Effects of time, sex, ethnic origin, and area of residence on prevalence of asthma in Israeli adolescents

Risk factors of asthma in the Asian population: a systematic review and meta-analysis

Background and objective

An increasing trend of asthma prevalence was observed in Asia; however, contributions of environmental and host-related risk factors to the development of this disease remain uncertain. This study aimed to perform a systematic review and meta-analysis for asthma-associated risk factors reported in Asia.

Methods

We systematically searched three public databases (Web of Science, PubMed, and Scopus) in Feb 2021. We only included articles that reported environmental and host-related risk factors associated with asthma in the Asian population. Random-effect meta-analyses were conducted for frequently reported asthma-associated risk factors to provide an overall risk estimate of asthma development.

Results

Of 4030 records obtained from public databases, 289 articles were selected for review. The most frequently reported asthma-associated risk factor was the family history of allergy-related conditions. The random-effect asthma risk estimates (pooled odds ratio, OR) were 4.66 (95% confidence interval (CI): 3.73–5.82) for the family history of asthma, 3.50 (95% CI: 2.62–4.67) for the family history of atopy, 3.57 (95% CI: 3.03–4.22) for the family history of any allergic diseases, 1.96 (95% CI: 1.47–2.61) for the family history of allergic rhinitis, and 2.75 (95% CI: 1.12–6.76) for the family history of atopic dermatitis. For housing-related factors, including the presence of mold, mold spots, mold odor, cockroach, water damage, and incense burning, the random-effect pooled OR ranged from 1.43 to 1.73. Other risk factors with significant pooled OR for asthma development included male gender (1.30, 95% CI: 1.23–1.38), cigarette smoke exposure (1.44, 95% CI: 1.30–1.60), cigarette smoking (1.66, 95% CI: 1.44–1.90), body mass index (BMI)–related parameters (pooled OR ranged from 1.06 to 2.02), various types of air pollution (NO₂, PM10, and O₃; pooled OR ranged from 1.03 to 1.22), and pre- and perinatal factors (low birth weight, preterm birth, and cesarean section; pooled OR ranged from 1.14 to 1.32).

Conclusions

The family history of asthma was the most frequently reported risk factor for asthma development in Asia with the highest risk estimate for asthma development. This suggests a major role of the genetic component in asthma pathogenesis. Further study on asthma genetics is required to improve the current understanding of asthma etiology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40101-021-00273-x.

Prevalence and Risk Factors of Asthma and Allergy-Related Diseases among Adolescents (PERFORMANCE) study: rationale and methods

Despite a considerable number of international reports on allergic diseases among children, information about the prevalence and risk factors of asthma and allergy-related diseases among Indian adolescents is relatively sparse. The Prevalence and Risk Factors of Asthma and Allergy-Related Diseases among Adolescents (PERFORMANCE) study has been conceived to study the aetiology of asthma and allergic diseases including rhinoconjunctivitis, atopic eczema and food allergies among adolescents in West Bengal, India, using standardised methods and collaborations. The aims of the study are: 1) to estimate the prevalence and risk factors of asthma and allergic diseases among the adolescents residing in rural, suburban and urban areas of West Bengal; 2) to obtain information about the possible role of lifestyle factors (smoking, diet and physical activity) on the disease prevalence; and 3) to create a network for further investigation on social, environmental and genetic factors affecting the diseases. The PERFORMANCE study comprises two phases. The phase I study will investigate the prevalence and possible contributing factors of asthma and allergic diseases in a defined population. The phase II study will be performed as a follow-up of phase I to assess the incidence of asthma and allergic diseases.

The PERFORMANCE study: investigating the prevalence and risk factors of allergy and asthma among Indian adolescentshttp://ow.ly/jP2v30kmt8u

Seasonal Cycle and Relationship of Seasonal Rhino- and Influenza Virus Epidemics With Episodes of Asthma Exacerbation in Different Age Groups

Purpose

Seasonal variations in asthma exacerbation (AE) are associated with respiratory virus outbreaks and the return of children to school after vacation. This study aims to elucidate the period, phase, and amplitude of seasonal cycles of AE in 5 different age groups with regard to rhino- and influenza virus epidemics in Korea.

Methods

The number of daily emergency department (ED) visits for AE in all age groups of Korea and the nationwide weekly incidence of rhino- and influenza virus, were obtained for 2008-2012. Fourier regression was used to model rhythmicity, and the Cosinor method was used to determine the amplitude and phase of the cycles in each age group. The cross-correlation function (CCF) between AE and the rhino- and influenza virus epidemics was also calculated.

Results

There were 157,559 events of AE (0.62 events/1,000 individuals/year) during the study period. There were spring and fall peaks of AE in children and adults, but only 1 winter peak in the elderly. The amplitude of the AE peak in infants was higher in spring than in fall (9.16 vs 3.04, P<0.010), and the fall peak was approximately 1 month later in infants than in school children (October 11 vs November 13, P<0.010). The association between AE and rhinovirus was greatest in school children (rho=0.331), and the association between AE and influenza virus was greatest in those aged ≥60 years (rho=0.682).

Conclusions

The rhythmicity, amplitude, and phase of the annual cycle of AE differed among different age groups. The patterns of AE were related to the annual rhino- and influenza virus epidemics.

Seasonality of asthma: a retrospective population study

OBJECTIVES

Seasonal variations in asthma are widely recognized, with the highest incidence during September. This retrospective population study aimed to investigate whether this holds true in a large group of asthmatic children in primary care and to assess the impact of age, gender, urban/rural living, and population sector.

METHODS

The key study outcomes were the diagnosis of asthma exacerbations and asthma medication prescriptions, recorded by family physicians during 2005 to 2009. These were analyzed by "week of diagnosis" in Clalit Health Services' electronic medical record database. Regression models were built to assess relative strength of secular trends, seasonality, and age-group in explaining the incidence of asthma exacerbations.

RESULTS

A total of 919,873 children aged 2 to 15 years were identified. Of these, 82,234 (8.9%) were asthmatic, 61.6% boys and 38.4% girls; 49.1% aged 2 to 5 years, 24.1% 6 to 9 years, and 26.8% 10 to 15 years. We observed a 2.01-fold increase in pediatric asthma exacerbations and 2.28-fold increase in prescriptions of asthma bronchodilator medications during September (weeks 37-39 vs weeks 34-36) compared with August. The association between the opening of school and the incidence of asthma-related visits to the primary care physician was greatest in children aged 2 to 5 years (odds ratio, 2.15) and 6 to 11 years (1.90-fold). Adolescents (age 12-15 years) had a lesser peak (1.81-fold). In late fall there was a second rise, lasting with fluctuations throughout winter, with a trough in summer.

CONCLUSIONS

Returning to school after summer is strongly associated with an increased risk for asthma exacerbations and unscheduled visits to the primary care physician.

Sunny hours and variations in the prevalence of asthma in schoolchildren according to the International Study of Asthma and Allergies (ISAAC) Phase III in Spain

The objective of this study was to estimate the relationship between the prevalence of asthma in schoolchildren aged 6-7 years and 13-14 years and the mean annual sunny hours (MASH) in Spain, and to explore predictive models for asthma prevalence. The prevalence of asthma was obtained from the International Study of Asthma and Allergies (ISAAC) Phase III 2002-2003, and climate and socio-economic variables from official sources. Nine centres were studied and a further four centres, two of which are in ISAAC, to test the predictive models. Logistic regression was used to estimate adjusted prevalence rates of asthma for each centre, and multiple regression models to study the effects of MASH and other meteorological and socio-economic variables. The adjusted prevalence rate of asthma decreased 0.6% [95% confidence interval (CI) 0.4-0.8%] for the 6-7 years group and 1.1% (95% CI 0.8-1.3%) for the 13-14 years group with an increase in the MASH of 100 h. Relative humidity was negatively associated with asthma in the older age group, and gross province product per capita (GPP) was positively associated with asthma in the younger age group. The predictive models, which included MASH, gender, relative humidity, and GPP, anticipated prevalence rates of asthma without significant differences between the levels observed and those expected in 9 of the 11 measurements carried out. The results indicate that sunny hours have a protective effect on the prevalence of asthma in schoolchildren.

S, DUMITRESCU D, MARSHALL M, MIRESTEAN I, MURESAN M, IACOB D, FARCAU M, ICHIM GE, NANULESCU MV. Epidemiological survey 6 years apart: increased prevalence of asthma and other allergic diseases in schoolchildren aged 13-14 years in cluj-napoca, romania (based on isaac questionnaire)

BACKGROUND

The prevalence of asthma and allergy has increased during recent decades.

OBJECTIVE

We investigate the prevalence of asthma and other allergic diseases in children aged 13-14 years and we evaluate the trend of prevalence after an interval of 6 years.

MATERIAL AND METHODS

We used a core questionnaire designed by the International Study of Asthma and Allergy in Children. In 1991, the questionnaire was administered to 2,866 children from a Romanian city and during 2001 to 1,657 children from the same area.

RESULTS

The prevalence of asthma increased from 3.3% in 1995 to 5.5% in 2001 (p<0.001). In 1995, 4.3% of children reported asthma-related symptoms, significantly fewer than the percentage 6 years later (13.6%; p<0.00001). Similar results were obtained with regard to allergic rhinitis (13.6% versus 20%; p<0.00001) and eczema (11.5% versus 16.2%; p=0.00015). As far as gender differences are concerned, in the first stage of study all three allergic disorders were found to occur more frequently in females. In the study undertaken in 2001, females proved to have a higher prevalence of asthma (p=0.226), but a lower prevalence for allergic rhinitis (p=0.121) and eczema (p=0.064).

CONCLUSIONS

The prevalence of asthma and allergy increased significantly during the past 6 years.

Influence of two different geo-climatic zones on the prevalence and time trends of asthma symptoms among Spanish adolescents and schoolchildren

Few studies have focused on the long-term influence of the climate on the prevalence of asthma. The aim of this study is to establish the influence of geo-climatic conditions on the prevalence of asthma symptoms both in adolescents and schoolchildren, and to discover if this influence is associated with their time trends. Eight centres in Spain performed both ISAAC phases I (1994) and III (2002) in children 13-14 years old. Six of them also surveyed children 6-7 years old. For each age group and phase, about 3,000 children were surveyed per centre. This study examines the prevalence of current wheeze and severe current wheeze in two different geo-climatic zones, coast and plateau, considering their relative humidity and temperature range. In both age groups, the mean asthma prevalence on the coast, for phase I and III, was significantly higher than on the plateau. Living on the plateau was an independent protective factor for current wheeze and severe current wheeze for the two age groups. Within the coastal centres, the increase of the annual relative humidity was a statistical significant risk factor for current wheeze, the same trend existing for current severe wheeze. These effects were independent of the sex and of the phase of the study. The prevalence of asthma and severe asthma symptoms is more frequent on the coast of Spain as compared to the inner plateau. This finding was repeated both in 1994 and in 2002.

Impact of specific allergen sensitization on the prevalence of asthma in patients with allergic rhinitis from adjacent distinct geographic areas

BACKGROUND

Patients with allergic rhinitis (AR) and perennial allergen sensitization are at increased risk for asthma.

OBJECTIVES

To determine the allergic profile of patients with clinical AR in regions of the coastal Mediterranean compared with the inland southern desert area of Israel and the impact of specific allergen sensitization on the prevalence of asthma in these patients.

METHODS

Retrospective evaluation of medical records from patients referred for evaluation during 2002 and 2003 to the allergy clinics of 3 medical centers located in different geoclimatic areas.

RESULTS

A total of 479 patients with AR were included (64% from the humid Mediterranean coast and 36% from the arid desert area), with a mean age of 32.8 years (range, 6-84 years). Sixty percent of the patients were male, and 33% had an additional diagnosis of asthma. Mite sensitization was 84%; cockroach, 34%; trees, 43%; weeds, 40%; grasses, 53%; and fungi, 30%. There were no significant differences in the prevalence of sensitization to any of the evaluated allergens except for weeds, which was higher in the arid region. A diagnosis of asthma was significantly associated with mite sensitization in the Mediterranean area (odds ratio, 2.24; 95% confidence interval, 1.14-4.4; P = .02) and mold sensitization in the arid climate zone (odds ratio, 2.18; 95% confidence interval, 1.05-4.6; P = .04).

CONCLUSION

Although sensitization to mites is high in the coastal areas and in the Negev desert-like environment, the presence of asthma in patients with AR is associated with mite sensitization in the humid environment but with fungal sensitization in the more arid environment.

Asthma hospitalizations among US military personnel, 1994 to 2004

BACKGROUND

Acute asthma attacks strike unpredictably and may lead to hospitalization in otherwise healthy individuals. The burden of asthma hospitalization on the US health care system has greatly interested health care workers, many of whom see the incidence of asthma as increasing.

OBJECTIVES

To examine the annual incidence of hospitalization and the frequency of subsequent hospitalization for asthma among all active-duty US military personnel between 1994 and 2004 and to determine demographic and occupational risk factors of asthma hospitalization within this generally healthy US population.

METHODS

Annual demographic and occupational data were combined with electronic hospitalization records for patients with a discharge diagnosis of asthma. Using Cox proportional hazard modeling, the authors investigated demographic and occupational risk factors for asthma hospitalization.

RESULTS

Women, married persons, health care workers, enlisted personnel, US Army personnel, and older persons were found to have a significantly greater risk of asthma hospitalization. Yearly rates of hospitalization declined from 22.3 per 100,000 persons to 12.6 per 100,000 persons between 1994 and 2004.

CONCLUSIONS

Although these data have some limitations, they suggest that the burden of asthma hospitalizations in the large, healthy population of US military personnel has declined during the last decade. The decrease in hospitalization potentially reflects improved outpatient management strategies.

Cost-effectiveness of continuous combined hormone replacement therapy in long-term use: economic evaluation based on a 9-year study in Finland

OBJECTIVES

To investigate the cost-effectiveness of continuous combined hormone replacement therapy (ccHRT) (Indivina) in postmenopausal women in Finland treated for up to nine consecutive years in the course of a randomised controlled trial.

METHODS

In-study event data were accrued for cardiac and vascular events, cancers and fractures. These event incidence data were applied to first-year direct medical costs for these events, derived from published sources. Reference event incidence data were derived from hospital discharge records and relevant national registries for age-matched women (aged 50-70 years) in Finland with an assumed HRT usage rate of 40%. Cost-effectiveness was expressed as additional cost per quality-adjusted life year (QALY) gained for women on ccHRT compared with the general population. All input data were discounted at 3% per annum.

RESULTS

The additional cost per QALY gained for ccHRT was less than 5000 euro throughout the nine calendar years examined and remained well below the threshold of acceptability of 50,000 euro in a range of sensitivity analyses. The lowest dose-combination of ccHRT examined improved quality of life at no greater cost than no treatment.

CONCLUSIONS

This appraisal, based on event data from a uniquely long study of ccHRT, indicates that this intervention is cost-effective for the relief of symptoms of menopause.

One-year longitudinal study of young apprentices exposed to airway occupational sensitizers

BACKGROUND

The prevalence of diagnosed asthma and wheezing in young subjects is increasing; among environmental risk factors, occupational exposure can play a relevant role.

STUDY OBJECTIVES

The purpose of the study was to evaluate the effects of occupational exposure to a large variety of irritants and/or sensitizers on the incidence of respiratory symptoms and pulmonary function impairment in a group of young apprentices during the first year of work exposure, and to determine the prevalence of asthma-like symptoms and the role of different risk factors (gender, smoking habit, atopy and occupational exposure) in this young population.

DESIGN AND METHODS

We studied 448 young apprentices at the first pre-employment evaluation with a standardized questionnaire, spirometry and skin prick tests; in 244 of them clinical and functional evaluation was repeated after 1 year exposure to respiratory irritants or sensitizers.

RESULTS

At the first examination, males had higher prevalence of attacks of shortness of breath with wheeze, diagnosis of asthma, smoking habit and atopy than females. At the second examination there was no significant increase in the prevalence of respiratory symptoms. However, incident cases for cough, phlegm, wheezing, shortness of breath with wheeze (SOBWHZ) and asthma were all higher than remittent cases. Incidence of respiratory symptoms was associated with atopy and smoking habit.

CONCLUSIONS

Respiratory symptoms slightly increase over 1 year occupational exposure to sensitizers or irritants. The loss at the follow-up of subjects with higher smoking habit suggests a small "health worker effect" and could underestimate the effect of occupational exposure in apprentices.

Prevalence of asthma and asthma-like symptoms in inner-city schoolchildren

This study investigates the prevalence of asthma and asthma-related symptoms in New Orleans inner-city schoolchildren. A cross-sectional survey of 1535 elementary, middle, and high school children (aged 5-18) was conducted by using the International Study of Asthma and Allergies in Childhood (ISAAC) written questionnaire. Lifetime prevalence of wheezing was 39.4%, and lifetime prevalence of asthma was 24.4%. Wheezing during the previous 12 months was reported by 25.7% of the sample. Twenty-one percent of respondents reported having one or more attacks of wheezing per year, with 5.6% reporting four or more attacks per year. Many participants reported sleep disturbance (15.4%), with 6.2% reporting sleep disturbance more than once a week. The 12-month rate of speech limitation due to asthma exacerbation was 6.6%. Exercise-induced asthma was reported by 16.9% of the students, and nocturnal cough (not associated with cold) was reported by 27.3%. Overall, boys reported higher rates of symptoms than girls, and younger children (aged 6-7) reported greater symptoms than older children (aged 13-14). These findings show that prevalence of asthma in this population is elevated, and the ISAAC written questionnaire successfully identified inner-city children at risk for asthma in New Orleans.

Impact of adolescence and gender on asthma hospitalization: a population-based birth cohort study

Our objective was to determine the impact of gender and age on asthma hospitalization rates among children. We used a population-based retrospective birth cohort study to determine yearly age- and gender-specific asthma hospitalization rates between ages 2-18 years in a cohort of all children born in Washington State between 1980-1985. In addition, we assessed factors associated with the hospitalization of a given child for asthma both before and during adolescence, and factors associated with an initial asthma hospitalization during adolescence. Outcome measures included age- and gender-specific rates of hospitalization for asthma, diabetes, seizures/epilepsy, and nonasthma respiratory diagnoses. Asthma hospitalization rates for boys were significantly higher than for girls between ages 2-12 years, the gender gap in asthma hospitalizations reversed between ages 13-14 years, and rates for girls were significantly higher than boys between 16-18 years of age. The male peak asthma hospitalization rate per 100,000 cohort members occurred at age 4 years (12.7; 95% confidence interval (CI), 11.1-14.3), and the male trough rate occurred at age 18 years (4.1; 95% CI, 2.8-5.4), whereas the female peak asthma hospitalization rate occurred at age 17 years (9.4; 95% CI, 7.8-11) and the female trough rate at age 2 years (5.2; 95% CI, 4.2-6.2). Age-specific hospitalization rates for diabetes mellitus and epilepsy were similar for boys and girls throughout childhood. Female gender was strongly associated with asthma hospitalization occurring in an individual child both prior to and during adolescence (rate ratio (RR), 2.0; 95% CI, 1.4-2.9), and was modestly associated with initial hospitalization in adolescence (RR, 1.15; 95% CI, 1.0-1.3). In conclusion, asthma hospitalization rates for boys and girls exhibit strikingly different patterns during adolescence. Potential explanations for these gender differences include hormonal changes during puberty, or gender-specific differences in environmental exposures such as diet, obesity, allergen exposure, or cigarette smoking.

The role of climate on the geographic variability of asthma, allergic rhinitis and respiratory symptoms: results from the Italian study of asthma in young adults

BACKGROUND

Variations in the prevalence of respiratory symptoms according to geo-climatic factors could provide important clues to the knowledge of the aetiology of asthma.

METHODS

Geo-climatic variations in the prevalence of current asthma, allergic rhinitis and chronic cough, and phlegm were assessed on a random sample of 18 873 subjects (response rate = 72.7%) from different climatic regions of Italy. An ecological analysis, supported by robust statistical methods, was employed to investigate potential trends.

RESULTS

The prevalence of all symptoms was significantly heterogeneous throughout the peninsula. Only asthma-like symptoms showed a north-south trend: the prevalence increased at a decreasing latitude [odds ratio (OR) varies from 0.92 to 0.96, P < 0.05], at a decreasing distance from the sea (OR: 0.90-0.93 for 30 km distance, P < 0.05), at higher annual mean temperatures (OR: 1.11-1.14, P < 0.05) and at smaller annual temperature ranges (OR: 0.94-0.95, P < 0.05). Of the geo-climatic variables considered, temperature range had the greatest influence on most asthma-like symptoms. No association was found between geo-climatic variables and allergic rhinitis or chronic cough and phlegm.

CONCLUSIONS

Asthma prevalence seems to be significantly affected by climate as asthma-like symptoms were more common in central-southern Italy, with a Mediterranean climate, than in areas with a continental climate (northern Italy).

The impact of climate and traffic-related NO2 on the prevalence of asthma and allergic rhinitis in Italy

BACKGROUND

Environmental factors are likely to be involved in explaining the wide geographical variation in asthma and atopic diseases that has been documented in many recent epidemiological studies.

AIM

To evaluate to what extent climate and outdoor NO2 pollution can explain the geographical variation in the prevalence of asthma and allergic rhinitis, and to estimate the relative risk for exposure to different levels of these two factors.

METHODS

The impact of climate and long-term exposure to nitrogen dioxide (NO2) pollution on asthma and allergic rhinitis was assessed in a cross-sectional study, carried out during 1998 to 2000 on young adults aged 20 to 44 years (n = 18 873), living in 13 areas from two different Italian climatic regions (subcontinental and Mediterranean).

RESULTS

Mediterranean areas had a significantly higher prevalence of asthma-like symptoms (P < 0.001), higher annual mean temperature (16.2 degrees C vs. 12.9 degrees C), lower temperature range (16.0 C degrees vs. 22.1 degrees C) and lower NO2 levels (31.46 microg/m3 vs. 57.99 microg/m3) than subcontinental ones. Mediterranean climate was associated with an increased risk of wheeze (OR = 1.23; 95% CI 1.13 to 1.35), tightness in the chest (OR = 1.21; 95% CI 1.11 to 1.33), shortness of breath (OR = 1.21; 95% CI 1.08 to 1.36) and asthma attacks (OR = 1.19; 95% CI 1.07 to 1.31). After adjusting for climate, an increase of 18.3 microg/m3 in NO2 levels moderately increased the risk of asthma attacks (OR = 1.13; 95% CI 0.98 to 1.32), tightness in the chest (OR = 1.11; 95% CI 0.98 to 1.26) and wheeze (OR = 1.11; 95% CI 0.96 to 1.28). When the levels of outdoor NO2 exposure rose, the prevalence of allergic rhinitis increased significantly in the Mediterranean region (OR = 1.38; 95% CI 1.12 to 1.69), but not in the subcontinental one (OR = 1.03; 95% CI 0.83 to 1.28).

CONCLUSION

Our results show that the prevalence of asthma increases when annual mean temperature increases and temperature range decreases. Furthermore, climate interacts with NO2 outdoor exposure, increasing the risk for allergic rhinitis in people exposed to high stable temperatures. A long-term role for the effect of traffic pollution on asthma is also suggested.

Increased occurrence of asthma and allergy: critical appraisal of studies using allergic sensitization, bronchial hyper-responsiveness and lung function measurements

BACKGROUND

Many studies have reported an increase in the occurrence of asthma and respiratory allergies in recent decades, but this increase is mostly based on studies using rather subjective measurements of asthma and allergies, such as questionnaires and doctor's diagnosis. None of the reviews specifically focused on studies using more 'objective' measurements, such as sensitization (specific IgE or skin prick testing (SPT)), bronchial hyper-responsiveness (BHR) or lung function (LF).

OBJECTIVE

To review articles studying a time trend of occurrence of these 'more objective' measurements.

METHODS

A MEDLINE-search (1966-February 2000) was performed. The following criteria were used: population-based, using IgE, SPT, BHR or LF measurements in the same age-group at least twice, with at least 2 years between and using similar methods.

RESULTS

The MEDLINE-search resulted in only 16 articles, performed in 13 populations in seven different countries. Nine articles used the same objective measurements twice in the whole population. Three of these reported a non-significant increase or decrease. The other six articles found a significant increase in at least one objective measurement and of these only three reported a consistent significant increase.

CONCLUSIONS

The increase in the occurrence of reported asthma and allergy is supported by only a few articles confirming these results with 'more objective measurements'.

Asthma--the changing face of drug therapy

Until the recent introduction of long acting beta 2-agonists and the leukotriene antagonists, the drug treatment of asthma had remained largely unchanged for a quarter century. Recent studies have demonstrated the efficacy of the long acting beta 2-agonists in the management of asthma in children and highlighted their value as an adjunct to inhaled corticosteroids. The leukotriene antagonists are an important new class of drug therapy which target a specific area of asthma pathogenesis. Whilst they have been shown to be effective for asthma, their exact role in the clinical situation remains to be established. Recent guidelines have emphasised the important role of inflammation in persistent asthma and recommended the early institution of anti-inflammatory treatment. Many patients remain uncontrolled despite high doses of anti-inflammatory agents including oral corticosteroids. Recent experience with other immunomodulatory agents such as cyclosporin, methotrexate and intravenous immunoglobulin has highlighed their potential as steroid sparing agents. With improved understanding of asthma pathogenesis the potential for specific targeted therapies has become evident. Monoclonal antibodies to IgE and certain cytokines are being investigated as possible treatments for asthma. Similarly, preliminary studies of selective phosphodiesterase inhibitors in asthmatic individuals have been encouraging. Other potential therapies include platelet-activating factor receptor antagonists, tryptase inhibitors and prostaglandin E analogs. The continued development of such targeted treatments should ensure a greater diversity of therapeutic options for the management of asthma in the new millennium.

The occurrence, recrudescence, and worsening of asthma in a population of young adults: impact of varying types of occupation

OBJECTIVE

To describe the rates of exacerbation of existing asthma and incidence of new disease in Israeli men during military service.

DESIGN

All 17-year-old Israeli nationals are obliged by law to appear at the Israel Defense Forces (IDF) recruiting office for medical examination. The medical history of army recruits was noted during the 30-month period after their induction into the IDF, and medical examinations were performed by pulmonary specialists in all suspected cases of asthma. The duty status of the soldiers in combat units (CUs), maintenance units (MUs), and clerical tasks was related to their asthma status.

RESULTS

Of a total of 59,058 recruits, 1.0% developed asthma during the 30 months of this study; of those in CUs, 1.2% developed asthma; of those in MUs, 0.8% developed asthma; and of those performing clerical tasks, 0.6% developed asthma. The relative risk for developing or worsening of asthma was related to both the preexisting asthma status of the recruit and the environment in which he carried out his military service. The annual incidence of occupational-related asthma in MUs was found to be 800/million: five to six times the rates reported elsewhere.

CONCLUSIONS

Service in CUs was associated with an increased frequency of exacerbation of asthma among recruits with previous disease and with the appearance of disease de novo. "Normal" conscripts with a history of childhood asthma are at a higher risk of developing overt asthma when compared to subjects with no such history. We found a 25% relative excess of incident cases of asthma in soldiers posted in MUs compared to those performing clerical tasks [(0.8 to 0.6%)/0.8%]. This difference is probably attributed to the difference in occupational hazards in these categories. Further studies are needed to determine if this represents the elicitation of underlying preexisting airway lability by new work demands or other environmental conditions, or if this represents a new development of airway lability because of specific immune or nonimmune factors.

Emergency room visits of asthmatic children, relation to air pollution, weather, and airborne allergens

BACKGROUND

The worldwide increase in the incidence, prevalence, and severity of asthma may suggest that environmental factors play a role in these epidemiologic changes.

OBJECTIVE

To examine the correlations between air pollutants, weather conditions, airborne allergens, and the incidence of emergency room (ER) visits of children with acute asthma attacks.

DESIGN

One-year prospective study. Data of daily concentration of air pollutants, weather conditions, and selective airborne allergens were collected and compared with the number of ER visits of asthmatic children.

SUBJECTS

1076 asthmatic children (aged 1 to 18 years) who presented at the Pediatric ER between January 1 and December 31, 1993.

RESULTS

Correlations between fluctuations in ER visits of asthmatic children and various environmental parameters were more relevant for weekly than for daily values. Emergency room visits correlated positively with concentrations of NOx, SO2 and with high barometric pressure; and negatively with O3 concentration and minimal and maximal temperature. There were no significant correlations with concentrations of particulates, humidity, or airborne pollen and spores. An exceptionally high incidence of ER visits of asthmatic children was observed during September. This peak coincided with the beginning of the school year and the Jewish holidays. The correlations between ER visits and the environmental factors increased significantly when the September peak was excluded, revealing that 61% of the variance in ER visits was explained by NOx, SO2, and 03 concentrations, 46% by weather parameters, 66% by NOx, SO2 and barometric pressure, and 69% by the combination of air pollutants and weather parameters.

CONCLUSION

The major factors found to be associated with ER visits of asthmatic children were high NOx, high SO2, and high barometric pressure. Negative correlation was found between ER visits of asthmatic children and ozone concentrations. The particularly high number of ER visits at the beginning of the school year and the Jewish holidays was probably associated with an increase in the number of viral infections and/or emotional stress.

The International Study of Asthma and Allergies in Childhood (ISAAC). ISAAC Steering Committee

Despite considerable research, the aetiology of asthma and allergic disease remains poorly understood. The International Study of Asthma and Allergies In Childhood (ISAAC), was founded to maximize the value of epidemiological research into asthma and allergic disease by establishing a standardized methodology and facilitating international collaboration. It has achieved its specific aims which are to describe the prevalence and severity of asthma, rhinitis and eczema in children living in different centres and to make comparisons within and between countries; to obtain baseline measures for assessment of future trends in the prevalence and severity of these diseases; and to provide a framework for further aetiological research into genetic, lifestyle, environmental and medical care factors affecting these diseases. The ISAAC design comprises three phases. Phase One used simple core written questionnaires for two age groups, and was completed in 156 collaborating centres in 56 countries and a total of 721 601 children participated. In the 13-14 years age group 155 centres from 56 countries participated, of which 99 centres completed a video questionnaire. For the 6-7 years age group there were 91 collaborating centres in 38 countries. ISAAC Phase One has demonstrated a large variation in the prevalence of asthma symptoms in children throughout the world including hitherto unstudied populations. It is likely that environmental factors were responsible for major differences between countries. The results provide a framework for studies between populations in contrasting environments which are likely to yield new clues about the aetiology of asthma. ISAAC Phase Two will investigate possible aetiological factors, particularly those suggested by the findings of Phase One. ISAAC Phase Three will be a repetition of Phase One in the year 2000 to assess trends in prevalence.

High rate of asthma among immigrants

Articles dealing with the epidemiological aspects of asthma were carefully reviewed in order to support or reject our clinical impression of increased rate of asthma among immigrants. Particular emphasis was put on data on very high or very low rates of asthma. The proposed theories to explain these differences were critically examined. The prevalence of asthma in China and in Africa is 1-2% and 0.5-5%, respectively. The prevalence of the disease in other indigenous populations ranges between 0.5% and 12%. On the other hand, asthma is much more frequently seen in Australia and in New Zealand (approximately 20-25%), where peoples' ancestors immigrated from distant areas. Statistical meta-analysis found a significant difference between the rates of asthma in the two groups of populations (P < 0.001). Immunoglobulin E levels of immigrants in Sweden are higher than those of native Swedes. Similarly, cord blood immunoglobulin E concentrations are more elevated in neonates whose mothers emigrated to Germany from Eastern countries than in those of native German mothers. There is an increased rate of IgE-mediated asthma among immigrant populations.

Prevalence of adult asthma symptoms in relation to climate in New Zealand

We conducted an ecological study linking prevalence of adult asthma symptoms with climate in the 93 New Zealand general electorates. For each electorate, the 12-month period prevalence of self-reported asthma symptoms was determined using a random sample of adults aged 20-44 on the 1991 New Zealand electoral roll. Long-term average climate was estimated using a national climate database and a geographic information system. Asthma prevalence was calculated within quartiles of the exposure variables. Independent effects of climate variables were assessed using linear regression models, with adjustment for confounding by climate, social deprivation, and geographic variables. There was a statistically significant association between asthma prevalence and mean temperature, with the lowest quartile of mean temperature having an approximately 2% lower asthma prevalence. After adjusting for confounding, there was a monotonic increase in asthma prevalence within quartiles of temperature. The results of this study are in agreement with other research suggesting a lower prevalence of asthma at low temperatures. Although on short (day-to-day) time scales, low temperatures may have a direct effect resulting in acute exacerbations of asthma symptoms, warmer average temperatures are associated with increased asthma prevalence. The reasons for this are unclear, although it is possible that on longer term (annual) time scales, higher temperatures are associated with higher levels of allergen exposure.

Variations in hospitalization rates for asthma among black and minority ethnic communities

In response to the introduction of ethnic monitoring within the U.K. hospital inpatient data set, this study investigates the variations in secondary healthcare utilization by Black and minority ethnic communities whose cause of admission is related to asthma. The study examines all residents of the West Midlands: over 5 million people, of whom 8.5% are from Black and minority ethnic groups. A retrospective study of 15,921 asthma-related hospital admissions, from 1 April 1995 to 31 March 1996, was carried out. Age-standardized admission rates were higher in all Black and minority ethnic groups studied than in the White group. There were elevated rates in Black children aged 5-14 years, and particular differences were observed for Indian and Bangladeshi men and women aged 65 years or over. Emergency admissions to hospital for asthma were strongly associated with patients' socioeconomic background but this was largely observed for Black and minority ethnic groups that also generally experience high levels of deprivation. The findings support previous studies which suggest that hospital utilization rates for asthma among people from Black and minority ethnic groups are high compared with the White group, despite little evidence in measured prevalence. This study suggests that ethnic background is more important in asthma admissions than deprivation, which raises serious concerns on the appropriateness and quality of asthma care for these patient groups within our society. Future studies need to examine pathways to care, that is the health-seeking behaviour of Black and minority ethnic groups, the type of treatment received at the primary care level and referral patterns to secondary care.