Declining incidence of episodes of asthma: a study of trends in new episodes presenting to general practitioners in the period 1989-98

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.

Alternative ways of expressing forced expiratory volume in the first second and long-term mortality in elderly patients with asthma

BACKGROUND

Clinical and epidemiologic evidence on asthma in the elderly is scant. There is evidence that forced expiratory volume in the first second (FEV1), a commonly used indicator of overall pulmonary function, might not be an independent predictor of 5-year mortality in elderly patients with asthma.

OBJECTIVE

To investigate the association between FEV1 expressed using 3 alternative methods and 5-, 10-, and 15-year mortality in a population of elderly patients with asthma.

METHODS

Participants in the Salute Respiratoria nell' Anziano study were included. Asthma was diagnosed at baseline according to spirometric and clinical data. Vital status at 15 years was assessed using death registries. FEV1 was expressed as percentage of predicted, divided by height cubed, and as a multiple of the sex-specific first percentile. The association between FEV1 and mortality was evaluated using Cox proportional hazard models.

RESULTS

Two hundred patients were studied (52% women, mean age 73.1 years, standard deviation 6.2 years). All FEV1 measurements were associated with mortality at unadjusted analysis. After correction for potential confounders, no association was found between FEV1 and 5-year mortality. Only FEV1 as a multiple of the sex-specific first percentile was independently associated with 10-year (hazard ratio 0.35, 95% confidence interval 0.14-0.87) and 15-year (hazard ratio 0.38, 95% confidence interval 0.19-0.79) mortality.

CONCLUSION

Although extensively used, FEV1 expressed as percentage of predicted does not seem to be the best predictor of mortality in elderly patients with asthma. Although no spirometric index can predict 5-year mortality in this population, FEV1 as a multiple of the sex-specific first percentile should be considered when longer-term prognostic stratification is needed.

The burden of allergic asthma in children: a landscape comparison based on data from Lithuanian, Latvian, and Taiwanese populations

Asthma is one of the most common chronic respiratory diseases with an increasing prevalence and financial burden worldwide. This disease affects individuals in all countries and all ethnic groups; however, prevalence rates of asthma have been reported to vary significantly between different regions. To understand the origin of asthma and to manage it effectively, it is necessary to analyze the genetic and environmental factors that cause these geographic differences. Therefore, we aimed to review published data from the investigations of asthma patients in Eastern Europe, represented by Latvia and Lithuania, and of patients from Eastern Asia represented by Taiwan. We hope that some of the common factors can be identified and different variants can be compared among these three countries for development of a new strategy to prevent childhood asthma.

Asthma and other recurrent wheezing disorders in children (acute)

INTRODUCTION

Acute childhood asthma is a common clinical emergency presenting across a range of ages and with a range of severities.

METHODS AND OUTCOMES

We conducted a systematic review and aimed to answer the following clinical question: What are the effects of treatments for acute asthma in children? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2010 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

RESULTS

We found 35 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

CONCLUSIONS

In this systematic review we present information relating to the effectiveness and safety of the following interventions: beta2 agonists (high-dose nebulised, metered-dose inhaler plus spacer device versus nebuliser, intravenous), corticosteroids (systemic, high-dose inhaled), ipratropium bromide (single- or multiple-dose inhaled), magnesium sulphate, oxygen, and theophylline or aminophylline.

Fifty years of pediatric asthma in developed countries: how reliable are the basic data sources?

Given the difficulties in diagnosing, or even defining, asthma in children, claims of a pediatric asthma epidemic in Canada and other developed countries are accepted with surprisingly little critical examination. We reviewed a broad range of data sources to understand how the epidemic evolved during the last 50 years and also to assess the reliability of the conclusions drawn from that data. We obtained Canadian National and Provincial data from Statistics Canada National Population Health Survey, and the British Columbia Ministry of Health respiratory database. International data were obtained by extensive review of pediatric asthma epidemiological surveys published during the last 50 years. In many developed countries, there have been three separate epidemics involving different aspects of pediatric asthma during the last 50 years: a double peaked mortality epidemic (1960s and 1980s), a hospital admission epidemic (peaked around 1990) and a steadily growing epidemic of children who report asthmatic symptoms on questionnaires. Canadian pediatric rates for asthma mortality (1-2/million/year) and hospital admission (1-2/thousand/year) are low and have fallen for the last 20 years. Rates based on questionnaire studies are high (10-15/hundred) and rose steadily over the same period. Objective reductions in asthma deaths and hospital admission likely reflect improved education and treatment programmes. Current claims of an epidemic based largely on subjective self-reported symptoms require more careful analysis. The possibility that symptom misperception, disease fashions, and poor recall, may be part of the explanation for the current high levels of self-reported symptoms deserves more attention.

Trends in childhood asthma hospitalisation in three Asia Pacific countries

AIM

The study aims to examine recent childhood asthma hospitalisation rates in the Asia Pacific countries of Australia, Hong Kong and Singapore. On the background of reported decline in many countries with high asthma prevalence during late 1990s.

METHODS

Annual asthma hospitalisation (ICD9-CM: 493 or ICD10-AM: J45-46)* and population data from 1994 to 2008, of children aged 0-14 years old, were obtained from the Australian National Hospital Morbidity Database, from the Hospital Authority in Hong Kong and from the Ministry of Health in Singapore. Data were stratified in two age groups: 0-4 and 5-14 years old, and also in different periods of calendar years. Time-series regression analyses were used to examine temporal trends. Diagnostic transfer was addressed by examining bronchitis hospitalisations.

RESULTS

Significant decreases of up to 6.5% per annum in childhood asthma hospitalisation rates were found over the study period. However, the latter half of the study period showed increases in hospitalisation rates in all countries studied. No evidence of diagnostic transfer was found.

CONCLUSION

Although there has been a decrease in childhood asthma hospitalisation rates since the 1990s, a modest increase was observed from 2003 to 2008. Ongoing monitoring is required.

Systems for the management of respiratory disease in primary care--an international series: United Kingdom

INTRODUCTION

The UK National Health Service (NHS) is essentially publicly funded through general taxation. Challenges facing the NHS include the rise in prevalence of long-term conditions and financial pressures. NATIONAL POLICY TRENDS: Political devolution within the UK has led to variations in the way services are organised and delivered between the four nations. PRIMARY CARE RESPIRATORY SERVICES IN THE UK: Primary care is the first point of contact with services. Most respiratory conditions are managed here, including prevention, diagnosis, treatment and palliative care.

EPIDEMIOLOGY

Respiratory disease accounts for more primary care consultations than any other type of illness, with 24 million consultations annually.

ACCESS TO CARE

Equitable access to care is an ongoing challenge: telehealthcare is being tried as a possible solution for monitoring of asthma and COPD. REFERRAL AND ACCESS TO SPECIALIST CARE: Referrals for specialist advice are usually to a secondary care respiratory physician, though respiratory General Practitioners with a Special Interest (GPwSIs) are an option in some localities.

CONCLUSIONS

Prevalence of asthma and COPD is high. Asthma services are predominantly nurse-led. Self-management strategies are widely promoted but poorly implemented. COPD is high on the policy agenda with a shift in focus to preventive lung health and longterm condition management.

[Risk factors and prevalence of asthma and rhinitis among primary school children in Lisbon]

AIMS

A cross-sectional study was carried out with the objective of identifying nutrition habits and housing conditions as risk factors for respiratory problems in schoolchildren in Lisbon.

MATERIAL AND METHODS

Between October and December 2008, parents of 900 students of the basic schools of Lisbon were invited to answer a questionnaire of the International Study of Asthma and Allergies in Childhood Program (ISAAC). The response rate was 40%. Logistic regression was used in the analysis of results.

RESULTS

The prevalence of asthma, allergic rhinitis and wheeze was 5.6%, 43.0% and 43.3%, respectively. Risk factors independently associated with asthma were wheezing attacks, and dry cough at night not related to common cold in the last 12 months. Wheezing crises were found to affect children daily activities. Risk factors for wheeze were hay fever and the presence of a pet at home. A risk factor for rhinitis was cough at night. The frequent consumption of egg was also associated with increased risk of rhinitis.

CONCLUSION

Contrarily to asthma, the prevalence of allergic rhinitis and wheeze increased in comparison with previous ISAAC studies. Wheezing attacks were associated with asthma and hay fever was identified as a risk factor of manifesting wheezing symptoms. Having pets at home was pointed out as a significant risk factor for rhinitis, but not smoking exposure, mould, plush toys, diet (except egg consumption), breastfeeding or other conditions.

Allele-specific transcription of the asthma-associated PHD finger protein 11 gene (PHF11) modulated by octamer-binding transcription factor 1 (Oct-1)

BACKGROUND

Asthma is a common, chronic inflammatory airway disease of major public health importance with multiple genetic determinants. Previously, we found by positional cloning that PHD finger protein 11 (PHF11) on chromosome 13q14 modifies serum immunoglobulin E (IgE) concentrations and asthma susceptibility. No coding variants in PHF11 were identified.

OBJECTIVE

Here we investigate the 3 single nucleotide polymorphisms (SNPs) in this gene most significantly associated with total serum IgE levels--rs3765526, rs9526569, and rs1046295--for a role in transcription factor binding.

METHODS

We used electrophoretic mobility shift assays to examine the effect of the 3 SNPs on transcription factor binding in 3 cell lines relevant to asthma pathogenesis. Relative preferential expression of alleles was investigated by using the allelotyping method.

RESULTS

Electrophoretic mobility shift assays show that rs1046295 modulates allele-specific binding by the octamer-binding transcription factor 1 (Oct-1). Analysis of the relative expression levels of the 2 alleles of this SNP in heterozygous individuals showed a modest, but highly significant (P = 6.5 × 10(-16)), preferential expression of the A allele consistent with a functional role for rs1046295.

CONCLUSION

These results suggest a mechanism by which rs1046295 may act as a regulatory variant modulating transcription at this locus and altering asthma susceptibility.

Asthma management in primary care: does increasing patient medication improve symptoms?

AIMS

We set out to observe the General Practitioner (GP) management of a cohort of asthma patients over a 2-year period by comparing asthma health status, spirometry, British Thoracic Society treatment step, inhaled medication uptake and psychological status. Changes in these parameters were assessed over the 2-year period.

METHODS

One hundred fourteen subjects were recruited from four GP practices, two in the inner city and two in suburbia. Subjects were assessed at baseline and at 2 years using the Juniper asthma quality of life questionnaire, the locally devised Q score (a simple patient-focused morbidity index) and the hospital anxiety and depression (HAD) scale. Spirometry (forced expiratory volume in 1 s, forced vital capacity and peak expiratory flow) was recorded using a Micro Medical portable spirometer (Micro Medical Ltd, Chatham, UK); the best values from three acceptable attempts were recorded.

RESULTS

Data for 90 subjects reviewed at baseline and at 24 months were compared to the original cohort of 114 subjects. Patients who had the treatment increased showed no apparent benefit over 2 years. They had similar physiology and symptom scores at baseline but had higher HAD scores (particularly depression element P < 0.05) initially. The picture remained constant over the 2 years.

CONCLUSION

Asthma guidelines define the aim of treatment to minimise or abolish symptoms. We suggest that if the symptoms are not measured, they remain unrecognised. This is something that could and should be incorporated routinely into clinical practice because this is morbidity that is largely treatable.

Trends in prevalence of childhood and parental asthma in Merseyside, 1991-2006

BACKGROUND

To determine changes in prevalence of parental and childhood asthma in Merseyside between 1991 and 2006.

METHODS

Four standardized cross-sectional respiratory surveys using a parent-completed questionnaire were completed in 1991 (n = 1171), 1993 (n = 2368) 1998 (n = 1964) and in 2006 (n = 1074) among primary school children attending the same schools in lower socio-economic areas of Merseyside. Main outcome measures were prevalence of doctor diagnosed asthma (DDA) and the symptom triad of cough, wheeze and breathlessness (C+W+B+).

RESULTS

Between 1991 and 1998 prevalence of DDA increased (P < 0.001), but in 2006 this decreased from 29.8 to 19.4% (P < 0.001). Prevalence of C+W+B+ increased from 7.8 to 8.0% by 1998, then decreased to 6.7% in 2006 (P = 0.39). Between 1998 and 2006, childhood hospital admissions for respiratory illness decreased from 11.3 to 9.7% (P = 0.23). During this period paternal asthma prevalence increased from 8.6 to 10.7% (P = 0.001) and maternal asthma from 11.2 to 13.4% (P = 0.09).

CONCLUSIONS

An increase in the prevalence of DDA and asthmatic respiratory symptoms occurred in children prior to 1998, but this had decreased by 2006. Prevalence of parental asthma increased during the same period.

Prevalence of allergic diseases of schoolchildren in central taiwan. From ISAAC surveys 5 years apart

The prevalence of allergic disorders is increasing around the world. This study used the standardized written questionnaire from International Study of Asthma and Allergies in Childhood (ISAAC, phase III) to collect two cross-sectional appraisals of schoolchildren 5 years apart-one performed 2002 and another on 2007, to focus on the secular trends in prevalence of allergies in central Taiwan. This questionnaire was administered to schoolchildren from over 46 schools across Changhwa County in 2002, and again in 2007. The present study is a follow-up study and uses data collected from a previously reported study conducted in the year 2002 of the same location using the same methodology. Although the repeated cross-sectional survey after a 5-year lapse suggests a mere increase of diagnosed asthma cases from 7.1% to 7.4%, the prevalence of its related symptoms--nocturnal cough, rhinitis, and eczema--was found to increase significantly by 2.6% (p < 0.0001), 6.8% (p < 0.001), and 5.9% (p < 0.001), respectively. Additionally, comparing the secular trends in asthma prevalence, rhinitis, and eczema between several polluted areas in Changhwa County with its less polluted neighbors in 2002 and 2007 indicates that schoolchildren in TaiHao area, which is noted to be polluted by a petrochemical company, has a significantly increased prevalence of wheezing (3.7%, p < 0.05) and nocturnal cough (3.6%, p < 0.05). For schoolchildren living in the coastal areas, a 6% (p < 0.05) increase in the prevalence of rhinitis is noted. The prevalence of eczema uniformly increased for all areas of Changhwa County (p < 0.01). In the downtown areas, besides eczema, the prevalence of asthma and rhinitis also increased significantly (p < 0.05). Of note is the consistent finding in these two periods of the higher prevalence of childhood asthma, rhinitis, and eczema in the downtown areas compared with that from both the polluted and coastal areas. The secular trends in prevalence of asthma, rhinitis, and eczema in these two periods seem to correlate to environmental factors. While the symptoms of asthma, rhinitis, and eczema in schoolchildren affected boys more than girls, it is observed that affected girls have more marked manifestations, although it did not reach statistical significance.

Relationship between social inequalities and ambulatory care-sensitive hospitalizations persists for up to 9 years among children born in a major Canadian urban center

OBJECTIVE

Hospitalizations for ambulatory care-sensitive (ACS) conditions have been considered a marker for access to timely and effective primary care, but there are few pediatric studies. Our purpose was to examine socioeconomic disparities in ACS and non-ACS admissions among birth cohorts in a universal health insurance setting.

METHODS

We examined ACS and all hospitalizations of children born from 1993 to 2000 in Toronto, Canada, by birth year, calendar year, and socioeconomic status (SES). SES was evaluated by using quintiles of mean neighborhood income from the 1996 Canadian census. Cohort, age, and temporal effects were described for all admissions, ACS admissions, and specific ACS conditions. Attributable risk by SES was calculated by using rates for the highest and lowest SES quintiles.

RESULTS

Among 255,284 children born in Toronto during 1993-2001, ACS conditions were responsible for 28% of hospitalizations during the first 2 years of life and close to half of admissions during the third year. Low income was associated with 50% higher rates of ACS hospitalizations (relative risk [RR] = 1.50, 95% confidence interval [95% CI] 1.43-1.58), including asthma (RR = 1.69, 95% CI 1.54-1.86) and bacterial pneumonia (RR = 1.59, 95% CI 1.40-1.81), the leading causes of admission. Socioeconomic disparities in ACS and all admissions occurred in every cohort, every calendar year, and every age group.

CONCLUSIONS

The relationship between socioeconomic disadvantage and both ACS and all-cause hospitalization in children was large, consistent across many conditions, remained stable over time, and persisted up to 9 years of age. These effects occurred in a universal health insurance setting without direct financial barriers to physician or hospital care. The effect of SES on hospitalizations in children in our setting appears to be mediated by factors other than financial access to care.

Time trend of asthma prevalence among school children in Taiwan. [corrected]

The standardized International Study of Asthma and Allergies in Childhood (ISAAC) is a valid tool in assessing prevalence of asthma indices. In order to determine the time trends of childhood asthma in Taiwan, we compared data from nationwide ISAAC surveys from a very large sample of Taiwanese 12- to 15-year-old school children, using ISAAC core written and video questionnaires. The number of participants was 44,104 in 1995-96 (phase I) and 11,048 in 2001 (phase III). We found a general tendency towards an increase in lifetime prevalence of physician-diagnosed asthma and asthma symptoms between two surveys, more marked for girls than for boys. Most of the 12-month prevalence of asthma symptoms decreased among boys but stabilized among girls. When comparing different severity levels, we also noted that the decreasing trends of current symptoms were more marked with regard to severe symptoms than mild symptoms in both sexes. A combination of both improved awareness and management of asthma might in part explain this circumstance. Over the past decade in Taiwan, the lifetime prevalence of childhood asthma was increasing, more marked among girls; however, the 12-month prevalence of asthma symptoms was decreasing, mostly among boys. The exact reasons for such trends remain to be explored.

Practice development plans to improve the primary care management of acute asthma: randomised controlled trial

Background

Our professional development plan aimed to improve the primary care management of acute asthma, which is known to be suboptimal.

Methods

We invited 59 general practices in Grampian, Scotland to participate. Consenting practices were randomised to early and delayed intervention groups. Practices undertook audits of their management of all acute attacks (excluding children under 5 years) occurring in the 3 months preceding baseline, 6-months and 12-months study time-points. The educational programme [including feedback of audit results, attendance at a multidisciplinary interactive workshop, and formulation of development plan by practice teams] was delivered to the early group at baseline and to the delayed group at 6 months. Primary outcome measure was recording of peak flow compared to best/predicted at 6 months. Analyses are presented both with, and without adjustment for clustering.

Results

23 consenting practices were randomised: 11 to early intervention. Baseline practice demography was similar. Six early intervention practices withdraw before completing the baseline audit. There was no significant improvement in our primary outcome measure (the proportion with peak flow compared to best/predicted) at either the 6 or 12 month time points after adjustment for baseline and practice effects. However, the between group difference in the adjusted combined assessment score, whilst non-significant at 6 months (Early: 2.48 (SE 0.43) vs. Delayed 2.26 (SE 0.33) p = 0.69) reached significance at 12 m (Early:3.60 (SE 0.35) vs. Delayed 2.30 (SE 0.28) p = 0.02).

Conclusion

We demonstrated no significant benefit at the a priori 6-month assessment point, though improvement in the objective assessment of attacks was shown after 12 months. Our practice development programme, incorporating audit, feedback and a workshop, successfully engaged the healthcare team of participating practices, though future randomised trials of educational interventions need to recognise that effecting change in primary care practices takes time. Monitoring of the assessment of acute attacks proved to be a feasible and responsive indicator of quality care.

50 years of asthma: UK trends from 1955 to 2004

Trends in asthma indicators from population surveys (prevalence) and routine statistics (primary care, prescriptions, hospital admissions and mortality) in the UK were reviewed from 1955 to 2004. The prevalence of asthma increased in children by 2 to 3-fold, but may have flattened or even fallen recently. Current trends in adult prevalence are flat. The prevalence of a life-time diagnosis of asthma increased in all age groups. The incidence of new asthma episodes presenting to general practitioners increased in all ages to a plateau in the mid 1990s and has declined since. During the 1990s, the annual prevalence of new cases of asthma and of treated asthma in general practice showed no major change. Hospital admissions increased from the early 1960s, more so in children, until the late 1980s and have fallen since. Asthma mortality showed two waves, a shorter and more intense one in the mid 1960s and a longer and less intense one in the late 1970s and early 1980s. The relative roles of diagnostic transfer, coding changes, medical care and epidemiological factors are discussed.

Is the global rise of asthma an early impact of anthropogenic climate change?

The increase in asthma incidence, prevalence, and morbidity over recent decades presents a significant challenge to public health. Pollen is an important trigger of some types of asthma, and both pollen quantity and season depend on climatic and meteorological variables. Over the same period as the global rise in asthma, there have been considerable increases in atmospheric carbon dioxide concentration and global average surface temperature. We hypothesize anthropogenic climate change as a plausible contributor to the rise in asthma. Greater concentrations of carbon dioxide and higher temperatures may increase pollen quantity and induce longer pollen seasons. Pollen allergenicity can also increase as a result of these changes in climate. Exposure in early life to a more allergenic environment may also provoke the development of other atopic conditions, such as eczema and allergic rhinitis. Although the etiology of asthma is complex, the recent global rise in asthma could be an early health effect of anthropogenic climate change.

[Current prevalence of asthma in schoolchildren in San Sebastián (Spain)]

OBJECTIVE

To determine the current prevalence of asthma in children aged 6-12 years old in San Sebastian (Guipuzcoa, Spain).

PATIENTS AND METHODS

An observational, cross sectional study was performed in 6-12-year-old children in schools. The International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire was employed. Bronchial hyperresponsiveness was investigated using the free running test, with peak expiratory flow (PEF) measured with a peak flow meter as the main measurement. The ISAAC questionnaire (n = 919) was distributed to 460 boys (50.1%) and 459 girls (49.9%) with a mean age of 8 years (SD 1.87). The response rate to the questionnaire was 93 % (n = 855). Participation in the free running test was 90.8% (n = 835). A total of 89.88% of the children (n = 826) completed both tests.

RESULTS

The questionnaire of symptoms and signs compatible with asthma revealed a current prevalence of asthma of 25.56% (n = 216) and a cumulative prevalence of 25.44% (n = 85). Nocturnal asthma was found in 29.37% (n = 47) and severe asthma in 9.27% (n = 14). Bronchial hyperresponsiveness was found in 23% of the participants. An epidemiological diagnosis of asthma (asthma-related symptoms plus bronchial hyperresponsiveness) was made in 6.54%.

CONCLUSIONS

The current prevalence of asthma in 6-12-year-old schoolchildren in San Sebastian, determined through symptoms and signs compatible with asthma in the previous year and a positive free running test, is similar to that reported in other national studies.

Too clean, or not too clean: the hygiene hypothesis and home hygiene

The 'hygiene hypothesis' as originally formulated by Strachan, proposes that a cause of the recent rapid rise in atopic disorders could be a lower incidence of infection in early childhood, transmitted by unhygienic contact with older siblings. Use of the term 'hygiene hypothesis' has led to several interpretations, some of which are not supported by a broader survey of the evidence. The increase in allergic disorders does not correlate with the decrease in infection with pathogenic organisms, nor can it be explained by changes in domestic hygiene. A consensus is beginning to develop round the view that more fundamental changes in lifestyle have led to decreased exposure to certain microbial or other species, such as helminths, that are important for the development of immunoregulatory mechanisms. Although this review concludes that the relationship of the hypothesis to hygiene practice is not proven, it lends strong support to initiatives seeking to improve hygiene practice. It would however be helpful if the hypothesis were renamed, e.g. as the 'microbial exposure' hypothesis, or 'microbial deprivation' hypothesis, as proposed for instance by Bjorksten. Avoiding the term 'hygiene' would help focus attention on determining the true impact of microbes on atopic diseases, while minimizing risks of discouraging good hygiene practice.

Physician-diagnosed asthma and allergic rhinitis in Manitoba: 1985-1998

BACKGROUND

A worldwide increase has been noted in the prevalence of asthma, but the data for other allergic disorders are less consistent.

OBJECTIVE

To study 14-year trends in utilization of physician resources for asthma and compare them to trends for allergic rhinitis.

METHODS

We studied visits to physicians by Manitoba residents for asthma (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] code 493) and allergic rhinitis (ICD-9 code 477) between 1985 and 1998. Prevalence and incidence of physician resources utilization were calculated annually for the total population and by age groups. Aggregate statistics and frequency of physician resources utilization were also analyzed.

RESULTS

The prevalence and incidence of physician resources utilization for asthma increased more than for allergic rhinitis; differences were most striking in the youngest age groups. In adults, the differences were smaller and changed little with time. Most of the increase in asthma care occurred in children and in people without allergic rhinitis. Overall, 17% of Manitobans were diagnosed as having asthma, and the average asthmatic patient made 6 visits. Approximately 14% had an allergic rhinitis diagnosis, each person being seen twice on average. Coexistence of asthma and allergic rhinitis led to increased physician resources utilization for each of the conditions.

CONCLUSIONS

Trends in utilization of physician resources for allergic rhinitis differed strikingly from trends for asthma, particularly in the youngest age group. Asthma and allergic rhinitis affected comparable proportions of the population, but a diagnosis of asthma resulted in much higher utilization of physician resources. The relationship of physician-diagnosed asthma and atopy, as indicated by the diagnosis of allergic rhinitis, appears to have weakened with time in children but not in adults.

When allergies complicate allergies

The 'allergic march' is a term used to describe an individual's progress from one clinical manifestation of allergy to another, with age. Not all sensitized children will join the allergic march, but it appears that individuals who do not join the allergic march have a greater risk of displaying symptoms of allergic disease in adulthood. Consequently, there is a need for early diagnosis of allergy in children. Immunoglobulin E (IgE) antibody quantification is increasingly used for this purpose. However, rather than making a diagnosis based on single positive IgE antibody results only, it may be more efficient to test a profile of airborne and food allergens and use the sum of IgE antibody concentrations > or =3.5 kUA/l in combination with the number of allergens that elicit positive results tests. Allergic diseases often co-exist in patients, and the combination of several exposures at a given time (the allergen load) is related to disease severity. Therefore, a reduction of the allergen load is a key to successful treatment.

Childhood asthma in South London: trends in prevalence and use of medical services 1991-2002

BACKGROUND

Hospital admission rates for asthma in Britain rose during the 1980s and fell during the 1990s, but less is known about recent trends in the prevalence of asthma.

METHODS

In 1991 and 2002 the same questionnaire was distributed to parents of all school pupils in year 3 (aged 7-8 years) in the London borough of Croydon. Parents of currently wheezy children were then invited for home interview (100% targeted in 1991, 66% in 2002).

RESULTS

The prevalence of wheeze during the previous year increased from 12.9% in 1991 to 17.8% in 2002 (prevalence ratio 1.39 (95% CI 1.23 to 1.56)). Increases were observed in frequent (1.54 (95% CI 1.16 to 2.03)) and infrequent attacks, severe speech limiting episodes (2.25 (95% CI 1.34 to 3.77)), and night waking (1.36 (95% CI 1.07 to 1.72)), and in the reported use of steroids (19.9% v 64.1% of currently wheezy children). Nevertheless, the proportions reporting a visit to the GP at his/her surgery for wheeze in the previous year (prevalence ratio 1.15 (95% CI 0.91 to 1.45)) or an outpatient visit (0.98 (95% CI 0.49 to 1.94)) changed little and an increase in reported casualty attendance (1.66 (95% CI 0.89 to 3.07)) was non-significant.

CONCLUSIONS

There is evidence of an increase in the prevalence of asthma among British primary school children between 1991 and 2002. The absence of a corresponding increase in health service utilisation data may reflect more widespread prophylactic treatment and/or changes in the use and provision of medical services.

12-year change in prevalence of respiratory symptoms in elderly Chinese living in Hong Kong

Respiratory diseases may cause considerable disability in the elderly because of their limited respiratory reserve related to aging. This study aimed to assess the time trend of respiratory symptoms and common chronic respiratory diseases in the elderly Chinese living in Hong Kong. Two questionnaire surveys were conducted in 1991-1992 and 2003-2004. Subjects aged > or = 70 years were invited to complete a respiratory questionnaire. A total of 2032 (999 male) and 1524 (698 male) subjects completed the questionnaire surveys in 1991 and 2003, respectively. The response rates were 60% in 1991 and 78% in 2003. The prevalence of most respiratory symptoms increased over time after adjusting the data for age, sex, social status and smoking habits. Comparing the symptoms between 1991 and 2003, wheeze over the past 12 months increased from 7.5 to 12.1% (adjusted OR 2.00, 95% CI 1.54-2.61) and morning chest tightness from 4.2 to 8.8% (adjusted OR 2.48, 95% CI 1.79-3.43). The prevalence of self-reported physician-diagnosed emphysema increased over time (2.4-3.1%, adjusted OR 1.78, 95% CI 1.12-2.86), but there was no change for asthma (5.1% in 1991 and 5.8% in 2003) or chronic bronchitis (6.7% in 1991 and 7.7% in 2003). The prevalence of respiratory symptoms has increased over the past 12 years and this may be related to environmental factors especially increasing air pollution in Hong Kong.

Prevalence of asthma, eczema and allergic rhinitis: two surveys, 6 years apart, in Kota Bharu, Malaysia

OBJECTIVE

This study was undertaken to determine the prevalence of asthma, eczema, and allergic rhinitis in school children in Kota Bharu, Malaysia, and in so doing to determine the differences in symptom prevalence rates of asthma, and atopic diseases in Kota Bharu school children between 1995 and 2001.

METHODOLOGY

In two studies (1995 and 2001), year one primary school (PS) pupils (6-7 years old) and secondary school (SS) year two pupils (13-14 years old) were randomly selected from the district of Kota Bharu, Kelantan, Malaysia. In 1995, 3939 PS children and 3116 SS children participated, and in 2001 3157 PS children and 3004 SS children participated. The Phase I International Study of Asthma and Allergies in Childhood prevalence written questionnaire and video questionnaire (only shown to SS children) were used in both studies.

RESULTS

The written questionnaire showed no significant changes in the prevalence (1995, 2001) of ever wheeze (8.3%, 6.9%P = 0.06), current wheeze (5.4%, 4.3%P = 0.08), exercise-induced wheeze (EIW; 3.9%, 3.7%P = 0.63), and rhinoconjunctivitis (4.6%, 5%P = 0.42) among PS children. The prevalence of flexural itchy rash increased from 14% to 17.6% (P = 0.004) and night cough decreased from 20.4% to 17.5% (P = 0.005). There were also no significant changes in these symptoms among SS children (1995, 2001): ever wheeze (10.7%, 12%P = 0.37), current wheeze (6.8%, 5.7%P = 0.20), EIW (9.9%, 11.6%P = 0.28), night cough (21.6%, 24%P = 0.39), rhinoconjunctivitis (11%, 15%P = 0.11), and flexural itchy rash (12%, 13%P = 0.11). The video questionnaire showed no significant changes in the prevalence of symptoms in the previous 12 months (1995 vs 2001) for wheeze at rest (3.8%, 2.8%P = 0.12), EIW (6.9%, 8.8%P = 0.32), waking with wheeze (1.7%, 1.7%P = 1.0), and severe wheeze (2.1%, 3%P = 0.12). Night cough in the previous 12 months increased significantly from 5.1% to 8.3% (P = 0.007).

CONCLUSION

Although asthma and atopic disorders are common in this country, the results revealed no major changes in the prevalence rates of these diseases over a period of 6 years.

Asthma prevalence in 1973, 1988 and 2003

BACKGROUND

A study was undertaken to see whether the prevalence of asthma has changed since a survey was conducted in 1988, using the same methods that showed an increase during the previous 15 years.

METHODS

A survey of 12 year old children was conducted in schools in South Wales where surveys had taken place in 1973 and 1988. The survey comprised a parentally completed questionnaire and an exercise challenge test, performed when no bronchodilator had been recently used.

RESULTS

In 1973, 1988, and 2003, questionnaires were obtained for 817, 965 and 1148 children, respectively; the exercise test was performed by 812, 960 and 1019 children, respectively. The prevalence of reported wheeze in the last year rose during each 15 year period (9.8%, 15.2%, 19.7%), with an even steeper rise in reported asthma ever (5.5%, 12.0%, 27.3%). There was a continued increase in wheeze attributed to running, in terms of all children (5.8%, 10.5%, 16.0%) and also as the proportion of those with a history of wheeze (34.1%, 47.0%, 57.3%). The use of inhaled corticosteroids (not available in 1973) increased fourfold between 1988 and 2003. The prevalence of exercise induced bronchoconstriction rose between 1973 and 1988 but had declined by 2003.

CONCLUSIONS

The rise in the prevalence of asthmatic symptoms has continued since 1988. This appears to conflict with a reported recent decline, unless asthma prevalence peaked in the 1990s. The decline in exercise induced bronchoconstriction is probably attributable to better control of the disease as more children are now using inhaled corticosteroids as preventive treatment.

High prevalence of asthma symptoms in the Canary Islands: climatic influence?

The worldwide variation in asthma prevalence prompted us to carry out a study to assess the variability of asthma-related symptoms in young adults on the islands of Gran Canaria and Tenerife. We used the questionnaire used in the European Community Respiratory Health Survey with the addition of two questions on smoking and ancestors from the Canary Islands. In each island, this questionnaire was distributed to a random sample of 5000 subjects aged 20-44 years. Of the 10,000 subjects, 9,506 (95.06%) were considered eligible. We obtained 7,132 (75.03%) responses. The prevalence of the different symptoms was wheezing 25.3%, nocturnal thoracic tightness 18.0%, awakened by an attack of shortness of breath 13.1%, attack of nocturnal coughing 33.3%, attack of asthma 4.3%, current asthma treatment 6.2%, and nasal allergies 18.0%. Women and smokers showed a significantly higher prevalence of asthma symptoms. No significant difference in symptoms was found between subjects whose ancestors were of Canarian origin and those with ancestors born outside the Canaries. As has been observed on other islands (Great Britain and New Zealand), asthma is common in individuals from 20 to 44 years of age in the Canaries. We hypothesize that climatic conditions play an important role in the prevalence of asthma symptoms.

Temporal change in the prevalence of respiratory symptoms and obstructive airways disease 1993-2001

BACKGROUND

There has been little available information regarding secular changes in the prevalence of respiratory symptoms since the mid-1990s.

AIM

To examine changes in the prevalence of respiratory symptoms for 1993-2001.

DESIGN OF STUDY

A series of postal questionnaire surveys.

SETTING

Two general practice populations, including all age groups.

METHOD

Four postal respiratory questionnaire surveys were conducted between 1993 and 2001. Subjects who replied to two or more surveys (8058 adults and 2350 children) were included in the main analyses. Validated scoring systems were used to define obstructive airways disease in adults and asthma in children.

RESULTS

Over the 8-year observation period there were increases among adults in the crude prevalence of wheeze, being woken by cough, receipt of current asthma medication, and of obstructive airways disease, compared with decreases in children for wheeze, night cough, asthma attacks, and asthma. For adults, adjusted odds ratios per year of secular increase were 1.03 (95% confidence interval [CI] = 1.02 to 1.03) for wheeze, 1.03 (95% CI = 1.02 to 1.03) for being woken by cough, 1.03 (95% CI = 1.02 to 1.04) for asthma medication, and 1.02 (95% CI = 1.01 to 1.03) for obstructive airways disease. These increases were greater in those aged over 44 years, in males, and in those without a family history of asthma or a history of hayfever or eczema. Corresponding decreases for children were 0.94 (95% CI = 0.92 to 0.97) for wheeze, 0.93 (95% CI = 0.91 to 0.96) for night cough, 0.93 (95% CI = 0.90 to 0.95) for asthma attacks and 0.98 (95% CI = 0.95 to 1.00) for asthma.

CONCLUSION

The increases found in adults are more likely to be due to chronic obstructive pulmonary disease (COPD) than asthma. This is supported by the decreases in symptom and asthma prevalence in children.

Is the global rise of asthma an early impact of anthropogenic climate change?

The increase in asthma incidence, prevalence, and morbidity over recent decades presents a significant challenge to public health. Pollen is an important trigger of some types of asthma, and both pollen quantity and season depend on climatic and meteorologic variables. Over the same period as the global rise in asthma, there have been considerable increases in atmospheric carbon dioxide concentration and global average surface temperature. We hypothesize anthropogenic climate change as a plausible contributor to the rise in asthma. Greater concentrations of carbon dioxide and higher temperatures may increase pollen quantity and induce longer pollen seasons. Pollen allergenicity can also increase as a result of these changes in climate. Exposure in early life to a more allergenic environment may also provoke the development of other atopic conditions, such as eczema and allergic rhinitis. Although the etiology of asthma is complex, the recent global rise in asthma could be an early health effect of anthropogenic climate change.

Respiratory illness associated with influenza and respiratory syncytial virus infection

AIMS

To estimate excess morbidity during periods of influenza and respiratory syncytial virus (RSV) activity.

METHODS

Retrospective analysis of a sentinel practice network database in active and non-active virus periods.

MAIN OUTCOME MEASURES

clinical diagnoses of new episodes of influenza-like illness (ILI), acute bronchitis, asthma, and otitis media.

RESULTS

The clinical diagnosis of ILI was consistent with influenza virus activity and acute bronchitis with RSV. During periods of virus activity, estimates of excess morbidity in children aged 1-4 and 5-14 years diagnosed as having acute otitis media exceeded those diagnosed with each of the other three conditions; in children <1 year estimates for acute bronchitis were highest. Using a broad definition of virus activity and summarising the data for all children diagnosed with ILI, 60% was attributable to influenza (40% RSV) as were 37% of episodes diagnosed as acute bronchitis, 9% of those with asthma and 48% of those with otitis media. Using a narrow definition, corresponding proportions were: for ILI diagnoses 77% (23% RSV), acute bronchitis 32%, asthma zero, and otitis media 45%. Acute bronchitis was diagnosed twice as frequently in association with RSV as with influenza in all age groups: excess asthma episodes were only evident in RSV active periods.

CONCLUSIONS

Except in relation to ILI, RSV caused more illness than the influenza virus in the respiratory diagnoses examined, emphasising the need for RSV prevention and treatment. Influenza was not associated with excess asthma episodes.

Compromised arterial oxygen saturation in elderly asthma sufferers results in selective cognitive impairment

Forty elderly patients with asthma or chronic obstructive pulmonary disorder (COPD) were compared to a comparison group of forty age-matched healthy volunteers on a range of measures of cognitive performance, and levels of arterial haemoglobin oxygen saturation recorded. Members of the patient group were found to have significantly lower oxygen saturation compared to the comparison group, and performed significantly poorer on tests of delayed word recall and serial subtractions, but not on other tasks. Correlational analysis between participants' oxygen saturation levels and test scores across the whole sample indicated significant positive relationships existed for the digit symbol substitution and serial subtractions tasks. The results are discussed in terms of cerebral oxygen delivery, glucose metabolism, age related cognitive decline, and relative task demands.

Trends in primary care consultations for asthma in Switzerland, 1989-2002

BACKGROUND

There is widespread debate about trends in the occurrence of asthma in industrialized countries. This study was conducted to investigate time trends in consultations for asthma in primary care in Switzerland.

METHODS

Prospective observational study from 1989 to 2002 within the Swiss Sentinel Surveillance Network; a primary care surveillance system. We used time series analysis and non-parametric smoothing methods to investigate long-term and short-term trends in rates of asthma episodes per 1000 consultations. From 1994 to 2002 we compared rates of first episodes with all subsequent consultations for asthma.

RESULTS

Overall consultation rates for asthma per 1000 primary care consultations increased from 1989 to 1994 then stabilized and have declined since 2000. Long-term trends showed a small decline in first consultations for asthma from an average of 0.78 (95% credibility intervals (CI) 0.74-0.81) in 1999 to 0.62 (95% CI 0.55-0.69) per 1000 consultations in 2002. Subsequent consultations for asthma have been declining since at least 1994, from an average of 1.5 (95% CI 1.40-1.61) per 1000 consultations in 1994 to 0.93 (95% CI 0.82-1.04) in 2002. In addition, the ratio of subsequent to first episodes of asthma fell in all age groups.

CONCLUSIONS

In Switzerland, primary care consultations for asthma, subsequent to the initial diagnosis, have been declining since 1994. This is more likely to be owing to an increase in the use of home medication than to a shift in care to hospital settings. The incidence of diagnosed asthma might also be decreasing.

Prevalence of respiratory symptoms in under 5s: 1993 to 2001

AIM

To describe changes in the prevalence of respiratory symptoms in 1-4 year olds in two general practice populations observed on four occasions over an eight year period.

METHODS

In 1993, 1995, 1999, and 2001, questionnaires were posted to the parents of patients aged 15 years or younger and registered with either of two general practices. Only children aged 1-4 years at time of questionnaire completion were included in this study. For each survey, the prevalence of five key variables was determined.

RESULTS

The response rates for all children in the four surveys were 72.8%, 70.6%, 65.0%, and 60.7% respectively. When respondents aged 1-4 years old were stratified into one-year age bands, there was a decrease in the prevalence of symptoms over the study period. This was statistically significant for wheeze and night cough in 2 year olds and for night cough in 4 year olds. Repeated antibiotic prescriptions decreased significantly for 2 and 3 year olds. There were no changes in the prevalence of hay fever or eczema and family history of asthma.

CONCLUSIONS

The downward trend in symptom prevalence might represent a real decrease in symptoms or improvements in treatment. In the absence of changes in the prevalence of hay fever and family history of asthma, the downward trend in symptom prevalence may suggest changes in the prevalence of conditions other than asthma.

Quantitative analysis of IgE antibodies to food and inhalant allergens in 4-year-old children reflects their likelihood of allergic disease

BACKGROUND

It is well established that early diagnosis of allergic disease is warranted.

METHODS

In a prospective birth cohort study (BAMSE) 3743 children at 4 years of age were included. Children were classified as having any allergic disease, e.g. asthma, suspected allergic rhinitis (suspAR), eczema or oro-gastro-intestinal symptoms with questionnaire. Blood was obtained from 2612 of these children and analysed for IgE antibodies (ab) towards 14 common food and airborne allergens.

RESULTS

Positive IgE ab results were found in 38% of the children with any allergic disease, whereas such IgE ab results were found in 17% among those without any allergic disease. Furthermore, among children with any allergic disease the median summated IgE ab levels were 10.7 kU(A)/l compared with 1.5 kU(A)/l among those without such symptoms. The highest IgE ab levels were found to birch, peanut, cat and horse. When the sum of the IgE-ab levels towards the selected allergens was at least 34 kU(A)/l, or, alternatively, more than four allergen tests were positive, there was a 75% likelihood of identifying the individual with any allergic disease. To identify those with asthma, as well as those with suspAR, a significant interaction was found for the combination of the sum of IgE-ab levels and number of allergens positive at test. For eczema only, the number of positive allergens at test was associated to the likelihood of such disease.

CONCLUSIONS

In children, 4 years of age, allergic disease was frequently not associated with the presence of single positive IgE antibody results, whereas increased IgE ab levels were significantly more prevalent among those with allergic disease. Thus, testing a certain profile of airborne and food allergens, and utilizing the sum of the IgE-ab levels in combination with the number of allergens positive at tests, may represent a more efficient diagnostic tool then to use just single positive IgE-ab results.

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.

Changing prevalence of asthma in Taiwanese adolescents: two surveys 6 years apart

This study compared the prevalence of asthma among Taiwanese adolescents with individual-level risk factors and municipal-level air pollution and meteorology data to determine whether changes in these factors could explain the observed change in prevalence. We conducted two national surveys of respiratory illness and symptoms in Taiwanese middle-school students in 1995-96 and 2001. The effects of personal and environmental factors were assessed and temporal changes of outdoor monitoring data were also compared with asthma prevalence difference. A total of 44,104 children from the 1995-96 survey and 11,048 children from the 2001 survey attended schools located within 1 km of 22 monitoring stations. Lifetime prevalences of physician-diagnosed and questionnaire-determined asthma increased during this period. After adjustment for potential risk factors, the prevalence differences were statistically unchanged. Although parental education level contributed most, changes in investigated personal and environmental factors might not explain the observed changes in asthma prevalence. Municipalities with higher temperature increase were significantly associated with prevalence difference in questionnaire-determined asthma. We concluded that correlates of the investigated individual-level factors, which have changed over time, still underlie changes in asthma prevalence. Increasing temperature might be the main reason for the rising trends of asthma in Taiwanese adolescents.

Trends in the prevalence of respiratory symptoms and treatment in Dutch children over a 12 year period: results of the fourth consecutive survey

BACKGROUND

Although there is considerable evidence that the prevalence of childhood asthma has increased over the last decades, it is not clear if this trend is still ongoing. A study was undertaken to investigate whether previously observed trends in the prevalence of respiratory symptoms, physician visits, medication use, and absence from school in Dutch children aged 8-9 years persisted in 2001.

METHODS

Parents of 1154 children aged 8-9 years eligible for a routine physical examination in 2001 were asked to complete a questionnaire on the respiratory health of their child.

RESULTS

In 2001, 1102 children (95.5%) participated in the survey. Similarly high response rates were obtained in the surveys of 1989, 1993 and 1997, with 1794, 1526 and 1670 children aged 8-9 years participating in the respective surveys. The decreasing trend previously observed for recent wheeze between 1989 and 1997 persisted into 2001, particularly in boys. After increasing between 1989 and 1997, the prevalence of shortness of breath with wheeze decreased between 1997 and 2001. The proportion of wheezy children using medication increased between 1989 and 2001 in boys (42.9% v 64.8%; p = 0.003), but the increase was not statistically significant in girls (34.0% v 45.7%; p = 0.096).

CONCLUSION

The prevalence of recent wheeze in Dutch school children has declined steadily since 1989. The rising prevalence of medication use in symptomatic children over time may reflect better asthma control and may partly explain the concurrently decreasing trend in the prevalence of asthma symptoms in our study population.

Declining asthma prevalence in Hong Kong Chinese schoolchildren

BACKGROUND

Many studies have reported an increase in the prevalence of asthma and related atopic disorders. The lack of standardized methodologies and 'objective' measurements make reliable comparison and monitoring of trends of asthma very difficult.

METHODS

In this study, a total of 3321 schoolchildren aged 13-14 years were recruited for study using the Phase III Protocol of the International Study of Asthma and Allergic disease in Childhood (ISAAC). The results were compared with those obtained in the Phase I ISAAC study (1994-95), which used the identical and validated core questionnaires.

RESULTS

The prevalence rates of physicians' diagnosis of asthma were similar in the two surveys (11.2% and 10.2%), but the prevalence rates of wheeze (written questionnaire) in the past year have decreased from 12.4% in 1994-95 to 8.7% in 2002 (P<0.001). For the video questionnaire, all asthmatic symptoms in the preceding 12 months were significantly lower in 2002 when compared with those in 1994-95. Among the subjects with diagnosed asthma, the prevalence rates of wheeze in the past 12 months (written questionnaire) has decreased from 39.1% to 27.6% (P<0.001). The prevalence rates of having wheezing attack at least once per month (video questionnaire) has decreased from 10.5% to 5.6% (P=0.013).

CONCLUSION

Using the same standardized and validated ISAAC questionnaire, the prevalence rates of asthma symptoms in Hong Kong Chinese schoolchildren have decreased since 1994. The exact reasons for such trend remain to be explored.

Stabilization of asthma prevalence among adolescents and increase among schoolchildren (ISAAC phases I and III) in Spain

BACKGROUND

Most studies show a steep increase in asthma prevalence in the last decades, although few studies had applied the same methodology. Recent reports point out the possibility that the epidemic has come to an end. We have studied the prevalence of asthma in a very large sample of children, repeating the study eight years apart.

METHODS

Repeated cross-sectional studies using the International Study of Asthma and Allergies in Childhood (ISAAC) protocol in a sample of Spanish schoolchildren 6-7 (parent-reported) and 13-14 (self-reported) years old in 1994-95 (phase I) and 2002-2003 (phase III). The number of participants was 42 417 in phase I and 42 813 in phase III. The participation rate was over 87% (13-14 years) and 70% (6-7 years).

RESULTS

The prevalence of wheezing in the previous year in children aged 13-14 years was 9.0 and 9.3% for boys and 9.6 and 9.2% for girls for phases I and III, respectively. Children 6-7 years of age showed a substantial increase in wheezing in the previous year (7.0 and 10.7% for boys and 5.3 and 8.2% for girls). Other symptoms and severity indexes followed the same patterns.

CONCLUSIONS

In the last 8 years, the prevalence of asthma has not changed in 13-14-year-old Spanish children but has increased substantially in 6-7-year olds.

Domestic risk factors for wheeze in urban and rural Ethiopian children

BACKGROUND

To identify which environmental exposures underpin the emergence of asthma epidemics, we need to study epidemics as they appear, as is now happening in the Jimma region of Ethiopia. We have previously studied risk factors for asthma in adults in Jimma and have now completed a survey of young children.

AIM

To establish the prevalence of asthma in urban and rural children in Jimma, and to identify locally important risk factors.

DESIGN

Cross-sectional survey.

METHODS

All children aged 1-5 years living in Jimma town and three surrounding rural regions were identified. Data were collected using an interviewer-led questionnaire, and consenting children had skin prick tests to house dust mite and cockroach.

RESULTS

We surveyed 7155 children, of whom 3623 (51%) were female and 4285 (60%) lived in the urban area. The prevalence of wheeze in the last year was 3.4%, and was lower in the rural area (OR 0.47; 95%CI 0.34-0.66). In the urban area, the main risk factors for wheeze were a longer duration of breastfeeding, use of kerosene, and environmental tobacco smoke, while living with animals was protective. In rural children, the main risk factors were a positive skin prick test and living with animals.

DISCUSSION

The prevalence of wheeze in children in the Jimma region is low, particularly in rural children. In addition to having an impact on disease prevalence, place of residence also appears to modify the impact of environmental risk factors for wheeze.

Burden of allergic disease in the UK: secondary analyses of national databases

BACKGROUND

Although allergy represents an important source of patient morbidity and healthcare utilization, there is little reliable information on the overall disease burden posed by allergic conditions in the UK.

OBJECTIVES

Focusing on the following conditions: allergic rhinitis, anaphylaxis, asthma, conjunctivitis, eczema/dermatitis, food allergy and urticaria/angioedema, we sought to (i) describe the prevalence, incidence and outcomes of allergic disorders; (ii) describe the NHS healthcare burden posed by allergic disorders; (iii) estimate the costs of allergic disorders from a healthcare perspective.

METHODS

Secondary analyses of data from the Health Survey for England, Scottish Health Survey, International Study of Allergies and Asthma in Childhood, European Community Respiratory Health Survey, Morbidity Statistics from General Practice 1991/1992, Royal College of General Practitioners Weekly Returns Service, Prescribing Analysis and Cost data, Hospital Episodes Statistics and national mortality data.

RESULTS

Thirty-nine percent of children and 30% of adults have been diagnosed with one or more atopic conditions. Six percent of general practice consultations and 0.8% of hospital admissions are for allergic diseases. Treatments for asthma and other allergic disorders currently account for 10% of primary care prescribing costs. Direct NHS costs for managing allergic problems are estimated at over one billion UK pounds per annum.

CONCLUSIONS

Allergic disorders are common throughout the UK, affecting males and females of all ages and peoples from all social classes and ethnic groups. They currently represent a substantial burden of morbidity and health service cost.

Trends of asthma in Mexico: an 11-year analysis in a nationwide institution

STUDY OBJECTIVES

Asthma prevalence is increasing in many countries. Some recent articles, however, claim that this tendency is ending. Our aim was to investigate asthma trends in Mexico.

DESIGN

Annual data on health services provided to asthmatic patients were retrospectively analyzed from 1991 to 2001.

SETTING

The Instituto Mexicano del Seguro Social, the largest nationwide medical institution in Mexico (approximately 24 to 32 million insured subjects).

PARTICIPANTS

Health services provided to subjects of any age.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Asthma-associated health services, either expressed as absolute number or as rate per insured subjects, progressively increased until 1997 in family physician office visits (FPOVs) [newly diagnosed cases only], emergency department visits (ERVs), and hospital discharges (HDs). From that year onward, the number and rates of asthma-associated health services decreased. The same trends were observed for age groups 0 to 4 years, 5 to 14 years, 15 to 44 years, and 45 to 64 years. Using a different approach, asthma was diagnosed each year in approximately 0.4% of all FPOVs, but a decrease in this percentage was observed from 1997 onward. Likewise, asthma caused increasing percentages of all ERVs and HDs until 1997, followed by a sharp decline thereafter.

CONCLUSIONS

A decline in absolute and relative numbers of asthma-associated health services occurred over recent years in all medical settings, suggesting that the epidemic of new asthma cases is ending and/or that better control of the disease has been achieved.

Trends in childhood illness and treatment in Australian general practice, 1971-2001

OBJECTIVE

To determine changes in morbidity and management of disease in children in Australian general practice.

DESIGN AND SETTING

A comparative study of general practice consultations in children under 15 years, using data from cross-sectional general practice surveys (1990-91 and 2000-01), and a descriptive comparison with a similar study from 1971.

MAIN OUTCOME MEASURES

Relative rates of management (rate/100 general practice encounters) of the most common children's problems and treatments.

RESULTS

Problems with significantly higher management rates in 2000-01 compared with 1990-91 included vaccination (11.1 v 7.6 per 100 encounters in 1990-91) and contact/allergic dermatitis (3.1 v 2.5). Those managed significantly less often in 2000-01 v 1990-91 included acute otitis media (7.7 v 9.4), asthma (5.4 v 8.8), tonsillitis (4.4 v 6.0), acute bronchitis (3.8 v 5.3) and gastroenteritis (1.7 v 2.7). Asthma management rates rose from 2.4% of all problems managed in 1971 to 7.2% in 1990-91, then fell in 2000-01 to 4.6%. More frequent rates of counselling and advice in 2000-01 (28.4% of encounters v 22.9% in 1990-91) were associated with a decrease in rates of prescribing and supply of medication (56.6% of encounters v 64.3% in 1990-91). Antibiotic prescribing declined significantly (from 33.8 per 100 encounters in 1990-91 to 25.2 in 2000-01), as did prescribing of respiratory medications (from 15.5 to 9.9 per 100 encounters), while prescribing of vaccines and systemic corticosteroids doubled (from 9.6 to 18.8 per 100 encounters, and from 0.6 to 1.2, respectively). (All comparisons between 1990-91 and 2000-01 are significant at P < 0.01.)

CONCLUSIONS

These findings point to the emergence of a generation of Australian children who are generally well vaccinated and are less likely to present to GPs with "traditional" childhood illnesses.

Continuing decline in acute asthma episodes in the community

BACKGROUND

Acute asthma episodes prompting consultation with general practitioners in the sentinel practices of the Weekly Returns Service (WRS) of the Royal College of General Practitioners increased through the 1980s and early 1990s, reaching a peak in 1993.

AIMS AND METHODS

To report on trends in the incidence of asthma episodes in children reported to the WRS over the period 1980-2002.

RESULTS

Data confirm the steady upward trend from 1980 to 1993. The downward trend since 1993 was consistent in both male and female preschool and school age children, in all regions of the country simultaneously, and during all seasons until 1999 since when it has stabilised. No causative factor has been identified and no temporal association found between factors previously postulated as causing the increase in acute asthma. The decline in acute asthma episodes in children is consistent with observed declines in all other respiratory infections in this community.