Changing prevalence of asthma in Australian children

Epidemiological change of atopic dermatitis and food allergy in school-aged children in Korea between 1995 and 2000

Little is known about the prevalence of atopic dermatitis and food allergy outside North America and Europe. We evaluated the prevalence of atopic dermatitis and food allergy with the comparison of prevalence between 1995 and 2000 in Korea and evaluated the correlation of prevalence between atopic dermatitis and food allergy. A cross-sectional questionnaire survey was conducted on random samples of schoolchildren 6 to 14 yr at two time points, 1995 and 2000 throughout Korea. The last twelve months prevalence of atopic dermatitis in Korean school-aged children was increased from 1995 to 2000. The twelve-month prevalence of atopic dermatitis and food allergy were higher in Seoul than in any other provincial cities in 1995, but the prevalence of both diseases in Seoul and Provincial Centers became to be similar in 2000. The rate responded to food allergy of children with atopic dermatitis (9.5%) was lower than that of the western countries (60%). And our data demonstrated paternal and maternal allergy history is very significantly correlated to developing atopic dermatitis in their offspring. The further objective evaluations are required to confirm these outcomes because the environmental and risk factors may be different among the countries according to their living cultures.

Association of domestic exposure to volatile organic compounds with asthma in young children

AIM

To investigate the association between domestic exposure to volatile organic compounds (VOCs) and asthma in young children.

METHODS

A population based case-control study was conducted in Perth, Western Australia in children aged between 6 months and 3 years. Cases (n = 88) were children recruited at Princess Margaret Hospital accident and emergency department and discharged with asthma as the primary diagnosis; 104 controls consisted of children from the same age group without an asthma diagnosis identified through the Health Department of Western Australia. Information regarding the health status of the study children and characteristics of the home was collected using a standardised questionnaire. Exposure to VOCs, average temperature and relative humidity were measured in winter and summer in the living room of each participating household.

RESULTS

Cases were exposed to significantly higher VOC levels (microg/m3) than controls (p<0.01). Most of the individual VOCs appeared to be significant risk factors for asthma with the highest odds ratios for benzene followed by ethylbenzene and toluene. For every 10 unit increase in the concentration of toluene and benzene (microg/m3) the risk of having asthma increased by almost two and three times, respectively.

CONCLUSIONS

Domestic exposure to VOCs at levels below currently accepted recommendations may increase the risk of childhood asthma. Measurement of total VOCs may underestimate the risks associated with individual compounds.

Spectrum of acute allergic diseases in an emergency department: an evaluation of one years' experience

OBJECTIVE

There is limited available literature on the incidence of allergic diseases in ED. The objective of this study was to investigate the clinical records of patients admitted to the ED with a suspected allergic reaction.

METHODS

A 1 year retrospective study was carried out and data were collected from the patients' computerized medical reports.

RESULTS

A total of 324 patients were admitted for an allergic event. Of those, 165 patients (50.9%) were female and their mean age was 55 +/- 18.5 years. Diagnoses included: asthma in 100 patients (30.9%); hymenoptera allergy in 78 patients (24.1%); food allergy in 31 patients (9.5%); drug allergy in 25 patients (7.7%); and allergic conjunctivitis in 12 patients (3.7%). No diagnosis was found in the medical records of 78 patients (24.1%). Anaphylactic shock was observed in 12 patients (3.7%) with a diagnosis of food allergy (six cases), drug allergy (three cases) and hymenoptera allergy (three cases). Ninety patients (27.7%) were hospitalized in the following units: 38 in allergy unit (42.2%); 20 in intensive care unit (22.2%); 10 in pulmonary unit (11.1%); eight in the dermatology unit (8.9%); six in the internal medicine unit (6.7%); and eight in other units (8.9%). Overall, 42 patients (12.9%) were evaluated by an allergologist after ED discharge with positive allergy results in 28 cases (66.6%).

CONCLUSIONS

Acute allergic diseases are not rare in ED, representing 1% of the annual visits in our series. A low rate of allergologist referral was observed. Emergency physicians must work closely with allergologists to ensure a better evaluation, long-term care and preventive management of patients with allergic diseases admitted to the ED.

Ratio of omega-6 to omega-3 fatty acids and childhood asthma

Asthma is a leading cause of morbidity for children and is a major public health problem in Australia. Ecological and temporal data suggest that dietary factors may have a role in recent increases in the prevalence of asthma.

AIM

The aim of conducting this study was to investigate whether childhood asthma was associated with the ratio of omega 6 (n-6) to omega 3 (n-3) fatty acids in the diet (n-6:n-3).

METHOD

The Western Australian Pregnancy Cohort Study is a prospective birth cohort of 2602 children. Using a nested case-control cross-sectional study design within this cohort, a group of children were identified as cases with current asthma at 6 or at 8 years of age or as controls with no asthma at 6 or at 8 years. Dietary details including n-6 and n-3 fatty acid intake data were collected by parent response to a questionnaire when the children were 8 years old. Logistical regression was used to compare quartiles of n-6:n-3 intake in cases and controls. Adjustment was made for covariates: gender, gestational age, breastfeeding, older siblings, maternal smoking during pregnancy, maternal age, maternal asthma, child's current age in months, body mass index, total energy intake, and antioxidant intake (vitamins A, C, E, and zinc).

RESULTS

A response rate of 83% was achieved by providing complete data from 335 children [49% cases with current asthma (n = 166), 51% controls (n = 169)]. Following adjustment for covariates the association between the ratio of n-6:n-3 fatty acids and risk for current asthma was statistically significant (p = 0.022).

CONCLUSION

We found evidence for a modulatory effect of the dietary n-6:n-3 fatty acid ratio on the presence of asthma in children. Our results provide evidence that promotion of a diet with increased n-3 fatty acids and reduced n-6 fatty acids to protect children against symptoms of asthma is warranted.

Role of atypical bacterial infection of the lung in predisposition/protection of asthma

Asthma is a common inflammatory disease of the airways that results in airway narrowing and wheezing. Allergic asthma is characterised by a T-helper cell-type (Th) 2 response, immunoglobulin (Ig) E production, and eosinophilic influx into the airways. Recently, many clinical studies have implicated Mycoplasma pneumoniae and Chlamydia pneumoniae in the development and exacerbation of both chronic and acute asthma. It is widely accepted that M. pneumoniae and C. pneumoniae infections require Th1 immunity for clearance; therefore, according to the hygiene hypothesis, these infections should be protective against asthma. Here, we review the clinical evidence for the association and mechanisms of predisposition to and protection against asthma by these infections. We will examine the following question: Is it the absence of infection or the age of the individual on infection that confers susceptibility or resistance to asthma and does this vary between normal and predisposed individuals? We put forward a hypothesis of the effects of these infections on the development and prevention of asthma and how novel preventative and treatment strategies involving these microbes may be targeted against asthma.

Comparison of selected reasons for hospitalization of children among children's/tertiary hospitals, Australia, 1996-97 and 1997-98

OBJECTIVES

To describe the major characteristics of admissions to children's/tertiary hospitals (compared to other hospitals) and to compare characteristics of local and non-local admissions to specialist children's hospitals.

METHODS

A cross-sectional analysis of a routinely collected data set of hospitalizations in Australia in 1996-97 and 1997-98.

RESULTS

Hospital-specific proportions of asthma and bronchitis, tonsillectomy and/or adenoidectomy and gastroenteritis varied considerably. Multivariate analysis comparing the characteristics of admitted patients by locality showed that non-local admissions of patients with asthma and bronchitis and gastroenteritis to selected children's hospitals were significantly more likely to be Indigenous children and/or children who had been transferred from another hospital. Non-local admissions of tonsillectomy and/or adenoidectomy patients to selected hospitals were significantly more likely to be public patients.

CONCLUSIONS

Differences in the characteristics of admitted patients to children's hospitals by locality raise issues about equality of access and availability of appropriate services for these children and their families.

Reported versus confirmed wheeze and lung function in early life

AIMS

To investigate the relation between parentally reported wheeze (unconfirmed), physician confirmed wheeze, and subsequent lung function.

METHODS

Children at risk of allergic disease (one parent atopic) were recruited antenatally and followed prospectively from birth. During the first three years of life parents were asked to contact the study team if their child was wheezy. The presence of wheeze was confirmed or not by the primary care or study physician. Respiratory questionnaire and specific airway resistance measurement (sR(aw), body plethysmograph) were completed at age 3 years.

RESULTS

A total of 454 children were followed from birth to 3 years of age. One hundred and eighty six (40.9%) of the parents reported their child wheezing in the first three years of life, and in 130 (28.6%) the wheeze was confirmed. A total of 428 children attended the three year clinic review, of whom 274 (64%) successfully carried out lung function tests. There was no significant difference in sR(aw) (kPa.s; geometric mean, 95% CI) between children who had never wheezed (n = 152; 1.03, 1.00 to 1.06) and those with a parentally reported but unconfirmed wheeze (n = 36; 1.02, 0.96 to 1.07, p = 1.00). sR(aw) was significantly higher in children with a physician confirmed wheeze (n = 86; 1.17, 1.11 to 1.22, p < 0.001) compared to those with no history of wheeze or with unconfirmed wheeze.

CONCLUSIONS

Children with physician confirmed wheeze have significantly poorer lung function compared to those with parentally reported but unconfirmed and those who have never wheezed. A proportion of parents may have little understanding of what medical professionals mean by the term "wheeze".

Relationship between socioeconomic status and asthma: a longitudinal cohort study

BACKGROUND

There is conflicting information about the relationship between asthma and socioeconomic status, with different studies reporting no, positive, or inverse associations. Most of these studies have been cross sectional in design and have relied on subjective markers of asthma such as symptoms of wheeze. Many have been unable to control adequately for potential confounding factors.

METHODS

We report a prospective cohort study of approximately 1000 individuals born in Dunedin, New Zealand in 1972-3. This sample has been assessed regularly throughout childhood and into adulthood, with detailed information collected on asthma symptoms, lung function, airway responsiveness, and atopy. The prevalence of these in relation to measures of socioeconomic status were analysed with and without controls for potential confounding influences including parental history of asthma, smoking, breast feeding, and birth order using cross sectional time series models.

RESULTS

No consistent association was found between childhood or adult socioeconomic status and asthma prevalence, lung function, or airway responsiveness at any age. Having asthma made no difference to educational attainment or socioeconomic status by age 26. There were trends to increased atopy in children from higher socioeconomic status families consistent with previous reports.

CONCLUSIONS

Socioeconomic status in childhood had no significant impact on the prevalence of asthma in this New Zealand born cohort. Generalisation of these results to other societies should be done with caution, but our results suggest that the previously reported associations may be due to confounding.

Acute effects of urban ambient air pollution on respiratory symptoms, asthma medication use, and doctor visits for asthma in a cohort of Australian children

We enrolled a cohort of primary school children with a history of wheeze (n=148) in an 11-month longitudinal study to examine the relationship between ambient air pollution and respiratory morbidity. We obtained daily air pollution (ozone, particulate matter less than 10 microm, and nitrogen dioxide), meteorological, and pollen data. One hundred twenty-five children remained in the final analysis. We used logistic regression models to determine associations between air pollution and respiratory symptoms, asthma medication use, and doctor visits for asthma. There were no associations between ambient ozone concentrations and respiratory symptoms, asthma medication use, and doctor visits for asthma. There was, however, an association between PM(10) concentrations and doctor visits for asthma (RR=1.11, 95% CI=1.04-1.19) and between NO(2) concentration and wet cough (RR=1.05, 95% CI=1.003-1.10) in single-pollutant models. The associations remained significant in multipollutant models. There was no consistent evidence that children with wheeze, positive histamine challenge, and doctor diagnosis of asthma reacted differently to air pollution from children with wheeze and doctor diagnosis of asthma and children with wheeze only. There were significant associations between PM(10) levels and doctor visits for asthma and an association between NO(2) levels and the prevalence of wet cough. We were, however, unable to demonstrate that current levels of ambient air pollution in western Sydney have a coherent range of adverse health effects on children with a history of wheezing.

The prevalence of asthma and allergies in Singapore; data from two ISAAC surveys seven years apart

BACKGROUND AND AIMS

Over the past few decades, the prevalence of asthma has been increasing in the industrialised world. Despite the suggestion of a similar increase in Singapore, the 12 month prevalence of wheeze among schoolchildren in 1994 was 2.5-fold less than that reported in western populations. It was hypothesised that with increasing affluence in Singapore, the asthma prevalence would further increase and approach Western figures. A second ISAAC survey was carried out seven years later to evaluate this hypothesis.

METHODS

The cross-sectional data from two ISAAC questionnaire based surveys conducted in 1994 (n = 6238) and in 2001 (n = 9363) on two groups of schoolchildren aged 6-7 and 12-15 years were compared. The instruments used were identical and the procedures standardised in both surveys.

RESULTS

Comparing data from both studies, the change in the prevalence of current wheeze occurred in opposing directions in both age groups--decreasing in the 6-7 year age group (16.6% to 10.2%) but increasing to a small extent in the 12-15 year age group (9.9% to 11.9%). The 12 month prevalence of rhinitis did not change; there was an increase in the current eczema symptoms in both age groups.

CONCLUSION

The prevalence of current wheeze, a surrogate measure of asthma prevalence, has decreased significantly in the 6-7 year age group. Eczema was the only allergic disease that showed a modest increase in prevalence in both age groups.

Asthma prevalence in Melbourne schoolchildren: have we reached the peak?

OBJECTIVE

To determine the change in prevalence of asthma, eczema and allergic rhinitis in Australian schoolchildren between 1993 and 2002.

DESIGN

Questionnaire based survey, using the protocol of the International Study of Asthma and Allergy in Childhood.

SETTING

Metropolitan Melbourne primary schools within a 20 km radius of the GPO in 1993 and 2002.

SUBJECTS

All children in school years 1 and 2 (ages 6 and 7) attending a random sample of 84 schools in 1993 and 63 schools in 2002.

MAIN OUTCOME MEASURES

Parent-reported symptoms of atopic disease; treatment for asthma; country of birth.

RESULTS

There was a 26% reduction in the 12-month period prevalence of reported wheeze, from 27.2% in 1993 to 20.0% in 2002. The magnitude of reduction was similar for boys (27%) and girls (25%). The 12-month period prevalence of reported eczema increased from 11.1% in 1993 to 17.2% in 2002, and rhinitis increased from 9.7% to 12.7%. There were reductions in the proportion of children attending an emergency department for asthma in the previous year (3.6% to 2.3%), the proportion admitted to hospital (1.7% to 1.1%) and the proportion taking asthma medication (18.5% to 13.4%). Of those who reported frequent wheeze, there was an increase in the proportion taking regular inhaled steroids (34.5% to 40.9%).

CONCLUSION

There has been a significant reduction in the prevalence of reported asthma in Melbourne schoolchildren, whereas the prevalence of eczema and allergic rhinitis has continued to increase.

Increasing prevalence of allergic rhinitis but not asthma among children in Hong Kong from 1995 to 2001 (Phase 3 International Study of Asthma and Allergies in Childhood)

There is a worldwide belief that the prevalence of asthma and other allergic diseases is increasing but the measures used in many studies are susceptible to systematic errors. We examined the trend of asthma, allergic rhinitis and eczema prevalence in school children aged 6-7 years in Hong Kong from 1995 to 2001 using standardized ISAAC methodology. There were 4448 and 3618 children participating in 2001 and 1995, respectively. The prevalence of life-time rhinitis (42.4% vs. 38.9%, p < 0.01), current rhinitis (37.4% vs. 35.1%, p < 0.03), current rhinoconjunctivitis (17.2 vs. 13.6%, p < 0.01) and life-time eczema (30.7% vs. 28.1%, p = 0.01) increased significantly. There was no significant change in prevalence of life-time asthma, life-time wheeze and current wheeze albeit a significant increase in severe asthma symptoms. We investigated a number of potential risk factors including sex, family history of atopy, sibship size, birth weight, respiratory tract infections, pet ownership and exposure to tobacco smoke. However, the increases in prevalence of rhinitis and eczema could not be entirely explained by the change of prevalence of these risk factors. The odds ratio OR for the study period remained significantly associated with current rhinitis (OR 1.31, 95% confidence intervals CI 1.17-1.46), current rhinoconjunctivitis (OR 1.63, 95% CI 1.41-1.87) and life-time eczema (OR 1.30, 95% CI 1.16-1.45) after adjustment for these confounding variables using logistic regression model. Further study is warranted to elucidate the factors contributing to the observable change in the prevalence of rhinitis in our population.

Asthma and atopy in overweight children

BACKGROUND

Obesity may be associated with an increase in asthma and atopy in children. If so, the effect could be due to an effect of obesity on lung volume and thus airway hyperresponsiveness.

METHODS

Data from 5993 caucasian children aged 7-12 years from seven epidemiological studies performed in NSW were analysed. Subjects were included if data were available for height, weight, age, skin prick test results to a common panel of aeroallergens, and a measure of airway responsiveness. History of doctor diagnosed asthma, wheeze, cough, and medication use was obtained by questionnaire. Recent asthma was defined as a doctor diagnosis of asthma ever and wheeze in the last 12 months. Body mass index (BMI) percentiles, divided into quintiles per year age, were used as a measure of standardised weight. Dose response ratio (DRR) was used as a measure of airway responsiveness. Airway hyperresponsiveness was defined as a DRR of >/=8.1. Adjusted odds ratios were obtained by logistic regression.

RESULTS

After adjusting for atopy, sex, age, smoking and family history, BMI was a significant risk factor for wheeze ever (OR = 1.06, p = 0.007) and cough (OR = 1.08, p = 0.001), but not for recent asthma (OR = 1.02, p = 0.43) or airway hyperresponsiveness (OR = 0.97 p = 0.17). In girls a higher BMI was significantly associated with higher prevalence of atopy (chi(2) trend 7.9, p = 0.005), wheeze ever (chi(2) trend 10.4, p = 0.001), and cough (chi(2) trend 12.3, p<0.001). These were not significant in boys.

CONCLUSIONS

Higher BMI is a risk factor for atopy, wheeze ever, and cough in girls only. Higher BMI is not a risk factor for asthma or airway hyperresponsiveness in either boys or girls.

Prevalence of peanut allergy in primary-school children in Montreal, Canada

BACKGROUND

Peanut allergy is receiving increasing attention. Only one study has estimated the prevalence in North America, but it did not corroborate history with diagnostic testing.

OBJECTIVE

We estimated the prevalence of peanut allergy in Montreal by administering questionnaires regarding peanut ingestion to children in kindergarten through grade 3 in randomly selected schools.

METHODS

Respondents were stratified as follows: (1). peanut tolerant, (2). never-rarely ingest peanut, (3). convincing history of peanut allergy, and (4). uncertain history of peanut allergy. Groups 2, 3, and 4 underwent peanut skin prick tests (SPTs), and if the responses were positive in groups 2 or 4, measurement of peanut-specific IgE were undertaken. Children in group 3 with a positive SPT response were considered allergic to peanut without further testing. Children in groups 2 and 4 with peanut-specific IgE levels of less than 15 kU/L underwent oral peanut challenges.

RESULTS

Of the 7768 children surveyed, 4339 responded, 94.6% in group 1. The prevalence of peanut allergy was 1.50% (95% CI, 1.16%-1.92%). When multiple imputation was used to incorporate data on those responding to the questionnaire but withdrawing before testing, the estimated prevalence increased to 1.76% (95% CI, 1.38%-2.21%). When data regarding the peanut allergy status of nonresponders (as declared to the school before the study) were also incorporated, the estimated prevalence was 1.34% (95% CI, 1.08%-1.64%).

CONCLUSION

Our prevalence study is the first in North America to corroborate history with confirmatory testing and the largest worldwide to incorporate these techniques. We have shown that, even with conservative assumptions, prevalence exceeds 1.0%.

Age-specific relationship between CD14 and atopy in a cohort assessed from age 8 to 25 years

CD14 influences postnatal switching of T helper cell responses. CD14 C-159T has been associated with altered CD14 and IgE levels in cross-sectional studies. Identifying whether associations vary with age requires data from children of the same age followed longitudinally over many years. In this study, an unselected population with extensive longitudinal data was used to test the hypothesis that CD14 C-159T was associated with early-onset atopy. A total of 305 subjects were assessed on up to seven occasions between ages 8 and 25 years by questionnaire, histamine challenge, and skin prick test. For atopy, airway hyperresponsiveness (AHR), and wheeze, each subject was classified as having early onset, late onset, or no disease onset during follow-up. Compared with subjects with -159CT and -159TT, subjects with -159CC had an odds ratio of 2.2 (p = 0.018) for early-onset atopy and an odds ratio of 2.6 (p = 0.019) for early-onset AHR. Cross-sectional analysis showed increased prevalence of -159CC in subjects with atopy and AHR in childhood but not adulthood. These data suggest that the influence of CD14 -159C on the atopic phenotype may be age specific, exerting an effect during midchildhood, which is no longer apparent by early adulthood.

Asthma and tooth erosion. Is there an association?

OBJECTIVES

To investigate whether there is an association between asthma and tooth erosion in a representative random sample of adolescents in the East Midlands.

METHODS

A random sample of 1753 12-year-old children was examined in all schools in Leicestershire and Rutland. 1308 children were re-examined 2 years later. Tooth erosion was assessed using the index employed in the Children's Dental Health in the UK Survey 1993. Asthma presence was recorded on a self-completed questionnaire at the time of the 12 years examination. Data on asthma prescribing over a one year period was obtained from the Prescription Pricing Authority.

RESULTS

Asthma was present in 16.8% of 12-year-olds. Tooth erosion was recorded in 59% of children with asthma and in 59.7% who were asthma free. There was no significant difference in erosion prevalence between asthmatics and asthma free in a cohort of children at age 12 or 14 years, and the incidence of erosion was 12.8% and 12.3%, respectively. 88% of drugs prescribed for treatment of asthma had a pH above the critical pH of 5.5.

CONCLUSION

There was no association between asthma and tooth erosion. The majority of drugs prescribed for the treatment of asthma are not potentially erosive.

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.

[An increase in allergic diseases in childhood--current hypotheses and possible prevention]

During the last few decades there has ben a significant rise in the prevalence of allergic diseases such as asthma, hay fever and atopic dermatitis. Epidemiological studies strongly suggest that this increase is real and not due to changes in diagnostic labelling. It has become increasingly clear that a complex interplay between genetic and environmental factors account for this phenomenon. Genetically predisposed individuals are at an increased susceptibility to develop asthma or other allergic diseases when exposed to certain environmental or lifestyle factors. Particularly passive smoking has been shown to increase the risk for asthma in many studies and for atopy at least in some studies. This association is less clear for the exposure to sulfur dioxide, particulate matter, diesel exhaust and ozone. Lifestyle factors like socioeconomic status, sib-ship size, early childhood infections, dietary habits, growing up in antroposophic families or on a farm are more and more realised to be of great relevance for the development of allergic conditions. At the moment, there is a lot of uncertainty about which recommendations should be given for primary prevention. Recent studies have challenged the old paradigma that avoidance of early allergen contact could prevent the development of allergic disease. However, there is consensus that avoidance of smoking during pregnancy and avoidance of passive smoking during childhood should be recommended for primary prevention of asthma.

Determinants of endotoxin levels in carpets in New Zealand homes

Endotoxin in house dust has been shown to be associated with asthma severity. Little is known about the influence of housing characteristics on endotoxin distribution. Using standardized methods, dust was sampled from a 1m(2) site and the whole accessible carpet area in selected Wellington, New Zealand homes (n = 77). Endotoxin was measured using a Limulus Amoebocyte Lysate assay. Relative humidity and temperature were recorded using sensors placed in carpet bases. Questionnaires were used to collect information on housing characteristics. All analyses were performed for endotoxin units (EU)/mg and EU/m2 for each site. Geometric mean endotoxin levels were 22.7 EU/mg [geometric standard deviation (GSD) = 2.4] or 30,544 EU/m2 (GSD = 3.2) from the 1m(2) site, and 28.4 EU/mg (GSD = 3.4) or 5653 EU/m2 (GSD = 6.4) from the whole room. After controlling for confounding, endotoxin was positively associated with dogs inside [geometric mean ratio (GMR): 0.9-2.0], total household occupants (GMR: 1.7-2.0, for 1 m2 sample only), vacuum cleaners <1-year old (GMR: 2.3-2.7), reusing vacuum dust collection bags (GMR: 1.4-3.1), steamcleaning or shampooing the carpet (GMR: 1.4-2.2) and high relative humidity (GMR: 1.4-1.6). Lower endotoxin was associated with floor insulation (GMR: 0.4-0.8), and north-facing living rooms (GMR: 0.4-0.8). This study has identified home characteristics that could be modified to reduce endotoxin exposure.

The role of house dust mite elimination in the management of childhood asthma: an unresolved issue

Indoor allergens are likely to be direct environmental causes of asthma and mite exposure, and sensitization is the most important environmental risk factor for childhood asthma in temperate zones. Analagous to occupational asthma, allergen avoidance in asthmatic children sensitized and exposed to mite allergens is associated with a reduction in airway hyperresponsiveness and symptoms associated with improvement in lung function. The long-term effect of this strategy needs to be prospectively evaluated considering both the timing and duration of exposure, as well as the timing and duration of removal. In order to be successful, it is important to achieve and maintain a major reduction on allergen levels, for a long period of time.

Outcome evaluation of early discharge from hospital with asthma

OBJECTIVE

The aim of the study was to determine whether it was safe to discharge children with asthma from hospital when stable on 3-hourly rather than 4-hourly doses of salbutamol.

METHODOLOGY

A retrospective study of 419 individual admissions of 359 children with asthma was undertaken. We defined a theoretical 'time ready for discharge' (TRD) for asthmatic admissions based on: (i) at least two doses of 3-hourly salbutamol and due for the third dose, (ii) no oxygen supplementation, (iii) no intravenous fluid or therapy, and (iv) time of discharge should be either before 17:30 hours or after 07:30 hours. Each admission was analysed using appropriate parameters to assess for risks and benefits of using this theoretical TRD as a guide for discharging asthmatic children from hospital.

RESULTS

A total of 116 (27.7%) children were discharged before our theoretical TRD, including 11 children who received salbutamol no less often than 2-hourly and 37 who had a single dose of 3-hourly salbutamol before discharge. Re-admission to hospital and representation to the Emergency Department without re-admission within 1 week of discharge were less common in the group who were discharged before they had achieved theoretical TRD than in those who were discharged at or after the theoretical TRD, although the numbers were too small to reach statistical significance. Between our theoretical TRD and actual time of discharge two children who received supplemental oxygen and more frequent salbutamol may have required re-admission.

CONCLUSIONS

From the medical viewpoint discharge when the child is stable on 3-hourly rather than 4-hourly doses appears safe. This can be expected to shorten length of stay by an average of 5.5 h (P < 0.001).

Food allergy: an overview

Food allergy affects between 5% and 7.5% of children and between 1% and 2% of adults. The greater prevalence of food allergy in children reflects both the increased predisposition of children to develop food allergies and the development of immunologic tolerance to certain foods over time. Immunoglobulin (Ig) E-mediated food allergies can be classified as those that persist indefinitely and those that are predominantly transient. Although there is overlap between the two groups, certain foods are more likely than others to be tolerated in late childhood and adulthood. The diagnosis of food allergy rests with the detection of food-specific IgE in the context of a convincing history of type I hypersensitivity-mediated symptoms after ingestion of the suspected food or by eliciting IgE-mediated symptoms after controlled administration of the suspected food. Presently, the only available treatment of food allergies is dietary vigilance and administration of self-injectable epinephrine.

Geographical variations of asthma and asthma symptoms among schoolchildren aged 5 to 8 years and 12 to 15 years in Palestine: the International Study of Asthma and Allergies in Childhood (ISAAC)

BACKGROUND

Many studies demonstrated the existence of geographic differences, within and between countries, in the prevalence of asthma, rhinitis, and eczema. However, in Palestine, there are no comprehensive Palestinian data to compare with those from other regional and international centers.

OBJECTIVE

To describe the prevalence of asthma and asthma symptoms in schoolchildren in two districts (Ramallah and North Gaza) in Palestine.

METHODS

After a two-stage stratified systematic sampling, approximately 14,500 schoolchildren, from the first and second grades of elementary school (ages 5 to 8 years) and eighth and ninth school grades (ages 12 to 15 years), were invited to participate in a survey using International Study of Asthma and Allergies in Childhood phase III questionnaires and protocols.

RESULTS

In general, younger children were reported to have a higher 12-month wheezing prevalence rate than older children (9.6 and 7.2%, respectively), and more physician-diagnosed asthma (8.4 and 5.9%, respectively). However, nocturnal cough and exercise-related wheezing were higher in the older age group compared with younger children. Younger children living in North Gaza district showed slightly higher prevalence rates for asthma and asthma symptoms, but older children had higher rates in Ramallah district. After adjustment using logistic regression analysis, male sex, living in inland areas, and younger age were shown to predict 12-month wheezing and physician-diagnosed asthma.

CONCLUSIONS

Palestinian children have asthma symptoms rates that are similar to several countries in the Mediterranean region such as Spain and Turkey, but still lower than other Middle East countries such as Saudi Arabia and Israel.

Options for self-management education for adults with asthma

BACKGROUND

Asthma education and self-management are key recommendations of asthma management guidelines because they improve health outcomes. There are several different modalities for the delivery of asthma self-management education.

OBJECTIVES

We evaluated programmes that: 1) Optimised asthma control through inhaled corticosteroid use by regular medical review or optimised asthma control by individualised written action plans 2) Used written self-management plans based on peak expiratory flow self-monitoring compared with symptom self-monitoring 3) Compared different options for the delivery of optimal self-management programmes.

SEARCH STRATEGY

We searched the Cochrane Airways Group trials register and reference lists of articles.

SELECTION CRITERIA

Randomised trials of asthma self-management education interventions in adults over 16 years of age with asthma.

DATA COLLECTION AND ANALYSIS

Fifteen trials met the inclusion criteria. Trial quality was assessed and data were extracted independently by two reviewers. Study authors were contacted for confirmation.

MAIN RESULTS

1) Six studies compared optimal self-management allowing self-adjustment of medications according to an individualised written action plan to adjustment of medications by a doctor. These two styles of asthma management gave equivalent effects for hospitalisation, ER visits, unscheduled doctor visits and nocturnal asthma. 2) Self-management using a written action plan based on PEF was found to be equivalent to self-management using a symptoms based written action plan in the six studies which compared these interventions. 3) Three studies compared self-management options. In one, that provided optimal therapy but tested the omission of regular review, the latter was associated with more health centre visits and sickness days. In another, comparing high and low intensity education, the latter was associated with more unscheduled doctor visits. In a third, no difference in health care utilisation or lung function was reported between verbal instruction and written action plans.

REVIEWER'S CONCLUSIONS

Optimal self-management allowing for optimisation of asthma control by adjustment of medications may be conducted by either self-adjustment with the aid of a written action plan or by regular medical review. Individualised written action plans based on peak expiratory flow are equivalent to action plans based on symptoms. Reducing the intensity of self-management education or level of clinical review may reduce its effectiveness.

Fetal growth and hospitalization with asthma during early childhood: a follow-up study in Denmark

BACKGROUND

Childhood asthma may have a fetal origin. In order to examine this hypothesis we examined the association between fetal growth indicators and hospitalization with asthma during early childhood.

METHODS

We performed a cohort study with 10 440 children whose mothers attended the midwife centres in Odense and Aalborg, Denmark, from April 1984 to April 1987 at approximately the 36th week of gestation. Information on hospitalization with asthma was extracted from the National Hospital Discharge Registry, which allowed a complete follow-up of all members of the cohort who remained alive and residents in the county.

RESULTS

The cumulative incidence rates of hospitalization with 'definite' and 'any' asthma were 3.5% and 5.0%, respectively, at 12 years of age. After adjusting for potential confounders, there were increased trends in the risk of asthma hospitalization with birthweight and ponderal index. More pronounced trends, particularly in the risk of definite asthma, were found among children of over the average birthweight (IRR = 1.62, 95% CI: 1.02-2.59 per 1000 g increase) or ponderal index (IRR = 1.06, 95% CI: 1.02-1.10 per 0.1 g/cm(3) increase). However, the increased risk in large babies was seen only in children with a ponderal index of > or =2.5 g/cm3.

CONCLUSION

Birthweight and ponderal index were associated with childhood asthma indicated by hospitalization. Fetal growth itself, determinants of fetal growth, or any unadjusted factors that correlate with fetal growth, could cause the association.

Farm residence and exposures and the risk of allergic diseases in New Zealand children

BACKGROUND

Studies in Europe have reported a reduced prevalence of allergy in farmers' children. We aimed to determine if there is a similar reduction in allergy among New Zealand farm children.

METHODS

Two hundred and ninety-three children participated (60%) aged 7-10 years, from selected schools in small towns and the surrounding rural area. Skin prick tests (SPT) to eight common allergens were performed. Parents completed questionnaires about allergic and infectious diseases, place of residence, exposure to animals, and diet, and they provided dust from the living-room floor. Endotoxin was measured using an Limulus amoebocyte lysate (LAL) assay and Der p 1 using enzyme-linked immunoassay (ELISA).

RESULTS

Current farm abode was found to increase the risk of having symptoms associated with allergy, but not SPT positivity. Independent inverse associations were found for early-life exposures: at least weekly consumption of yoghurt with hayfever (odds ratio (OR) = 0.3, 95% confidence intervals (CI) 0.1-0.7) and allergic rhinitis (OR = 0.3, 95% CI 0.2-0.7); any unpasteurized milk consumption with atopic eczema/dermatitis syndrome (AEDS) (OR = 0.2, 95% CI 0.1-0.8); cats inside or outside with hayfever (OR = 0.4, 95% CI 0.1-1.0) and AEDS (OR = 0.4, 95% CI 0.2-0.8); dogs inside or outside with asthma (OR = 0.4, 95% CI 0.2-0.8); and pigs with SPT positivity (OR = 0.2, 95% CI 0.1-0.9).

CONCLUSIONS

Despite finding a protective effect of early-life animal exposures, we found a greater prevalence of allergic disease on farms.

Does remodelling of the airway wall precede asthma?

Bronchial asthma is very common in childhood but the occurrence of wheeze with viral infections makes asthma difficult to diagnose in the pre-school child. Longitudinal studies suggest that there is a loss of airway function associated with early childhood asthma. Extrapolating from adult disease and the few tissue-based studies of children, this would appear to be related to abnormal postnatal development or remodelling of the airway walls. This appears to be associated with persistent airway inflammation without clinical evidence of airways obstruction. Abnormally thickened airways may be the mechanism underlying both bronchial hyper-responsiveness and fixed loss of respiratory function. The challenges for the future are to identify those children among the pre-school wheezers who will become asthmatic and to construct trials of therapies that may potentially prevent the development of clinical asthma or ameliorate the associated loss of airway function.

Food allergy: what can be done to prevent progression to asthma?

OBJECTIVES

The primary objective of this review is to discuss risk factors for asthma development in food allergen-sensitized children. In the paper we discuss the possible measures to prevent progression to asthma by allergen and other adjuvant factor avoidance.

DATA SOURCES

A review from literature of articles on these topics was performed.

STUDY SELECTION

Relevant publications on asthma risk factors and implementation of protective factors were critically evaluated.

RESULTS

Children with familiar history of atopy and sensitization to food proteins in early infancy are at high risk of subsequent respiratory allergic diseases and require specific prevention. Because early allergic sensitization is a significant risk factor for later development of asthma, prevention of asthma by early allergen avoidance is mandatory in high-risk children. Adjuvant factors such as tobacco smoke and mold exposure may act as nonspecific triggers for the development of atopy. The role of protective factors such as infections in early life, breast-feeding, a "healthy" diet needs to be evaluated in prospective studies. Pharmacologic intervention with antihistamines led to significant reduction in incidence of asthma in high-risk children, but confirmatory longitudinal studies in large populations are necessary.

CONCLUSIONS

There is now accumulating evidence that preventing exposure to house-dust mite may significantly reduce the prevalence of childhood asthma. However, allergen avoidance can not be recommended as the only strategy. Avoidance of adjuvant factors and implementation of potential protective factors aimed to reduce the risk to progression to asthma need to be evaluated in prospective studies.

Rising prevalence of allergy to peanut in children: Data from 2 sequential cohorts

BACKGROUND

Allergy to peanut is common. However, it is not known whether the prevalence of sensitization and clinical allergy to peanut is increasing.

OBJECTIVE

We sought to determine any change in the prevalence of peanut sensitization and reactivity in early childhood in 2 sequential cohorts in the same geographic area 6 years apart.

METHODS

Of 2878 children born between September 1, 1994, and August 31, 1996, living on the Isle of Wight, 1273 completed questionnaires, and 1246 had skin prick tests at the age of 3 to 4 years. Those with positive skin prick test responses to peanut were subjected to oral peanut challenges, unless there was a history of immediate systemic reaction. These data were compared with information on sensitization and clinical allergy to peanut available from a previous cohort born in 1989 in the same geographic area.

RESULTS

There was a 2-fold increase in reported peanut allergy (0.5 % [6/1218] to 1.0 % [13/1273]), but the difference was nonsignificant (P =.2). Peanut sensitization increased 3-fold, with 41 (3.3 %) of 1246 children sensitized in 1994 to 1996 compared with 11 (1.1 %) of 981 sensitized 6 years ago (P =.001). Of 41 sensitized children in the current study, 10 reported a convincing clinical reaction to peanut, and 8 had positive oral challenge results, giving an overall estimate of peanut allergy of 1.5% (18/1246).

CONCLUSIONS

Sensitization to peanut had increased between 1989 and 1994 to 1996. There was a strong but statistically nonsignificant trend for increase in reported peanut allergy.

Epidemiological studies of the very high prevalence of asthma and related symptoms among school children in Costa Rica from 1989 to 1998

The aim of our study was to determine the prevalence of asthma and related respiratory symptoms in school children from Costa Rica during the last 10 years, from 1989 to 1998. Using nationally representative samples of school children from Costa Rica during the last 10 years we have performed three studies. Altogether 9,931 children were investigated. The age groups: study I, 5-17 years (n = 2,682), study II, 6-7 years (n = 2,944), 13-14 years (n = 3,200) and study III, 10 years (n = 1,105). The diagnostic criteria for asthma used in these studies was as follows: study I (1989), diagnosis by a doctor in combination with the presence of four kinds of respiratory symptoms; studies II (1995) and III (1998), history of wheeze in the past 12 months. The two latter were part of the International Study of Asthma and Allergies in Childhood (ISAAC). A very high prevalence of a history of wheezing was found in the three studies (46.8%, 42.9%, and 45.1%) as well as a diagnosis of asthma (23.4%, 27.7% and 27.1%). The physician's diagnosis of asthma reported in the first study (23%) increased from 23.1 in study II to 27.7% in study III (p = 0.004). This increment could be a real increase in asthma prevalence, or be due to a better awareness about asthma. In study II the group of 6-7-year-olds had respiratory symptoms significantly more often than 13-14-year-olds (p < 0.001). Boys more often had a history of wheezing (p = 0.001), wheeze during the previous 12 months (p = 0.01) and an asthma diagnosis at the age of 6-7 years (p = 0.002) than girls, but girls had more respiratory symptoms than boys at the age of 13-14 years (p < 0.005). Wheezing in the past 12 months was more common for those living in urban areas aged 6-7 years (p = 0.04), and there was an increase of wheeze after exercise (p = 0.01). For the 13-14-year-olds the risk of wheezing was higher during the previous 12 months if they lived in temperate areas (<20 degrees C) and at a high altitude (>1,000 m). Living in a rural area and in a warm region (>20 degrees C), increased the risk of dry cough during the previous 12 months in the group of 13-14-year-olds. In conclusion, Costa Rica is located in the tropics with a very high humidity, an enormous variety of flora and fauna and a very high prevalence of mite and cockroach allergens, which provide important risk factors that may explain the high prevalence of asthma and asthma-related symptoms. Further possible factors, such as the change towards a more Western life style, resulting in fewer infections and parasitic diseases in the first years of life and changes in bedding material, may also be unresolved. Increased environmental pollution may add to the very high prevalence of asthma and related respiratory symptoms. The very extensive exposure to mites and cockroaches in bed material and in homes with poor ventilation may be an important factor, but many asthmatic children behave as non atopic, with a viral respiratory infection as a major precipitating factor.

Is asthma prevention possible with dietary manipulation?

What we know: Primary prevention of asthma should be possible because the recent increase in asthma is due to environmental factors. The major modifiable dietary environmental risk factors for childhood asthma are lack of breastfeeding and low intake of omega-3 fatty acids. Randomised controlled trials (RCTs) have shown that interventions using probiotics, hydrolysed milk formulas, and combined dietary manipulation plus airborne allergen avoidance reduce asthma and/or atopy in newborns. Observational studies have shown a 30%-50% reduction in childhood asthma with exclusive breastfeeding for three months, and similar reductions in children who eat fish regularly (ie, have a high intake of omega-3 fatty acids). What we need to know: Will further RCTs using intervention with probiotics reveal identifiable subgroups of children who respond and children who do not respond? Will supplementation of the diet with omega-3 oil reduce the rate of significant clinical atopic disease, particularly asthma? If so, for how long will supplements need to be given? Will effective primary prevention require multiple intervention strategies? If so, how feasible are these as public health interventions? What are the benefits and harms of allergen-avoidance diets in high-risk women who are breastfeeding? Can protein hydrolysate formulas reduce rates of atopy and/or asthma?

Novel probiotics for the management of allergic inflammation

Several pathologies of the gastrointestinal tract, particularly food allergy, are due to an exaggerated and imbalanced response of the gut mucosal immune system. The intestinal microflora is an important constituent of the gut mucosal barrier against food allergens and there is increasing evidence that one important acquired factor predisposing to food allergy in infants is the gut microflora. Indeed, the balance of bifidobacteria versus Clostridia in the neonatal flora appears to determine the allergic status in infants. In earlier studies, it was shown that the higher prevalence of allergies in infants fed standard formulas, compared to breast-fed infants, correlated with lower frequencies of bifidobacteria in their faeces. Certain Lactobacillus probiotic strains can have an inhibitory impact on allergic inflammation. The mechanisms implicated are still unclear, but it seems that they can involve both proteolytic and/or immunomodulatory functions. One challenge will be to find a probiotic strain that elicits all these functions and that fulfills all safety criteria.

Factors associated with different hygiene practices in the homes of 15 month old infants

BACKGROUND

Improved hygiene in Westernised regions of the world may be partly responsible for the increased prevalence of diseases of the immune system, such as asthma and atopy. There is a paucity of data on cleanliness norms in young children in the UK and there has been no attempt to identify factors that influence the adoption of particular hygiene practices in the home.

AIMS

To examine levels of hygiene in a contemporary cohort of children and identify social and lifestyle factors influencing hygiene practices in the home.

METHODS

The sample under study are participants in the Avon Longitudinal Study of Parents and Children (ALSPAC). Parental self completion questionnaires provided data on hygiene levels in children at 15 months of age, and a hygiene score was derived from these responses. Multivariable logistic regression models investigated associations between high hygiene scores (top quintile) and a number of perinatal, maternal, social, and environmental factors.

RESULTS

Maternal smoking during pregnancy, low maternal educational achievement, and living in local authority housing were factors independently associated with high hygiene scores, as was increased use of chemical household products. High hygiene scores were inversely related to living in damp housing and attendance at day care. There were no gender or ethnic differences in hygiene score.

CONCLUSION

Important data on cleanliness norms for infants have been presented. The adoption of hygiene practices is influenced to some degree by social, lifestyle, and environmental factors-with higher hygiene scores occurring in more socially disadvantaged groups. Increased use of chemical household products in the more socially disadvantaged groups within ALSPAC has emerged as an important confounder in any study of hygiene and ill health.

Mode of delivery and asthma -- is there a connection?

Genetic factors cannot explain the recent rapid increase in the incidence of atopic diseases. The phenomenon has been explained by environmental factors, and there are data for and against the hypothesis that a decline in the pressure of microbial stimulation early in life could be behind the allergy epidemic. Changes have also occurred in maternity care, among them a rise in the caesarean section rate, which could diminish initial microbial exposure and thereby alter T helper 1 cell/T helper-2 cell development and affect the risk of developing atopy. In this study, we sought to establish whether mode of delivery does influence the development of atopic asthma. Finnish 1987 Medical Birth Register (n = 59,927 live births) information was linked between several national health registers to obtain information on asthma and mode of delivery in children registered. The data were adjusted for maternal age, previous deliveries, child's sex, and birth size. Atopy was evaluated in the second study (Turku Birth Cohort), which involved 219 children born by vaginal delivery (n = 106) or caesarean section (n = 113); history of atopic symptoms was established by questionnaire and a clinical examination was conducted, including skin prick testing and determination of total and allergen-specific IgE in serum. The register study showed the cumulative incidence of asthma at the age of seven to be significantly higher in children born by caesarean section (4.2%) than in those vaginally delivered (3.3%), the adjusted odds ratio (OR) for confounding variables being 1.21 (1.08-1.36), p < 0.01. In the second study, significantly more positive allergy tests were reported in questionnaires in the caesarean (22%) than in the vaginal delivery group (11%), OR 2.22 (1.06-4.64), p < 0.01, and a trend toward more positive skin prick reactions was documented at clinical examination; 41% versus 29%, OR 1.31 (0.65-2.65), p = 0.11. In conclusion, these results suggest that caesarean section delivery may be associated with an increased prevalence of atopic asthma.

The effect of corona discharge on Der p 1

BACKGROUND

Reduction of house dust mite allergens in the domestic environment can play an important part in reducing sensitization and in the amelioration of symptoms in atopic individuals. Chemical and physical methods have been tried with varied levels of success. The present paper presents a novel electrostatic way of destroying Der p 1, the major mite allergen.

OBJECTIVE

To assess the efficacy of negative Trichel, negative continuous glow, positive pulse and positive continuous glow corona in destroying Der p 1. To determine whether ozone has any effect on the integrity of Der p 1 in the experimental conditions present.

METHODS

A simple point-to-plane apparatus was used to irradiate samples of Der p 1 for periods of 1, 15, 30, 45, 60, 120, 180, 240 and 300 min. Controls were exposed to the atmosphere with no corona products present for the equivalent time. The effect of the corona by-product ozone was investigated alone by exposing samples of Der p 1 to molecular ozone for 60 min. Der p 1 concentration was quantified by two-site monoclonal antibody ELISA.

RESULTS

High current negative glow resulted in a 67.37% reduction in Der p 1 concentration after 300 min compared with a 50.5% reduction from a low current Trichel regime. High current positive glow corona gave a reduction of 25.22% while a low current positive pulse corona caused a 13.72% reduction after 300 min. All these reductions were statistically significant (P < 0.05) compared with unexposed controls. Negative corona always gave greater percentage reductions in Der p 1 concentration for each time exposure investigated. The pattern of percentage reduction follows an exponential rise to maximum relationship in respect to time. Samples of Der p 1 were not affected by exposure to molecular ozone.

CONCLUSION

These data indicate corona products to be a powerful new method of destroying Der p 1 allergen that is not dependent on the presence of the oxidizing corona product ozone.

Allergic diseases, skin prick test responses, and IgE levels in North Karelia, Finland, and the Republic of Karelia, Russia

BACKGROUND

There is growing evidence to show that atopic diseases are more common in Western Europe than in the former socialist countries of Eastern Europe.

OBJECTIVE

The aim of this study was to assess whether a similar difference exists between the most eastern province of Finland and a neighboring western district of Russia.

METHODS

A random sample of 25- to 54-year-old subjects was taken from the population registers in the North Karelia Province in eastern Finland and from the Pitkäranta district across the border in the western part of Russia. Participants filled out a questionnaire on atopic and allergic symptoms and participated in a clinical study, which included skin prick tests with 11 airborne allergens and IgE measurements.

RESULTS

Self-reported hay fever, allergic eye symptoms, atopic eczema, and asthma were much more common in Finland than in Russia. In Finland 34.2% and in Russia 21.8% had at least one positive skin prick test reaction. In Finland 21.5% but in Russia only 15.8% had at least one elevated allergen-specific IgE value of the 5 values measured. From 6% to 47% of the differences in self-reported symptoms between the countries were explained by atopy, as measured by means of skin prick testing or specific IgE values.

CONCLUSIONS

A major difference in clinical allergic diseases and signs of symptoms was observed between the 2 geographically adjacent areas. This suggests that the difference in clinical allergy and atopic disposition is related to the differences in lifestyle and environmental factors.

The prevalence of asthma and wheezing illnesses amongst 10-year-old schoolchildren

Asthma and wheezing illnesses carry a significant burden of disease during childhood. Prevalence studies have the capacity to provide invaluable insights into the nature of these common conditions. As part of the Isle of Wight Whole Population Birth Cohort Study (n=1456) we have examined wheezing and asthma development amongst 10-year-old children. At this age 1373 children completed ISAAC written questionnaires whilst 1043 children performed further testing including skin-prick testing, serum inhalant IgE antibody screening, spirometry and bronchial challenge. At 10-years, prevalence of current wheeze was 18.9%, current asthma (symptomatic bronchial hyper-responsiveness--BHR) 14.4% and currently diagnosed asthma (current wheeze and asthma ever--CDA) 13.0%. Both wheezing and asthma at 10 years were associated with average symptom onset at 3 years of age indicating an early life origin for such conditions. Current wheeze (P=0.011) and CDA (P=0.008) showed significant male predominance. Considerable disease morbidity was identified for these states that tended to be greatest amongst children defined asthmatic rather than simply current wheezers. Wheezing and asthma were significantly associated with both atopy (P<0.001) and allergic co-morbidity Children with these states, particularly current asthma, also demonstrated impaired lung function (FEV1, P<0.001 and FEV1/FVC, P=0.010) and increased BHR (inverse slope, P<0.001). In conclusion, Asthma and wheezing showed substantial prevalence at 10 years of age. Strong associations to male gender, atopy, impaired lung function and BHR were seen for both wheeze and asthma. In regard to prevalence and morbidity characteristics, a questionnaire-based definition of currently diagnosed asthma gave similar results to the use of symptomatic BHR in defining current asthma.

Common respiratory infections early in life may reduce the risk of atopic dermatitis

Infections that occur early in life may protect against atopic disease later in life. To investigate the relationship between common acute respiratory infections and atopic dermatitis in early childhood, we closely observed a cohort of 329 children from the ages of 2 to 24 months. We assessed the effect of proven viral infections and acute otitis media on the occurrence of atopic dermatitis. If the child had his or her first respiratory infection before the age of 6 months, the child's remaining risk of developing atopic dermatitis was reduced by 49% (95% confidence interval, -24% to 79%). The individual risk of developing atopic dermatitis was similarly reduced after infection experienced at >/=6 months of age, but the remaining risk was low, because most cases of atopic dermatitis had manifested by this time. Our results are consistent with the hypothesis that early infections may reduce the risk of atopic disease.

Risk factors for onset and remission of atopy, wheeze, and airway hyperresponsiveness

BACKGROUND

Although many children with asthma may have a remission as they grow and other children who did not have asthma may develop asthma in adult life, knowledge about the factors that influence the onset and prognosis of asthma during adolescence and young adulthood is very limited.

METHODS

A cohort of 8-10 year old children (n=718) living in Belmont, New South Wales, Australia were surveyed six times at 2 yearly intervals from 1982 to 1992, and then again 5 years later in 1997. From this cohort, 498 subjects had between three and seven assessments and were included in the analysis. Atopy, airway hyperresponsiveness (AHR), and wheeze in the last 12 months were measured at each survey. Late onset, remission, and persistence were defined based on characteristics at the initial survey and the changes in characteristics at the follow up surveys.

RESULTS

The proportion of subjects with late onset atopy (13.7%) and wheeze (12.4%) was greater than the proportion with remission of atopy (3.2%) and wheeze (5.6%). Having atopy at age 8-12 years (OR 2.8, 95% CI 1.5 to 5.1) and having a parental history of asthma (OR 2.0, 95% CI 1.02 to 4.13) were significant risk factors for the onset of wheeze. Having AHR at age 8-12 years was a significant risk factor for the persistence of wheeze (OR 4.3, 95% CI 1.3 to 15.0). Female sex (OR 1.9, 95% CI 1.01 to 3.60) was a significant risk factor for late onset AHR whereas male sex (OR 1.9, 95% CI 1.1 to 2.8) was a significant risk factor for late onset atopy.

CONCLUSIONS

The onset of AHR is uncommon during adolescence, but the risk of acquiring atopy and recent wheeze for the first time continues during this period. Atopy, particularly present at the age of 8-10 years, predicts the subsequent onset of wheeze.

Changing approaches to asthma management in Australia: effects on asthma morbidity

Asthma is an important public health issue in Australia and is responsible for significant morbidity and mortality in the community. Recognition of the impact of asthma on the health of Australians, and the apparent failure of new medications to reduce mortality and hospital admission rates resulted in a major review by the stakeholders in asthma care. This led to new approaches to asthma management based on strategic use of asthma medications and the development of the Asthma Management Plan (AMP). The AMP drew together current understanding of asthma to develop a simple stepwise approach to management that could be readily applied in patient management. The National Asthma Campaign (NAC), a coalition of the major stakeholders in asthma care, was launched in 1990 to lead the dissemination of the AMP. In association with other organisations interested in asthma care in Australia, the NAC has developed the AMP, and co-ordinated a decade of education and advocacy about asthma that targeted doctors, health professionals and the general public. These activities have been successful in raising awareness about asthma in the community. However, recent research, while demonstrating the continued uptake of written asthma action plans for asthma and decrease in use of inhaled bronchodilator medications, reported a decrease in use of preventive therapy by people with asthma. These activities have had a sustained impact on asthma-related health outcomes with mortality at the lowest level since 1960 and a decline in hospital readmission rates. This is useful information because there is sound evidence that the prevalence and possibly severity of asthma in children has increased. However, review of management in primary care and among people who present to emergency services with acute asthma suggest that many people continue to manage their asthma poorly. Continued education is needed to build on the progress that has been made. There are opportunities to do this through efforts to integrate general practitioners into the wider health system through the formation of Divisions of General Practice. Recognition of asthma as a health priority area at a national level will help to enhance and maintain awareness of the public health importance of asthma and facilitate the further development of the initiatives begun during the last decade or more.

A birth cohort study of subjects at risk of atopy: twenty-two-year follow-up of wheeze and atopic status

This study describes the natural history of atopic and wheezy disorders from birth to adult life in a cohort at risk of atopy. One hundred subjects born in Poole, England, were selected at birth in 1976 on the basis that at least one parent was atopic. Subjects were examined annually in the preschool years, and at the ages of 11 and 22 yr. Skin prick tests and total serum immunoglobulin E (IgE) were performed at each visit, and at 11 and 22 yr, bronchial hyperresponsiveness (BHR) to inhaled histamine was measured. Sixty-three subjects remained on follow-up at 22 yr. The annual prevalence of both wheeze and atopy increased with age. Twenty-five percent of adults showed both wheeze and BHR (asthma). Remission of wheeze was common in subjects younger than 5 yr of age and likely if wheezing occurred on less than two occasions, but wheeze at 11 yr was likely to persist. Sixty percent of the adult subjects with asthma developed sensitivity to common allergens by the age of 2 yr and were showing BHR by mid-childhood. Sensitization to dietary allergens occurred in infancy and waned after early childhood but predicted the early sensitization to inhalant allergens. In conclusion, adults with asthma can begin wheezing at any age but tend to sensitize early and have abnormal airway characteristics by the age of 11 yr.