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)

Trends of allergic symptoms in school children: large-scale long-term consecutive cross-sectional studies in Osaka Prefecture, Japan

BACKGROUND

Trends in the prevalence rates of allergic symptoms in children have been discussed extensively, but it remains uncertain which symptoms increase or decrease over time owing to the lack of large-scale long-term consecutive cross-sectional studies performed on a representative population of children.

OBJECTIVE

To clarify the trends in the prevalence rates of allergic symptoms in Japanese children.

METHODS

Total population questionnaire surveys were conducted 15 times from 1975 to 2006 for all children attending public elementary schools in Osaka Prefecture, Japan, with the number of subjects ranging from 460,000 to 900,000. Parents of the children completed the questionnaire about allergic symptoms and other symptoms, including wheeze, physician-diagnosed atopic dermatitis, rhinitis, and itching eyes.

RESULTS

Response rates were consistently over 90%. The prevalence of wheezing was constant until 1983, then increased from 1983 until 1993, then stabilized at about 4.4%. The lifetime prevalence of atopic dermatitis increased to 24% by 1993, and then decreased. The prevalence of rhinitis increased to 25% by 2003, whereas the prevalence of non-seasonal symptoms plateaued from 1993 on at 11% and vernal symptoms increased. The prevalence of itching eyes continued to increase to 21% in 2006, and vernal symptoms increased sharply.

CONCLUSIONS

In Osaka Prefecture, Japan, the turning point when the prevalence of wheezing in schoolchildren had begun to increase was 1983. And the turning point when the increase in the prevalence of wheezing, atopic dermatitis, and non-seasonal allergic rhinitis turned to decrease or constant was 1993. The prevalence of rhinitis and itching eyes in spring was still increasing in 2006.

Association between short sleep duration and the risk of sensitization to food and aero allergens in rural Chinese adolescents

BACKGROUND

Both long and short sleep duration have been associated with obesity, cardiovascular disease, and diabetes. However, there have been no previous studies investigating the potential relationship between altered sleep duration and allergen sensitization.

OBJECTIVE

To explore the association between sleep duration and sensitization to food and aeroallergens.

METHODS

This study includes 1534 rural Chinese adolescent twins aged 12-21 years who completed standard sleep questionnaires and skin prick tests (SPTs) to nine food and five aeroallergens. Total sleep time was defined as the interval from bedtime to wake-up time minus sleep latency. Sensitization was defined as having at least one positive SPT.

RESULTS

Compared with individuals with the highest (third) tertile of sleep duration, those who slept less were more likely to be sensitized to any food allergen with odds ratios (ORs) of 1.9 [95% confidence interval (CI): 1.3-2.7] and 1.4 (95% CI: 1.0-1.9) for the first and second tertiles (trend test P(trend)=3×10(-4)), respectively. The corresponding ORs for sensitization to any aeroallergen were 1.5 (95% CI: 1.1-2.0) and 1.3 (95% CI: 1.0-1.7) (P(trend)=8×10(-3)). These associations were independent of percent body fat. In addition, we observed a significant dose-response association between the number of positive SPTs and percentage of shortest sleep duration (first tertile) (P(trend)=1×10(-3)).

CONCLUSIONS AND CLINICAL RELEVANCE

In this sample of relatively lean rural Chinese adolescents, we found that short sleep duration was associated with increasing risk of sensitization to food and aeroallergens, independent of percent body fat. Longitudinal studies are needed to further determine the temporal and causal relationships. If short sleep duration indeed is one of the risk factors for allergic sensitization, the global burden of allergic diseases could be dramatically reduced by providing appropriate guidance on sleep duration for youth.

Allergies in Asia: differences in prevalence and management compared with western populations

There is wide variability in the epidemiology and management of childhood asthma and related atopic diseases globally. Urbanized, affluent Western countries tend to have a higher prevalence of these diseases compared with Asian nations. However, recent studies have shown that the prevalence in Asia is increasing, although the rate of increase has slowed in the more developed Asian cities. Some possible causes for these differences are socioeconomic status, degree of urbanization, rates of infection, healthcare practices and genetic factors. Importantly, there are significant differences in the way asthma and allergic diseases are managed within Asia. This is of great concern because of the health implications, as these diseases are some of the most common chronic conditions that affect both adults and children. This review compares the differences in prevalence and management between Asia and the West, and discusses some of the possible reasons behind these variations.

Risk for asthma in offspring of asthmatic mothers versus fathers: a meta-analysis

BACKGROUND

Many human epidemiologic studies demonstrate that maternal asthma confers greater risk of asthma to offspring than does paternal disease. However, a handful have shown the opposite. Given this disparity, a meta-analysis is necessary to determine the veracity and magnitude of the "maternal effect."

METHODOLOGY/PRINCIPAL FINDINGS

We screened the medical literature from 1966 to 2009 and performed a meta-analysis to compare the effect of maternal asthma vs. paternal asthma on offspring asthma susceptibility. Aggregating data from 33 studies, the odds ratio for asthma in children of asthmatic mothers compared with non-asthmatic mothers was significantly increased at 3.04 (95% confidence interval: 2.59-3.56). The corresponding odds ratio for asthma in children of asthmatic fathers was increased at 2.44 (2.14-2.79). When comparing the odds ratios, maternal asthma conferred greater risk of disease than did paternal asthma (3.04 vs. 2.44, p = 0.037). When analyzing the studies in which asthma was diagnosed by a physician the odds ratios were attenuated and no significant differences were observed (2.85 vs. 2.48, N = 18, p = 0.37). Similarly, no significant differences were observed between maternal and paternal odds ratios when analyzing the studies in which the patient population was 5 years or older (3.15 vs. 2.60, p = 0.14). However, in all cases the trend remained the same, that maternal asthma was a greater risk factor for asthma than paternal.

CONCLUSIONS/SIGNIFICANCE

The results show that maternal asthma increases offspring disease risk to a greater extent than paternal disease.

Epidemiology of colorectal cancer in Asia

The prevalence of colorectal cancer is increasing in Asia. However, the age-standardized rate has reached a plateau in some countries. Some studies have shown a male predominance difference and increasing risk in the elderly, but not in the younger population. 'Right shifting' of colorectal cancer, not accountable by difference in age or the indications for endoscopic examination, has also been noted. Westernized diet is associated with colorectal cancer, but controversy remains on how it causes colorectal cancer. Alcohol consumption, obesity, diabetes mellitus, consumption of red and processed meat and cigarette smoking are linked to bowel cancer epidemiologically. Only high dietary calcium has a consistent negative (or 'protective') effect. The efficacy of fish oil, vitamin D, soy, phytoestrogens, folate, methionine, riboflavin and vitamin B6 has not been established. Aspirin and non-steroidal anti-inflammatory drugs use decrease risk of colorectal cancer after 5-10 years of use. There is no evidence for a detrimental effect of proton pump inhibitors or benefit of statins in colorectal cancer. In conclusion, there is a rising trend and prevalence of colorectal cancer in Asia. Dietary modification or supplementation may not be effective in preventing colorectal cancer. Surveillance of colorectal cancer in high-risk groups, according to current recommendation, is probably most effective.

Changing prevalence and severity of childhood allergic diseases in kyoto, Japan, from 1996 to 2006

BACKGROUND

Published data regarding changes in the prevalence of childhood allergic diseases in Japan have been limited.

METHODS

To observe changes in the recent trends of the childhood allergy epidemic in Japan, a population-based questionnaire survey of allergic diseases was conducted among 13,215 schoolchildren, aged 7 to 15 years, in Kyoto, Japan in 2006. The results were compared with those obtained in the 1996 survey using the same scale and methods in the same region.

RESULTS

The prevalences of bronchial asthma (BA), atopic dermatitis (AD), allergic rhinitis (AR), and allergic conjunctivitis (AC) in 1996 and 2006 were 5.1% and 5.0% (p = 0.58), 4.2% and 5.6% (p < 0.0001), 20.3% and 27.4% (p < 0.0001), and 13.3% and 25.2% (p < 0.0001), respectively. Although the distribution of BA severity improved, the severity distribution of AD, AR, and AC all deteriorated. The lifetime prevalence (present prevalence and past history combined) of BA increased from 6.5% to 7.6% (p < 0.0001). The sex ratio analysis showed that the female predominance in the prevalence of AD observed in 1996 disappeared in 2006, indicating a particular rise in AD prevalence among boys.

CONCLUSIONS

Overall, the results indicate that the rising trend of allergic diseases, especially in AD, AR, and AC, continues among schoolchildren living in Kyoto, Japan. Special attention should be paid to skin and nasoocular symptoms.

High-level expression of early growth response-1 and association of polymorphism with total IgE and atopy in allergic rhinitis adults

BACKGROUND

Early growth response-1 (Egr-1) is expressed in human airways and its polymorphisms have been associated with total IgE and atopy in asthmatic patients. We investigated the effects of Chinese-tagging single nucleotide polymorphism (SNP) of Egr-1 and its mRNA expression on allergic rhinitis (AR) traits.

METHODS

Among 214 Chinese AR adults and 259 controls, tag SNP -4071 A-->G was genotyped and mRNA expression in peripheral blood was quantified by real-time PCR.

RESULTS

Egr-1 mRNA expression was significantly higher in patients than controls (median of 0.23 vs 0.15 fold GAPDH expression; p<0.001). Its expression was not associated with -4071 polymorphism. However, significant correlations were found between -4071 A-->G with increased plasma total IgE (p=0.028) and atopy (p=0.030) in patients. Logistic regression confirmed the association (p=0.034) with age and gender adjusted. Patients homozygous for the A allele had a 2.3-fold and 1.9-fold risks, respectively of having increased plasma total IgE and atopy than those G allele carriers.

CONCLUSIONS

We showed high levels of Egr-1 mRNA expression and demonstrated a significant association of polymorphism with increased plasma total IgE and atopy in AR patients. It may be useful to explore the pharmacogenetics of Egr-1 inhibitors.

Sibship size and prevalence of allergic disorders in Japan: the Ryukyus Child Health Study

A number of epidemiological studies have reported an inverse association between increasing sibship size and allergic disorders. The present cross-sectional study assessed the association between the number of siblings and the prevalence of allergic disorders during the past 12 months in Japanese schoolchildren. Study subjects were 22,750 children aged 6-15 yr in Okinawa. The outcomes were based on diagnostic criteria from the International Study of Asthma and Allergies in Childhood. Adjustment was made for age, gender, maternal age at childbirth, duration of breastfeeding, region of residence, smoking in the household, paternal and maternal history of asthma, atopic eczema, and allergic rhinitis, and paternal and maternal educational level. Significant exposure-response associations were observed between increasing total sibship size and all outcomes under investigation. Having two or more older siblings was significantly inversely related to the prevalence of atopic eczema and allergic rhinoconjunctivitis, but not wheeze or asthma. Having two or more younger siblings was independently associated with a decreased prevalence of atopic eczema, but not wheeze, asthma, or allergic rhinoconjunctivitis. The inverse relationships between sibship size and the prevalence of allergic disorders under study were weakened with advancing age, although the interactions between age groups were not statistically significant. No significant interactions were found in the association of having three or more siblings with allergic disorders between children with a positive or negative parental allergic history. These results are likely to support the in utero programming hypothesis because it is probable that the in utero environment would change with parity, although our observations could not refute the hygiene hypothesis.

What have we learnt from ISAAC phase III in the Asia-Pacific rim?

PURPOSE OF REVIEW

International Study of Asthma and Allergies in Childhood (ISAAC) phase III had provided a worldwide map of epidemiology of asthma and allergic diseases, as well as the changes in prevalence rate of these diseases when compared to data obtained in phase I. The wide variations of environmental factors and ethnic background in Asia provide excellent opportunities for research into the environmental and genetic determinants of asthma and allergies. This review summarizes important lessons learnt from ISAAC phase III results from Asia on asthma and allergy.

RECENT FINDINGS

ISAAC phase III provided epidemiological evidence of the wide variation and increasing prevalence of asthma and allergy in many Asian countries. When compared to other regions of the world, Asia has a relatively lower prevalence of asthma and allergic diseases. Comparative studies of populations of the same ethnic group living in different environments reveal striking disparity in prevalence of asthma and allergic diseases. The established risk factors could not explain the secular trend and variations of asthma prevalence in different Asian countries. Further research is needed in this rapidly changing region of Asia in order to identify the protective or risk factors associated with the development of asthma.

SUMMARY

ISAAC phase III provides standardized data on the prevalence and burden of asthma and allergy in the Asia-Pacific region. Further research is needed to reveal the underlying factors responsible for the wide variations in disease manifestations in the region.

Genetic and environmental contributions to allergen sensitization in a Chinese twin study

BACKGROUND

Allergic disease is on the rise worldwide. Effective prevention of allergic disease requires comprehensive understanding of the factors that contribute to its intermediate phenotypes, such as sensitization to common allergens.

OBJECTIVE

To estimate the degree of genetic and environmental contributions to sensitization to food and aeroallergens.

METHODS

Sensitization was defined as a positive skin prick test to an allergen. We calculated the zygosity-specific concordance rates and odds ratios (ORs) for sensitization to food and aeroallergens in 826 Chinese twin pairs [472 monozygotic (MZ) and 354 dizygotic (DZ)] aged 12-28 years. We also applied structural equation modelling procedures to estimate genetic and environmental influences on sensitization.

RESULTS

The concordance rates and risk of sensitization in one twin given the presence vs. the absence of sensitization in the other twin were higher in MZ twins than those in DZ twins. However, a large number of MZ twins were discordant in sensitization to common allergens. These observations suggest both genetic and environmental factors influence sensitization. Consistently, the estimated heritability and individual environmental components of the liability to sensitization ranged from 0.51 to 0.68 and 0.32 to 0.49, respectively, based on the best-fitted structural equation model. We also observed high phenotypic correlations between sensitization to two aeroallergens (cockroach and dust mite: 0.83) and two food allergens (peanut and shellfish: 0.58), but only moderate correlations for the pairs between sensitization to a food and an aeroallergen (0.31-0.46). The shared genetic and environmental factors between paired sensitizations contribute to the observed correlations.

CONCLUSION

We demonstrated that sensitization to common food and aeroallergens were influenced by both genetic and environmental factors. Moreover, we found that paired allergen sensitizations might share some common sets of genes and environmental factors. This study underscores the need to further delineate unique and/or pleiotropic genetic and environmental factors for allergen sensitization.

Trends in asthma prevalence and severity in Omani schoolchildren: comparison between ISAAC phases I and III

BACKGROUND AND OBJECTIVE

This study evaluated changes in the prevalence of asthma symptoms and asthma severity in Omani school children over time.

METHODS

Two cross-sectional surveys, in 1995 and 2001, were conducted as part of the International Study of Asthma and Allergies in Children on Omani schoolchildren in two different age groups (6-7 and 13-14 years).

RESULTS

There were 7067 children surveyed in 1995 (3893 in the younger and 3174 in the older group) and 7879 in 2001 (4126 in the younger and 3753 in the older group). Over the 6 years there was a significant increase in the prevalence of current wheeze 'any wheeze during the past 12 months' (from 7.1% to 8.4%; P = 0.035) in the younger group with no significant change in asthma diagnosis (10.5% vs 10.6%) or any other asthma symptoms. In the older group, all asthma symptoms remained unchanged except speech-limiting wheeze which declined from 4.0% to 2.8% (P = 0.007). In both surveys, more than 60% of current wheezers reported severe asthma symptoms, while only 60% of these reported a diagnosis of asthma.

CONCLUSION

The prevalence of both asthma and severe asthma remains high among Omani children. There is significant 'under-diagnosis' and/or 'under-treatment' of asthmatic children which requires urgent evaluation and intervention.

Time trends of the prevalence of asthma and allergic disease in Austrian children

After a substantial increase in the prevalence of atopic disease in Europe, recent studies indicate that a plateau has been reached. However, variation across countries and age groups exists. We studied the prevalence and time trends of asthma and allergic disease among schoolchildren in Austria, a country with traditionally low rates of asthma, hay fever, and eczema. As part of the International Study of Asthma and Allergies in Childhood (ISAAC), symptoms and physician diagnoses of asthma and allergic disease of 13,399 Austrian children aged 6-7 yr and 1516 children aged 12-14 yr were surveyed between 1995 and 1997. A similar survey was conducted between 2001 and 2003. Among children aged 6-7 yr, significant increases were seen in the prevalence of physician-diagnosed asthma (+16%; p = 0.013), hay fever (+22%; p < 0.001), and eczema (+37%; p < 0.001) between 1995 and 2003. These changes were paralleled by an increase in the prevalence of symptoms typical for hay fever (itchy eyes and runny nose), but not by an increase in wheeze. Among children aged 12-14 yr, the lifetime prevalence of diagnosed asthma increased by 32%, of hay fever by 19%, and of eczema by 28% (all, p < 0.001). These changes were paralleled by increases in the prevalence of wheezing as documented by both questions before and after a video showing wheezing children but not by symptoms typical for hay fever such as itchy eyes and runny nose. In conclusion, in Austria, contrary to other European countries, the prevalence of asthma and allergic disease increased among schoolchildren. Additional studies are needed to continue monitoring the dynamics of the prevalence of asthma and allergic disease in Austria and to explore trends in their risk factors.

A temporal decline in asthma but not eczema prevalence from 2000 to 2005 at school entry in the Australian Capital Territory with further consideration of country of birth

BACKGROUND

Asthma prevalence has declined in some countries over the past 10 years. Most reports have been based on population surveys conducted at two points of time in a given location. Comparisons across countries and time periods can be limited by differences in study methodology or disease diagnostics in different communities. Here, we examined trends in asthma prevalence using serial annual data and further examine the importance of country of birth.

METHODS

The source population has children aged 4-6 commencing school in the Australian Capital Territory from 2000 to 2005 inclusive. Over 80% of these children and their families completed a health questionnaire on asthma, other atopic disease and respiratory symptoms using some questions from the International Study of Asthma and Allergies in Childhood (n = 22 882). Current asthma has been previously validated against physician assessment in this setting.

RESULTS

The prevalence of current asthma declined (P < 0.001) but eczema ever increased (P < 0.001) from 2000 to 2005. The asthma decline was predominantly linear in form, and accompanied by a reduction in night cough and shortness of breath but not recent wheeze. Compared with Australian-born children, children from New Zealand and the United Kingdom had a similar prevalence of asthma, hay fever and eczema history. However, children born in other countries, such as Asia, generally had a lower prevalence of these disorders. The temporal trends for atopic disorders or respiratory symptoms did not differ for overseas-born compared with Australian-born children.

CONCLUSION

The decline in current asthma prevalence from 2000 to 2005 was linear in form and appeared uncoupled from trends in child eczema. Country of birth was associated with marked variation in atopic disorder prevalence. The similar temporal trends for Australian vs overseas-born children indicate that the factors underlying the asthma prevalence decline are unlikely to be only in the pre-natal period.

Common characteristics of upper and lower airways in rhinitis and asthma: ARIA update, in collaboration with GA(2)LEN

This update aimed to review the new evidence available to support or refute prior Allergic Rhinitis and its Impact on Asthma (ARIA) statements. A Medline search of publications between 2000 and 2005 was conducted, with articles selected by experts. New evidence supports previous ARIA statements, such as: (i) allergic rhinitis (AR) is a risk factor for asthma; (ii) patients with persistent rhinitis should be evaluated for asthma; (iii) most patients with asthma have rhinitis; (iv) a combined strategy should be used to treat the airways and (v) in low- to middle-income countries, a different strategy may be needed. The increased risk of asthma has also been found among sufferers from non-AR. Recent reports show AR is a global problem. Many studies demonstrated parallel increasing prevalence of asthma and rhinitis, but in regions of highest prevalence, it may be reaching a plateau. Factors associated with a reduced risk of asthma and AR have been identified, confirming previous findings of protection related to exposure to infections. Treatment of rhinitis with intranasal glucocorticosteroids, antihistamines, leukotriene antagonists or immunotherapy may reduce morbidity because of asthma. To take advantage of the paradigm of unified airways, there is a need to rationalize diagnosis and treatment to optimize management.

Health effects of atmospheric particulates: a medical geology perspective

In this review, atmospheric particulates as composite airborne earth materials often containing both natural and anthropogenic components were examined in the context of medical geology. Despite a vast number of both experimental and epidemiological studies confirming the direct and indirect links between atmospheric particulates and human health, the exact nature of mechanisms affecting the particulate-induced pathogenesis largely remains unexplored. Future in depth research on these areas would be most successful if potential mechanisms are examined with reference to the physical (e.g., size, shape and surface), chemical, mineralogical and source characteristics of particulate matters. The underlying goal of this review was to present the relevant terminology and processes proposed in the literature to explain the interfaces and interactions between atmospheric particles and human body within the framework of "atmospheric particle cycles." The complexities of the interactions were demonstrated through case studies focusing on particulate matter air pollution and malignant mesothelioma occurrences due to environmental exposure to erionite-a fibrous zeolite mineral. There is an urgent need for a standard protocol or speciation methods applicable to earth-materials to guide and streamline studies on etiology of mineral-induced diseases. This protocol or speciation methods should provide relevant procedures to determine the level and extent of physical, chemical and mineralogical heterogeneity of particulate matters as well as quantitative in-situ particulate characteristics.

Time trends of the prevalence of asthma, rhinitis and eczema in Thai children-ISAAC (International Study of Asthma and Allergies in Childhood) Phase Three

Using the same questionnaire as in ISAAC Phase One study conducted in 1995, the ISAAC Phase Three was carried out in Bangkok and Chiang Mai, Thailand, in 2001, among children aged 6-7 and 13-14 years. There was an increase in the prevalence of the three diseases in the younger age group, i.e., current asthma, rhinitis, rhinoconjunctivitis, and flexural eczema. In the older age group, the prevalence of rhinitis and rhinoconjunctivitis increased. There was no change of prevalence of asthma in Bangkok, but prevalence decreased in Chiang Mai. Prevalence of eczema in older children increased in Bangkok, but remained the same in Chiang Mai.

Increasing prevalence of atopic eczema in Taiwanese adolescents from 1995 to 2001

BACKGROUND

The prevalence of atopic eczema in adolescents has recently been reported as increasing in many countries, a phenomenon yet to be fully explained. This study compared the prevalence of atopic eczema among Taiwanese adolescents with individual-level risk factors and community-level data of temperature, relative humidity, and air pollutants to determine whether changes in these factors could explain the observed change in prevalence.

METHODS

We conducted two nationwide, cross-sectional surveys of atopic illness and symptoms among Taiwanese 12-15-year-old schoolchildren in 1995-1996 and 2001. The effects of personal and environmental factors were assessed and temporal changes of outdoor monitoring data were also compared with the prevalence difference of atopic eczema.

RESULTS

A total of 42 919 adolescents from the 1995 to 1996 survey and 10 215 adolescents from the 2001 survey attended schools located within 1 km of 22 monitoring stations. The 12-month prevalence of atopic eczema increased significantly during this period [adjusted prevalence ratio (PR)=1.43, 95% confidence interval (CI) 1.21-1.70 in boys; PR=1.77, 95% CI 1.49-2.10 in girls]. After adjustment for potential risk factors, the prevalence differences were statistically unchanged. Although parental education level contributed the most, changes in personal and environmental factors might not explain the observed prevalence increases of atopic eczema. Temporal change in the relative humidity was significantly associated with prevalence increase among boys but its contribution was also small.

CONCLUSION

Correlates of the investigated risk factors that have changed over time still underlie the prevalence increases of atopic eczema in Taiwanese adolescents. The exact reasons for the rising trends remain to be elucidated.

Trends in the prevalence of asthma symptoms and allergic diseases in Israeli adolescents: results from a national survey 2003 and comparison with 1997

PURPOSE

To investigate the temporal trends in the prevalence of asthma symptoms and allergies in Israeli adolescents.

METHODS

A modified version of the International Study of Asthma and Allergies in Childhood questionnaire was administered to a national sample of Jewish and Arab schoolchildren in Israel. The results were compared to a similar survey conducted in 1997.

RESULTS

Asthma prevalence was 7.0% in 1997 and 6.4% 2003 respectively (p = 0.1). Wheezing in the past 12 months decreased significantly from 17.9% in 1997 to 13.8% in 2003 (p < 0.001). Allergic rhinitis and atopic dermatitis increased from 9.4% to 10.5%, and from 5.9% to 8.7% respectively. The prevalence of allergic disease remained higher in Jewish compared with Arabs.

CONCLUSIONS

The prevalence of asthma symptoms decreased in Israel from 1997 to 2003 while there was an increase in allergic rhinitis and atopic dermatitis.

The challenge of asthma in adolescence

The adolescents with asthma are a distinct group of patients with different problems and needs compared to children and adults. Specific issues of asthma in adolescence are the variability of the clinical spectrum, the presence of particular risk factors for the persistence of symptoms, underdiagnosis and undertreatment of the disease. Refusal of the sick role, denial of symptoms, carelessness about dangerous inhalation exposure, erratic self-medication, overexertion without taking precautions against exercise-induced asthma, and a poor relationship between patients, their families, and often doctors are the main obstacles to successful management of asthma in this critical age. There are also major problems of compliance for these patients. The goal of optimal quality of life will be achieved only if the physician thoroughly understands the adolescent's needs and provides optimal care.

[Prevalence of asthma and rhinitis symptoms in A Coruña (Spain)]

INTRODUCTION

The prevalence of asthma and rhinitis is high in childhood and has been increasing in the last few years. In both diseases underdiagnosis is frequent.

OBJECTIVE

To asses the prevalence of asthma and rhinitis symptoms in childhood.

MATERIAL AND METHODS

We performed a cross-sectional study using a written questionnaire, following the methodology of the International Study of Asthma and Allergies in Childhood (ISAAC), on the prevalence of symptoms of asthma and rhinitis in La Coruña.

RESULTS

A total of 3017 boys and girls aged 6-7 years old (response rate 73.9 %) and 2981 boys and girls aged 13-14 years old (response rate 93.6 %) were included. The prevalence of "wheezing at some time" was 25.3 % in adolescents aged 13-14 years old and was 37.2 % in children aged 6-7 years. The prevalence of "asthma at some time" was 18.5 % in adolescents and 13.7 % in children. The prevalence of "rhinitis at some time" was 30.4 % in the group aged 6-7 years and 47.3 % in the group of adolescents. The prevalence of rhinitis was highest in autumn.

CONCLUSIONS

The prevalence of asthma and rhinitis is high in our population and is higher than that observed in most Spanish populations studied.

Parental smoking behaviour and effects of tobacco smoke on children's health in Finland and Russia

BACKGROUND

There is little information on potential differences in smoking behaviour of parents between Finland and Russia and on the effects of environmental tobacco smoke (ETS) exposure on allergic and respiratory diseases among Finnish and Russian children. The aim of the study was to compare the smoking behaviour of parents and school children and to assess the relations of tobacco smoke exposure during pregnancy and childhood with occurrence of allergic diseases and respiratory infections among school children.

METHODS

We conducted a population-based cross-sectional study in the neighbour towns across the border of Imatra in Finland and Svetogorsk in Russia. The study population consisted of 512 Finnish and 581 Russian school children aged 7-16 years (response rate 79%).

RESULTS

Children's tobacco smoke exposure differed markedly between Finland and Russia. The risk of asthma was particularly related to high maternal smoking exposure during pregnancy (adjusted OR 3.51, 95% CI 1.00-12.3), infancy (3.34, 1.23-9.07) and currently (3.27, 1.26-8.48), and the risk of common cold was related to high combined parental smoking during infancy (1.83, 1.06-3.17) in Finnish children. Among Russian children allergic conjunctivitis was related to maternal smoking during infancy (4.53, 1.49-13.8) and currently (2.82, 1.07-7.44).

CONCLUSIONS

Smoking behaviour of parents and ETS exposure during childhood differed markedly between Finland and Russia. Asthma was particularly increased in relation to high exposure to maternal smoking in Finland. The results suggest that more efforts should be directed to reducing tobacco smoke exposure of children in both Finland and Russia. (250 words).

Association between air pollution and asthma admission among children in Hong Kong

Objective

To examine the association of air pollutants with hospital admission for childhood asthma in Hong Kong.

Methods

Data on hospital admissions for asthma, influenza and total hospital admissions in children aged ≤18 years at all Hospital Authority hospitals during 1997–2002 were obtained. Data on daily mean concentrations of particles with aerodynamic diameter <10 μm (i. e. PM₁₀) and <2.5 μm (i. e. PM_2.5), nitrogen dioxide (NO₂), sulphur dioxide (SO₂), and ozone (O₃) and data on meteorological variables were associated with asthma hospital admissions using Poisson's regression with generalized additive models for correction of yearly trend, temperature, humidity, day-of-week effect, holiday, influenza admissions and total hospital admission. The possibility of a lag effect of each pollutant and the interaction of different pollutants were also examined.

Results

The association between asthma admission with change of NO₂, PM₁₀, PM_2.5 and O₃ levels remained significant after adjustment for multi-pollutants effect and confounding variables, with increase in asthma admission rate of 5.64% (3.21–8.14) at lag 3 for NO₂, 3.67% (1.52–5.86) at lag 4 for PM₁₀, 3.24% (0.93–5.60) at lag 4 for PM_2.5 and 2.63% (0.64–4.67) at lag 2 for O₃. Effect of SO₂ was lost after adjustment.

Conclusion

Ambient levels of PM₁₀, PM_2.5, NO₂ and O₃ are associated with childhood asthma hospital admission in Hong Kong.

Trends in the prevalence and severity of asthma, rhinitis and atopic eczema in 6- to 7- and 13- to 14-yr-old children from the north-east of England

The aims of the present study were to assess time trends in symptoms of asthma, rhinitis and atopic eczema among children in the north-east of England. Two cross- sectional surveys 6 yr apart, 6- to 7- and 13- to 14 yr of age, using the International Study of Asthma and Allergies in Childhood, core questionnaire were performed. There was a general increase in symptoms for all the three conditions in both the age groups. In the age group 6- to 7 yr, the increase was generally the same in boys and girls, while in the age group 13- to 14 yr, the increase was generally more marked among boys. In the younger age group, indices related to lifetime diagnosed ever had asthma and having hay fever increased in girls but not in boys, while indices related to lifetime diagnosis of ever having eczema increased in boys and girls. In the older age group, indices related to lifetime diagnosis of ever had asthma slightly increased in boys but did not change in girls, while lifetime diagnosis of ever having hay fever slightly decreased in girls but did not change in boys. The prevalence of lifetime diagnosis of ever having eczema increased in boys and girls. Changes observed in the present study could be related to the changes in lifestyle or environmental factors, awareness or management of symptoms.

Prevalence and risk factors for allergic rhinitis in primary school children

OBJECTIVE

Allergic rhinitis is a common chronic illness of childhood. The aim of the study was to evaluate the prevalence and risk factors of allergic rhinitis in 6-12-year-old schoolchildren in Istanbul.

METHODS

A total of 2500 children aged between 6 and 12 years in randomly selected six primary schools of Istanbul were surveyed by using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire between April and May 2004.

RESULTS

Of them 2387 (1185 M/1202 F) questionnaires were appropriately completed by the parents with an overall response of 95.4%. The prevalence of physician-diagnosed allergic rhinitis was 7.9% (n=189). A family history of atopy (aOR=1.30, 95% CI=1.00-1.68), frequent respiratory tract infection (aOR=1.36, 95% CI=1.08-1.70) and sinusitis (aOR=2.29, 95% CI=1.64-3.19), antibiotic use in the first year of life (aOR=1.26, 95% CI=1.01-1.57), cat at home in the first year of life (aOR=2.21, 95% CI=1.36-3.61), dampness at home (aOR=1.31, 95% CI=1.04-1.65) and perianal redness (aOR=1.26, 95% CI=1.01-1.57) were significant for increased risk for allergic rhinitis. Frequent consumption of fruits and vegetables were inversely, and frequent consumption of lollipops and candies were positively associated with allergic rhinitis symptoms.

CONCLUSION

Our study reconfirmed that family history of atopy, frequent respiratory tract infections, antibiotics given in the first year of life, cat at home in the first year of life, dampness at home, perianal redness and dietary habits are important independent risk factors for AR. Researchers worldwide should be focused to these factors and try to develop policies for early intervention, primary and secondary preventions for allergic diseases.

Rising trend of asthma prevalence among Turkish schoolchildren (ISAAC phases I and III)

BACKGROUND

Asthma is a common chronic illness in childhood. The aim of the study was to examine time trends in the prevalence of asthma using the ISAAC questionnaire in 6- to 12-year-old schoolchildren in Istanbul and factors affecting asthma prevalence.

METHODS

Two cross-sectional surveys were performed, 9 years apart (1995 and 2004) using the ISAAC protocol. The survey conducted in 1995 was repeated in 2004 using the same questionnaire in the same age group, in the same schools in the same season. The 2500 questionnaires were distributed to the children to be completed by their parents at home.

RESULTS

A total of 2387 children (response rate 95.5%) in the 2004 study and 2216 children (response rate 94.3%) in 1995 were included in the final analysis. The overall lifetime prevalence of wheeze increased from 15.1% to 25.3%; prevalence odds ratio (POR) = 1.91, 95% confidence interval (95% CI) = 1.64-2.21, and P < 0.001. The overall 12-month prevalence of wheeze increased from 8.2% to 11.3%; POR = 1.43, 95% CI = 1.18-1.75, and P < 0.001. The prevalence of asthma increased significantly from 9.8% to 17.8%; POR = 1.99, 95% CI = 1.67-2.36, and P < 0.001. In both 1995 and 2004, family history of asthma, eczema diagnosed by a physician, food allergy diagnosed by a physician, frequent otitis, frequent sinusitis were associated significantly with high risk for asthma.

CONCLUSIONS

In the 9-year period from 1995 to 2004, the prevalence of asthma symptoms has increased in 6- to 12-year-old schoolchildren in Istanbul. Risk factors affecting asthma prevalence remained unchanged during the 9-year period.

Efficacy of Sanfujiu to treat allergies: patient outcomes at 1 year after treatment

Sanfujiu is a treatment method of applying herbal paste onto the acupoints Fengmen and Feishu during the three hottest days of summer to treat patients with allergies. The objectives of this study were to determine the treatment efficacy at 1 year after the Sanfujiu treatment, and examine variations in the perceived efficacy of Sanfujiu among different subgroups, based on the patients' ages, diagnoses and number of reactive symptoms immediately after the treatment. We enrolled 105 patients who completed Sanfujiu treatment at a medical university hospital in Taipei as the subjects. One year after treatment, trained interviewers conducted telephone interviews with the patients. Approximately 60% of them perceived the treatment as being effective at 1 year later, which was higher than that at 1 week after treatment (45.7%). Younger subjects (<19 years of age) and patients with asthma were more likely to report the treatment as being effective. Patients who had more reactive symptoms after the third Sanfujiu treatment were more likely to report the treatment as being effective. The results demonstrated that Sanfujiu was moderately effective, as perceived by patients in Taiwan, in treating their allergic symptoms.

Association between allergic rhinitis, bottle feeding, non-nutritive sucking habits, and malocclusion in the primary dentition

AIM

To determine the association between allergic rhinitis, bottle feeding, non-nutritive sucking habits, and malocclusion in the primary dentition.

METHODS

Data were collected on 1160 children aged 4-5 years, who had been longitudinally followed since the age of 4 months, when they were admitted to nurseries in a suburban area of Tampico-Madero, Mexico. Periodically, physical examinations were conducted and a questionnaire was given to their parents or tutors.

RESULTS

Malocclusion was detected in 640 of the children (51.03% had anterior open bite and 7.5% had posterior cross-bite). Allergic rhinitis alone (adjusted odds ratio = 2.87; 95% CI 1.57 to 5.25) or together with non-nutritive sucking habits (adjusted odds ratio = 3.31; 95% CI 1.55 to 7.09) had an effect on anterior open bite. Bottle feeding alone (adjusted odds ratio = 1.95; 95% CI 1.07 to 3.54) or together with allergic rhinitis (adjusted odds ratio = 3.96; 95% CI 1.80 to 8.74) had an effect on posterior cross-bite. Posterior cross-bite was more frequent in children with allergic rhinitis and non-nutritive sucking habits (10.4%).

CONCLUSIONS

Allergic rhinitis alone or together with non-nutritive sucking habits is related to anterior open bite. Non-nutritive sucking habits together with allergic rhinitis seem to be the most important factor for development of posterior open bite in children under the age of 5 years.

Asthma, eczema, and reports on pollen and cat allergy among pupils in Shanxi province, China

OBJECTIVES

To study self-reported asthma, eczema, and pollen and furry pet allergy among pupils (9-20 years) in Shanxi province, China, in relation to dietary and environmental factors.

METHODS

A standardised questionnaire was distributed to pupils in two primary and two secondary schools, one in Taiyuan city (3.0 milj. inhabitants), the others in Qingxu county, a rural area 30 km outside Taiyuan. Totally, 2,116 pupils (90%) participated.

RESULTS

Fifty percent were girls, 61% had been growing up on the countryside, 18% lived in Taiyuan now, 1.7% had ever had asthma, 0.8% had doctor's diagnosed asthma, 1.4% pollen allergy, 1.7% cat allergy, and 0% had dog allergy. Multiple logistic regression was applied, controlling for age, gender, diet, indoor exposures, rural childhood, and current urban residency. Girls had less eczema (OR = 0.51; 95%CI 0.28-0.92). Pupils in the city had more eczema (OR = 5.05; 95% CI 1.11-23.3). Those with a rural childhood had less asthma (OR = 0.17; 95% CI 0.05-0.60), eczema (OR = 0.15; 95% CI 0.13-0.66) and pollen/cat allergy (OR = 0.50; 95%CI 0.25-0.99). None of the indoor variables was related to asthma or allergy. Children with frequent fruit consumption had less asthma (OR = 0.40; 95% CI 0.19-0.82) and pollen/cat allergy (OR = 0.49; 95% CI 0.29-0.84). Those with frequent fish consumption had less asthma (OR = 0.32; 95% CI 0.11-0.97). Those with frequent hamburgers consumption had more asthma (OR = 2.05; 95% CI 1.09-3.87) and eczema (OR = 1.85; 95% CI 1.12-3.04).

CONCLUSION

Asthma, eczema, and pollen or pet allergy was uncommon, compared with western countries and other areas in China. Pupils with a rural childhood had less asthma and allergy, which is consistent with the "hygiene hypothesis". Fruit and fish consumption may reduce, and fast food consumption may increase the risk for asthma. Finally, the higher prevalence of asthma and eczema among younger children, born in the 1990s, indicates a cohort effect similar to that observed in western countries.

Trends in prevalence of asthma, allergic rhinitis and atopic dermatitis in 5-7-year old Swiss children from 1992 to 2001

BACKGROUND

Changing occurrence rates of asthma, allergic rhinitis and atopic dermatitis are of public health concern and require surveillance. Changes in prevalence rates of these atopic diseases were monitored during 10 years and their trend with time was determined taking into account the influence of personal and environmental risk factors.

METHODS

Four cross-sectional surveys in 5-7-year old children were performed in seven different communities in Switzerland between 1992 and 2001. Prevalence of respiratory and allergic symptoms and of affecting risk factors including parental environmental concern were assessed using a standardized parental questionnaire.

RESULTS

A total of 988 (74.1%), 1778 (79.0%), 1406 (82.6%) and 1274 (78.9%) children participated, respectively, in the 1992, 1995, 1998 and 2001 surveys. Prevalence rates of asthma and hay fever symptoms remained quite stable over time (wheeze/past year: 8.8%, 7.8%, 6.4% and 7.4%, sneezing attack during pollen season: 5.0%, 5.6%, 5.4% and 4.6%). Rates of reported atopic dermatitis symptoms (specific skin rash/past year: 4.6%, 6.5%,7.4% and 7.6%) showed an increase over time, but those of diagnosis of eczema did not show a clear pattern (18.4%, 15.7%, 14.0% and 15.2%). Stratified analysis by parental environmental concern and by parental atopy showed similar trends. Rates of atopic dermatitis symptoms showed significant increase in girls but stayed stable in boys.

CONCLUSION

Results of these four consecutive surveys suggest that the increase in prevalence of asthma and hay fever in 5-7-year old children living in Switzerland may have ceased. However, symptoms of atopic dermatitis may still be on the rise, especially among girls.

Effect of a structured asthma education program on hospitalized asthmatic children: a randomized controlled study

BACKGROUND

The aim of this study was to compare the effectiveness of an intensive asthma education program (group B) with that of a standard asthma education program (group A).

METHODS

A prospective randomized single blinded study was conducted in the pediatric department of a public hospital in Hong Kong. Children aged 2-15 years admitted to the pediatric department with an acute attack of asthma were recruited. A standard asthma education program (group A) or an intensive asthma education program (group B) for children were offered. The main outcome measures include the number of visits to the emergency department and the number of hospitalization for asthma during the 3 month follow-up period.

RESULTS

A total of 45 children were in group A and 55 in group B. Group B had statistically significant reductions in the number of visits to the emergency department and the number of hospitalizations. Drug compliance was also significantly improved in group B. Parents' satisfaction rate was also higher in group B.

CONCLUSION

The intensive asthma education program might be more cost effective than the standard asthma education program in the management of asthmatic children admitted to hospital in Hong Kong.

Changes in prevalence of asthma and allergies among children and adolescents in Italy: 1994-2002

BACKGROUND

Several studies conducted during the 1990s indicated an increase in the prevalence of symptoms of asthma; more recent investigations suggest that the trend is stabilizing or may even be reversing.

OBJECTIVE

We compared 2 cross-sectional surveys conducted in 1994 and 2002 in 8 areas in northern and central Italy, to evaluate prevalence changes for asthma, allergic rhinitis, and eczema.

METHODS

The International Study of Asthma and Allergies in Childhood methods and questionnaires were used to investigate 6- to 7-year-old children (16,115 and 11,287 questionnaires completed by parents in 1994-1995 and 2002, respectively) and 13- to 14-year-old adolescents (19,723 and 10,267 questionnaires completed by adolescents in 1994-1995 and 2002, respectively). In each phase, the overall response rate was >90%. Prevalence changes were calculated as the absolute difference between the prevalence recorded on the 2 occasions.

RESULTS

The prevalence of wheeze (past 12 months) increased slightly among children (change: 0.8%; 95% confidence interval [CI]: 0.0% to 1.6%) and was rather stable among adolescents. Symptoms of allergic rhinitis (children: change: 5.2%; 95% CI: 4.0% to 6.4%; adolescents: change: 4.1%; 95% CI: 1.9% to 6.3%) and symptoms of atopic eczema (children: change: 4.4%; 95% CI: 3.6% to 5.2%; adolescents: change: 2.1%; 95% CI: 1.2% to 3.0%) increased clearly in both age groups. There was some heterogeneity across the centers among adolescents, especially for allergic rhinitis, with larger increases seen in the 3 metropolitan areas. The changes observed paralleled profound family changes, ie, better parental education, higher rates of maternal employment, and lower rates of exposure to parental smoke. These factors, however, do not explain all of the observed changes in prevalence.

CONCLUSIONS

The results indicate that the epidemiologic features of asthma and allergies in Italy are changing rapidly, although the causes are still uncertain.

Efficacy and safety of levocetirizine on symptoms and health-related quality of life of children with perennial allergic rhinitis: a double-blind, placebo-controlled randomized clinical trial

BACKGROUND

This randomized study examined the efficacy and safety of levocetirizine in pediatric patients with perennial allergic rhinitis. Health-related quality of life (HRQL) was also investigated, which is particularly relevant in children because of the effects of rhinitis on learning, social activities, and comorbidity.

OBJECTIVE

To evaluate the effect of levocetirizine on the Total 4 Symptoms Score, the 50% response rate, the Pediatric Rhinitis Quality of Life Questionnaire (PRQLQ), and investigators' global evaluation of symptom improvement.

METHODS

Double-blind, placebo-controlled, randomized, multicenter trial of levocetirizine, 5 mg once daily for 4 weeks, in 306 children with perennial allergic rhinitis aged 6 to 12 years. There were 154 children in the levocetirizine arm and 152 in the placebo group who completed daily diary cards, and the PRQLQ and investigators' global evaluations were conducted at 3 visits.

RESULTS

The levocetirizine group showed a significant improvement in 2-week and 4-week Total 4 Symptoms Score compared with placebo (P = .001 and P = .008, respectively). The 50% response rate for the first 2 weeks was 12.3% for the levocetirizine group compared with 3.9% for the placebo group (P = .01). The investigators' global evaluation also favored levocetirizine, because 57.1% of the children in the levocetirizine group were considered markedly or moderately improved compared with 44.7% in the placebo group. Levocetirizine also provided a significantly greater HRQL improvement than placebo at 2 weeks (P = .01), and the frequency of adverse events did not differ significantly from those seen in the placebo group.

CONCLUSION

The study confirmed the efficacy of levocetirizine in relieving symptoms of perennial allergic rhinitis in children between 6 and 12 years of age. A HRQL benefit greater than placebo was shown. The treatment was well tolerated.

Diverging prevalence trends of atopic disorders in Norwegian children. Results from three cross-sectional studies

BACKGROUND

During the last decades there has been extensive epidemiological research to explore the increasing prevalence of asthma and allergy in childhood. The worldwide variations in prevalence of these diseases necessitate regional rapports. Furthermore, time-trend analyses with comparable methods are important in order to monitor the rapidly changing prevalence of these diseases.

METHODS

Three cross-sectional questionnaire-based studies of asthma and allergy in schoolchildren were conducted in the counties of Troms and Finnmark, in northern Norway in 1985, 1995 and 2000. The two former studies included children from randomly selected primary schools (n = 1794/1985, n = 1432/1995). The latter study was a part of ISAAC-II Europe study (n = 3853). Identical items of asthma and allergy were employed. The analyses comprised only children 9-11 years of age.

RESULTS

The prevalence of asthma was 9.3, 13.2 and 13.8% in 1985, 1995 and 2000, respectively. However, great gender differences were detected; the prevalence of asthma increased in males from 1995 to 2000, from 14.1 to 17.0%, RR = 1.2 (95% CI 1.0-1.5), but decreased in females 1995 to 2000, from 12.3 to 10.5%, RR = 0.9 (95% CI 0.7-1.1). Furthermore, in children with asthma, a changing trend was found in the external factors that perceived symptoms, from typical allergens towards other, unspecific agents. The prevalence of self-reported atopic eczema/dermatitis syndrome (AEDS) was 13.4, 21.1 and 20.8% in 1985, 1995 and 2000, respectively. The prevalence of self-reported allergic rhinoconjunctivitis was in 16.5, 24.7 and 29.6% 1985, 1995 and 2000, respectively, RR (2000/1995) = 1.2 (95% CI 1.1-1.3).

CONCLUSION

The prevalence of asthma in girls has reached a plateau and even decreased from 1995 to 2000 which is in contrast to the asthma prevalence in boys that tends to continuously increase. The prevalence of AEDS which increased substantially between 1985 and 1995 did not change from 1995 to 2000. However, the prevalence of allergic rhinoconjunctivitis increased steadily from 1985, 1995 to 2000.

Modest increase in seasonal allergic rhinitis and eczema over 8 years among Estonian schoolchildren

We studied time trends in the prevalence of asthma and allergic diseases in Estonian children born before and after the collapse of the Soviet Union, as this event markedly altered the lifestyle in Estonia. Two identical cross-sectional studies were performed as part of phase I and phase III of the International Study of Asthma and Allergies in Childhood (ISAAC). Children, aged 6-7 yr (n = 3070 in 1993-94 and 2383 in 2001-02) and 13-14 yr (n = 3476 and 3576, respectively), completed ISAAC core-written questionnaires, and 13-14-yr olds (n = 3427 and 3259, respectively) also video questionnaires. The prevalence of respiratory symptoms was mostly similar in the two studies. Despite this, the prevalence of diagnosed asthma increased. This was probably due to modified diagnostic criteria and increased awareness. Furthermore, the prevalence of rhinitis during the pollen season increased, e.g., rhinitis in May from 1.7% to 3.5%; sex-adjusted prevalence odds ratio (POR) 2.09 (95% confidence interval 1.47-2.96) in 6-7-yr olds, and from 2.6% to 5.5%; POR 2.22 (1.72-2.87) in 13-14-yr olds. The prevalence of flexural dermatitis also increased from 12.0% to 13.5%; POR 1.20 (1.02-1.41) in 6-7-yr olds, and from 7.7% to 9.4%; POR 1.26 (1.07-1.50) in 13-14-yr olds. The increase was similar in children born before and after the regaining of Estonian independence, indicating that the influence of factors related to a Western lifestyle and affecting the prevalence of allergic symptoms is not restricted to infancy, but may be operative throughout childhood.

Asthma epidemiology: has the crisis passed?

PURPOSE OF REVIEW

Asthma is a difficult, resource-intensive disease that can result in symptoms, hospitalization and, in rare cases, death. In the past few decades, there has been an abundance of evidence showing the prevalence of asthma to be increasing in certain regions. However, reports have recently emerged suggesting that asthma prevalence has stabilized. This has led to debate among researchers whether increases in asthma prevalence have come to an end. We reviewed recent literature in search of answers to the ongoing debate on whether the asthma crisis is over.

RECENT FINDINGS

In contrast with past reports, several recent studies have reported a stabilization of asthma prevalence. However, based on repeated cross-sectional studies, findings regarding the stabilization of asthma prevalence have been inconsistent, especially when considering the heterogeneity of the disease, which can result in a variety of patterns concerning asthma diagnosis, symptoms, and allergic sensitization. Temporal trends considering physician visits, hospitalizations, and mortality have been more consistent, with stabilizing and decreasing patterns of asthma burden in recent years.

SUMMARY

Because reasons for the original increases in asthma prevalence remain unclear, an explanation for the apparent stabilization of asthma prevalence reported in some studies also remains elusive. This is compounded by the difficulty in defining asthma accurately in population studies and inconsistencies in the results of prevalence estimation among repeated cross-sectional studies. Efforts should be made to continue monitoring asthma prevalence and to begin monitoring asthma prevalence in regions where environmental and social changes are occurring.

Signs of reversing trends in prevalence of asthma

Several recent reports have provided evidence that the burden of asthma may have levelled off, after increasing for decades. Implementation of the national and global asthma prevention and management guidelines that have led to earlier detection and improved treatment of asthmatics, is considered to be involved in this apparent change for the better. In addition, environmental influences associated with the modern life may have reached the maximum in inducing symptoms and disease in genetically susceptible individuals in some areas. Available data obtained from Canada and non-English-speaking countries in Europe show that the peak in asthma prevalence has been reached at the level of 8-12%. This review outlines the most recent literature on time trends in asthma prevalence and considers the possible causes of the current trends. Problems and pitfalls in appraising studies on time trends are also discussed.

Children with respiratory disease associated with metapneumovirus in Hong Kong

Human metapneumovirus (HMPV) is a newly discovered pathogen thought to be associated with respiratory disease. We report the results of a study of 587 children hospitalized with respiratory infection over a 13-month period. HMPV was detected in the nasopharyngeal aspirates from 32 (5.5%) children by reverse transcription-polymerase chain reaction. HMPV infection was associated with clinical diagnoses of pneumonia (36%), asthma exacerbation (23%), or acute bronchiolitis (10%). When compared to those with respiratory syncytial virus infection, children with HMPV infection were older, and wheezing was more likely to represent asthma exacerbation rather than acute bronchiolitis. HMPV viral activity peaked during the spring-summer period in Hong Kong. Phylogenetically, all HMPV virus strains from Hong Kong belonged to one of the two genetic lineages previously described. HMPV contributed to 441.6 hospital admissions per 100,000 population <6 years of age.