5% to at least 1 inhalant allergen at 1 year and 26% at 6 years of age), whereas sensitization rates to food allergens remained stable during the first 6 years of life (10%).

CONCLUSION

The earliest serologic marker for atopic immunoreactivity in infancy is the presence of IgE antibodies to egg, followed by milk. The development of sensitization to inhalant allergens occurs mostly after infancy. Beyond the third birthday annual incidence and prevalence increase markedly with age. Rates for outdoor allergens are twice those for indoor allergens.

Effect of pre- and postnatal tobacco smoke exposure on specific sensitization to food and inhalant allergens during the first 3 years of life. Multicenter Allergy Study Group, Germany

BACKGROUND

The study aimed to assess the effect of pre- and postnatal tobacco smoke exposure on specific sensitization to food allergens and inhalant allergens during the first 3 years of life.

METHODS

A total of 342 children of a prospective and observational birth cohort study on atopy (MAS) were included on the basis of a complete follow-up of specific IgE measurements at the ages of 1, 2, and 3 years with available questionnaire information about the parental smoking habit at birth, 18 months, and 3 years of age. Study children were grouped into four exposure categories representing in utero and postnatal environmental tobacco smoke (ETS) exposure, and according to the number of cigarettes smoked by the parents. The effect on the development of allergic sensitization to food, outdoor, and indoor allergens by 3 years of age was determined by multiple logistic regression analyses.

RESULTS

At the age of 3, children who were pre- and postnatally exposed to tobacco smoke had a significantly higher risk of sensitization to food allergens (odds ratio: 2.3, 95% C.I.: 1.1-4.6) than unexposed children. Children who were only postnatally exposed by a smoking mother also had a 2.2 times higher risk (95% C.I.: 0.9-5.9) of sensitization than unexposed children. These two categories (pre- and/or postnatal exposure) contribute to the significant overall effect of the tobacco smoke exposure (P< or =0.02). No significant association between tobacco smoke exposure and specific sensitization to inhalant allergens was observed. The determining risk factors for this type of sensitization were atopic family history and mite- and cat-allergen exposure levels.

CONCLUSIONS

During the first 3 years of life, both prenatal and postnatal tobacco smoke exposure has an adjuvant effect on allergic sensitization which seems to be restricted to allergens to which children are mainly exposed, in combination with the peak of the ETS exposure around the first birthday.

Atopy in children and parental social class

OBJECTIVES

This analysis was conducted to determine whether atopic disorders were related to social class in a pediatric population of a former socialist country.

METHODS

A cross-sectional study of 2471 schoolchildren was carried out in 1992 and 1993 in 3 towns in the former East Germany. Parents completed a standardized questionnaire regarding health events and lifestyle factors. In addition, skin-prick tests were performed and total serum immunoglobulin (IgE) was determined.

RESULTS

Lifetime prevalence rates for atopic disease and rates of allergic sensitization were highest in children from social class III (in which parents had more than 10 years of formal education) and lowest in social class I (less than 10 years of parental education), while rates in social class II (10 years of parental education) were constant at an intermediate level.

CONCLUSIONS

The data confirmed the assumption that in formerly socialist countries social inequalities existed under the socialist system, which were reflected by a social gradient in health outcomes. The findings support the hypothesis that increased access to modern lifestyle could be one reason for the increasing rates of atopic disorders during the last 3 decades.

Perinatal risk factors for atopic disease in conscripts

BACKGROUND

There is evidence to suggest that atopic disease in adulthood could be manifestations of events in early life.

OBJECTIVES

To investigate the relationship between perinatal risk factors and the prevalence of allergic rhinitis and asthma in conscripts.

METHODS

A retrospective cohort study, where information from the Military Service Enrolment Register was linked to the national Medical Birth Register. The study included 149 398 male conscripts who were born in Sweden in 1973, 1974 and 1975. Outcome measures were current asthma and allergic rhinitis recognized at the compulsory military conscript examinations.

RESULTS

Unifactorial analyses demonstrated that number of older siblings, young maternal age, multiple gestation, prematurity, low birth weight, growth retardation and perinatal asphyxia were all significantly related to a decreased risk of allergic rhinitis among male conscripts. The prevalence rates of allergic rhinitis among conscripts with and without older siblings were 14.1% and 16.2%, respectively (odds ratio 0.85; 95% confidence interval 0.82-0.87). The prevalence rates of allergic rhinitis among those with term birth (>36 weeks), moderately preterm birth (33-36 weeks) and very preterm birth (<33 weeks) were 15.2%, 13.1% and 11.6%, respectively. Older siblings, multiple gestation and young maternal age were highly significant independent determinants of allergic rhinitis. By contrast, the effects of prematurity, low birthweight and asphyxia were weaker and highly correlated. The only independent determinants of asthma were maternal age, birthweight and multiple gestation. Furthermore, maternal age and birthweight had opposite effects on asthma and allergic rhinitis.

CONCLUSIONS

In contrast to asthma, allergic rhinitis in young adult men was strongly associated with perinatal events. This may reflect the close relationship between allergic rhinitis and atopic sensitization, whereas asthma has a more multifactorial aetiology.

Cotinine excretion as a predictor of peak flow variability

Environmental tobacco smoke (ETS) is suspected to be an important risk factor for bronchial hyperresponsiveness. In order to test the effect of ETS, we measured expiratory flow rates and urine cotinine excretion (UCE) within a narrow time window in two consecutive years. Maternal smoking habits and medical history were ascertained by standardized questionnaires. The percentage ratio of the amplitude over the mean (AVAM) of the diurnal peak flow rates of children (complete values from at least five consecutive days) was calculated as an indicator of bronchial responsiveness. The association of UCE and log10AVAM was analyzed by multiple linear regression. Complete data were available for a sample of 417 children. The median of UCE in children of parents who smoked (3.2 ng/mg and 2.9 ng/mg creatinine, Surveys 1 and 2, respectively) was higher than the median in children of nonsmoking parents (0 ng/mg in both surveys). With increasing UCE the log10AVAM rose in the first and second surveys, as well as in the longitudinal analysis (p = 0.003). This association, however, showed up only in boys (p = 0.0001) and not in girls (p = 0.31). Our data suggest that there is a need both for further analysis of the gender difference and for more support of strategies against passive smoking as far as children are concerned, since airway hyperresponsiveness is a risk factor for chronic airway impairment.

Validation of a screening questionnaire for atopy with serum IgE tests in a population of pregnant Dutch women

BACKGROUND

We have started a large birth cohort study in which pregnant women with and without atopy are differentially included. In view of the large number of subjects to be screened (12000), a simple questionnaire was developed for the assessment of atopy in pregnant women.

OBJECTIVE

The objective of our study was to evaluate the efficacy of a questionnaire using serum IgE tests.

METHODS

During a antenatal visit to the midwife clinic, 175 expecting mothers completed a questionnaire and from each subject blood was obtained in which total and specific IgE against house dust mite, cat, dog, birch and grass was determined.

RESULTS

When atopy was defined as the presence of a positive test for IgE against at least one allergen, seven questions from the questionnaire had a sensitivity and specificity of 55.0% and 88.7%, respectively. With the use of the questionnaire it was possible to select about 50% of the subjects with specific IgE to one or more common inhalant allergens. The positive predictive value of the screening questions was 71.7%. Taking total IgE into account did not change these results.

CONCLUSION

The screening questionnaire is an efficient tool for differential inclusion of subjects with and without atopy in epidemiological studies.

Prevalence of atopy in students from Málaga, Spain

BACKGROUND

Epidemiologic studies are necessary to determine the prevalence of allergic diseases. This varies widely depending on allergen preparations and patients studied.

OBJECTIVE

To investigate the prevalence of atopic disease, skin test reactivity, total and specific IgE to common allergens, and other variables in a sample of students from Málaga, southern Spain.

METHODS

Three hundred sixty-five students (age 17.9 +/- 1.18) were interviewed by an allergist. Skin prick tests were performed with Dermatophagoides pteronyssinus, Artemisia vulgaris, Plantago lanceolata, Chenopodium album, Olea europaea, Phleum pratense, Parietaria judaica, Cynodon dactylon, Alternaria tenuis, and cat dander. Total and specific IgE to D. pteronyssinus, Olea, and Parietaria were determined.

RESULTS

Of all subjects studied, 19.9% suffered from rhinoconjunctivitis, 4.1% rhinoconjunctivitis plus asthma, 3.1% asthma alone, and 0.8% atopic dermatitis; 46.4% had a positive skin test to at least one allergen (28.2% to D. pteronyssinus, 20.4% to Olea, 13.8% to Phleum); and 43% had total IgE > 100 kU/L and 44.7% a family history of atopy. Allergic symptoms were strongly associated with skin test positivities and family allergic history. Patients with asthma or skin prick test positive had higher total IgE values than others (P < .01). There was a significant correlation between specific IgE values and wheal size in skin test.

CONCLUSIONS

Our findings confirm the high prevalence of atopic diseases, and the close relationship of skin tests reactivity (or presence of specific IgE) to allergens with symptoms of asthma and rhinitis. The presence of a family history of allergic diseases influences the development of positive skin tests and atopic illness. Dermatophagoides pteronyssinus and pollen of Olea europaea were found to be the most common allergens.

Health effects of passive smoking .5. Parental smoking and allergic sensitisation in children

BACKGROUND

A systematic review was conducted of the effects of parental smoking on immunoglobulin (IgE) levels, skin prick positivity, and allergic rhinitis or eczema in children. Asthma was excluded in order to distinguish more clearly the effect of passive smoke exposure on allergic sensitisation.

METHODS

Thirty six relevant publications were identified after consideration of 692 articles selected by electronic search of the Embase and Medline databases using keywords relevant to passive smoking in children. The search was completed in April 1997 and identified nine studies of IgE in neonates, eight of IgE in older children, 12 which included skin prick tests, and 10 describing symptoms of allergic disease other than asthma or wheezing. A quantitative meta-analysis was possible only for the studies reporting skin prick tests.

RESULTS

Several large studies failed to confirm early reports of a substantial or statistically significant association of maternal smoking with concentrations of total serum IgE in neonates or in older children. No consistent association emerged between parental smoking and allergic rhinitis or eczema. Few of these studies adjusted for potential confounding variables. The quantity and quality of evidence was greatest for skin prick tests, and studies of parental smoking during pregnancy or infancy were broadly consistent in showing no adverse effect on prick positivity (pooled odds ratio 0.87, 95% confidence interval 0.62 to 1.24). There was much greater and statistically significant (p = 0.002) heterogeneity of odds ratios relating current parental smoking to skin prick positivity.

CONCLUSIONS

Parental smoking, either before or immediately after birth, is unlikely to increase the risk of allergic sensitisation in children.

Skin sensitization in asthmatic children less than 36 months of age

BACKGROUND

Atopy is reported to play an insignificant role in wheezing during infancy in contrast to later childhood. For this reason skin testing may not be included in a workup of wheezing infants.

OBJECTIVE/METHOD

In order to evaluate the degree and evolution of skin sensitization to allergens in infants with asthma, we have retrospectively analyzed the skin test results from 40 referred asthmatic children less than 36 months of age, who had had more than three wheezing episodes and whose symptoms improved on treatment with beta-agonist and anti-inflammatory agents.

RESULTS

Skin sensitization (epicutaneous) to common indoor and outdoor aeroallergens and foods were demonstrated in 23 (58%) of these patients. Asthmatic children with the onset before 12 months of age and duration of less than 12 months were sensitive predominantly to foods. Those with later onset asthmas and longer duration developed sensitivity first to indoor and then to outdoor allergens. The most common food, indoor, and outdoor allergens were egg, dust mite, and pollens, respectively. Six of these patients had repeat skin tests later. Two demonstrated a decrease in skin sensitivities to foods, one gained a new sensitivity to grass, while three remained unsensitized.

CONCLUSION

Skin sensitization to allergens was common in selected asthmatic infants and evolves in the order of exposures: foods, indoor allergens, and outdoor allergens. Repeat skin tests showed changing skin test patterns in some patients.

The home environment and asthma symptoms in childhood: two population based case-control studies 13 years apart

BACKGROUND

Prevalence surveys of asthma and/or wheezing among all children aged between 7 1/2 and 8 1/2 attending state and private schools in the London Borough of Croydon were conducted in February 1978 and February 1991. Two population based case-control studies drawn from the survey responders were used to investigate the association between childhood wheeze and characteristics of the home environment and to assess whether changes in these characteristics between 1978 and 1991 may have contributed to an increase in the population prevalence of wheeze among school children.

METHODS

Information on exposure to potential indoor environmental risk factors was obtained from parents by home interview and compared between cases-that is, children with frequent (> or = 5) or in-frequent (1-4) attacks of asthma or wheezing in the past 12 months- and controls, with adjustment for study. Changes in exposure over time were assessed by comparing control groups.

RESULTS

Between 1978 and 1991 the population prevalence odds of wheeze increased by 20% (OR 1.20; 95% CI 1.04 to 1.39). Change in parental smoking, gas cooking, pet ownership, and central heating did not appear to explain the rise. Use of non-feather pillows was positively associated with childhood wheeze even after adjusting for other risk factors and after re-coding from non-feather to feather cases thought to have changed pillow in response to symptoms (OR 1.54; 95% CI 1.13 to 2.10). The proportion of control children reportedly using non-feather pillows was 44% in 1978 and 67% in 1991.

CONCLUSIONS

Increased use of non-feather pillows was the only domestic indoor exposure studied which appeared to explain a modest rise in prevalence of wheeze from 1978 to 1991. Our analysis attempts to address behavioural change in response to the child's symptoms but an artifact arising from lifelong avoidance of feather bedding in atopic families cannot be entirely discounted.

Sensitization to hen's egg at the age of twelve months is predictive for allergic sensitization to common indoor and outdoor allergens at the age of three years

BACKGROUND

Specific predictors for atopic sensitization in early infancy are prerequisites for preventive intervention studies.

OBJECTIVE

To identify predictors of allergic sensitization to common aeroallergens in infancy, 1314 children in five German cities were followed up from birth (1990) to the age of 3 years.

METHODS

Blood samples were taken from cord blood and at follow-up visits at the ages of 1, 2, and 3 years. Total serum IgE and specific IgE antibodies to common food and inhalant allergens were determined.

RESULTS

Among our study population, risk factors for sensitization to indoor and/or outdoor allergens at the age of 3 years were a positive family history, the presence of hen's egg-specific IgE antibodies (> or = 0.35 kU/L), and increased log- [total IgE] levels at the age of 12 months. Elevated cord blood IgE was not associated with sensitization to inhalant allergens at the age of 3 years. Egg-specific IgE greater than 2 kU/L in combination with a positive family history of atopy was a highly specific (specificity, 99%) and predictive (positive predictive value, 78%) marker for sensitization to inhalant allergens at 3 years of age.

CONCLUSIONS

Hen's egg-specific IgE at the age of 12 months is a valuable marker for subsequent allergic sensitization to allergens that cause asthma, allergic rhinitis, and atopic dermatitis.

Childhood antecedents of allergic sensitization in young British adults

OBJECTIVE

This study was designed to investigate whether associations of self-reported hay fever with sibship size, birth order, infant feeding, and childhood socioeconomic status reflect variations in sensitization to common aeroallergens.

METHODS

One thousand three hundred sixty-nine persons born throughout Britain in 1958 were followed up to age 34 to 35 years. The cohort included 1050 subjects with a history of asthma, wheezy bronchitis, wheezing, or pneumonia and 319 with no history of wheezing illness at ages 7, 11, 16, 23, or 33 years. Skin prick tests with extracts of mixed grass pollen, house dust mite (Der p 1), and cat fur were performed; and wheal diameters were measured.

RESULTS

The prevalence of positive skin test results (> or = 3 mm wheal) was independently related (p < 0.01) to male sex, reduced numbers of older siblings (but not younger siblings), and higher socioeconomic status in childhood. Current cigarette smoking and maternal smoking during pregnancy were independently associated (p < 0.01) with a reduced prevalence of skin prick test positivity. No significant independent effects (p > 0.10) were found for adult social class, maternal age, birth weight, gestation, breast feeding, preschool nursery attendance, urban birthplace, or gas stove exposure.

CONCLUSION

Factors related to small families and relative affluence in childhood promote atopic sensitization to a variety of aeroallergens in later life. These observations are consistent with the suggestion that early infection may protect against subsequent allergic disease.

Parental and neonatal risk factors for atopy, airway hyper-responsiveness, and asthma

BACKGROUND

Previous studies have not resolved the importance of several potential risk factors for the development of childhood atopy, airway hyperresponsiveness, and wheezing, which would allow the rational selection of interventions to reduce morbidity from asthma. Risk factors for these disorders were examined in a birth cohort of 1037 New Zealand children.

METHODS

Responses to questions on respiratory symptoms and measurements of lung function and airway responsiveness were obtained every two to three years throughout childhood and adolescence, with over 85% cohort retention at age 18 years. Atopy was determined by skin prick tests at age 13 years. Relations between parental and neonatal factors, the development of atopy, and features of asthma were determined by comparison of proportions and logistic regression.

RESULTS

Male sex was a significant independent predictor for atopy, airway hyper-responsiveness, hay fever, and asthma. A positive family history, especially maternal, of asthma strongly predicted childhood atopy, airway hyperresponsiveness, asthma, and hay fever. Maternal smoking in the last trimester was correlated with the onset of childhood asthma by the age of 1 year. Birth in the winter season increased the risk of sensitisation to cats. Among those with a parental history of asthma or hay fever, birth in autumn and winter also increased the risk of sensitisation to house dust mites. The number of siblings, position in the family, socioeconomic status, and birth weight were not consistently predictive of any characteristic of asthma.

CONCLUSIONS

Male sex, parental atopy, and maternal smoking during pregnancy are risk factors for asthma in young children. Children born in winter exhibit a greater prevalence of sensitisation to cats and house dust mites. These data suggest possible areas for intervention in children at risk because of parental atopy.

Sensitization to airborne allergens in children with respiratory symptoms

BACKGROUND

Allergy is one of the most common causes of respiratory symptoms in children and youth.

OBJECTIVE

Evaluate the presence and the type of allergic sensitization in a paediatric population with respiratory symptoms.

METHODS

We studied 564 consecutive children, 5 months to 17 years of age, with a male to female ratio (M/F) = 1.4, referred to our outpatient clinic in a 12-month period retrospectively. Patients were arbitrarily divided into four groups (grs) according to their age: gr1 = 5 months to 4 years old (181 patients), gr2 = 4 to 7 years (201 patients), gr3 = 7 to 10 years (96 patients), and gr4 = 10 to 17 years (86 patients). Sensitization to house dust mites, pollens, animal dander, and molds was determined by skin prick testing.

RESULTS

Sensitization to at least one class of allergen occurred in 304 of the 564 patients (53.9%, M/F ratio = 2.0); the percentage of allergic patients increased with age as follows: 29.8% (54 patients) of the patients in gr1, 55.2% (111 patients) in gr2, 68.8% (66 patients) in gr3 and 84.9% (73 patients) in gr4 (chi(2) = 84.1, P < .01). In the entire allergic population and in gr1 to gr3, the most common positive allergic reaction was to house dust mites (P < .01, chi(2) test each comparison). In contrast, gr4 patients showed a nearly equal percentage of sensitization to pollens and to house dust mites (79.5% and 78.1% respectively) (chi(2) = 0.0, P = >.1). Sensitization to only one class of allergen occurred in 51.3% of the allergic patients and the percentage of these monosensitized patients tended to decrease from gr1 to gr4 (chi(2) = 15.2, P < .1). In the monosensitized group, sensitization to house dust mites was the most frequent in gr1 to gr3 (age <10 years) as in the whole sample. In gr4, the frequency of sensitization to house dust mites was similar to that of sensitization to pollens. On the contrary, within the patient group sensitized to two or more allergens (polysensitized patients), sensitization to house dust mites was as frequent as sensitization to pollens already in gr2 as compared with monosensitized patients.

CONCLUSIONS

In children with respiratory symptoms, the percentage of allergic individuals was high and increased with the age of the patients. This phenomenon was associated with an age-related enhancement in the ratio of polysensitized to monosensitized patients and with an age-related increase in the frequency of sensitization to seasonal allergens (ie, pollens).

Mite allergy, clinical atopy, and restriction by HLA class II immune response genes

From a community-based study cohort of 1812 elementary schoolchildren we selected 129 unrelated participants to investigate the relevance of HLA-class II molecules (DPB, DQB, and DRB) to the regulation of immune response to the mite allergen Der p 1 and to clinical atopic disorders. On the basis of skin prick test results validated by measurement of specific IgE, individuals were selected and divided into three groups: group I (n = 20), controls without detectable specific IgE to common inhalant allergens; group II (n = 22), children sensitized only to non-mite allergens; group III (n = 85), children sensitized to Der p 1. Clinical history of asthma, eczema, and hay fever was ascertained using standardized questionnaires. In total, 43 different HLA class II alleles (DPB, n = 19; DQB, n = 14; and DRB, n = 10) were determined by sequence-specific oligonucleotide typing with PCR-amplified DNA. We were not able to demonstrate significant differences in gene frequencies of any HLA class II allele between the group of mite-sensitized children and one of the other two groups. However, the presence of certain DRB- and DPB-haplotypes (DRB *0100/*0300/*1100 and DPB *0201/*0401) was significantly associated (p < or = 0.01) with a history of asthma, hay fever, and atopy (defined as a history of asthma and/or hay fever and/or eczema). Other haplotypes, including DQB *0303/*0503, DRB *0200/ *0700, and DPB 0402 were negatively associated with a history of eczema, hay fever, and atopy (p < or = 0.01). Thus, our findings do not suggest a relevance of HLA-class II molecules to mite allergy; however, some HLA class II haplotypes appear to be predictive of the incidence of atopic disorders.

Home environment and severe asthma in adolescence: a population based case-control study

OBJECTIVE

To investigate the effects of the home environment on the risk of severe asthma during adolescence.

DESIGN

A questionnaire based case-control study drawn from a cross sectional survey of allergic diseases among secondary school pupils in Sheffield in 1991.

SUBJECTS

763 children whose parents had reported that over the previous 12 months they had suffered either 12 or more wheezing attacks or a speech limiting attack of wheeze. A further 763 children were frequency matched for age and school class to act as controls. Analysis was restricted to 486 affected children and 475 others born between 1975 and 1980 who had lived at their present address for more than three years.

RESULTS

Independent associations with severe wheeze were seen for non-feather bedding, especially foam pillows (odds ratio 2.78; 95% confidence interval 1.89 to 4.17), and the ownership of furry pets now (1.51; 1.04 to 2.20) and at birth (1.70; 1.20 to 2.40). These estimates were derived from subjects whose parents denied making changes in the bedroom or avoiding having a pet because of allergy. Parental smoking, use of gas for cooking, age of mattress, and mould growth in the child's bedroom were not significantly associated with wheezing.

CONCLUSIONS

Either our study questionnaire failed to detect the avoidance or removal of feather bedding by allergic families or there is some undetermined hazard related to foam pillows. Synthetic bedding and furry pets were both widespread in this population and may represent remediable causes of childhood asthma.

Risk factors for respiratory symptoms and atopic sensitisation in the Baltic area

Recent studies have indicated that atopic sensitisation is uncommon while respiratory symptoms are common among schoolchildren in Eastern Europe. Risk factors for respiratory symptoms and atopic sensitisation were evaluated in a cross sectional study involving 2594 schoolchildren (10-12 years) from Sweden (n = 665), Poland (n = 410), and Estonia (n = 1519). The measurements included parental questionnaires and skin prick tests with eight standardised allergens. Multiple logistic analyses demonstrated that atopic heredity was a significant independent risk factor for respiratory symptoms and atopic sensitisation in all the countries. Current dampness and maternal smoking were related to respiratory symptoms whereas domestic crowding, male gender, and passive smoking during infancy were related to atopic sensitisation. Current maternal smoking had a strong dose response association with current coughing attacks (nocturnal cough > 4 weeks or exercise induced coughing attacks) but only in Eastern Europe. A strong inverse relationship was recorded between domestic crowding and sensitisation as the risk for sensitisation increased with decreasing number of persons per room in the household (odds ratio (OR) 0.58, 95% confidence interval (CI) 0.43 to 0.77). Exposure to tobacco smoke at home during infancy was a risk factor for atopic sensitisation but only to animal dander and only in Eastern Europe (OR 1.41, 95% CI 1.03 to 1.93). In conclusion, there were small differences in the pattern of risk factors between Eastern and Western Europe. The only exception was environmental tobacco smoke being a risk factor only in Eastern Europe. The study also suggests that factors related to domestic crowding protect against atopic sensitisation in Estonia and Poland. A higher standard of living with less crowding may give rise to an increasing prevalence of atopic sensitisation also in Eastern Europe.