Aims: To explore associations of deprivation and smoking, with prevalence of asthma, wheeze, and quality of life.
Methods: Survey, using International Study of Asthma and Allergies in Childhood (ISAAC) methodology, of children aged 13–14 years attending Scottish schools previously surveyed in 1995.
Results: 4665/5247 (89%) pupils completed questionnaires. 3656/4665 (78.4%) had missed school for any reason in the last 12 months, 587 (12.6%) because of asthma or wheeze. Compared to children with 1–3 wheeze attacks per year, those with >12 attacks in the last year were more likely to have missed school, twice as likely to have missed physical education in the last month, to report interference with home activities, or to have visited accident and emergency departments, and three times more likely to have been hospitalised. Deprivation was not independently associated with self-reported asthma or wheeze, but was associated with school absence, either for any reason or specifically for asthma or wheeze, but not with use of services such as accident and emergency visits, doctor visits, or hospital admissions. Active smoking was associated with wheezy symptoms, and active and passive smoking with use of medical services. These associations were independent of wheeze severity, treatment taken, and other associated atopic conditions. Smoking also had an impact on school absence and home and school activities.
Conclusions: Deprivation does not affect the prevalence of asthma or wheeze. Exposure to cigarette smoke was associated with the increased use of services. Deprivation and smoking have independent adverse effects on the quality of life in subjects with asthma or wheeze.
Most of the studies investigating the prevalence of asthma in various countries have focused on children below the age of 15 years or adults above the age of 18 years. There is limited knowledge concerning the prevalence of asthma in 16- to 18-year-old adolescents. Our objective was to study the prevalence of asthma and associated symptoms in 16- to 18-year-old adolescents in Saudi Arabia.
A cross-sectional study was conducted in secondary (high) schools in the city of Riyadh utilizing the International Study of Asthma and Allergies in Children (ISAAC) questionnaire tool.
Out of 3073 students (1504 boys and 1569 girls), the prevalence of lifetime wheeze, wheeze during the past 12 months and physician-diagnosed asthma was 25.3%, 18.5% and 19.6%, respectively. The prevalence of exercise-induced wheezing and night coughing in the past 12 months was 20.2% and 25.7%, respectively. The prevalence of rhinitis symptoms in students with lifetime wheeze, physician-diagnosed asthma and exercise-induced wheeze was 61.1%, 59.9% and 57.4%, respectively. Rhinitis symptoms were significantly associated with lifetime wheeze (OR = 2.5, p value < 0.001), physician-diagnosed asthma (OR = 2.2, p < 0.001), and exercise-induced wheeze (OR = 1.9, p value < 0.001).
The prevalence of asthma and associated symptoms in 16- to 18-year-old adolescents in Saudi Arabia is high, although it is within range of reported prevalence rates from various parts of the world.
Asthma constitutes a serious public health problem in many regions of the world, including the city of Salvador, State of Bahia – Brazil. The purpose of this study was to analyse the factors associated with poor asthma control.
Two definitions were used for asthma: 1) wheezing in the last 12 months; 2) wheezing in the last 12 months plus other asthma symptoms or asthma diagnosis ever. The definition of poorly controlled asthma was: at least one reported hospitalisation due to asthma and/or high frequency of symptoms, in the last year. Children with poorly controlled asthma (N = 187/374) were compared with wheezing children with controlled asthma regarding age, gender, atopy, parental asthma, rhinitis, eczema, exposure to second hand tobacco smoke, presence of moulds, pets and pests in the house, helminth infections and body mass index. Crude and logistic regression adjusted odds ratios were used as measures of association. There was a higher proportion of poorly controlled asthma among children with eczema (OR = 1.55; 95% CI 1.02; 2.37). The strength of the association was greater among children with eczema and rhinitis (42.6%, 53.4% and 57.7%, respectively, in children who had no rhinitis nor eczema, had only one of those, and had both (p = 0.02 for trend test). The presence of mould in the houses was inversely associated with poorly controlled asthma (OR = 0.54; 95% CI 0.34; 0.87).
Our results indicate an association between eczema and poor asthma control in this environment, but emphasize the role of various other individual and environmental factors as determinants of poor control.
The International Study on Asthma and Allergies in Childhood (ISAAC) reported a prevalence of asthma symptoms in 17 centers in nine Latin American countries that was similar to prevalence rates reported in non-tropical countries. It has been proposed that the continuous exposure to infectious diseases in rural populations residing in tropical areas leads to a relatively low prevalence of asthma symptoms. As almost a quarter of Latin American people live in rural tropical areas, the encountered high prevalence of asthma symptoms is remarkable. Wood smoke exposure and environmental tobacco smoke have been identified as possible risk factors for having asthma symptoms.
We performed a cross-sectional observational study from June 1, 2012 to September 30, 2012 in which we interviewed parents and guardians of Warao Amerindian children from Venezuela. Asthma symptoms were defined according to the ISAAC definition as self-reported wheezing in the last 12 months. The associations between wood smoke exposure and environmental tobacco smoke and the prevalence of asthma symptoms were calculated by means of univariate and multivariable logistic regression analyses.
We included 630 children between two and ten years of age. Asthma symptoms were recorded in 164 of these children (26%). The prevalence of asthma symptoms was associated with the cooking method. Children exposed to the smoke produced by cooking on open wood fires were at higher risk of having asthma symptoms compared to children exposed to cooking with gas (AOR 2.12, 95% CI 1.18 - 3.84). Four percent of the children lived in a household where more than ten cigarettes were smoked per day and they had a higher risk of having asthma symptoms compared to children who were not exposed to cigarette smoke (AOR 2.69, 95% CI 1.11 - 6.48).
Our findings suggest that children living in rural settings in a household where wood is used for cooking or where more than ten cigarettes are smoked daily have a higher risk of having asthma symptoms.
Asthma[Mesh]; Wheeze; Woodsmoke; Tobacco smoke pollution[Mesh]; Smoke[Mesh]; Indigenous children
ecological analysis was conducted of the relationship between
tuberculosis notification rates and the prevalence of symptoms of
asthma, allergic rhinoconjunctivitis, and atopic eczema in 85 centres
from 23 countries in which standardised data are available. These
essentially comprised countries in Europe as well as the USA, Canada,
Australia, and New Zealand.
notification rates were obtained from the World Health Organization.
Data on the prevalence of symptoms of asthma, rhinitis, and eczema in
235 477 children aged 13-14 years were based on the responses to the
written and video questionnaires from the International Study of Asthma
and Allergies in Childhood (ISAAC). The analysis was adjusted for gross
national product (GNP) as an estimate of the level of affluence.
notification rates were significantly inversely associated with the
lifetime prevalence of wheeze and asthma and the 12 month period
prevalence of wheeze at rest as assessed by the video questionnaire. An
increase in the tuberculosis notification rates of 25 per 100 000 was
associated with an absolute decrease in the prevalence of wheeze ever
of 4.7%. Symptoms of allergic rhinoconjunctivitis in the past 12 months were inversely associated with tuberculosis notification rates,
but there were no other significant associations with other ISAAC
questions on allergic rhinoconjunctivitis or atopic eczema.
findings are consistent with recent experimental evidence which
suggests that exposure to Mycobacterium
tuberculosis may reduce the risk of developing asthma.
The relationships between chronic productive cough (CPC), environmental tobacco smoke (ETS) exposure, and asthma are not clearly established in children. Therefore, we wished to determine the prevalence of CPC and examine the relationships between CPC, ETS exposure, and asthma in young teenagers.
We performed a cross sectional survey of 2397 Seattle middle school students, 11–15 years old, using written and video respiratory-symptom questionnaires. We defined CPC as – daily cough productive of phlegm for at least 3 months out of the year; current asthma as – yes to "Have you had wheezing or whistling in your chest in the past 12 months?" and yes in the past year to any of the four video wheezing/asthma video scenarios; and ETS exposure as exposed to tobacco smoke at least several hours each day. We used multilogistic regression to examine relationships between CPC, asthma, and ETS exposure and included in the model the potentially confounding variables race, gender, and allergic rhinitis.
The prevalence of CPC was 7.2%. Forty-seven percent (82/173) of children with CPC met criteria for current asthma, while only 10% (214/2224) of those without CPC had current asthma. Current asthma had the strongest associated with CPC, odds ratio (OR) 6.4 [95% CI 4.5–9.0], and ETS was independently associated with both CPC, OR 2.7 [1.8–4.1] and asthma, OR 2.7 [1.5–4.7].
In a population of young teenagers, CPC was strongly associated with report of current asthma symptoms and also with ETS exposure. This suggests that asthma and ETS exposure may contribute to CPC in children. However, this study was not designed to determine whether asthma was the actual cause of CPC in this population of children.
Limited studies have prospectively examined the role of body mass index (BMI) as a major risk factor for asthma during adolescence. This study investigates whether BMI is associated with increased risk of developing physician-diagnosed asthma during 12-month follow-up among adolescents with undiagnosed asthma-like symptoms at baseline.
A total of 4,052 adolescents with undiagnosed asthma-like symptoms at baseline were re-examined after a 12-month follow-up. Asthma cases were considered confirmed only after diagnosis by a physician based on the New England core and International Study of Asthma and Allergies in Childhood (ISAAC) criteria video questionnaires, and accompanying pulmonary function tests. Logistic regression analyses were used to evaluate the relationship of BMI and the risk of acquiring asthma.
The results indicated that girls with higher BMI were at an increased risk of developing asthma during the 12-month follow-up. The odds ratios for girls developing physician-diagnosed asthma were 1.75 (95% CI = 1.18-2.61) and 1.12 (95% CI = 0.76-1.67), respectively, for overweight and obesity as compared to the normal weight reference group after adjustment for other covariates. A similar relationship was not observed for overweight and obese boys who were also significantly more active than their female counterparts.
Increased BMI exaggerates the risk of acquiring asthma in symptomatic adolescent females but not in adolescent males. Thus, gender is an important modifier of BMI-related asthma risk. Additional research will be required to determine whether the increased asthma risk results from genetic, physiological or behavioural differences.
prevalence of childhood asthma is increasing but few studies have
investigated trends in asthma severity. We investigated trends in
asthma diagnosis and symptom morbidity between an eight year time
period in a paired prevalence study.
children in one single school year aged 8-9 years in the city of
Sheffield were given a parent respondent questionnaire in 1991 and 1999 based on questions from the International Survey of Asthma and Allergy
in Children (ISAAC). Data were obtained regarding the prevalence of
asthma and wheeze and current (12month) prevalences of wheeze attacks,
speech limiting wheeze, nocturnal cough and wheeze, and exertional symptoms.
response rates in 1991 and 1999 were 4580/5321 (85.3%) and 5011/6021
(83.2%), respectively. There were significant increases between the
two surveys in the prevalence of asthma ever (19.9% v 29.7%, mean difference 11.9%, 95%
confidence interval (CI) 10.16to 13.57, p<0.001), current asthma
(10.3% v 13.0%, mean difference 2.7%,
95% CI 1.44 to 4.03, p<0.001), wheeze ever (30.3%
v 35.8%, mean difference 5.7%, 95% CI
3.76 to 7.56, p<0.001), wheeze in the previous 12 months (17.0%
v 19.4%, mean difference 2.5, 95% CI 0.95 to 4.07, p<0.01), and reporting of medication use (16.9% v 20%, mean difference 3.0%, 95% CI 1.46 to 4.62, p<0.001). There were also significant increases in reported
hayfever and eczema diagnoses.
labelling of asthma and lifetime prevalence of wheeze has increased.
The current 12 month point prevalence of wheeze has increased but this
is confined to occasional symptoms. The increased medication rate may
be responsible for the static prevalence of severe asthma symptoms. The
significant proportion of children receiving medication but reporting
no asthma symptoms identified from our 1999 survey suggests that some
children are being inappropriately treated or overtreated.
of the worldwide increases in asthma and allergic diseases in
childhood, which seem to relate to increasing prosperity, are unknown.
We have previously hypothesised that a reduction in the antioxidant
component of the diet is an important factor. An investigation was
undertaken of dietary and other risk factors for asthma in Saudi Arabia
where major lifestyle differences and prevalences of allergic disease
are found in different communities.
METHODS—From a cross
sectional study of 1444 children with a mean age of 12 (SD 1) years in
Jeddah and a group of rural Saudi villages, we selected 114 cases with
a history of asthma and wheeze in the last 12 months and 202 controls
who had never complained of wheeze or asthma, as recorded on the ISAAC
questionnaire. Risk factors for asthma and allergies (family history,
social class, infections, immunisations, family size, and diet) were
ascertained by questionnaire. Atopy was assessed by skin prick testing.
analyses, family history, atopy, and eating at fast food outlets were
significant risk factors for wheezy illness, as were the lowest intakes
of milk and vegetables and of fibre, vitamin E, calcium, magnesium,
sodium, and potassium. These differences were present also in the urban
children considered separately. Sex, family size, social class,
infections, and parental smoking showed no relationship to risk. In
multiple logistic regression analysis, urban residence, positive skin
tests, family history of allergic disease, and the lowest intakes of
vitamin E, magnesium and sodium related significantly and independently
to risk. The lowest tertile of intake of vitamin E was associated with
a threefold (95% CI 1.38 to 6.50) increase in risk when adjusted for
the other factors. Intake of milk and vegetables both showed inverse
linear relationships to being a case.
suggests that dietary factors during childhood are an important
influence in determining the expression of wheezy illness, after
allowing for urban/rural residence, sex, family history, and atopy. The
findings are consistent with previous studies in adults and with the
hypothesis that change in diet has been a determinant of the worldwide
increases in asthma and allergies.
This study was undertaken to determine whether exposure to
various indoor pollutants is associated with a higher prevalence of
respiratory symptoms, a diagnosis of asthma, or more variable peak flow
rates. Four hundred and twenty six children aged 8-11 years in four
junior schools at three locations recorded respiratory symptoms and
diagnosis of asthma using the ISAAC questionnaire. Daily peak flow
measurements were taken during two six-week periods (winter and
summer). Symptoms in children with and without asthma were not related
to gas fires, cookers, smokers, or pets in the home. However, the
variability of lung function, expressed as the coefficient of
variation, in all children was increased with a household smoker.
Environmental tobacco smoke increases airways variability in children
with and without asthma. Its effects were not apparent from a
questionnaire completed by parents, and the coefficient of variation of
serially measured peak flows was a more sensitive indicator of lung function.
Considerable variation in the prevalence of childhood asthma and its symptoms (wheezing) has been observed in previous studies and there is evidence that the prevalence has been increasing over time.
We have systematically reviewed the reported prevalence and time trends of wheezing symptoms among children, worldwide and within the same country over time. All studies comprising more than 1000 persons and meeting certain other quality criteria published over a 16-year period, between January 1990 and December 2005, are reported and a comparison of ISAAC (International Study of Asthma and Allergies in Childhood) and non-ISAAC studies is made, in part as a way of expanding the power to examine time trends (the older studies tend to be non-ISAAC), but also to examine possible methodological differences between ISAAC and non-ISAAC questions.
A wide range of current prevalence of wheeze was observed between and within countries over time. The UK had the highest recorded prevalence of 32.2% in children aged 13–14 in 1994–5 and Ethiopia had the lowest prevalence, 1.7% in children aged 10–19 in 1996. All studies in Australia and the UK were compared using multiple logistic regression. ISAAC phase I and III studies reported significantly higher prevalence of current wheeze (OR = 1.638) compared with non-ISAAC studies, after adjusting for various other factors (country, survey year, age of child, parental vs child response to the survey). Australia showed a significantly higher prevalence of current wheezing (OR = 1.343) compared with the UK, there was a significant increase in the prevalence odds ratio per survey year (2.5% per year), a significant decrease per age of child (0.7% per year), and a significantly higher response in current wheezing if the response was self-completed by the child (OR = 1.290). These factors, when explored separately for ISAAC and non-ISAAC studies, showed very different results. In ISAAC studies, or non-ISAAC studies using ISAAC questions, there was a significant decrease in current wheezing prevalence over time (2.5% per year). In non-ISAAC studies, which tend to cover an earlier period, there was a significant increase (2.6% per year) in current wheezing prevalence over time. This is very likely to be a result of prevalence of wheezing increasing from the 1970s up to the early 1990s, but decreasing since then.
The UK has the highest recorded prevalence of wheezing and Ethiopia the lowest. Prevalence of wheezing in Australia and the UK has increased from the 1970s up to the early 1990s, but decreased since then and ISAAC studies report significantly higher prevalences than non-ISAAC studies.
Incense burning has been reported to adversely affect respiratory health. The aim of this study was to explore whether exposure to bakhour contributes to the prevalence of asthma and/or triggers its symptoms in Omani children by comparing two Omani regions with different prevalence of asthma.
A randomly selected sample of 10 years old schoolchildren were surveyed using an Arabic version of ISAAC Phase II questionnaires with the addition of questions concerning the use and effect of Arabian incense on asthma symptoms. Current asthma was defined as positive response to wheeze in the past 12 months or positive response to "ever had asthma" together with a positive response to exercise wheeze or night cough in the past 12 months. Simple and multivariable logistic regression analyses were performed to estimate the effect of bakhour exposure and other variables on current asthma diagnosis and parents' response to the question: "Does exposure to bakhour affect your child breathing?"
Of the 2441 surveyed children, 15.4% had current asthma. Bakhour use more than twice a week was three times more likely to affect child breathing compared to no bakhour use (adjusted OR 3.01; 95% CI 2.23–4.08) and this effect was 2.55 times higher in asthmatics (adjusted OR 2.55; 95% CI 1.97–3.31) compared to non-asthmatics. In addition, bakhour caused worsening of wheeze in 38% of the asthmatics, making it the fourth most common trigger factor after dust (49.2%), weather (47.6%) and respiratory tract infections (42.2%). However, there was no significant association between bakhour use and the prevalence of current asthma (adjusted OR 0.87; 95% CI 0.63–1.20).
Arabian incense burning is a common trigger of wheezing among asthmatic children in Oman. However, it is not associated with the prevalence asthma.
It has been hypothesised that the rise in childhood asthma in the developed world could result at least in part from the increasing exposure of children to toxic chlorination products in the air of indoor swimming pools.
Ecological study to evaluate whether this hypothesis can explain the geographical variation in the prevalence of asthma and other atopic diseases in Europe.
The relationships between the prevalences of wheezing by written or video questionnaire, of ever asthma, hay fever, rhinitis, and atopic eczema as reported by the International Study of Asthma and Allergies in Childhood (ISAAC), and the number of indoor chlorinated swimming pools per inhabitant in the studied centres were examined. Associations with geoclimatic variables, the gross domestic product (GDP) per capita, and several other lifestyle indicators were also evaluated.
Among children aged 13–14 years, the prevalence of wheezing by written questionnaire, of wheezing by video questionnaire, and of ever asthma across Europe increased respectively by 3.39% (95% CI 1.96 to 4.81), 0.96% (95% CI 0.28 to 1.64), and 2.73% (95% CI 1.94 to 3.52), with an increase of one indoor chlorinated pool per 100 000 inhabitants. Similar increases were found when analysing separately centres in Western or Northern Europe and for ever asthma in Southern Europe. In children aged 6–7 years (33 centres), the prevalence of ever asthma also increased with swimming pool availability (1.47%; 95% CI 0.21 to 2.74). These consistent associations were not found with other atopic diseases and were independent of the influence of altitude, climate, and GDP per capita.
The prevalence of childhood asthma and availability of indoor swimming pools in Europe are linked through associations that are consistent with the hypothesis implicating pool chlorine in the rise of childhood asthma in industrialised countries.
childhood asthma; atopic diseases; hygiene hypothesis, chlorine, trichloramine, nitrogen trichloride, swimming pool
The International Study of Asthma and Allergies in Childhood (ISAAC) Phase One showed large worldwide variations in the prevalence of symptoms of asthma, rhinoconjunctivitis and eczema, up to 10 to 20 fold between countries. Ecological analyses were undertaken with ISAAC Phase One data to explore factors that may have contributed to these variations, and are summarised and reviewed here.
In ISAAC Phase One the prevalence of symptoms in the past 12 months of asthma, rhinoconjunctivitis and eczema were estimated from studies in 463,801 children aged 13 - 14 years in 155 centres in 56 countries, and in 257,800 children aged 6-7 years in 91 centres in 38 countries. Ecological analyses were undertaken between symptom prevalence and the following: Gross National Product per capita (GNP), food intake, immunisation rates, tuberculosis notifications, climatic factors, tobacco consumption, pollen, antibiotic sales, paracetamol sales, and outdoor air pollution.
Symptom prevalence of all three conditions was positively associated with GNP, trans fatty acids, paracetamol, and women smoking, and inversely associated with food of plant origin, pollen, immunisations, tuberculosis notifications, air pollution, and men smoking. The magnitude of these associations was small, but consistent in direction between conditions. There were mixed associations of climate and antibiotic sales with symptom prevalence.
The potential causality of these associations warrant further investigation. Factors which prevent the development of these conditions, or where there is an absence of a positive correlation at a population level may be as important from the policy viewpoint as a focus on the positive risk factors. Interventions based on small associations may have the potential for a large public health benefit.
This study was part of an international effort to evaluate the epidemiology of asthma and allergic diseases around the world. The aim was to assess the prevalence and severity of these disorders in Singapore schoolchildren. The international study of asthma and allergies in childhood (ISAAC) written questionnaire was administered to 6238 schoolchildren. The respondents were parents of a 6-7 year cohort (n = 2030), and schoolchildren aged 12-15 years (n = 4208). The overall cumulative and 12 month prevalence of wheezing were 22% and 12%, respectively. The prevalence of doctor diagnosed asthma was 20%. Rhinitis was reported by 44% and chronic rashes by 12%. Multiple logistic regression analysis showed that a higher prevalence of wheezing and rhinitis was associated with males, and subjects of higher socioeconomic status (based on type of housing and total family income). More severe asthma related symptoms were present in Malays and Indians than in the Chinese. Allergic disorders are common in Singapore and prevalence is comparable to some populations in the West. Demographic and socioeconomic factors appear to influence the prevalence and severity of these disorders.
Childhood asthma is a major concern because it leads to more hospital visits and a heavy economic burden. Proper management and prevention strategies for childhood asthma must be based on correct evaluation of prevalence and risk factors for its development. In Korea, nationwide studies were conducted in 1995 and 2000 on students from 68 elementary schools (age, 6-12 years) and junior high schools (age, 12-15 years) by the Korean Academy of Pediatric Allergy and Respiratory Diseases. We used the Korean version of the International Study of Asthma and Allergies in Childhood (ISAAC) written and video questionnaires at the same schools during the same period (October-November). The prevalence of asthma in junior high school children seemed to increase over 5 years. However, in elementary school children, the prevalence of asthma symptoms decreased, although the prevalence of 'diagnosis of asthma, ever' and 'treatment of asthma, last 12 months' increased. In addition, it was found that various factors, such as obesity, passive smoking, dietary habits, raising pets at home, and fever/antibiotic use during infancy were associated with childhood asthma. When prevalence of asthma in Korea was compared with that in different regions, the prevalence changes in the 6-7 years age group did not seem to be consistent between regions, whereas similar trends were observed among children aged 13-14 years. To conduct another epidemiological study to evaluate the time trend over time, a third nationwide survey is planned in 2010, and we anticipate ISAAC Phase 3 will explore recent changes in the prevalence of childhood asthma and assess its risk factors in Korean children. On the basis of accurate data on the current status of childhood asthma in 2010, we will be able to establish proper management strategies.
Asthma; child; Korea
Studies on the associations between smoking and allergic diseases have mostly focused on asthma. Epidemiological studies in adults on the effects of smoking on allergic diseases other than asthma, such as eczema and rhinoconjunctivitis, have been limited, and the information that is available has been inconsistent. The aim of this study was to investigate the association between smoking status and environmental tobacco smoke (ETS) exposure and the prevalence of allergic diseases.
Study subjects were 1743 pregnant Japanese women. The definitions of wheeze and asthma were based on criteria from the European Community Respiratory Health Survey whereas those of eczema and rhinoconjunctivitis were based on criteria from the International Study of Asthma and Allergies in Childhood. Adjustment was made for age; region of residence; family history of asthma, atopic eczema, and allergic rhinitis; household income; and education.
Compared with never smoking, current smoking and ≥ 4 pack-years of smoking were independently positively associated with the prevalence of wheeze. There were no associations between smoking status and the prevalence of asthma, eczema, or rhinoconjunctivitis. When subjects who had never smoked were classified into four categories based on the source of ETS exposure (never, only at home, only at work, and both), exposure occurring both at home and at work was independently associated with an increased prevalence of two outcomes: wheeze and rhinoconjunctivitis. No relationships were observed between exposure to ETS and the prevalence of asthma or eczema.
Our results provide evidence that current smoking and ETS exposure may increase the likelihood of wheeze. The possibility of a positive association between ETS exposure and rhinoconjunctivitis was also suggested.
Asthma; Cross-sectional studies; Eczema; Environmental tobacco smoke; Smoking; Wheeze; Rhinoconjunctivitis
Phase I of the International Study of Asthma and Allergies in Childhood (ISAAC) was designed to allow worldwide comparisons of the prevalence of asthma symptoms. In phase III the phase I survey was repeated in order to assess changes over time.
The phase I survey was repeated after an interval of 5–10 years in 106 centres in 56 countries in children aged 13–14 years (n = 304 679) and in 66 centres in 37 countries in children aged 6–7 years (n = 193 404).
The mean symptom prevalence of current wheeze in the last 12 months changed slightly from 13.2% to 13.7% in the 13–14 year age group (mean increase of 0.06% per year) and from 11.1% to 11.6% in the 6–7 year age group (mean increase of 0.13% per year). There was also little change in the mean symptom prevalence of severe asthma or the symptom prevalence measured with the asthma video questionnaire. However, the time trends in asthma symptom prevalence showed different regional patterns. In Western Europe, current wheeze decreased by 0.07% per year in children aged 13–14 years but increased by 0.20% per year in children aged 6–7 years. The corresponding findings per year for the other regions in children aged 13–14 years and 6–7 years, respectively, were: Oceania (−0.39% and −0.21%); Latin America (+0.32% and +0.07%); Northern and Eastern Europe (+0.26% and +0.05%); Africa (+0.16% and +0.10%); North America (+0.12% and +0.32%); Eastern Mediterranean (−0.10% and +0.79%); Asia‐Pacific (+0.07% and −0.06%); and the Indian subcontinent (+0.02% and +0.06%). There was a particularly marked reduction in current asthma symptom prevalence in English language countries (−0.51% and −0.09%). Similar patterns were observed for symptoms of severe asthma. However, the percentage of children reported to have had asthma at some time in their lives increased by 0.28% per year in the 13–14 year age group and by 0.18% per year in the 6–7 year age group.
These findings indicate that international differences in asthma symptom prevalence have reduced, particularly in the 13–14 year age group, with decreases in prevalence in English speaking countries and Western Europe and increases in prevalence in regions where prevalence was previously low. Although there was little change in the overall prevalence of current wheeze, the percentage of children reported to have had asthma increased significantly, possibly reflecting greater awareness of this condition and/or changes in diagnostic practice. The increases in asthma symptom prevalence in Africa, Latin America and parts of Asia indicate that the global burden of asthma is continuing to rise, but the global prevalence differences are lessening.
Tobacco smoke and genetic susceptibility are risk factors for asthma and wheezing. The aim of this study was to investigate whether there is a combined effect of interleukin-13 gene (IL13) polymorphisms and tobacco smoke on persistent childhood wheezing and asthma.
In the Isle of Wight birth cohort (UK, 1989–1999), five IL13 single nucleotide polymorphisms (SNPs): rs1800925 (-1112C/T), rs2066960, rs1295686, rs20541 (R130Q) and rs1295685 were genotyped. Parents were asked whether their children had wheezed in the last 12 months at ages 1, 2, 4 and 10 years. Children who reported wheeze in the first 4 years of life and also had wheezing at age 10 were classified as early-onset persistent wheeze phenotype; non-wheezers never wheezed up to age 10. Persistent asthma was defined as having a diagnosis of asthma both during the first four years of life and at age 10. Logistic regression methods were used to analyze data on 791 children with complete information. Potential confounders were gender, birth weight, duration of breast feeding, and household cat or dog present during pregnancy.
Maternal smoking during pregnancy was associated with early-onset persistent wheeze (OR 2.93, p < 0.0001); polymorphisms in IL13 were not (OR 1.15, p = 0.60 for the common haplotype pair). However, the effect of maternal smoking during pregnancy was stronger in children with the common IL13 haplotype pair compared to those without it (OR 5.58 and OR 1.29, respectively; p for interaction = 0.014). Single SNP analysis revealed a similar statistical significance for rs20541 (p for interaction = 0.02). Comparable results were observed for persistent childhood asthma (p for interaction = 0.03).
This is the first report that shows a combined effect of in utero exposure to smoking and IL13 on asthma phenotypes in childhood. The results emphasize that genetic studies need to take environmental exposures into account, since they may explain contradictory findings.
The reduction in asthma symptoms and bronchial hyperresponsiveness in adolescence is not well understood. Nor can the differences in asthma prevalence and severity between the sexes, which reverse at puberty, be explained. It has been suggested that the improvement in asthma during adolescence may result from diminished clinical and immunological responsiveness directly related to hormonal changes and that the effect of age on the prevalence of asthma in each sex may relate to differences in hormonal status, potentially influencing airway size, inflammation, and smooth muscle and vascular functions. However, few comprehensive studies are available. In summary, all wheezing is not asthma. Non-asthmatic wheezing illnesses may in part be attributable to anatomical abnormalities of the lung (transient early wheezing, premature birth). Little is known about the genetic and environmental determinants of childhood asthma, and factors related to the development of atopic sensitisation, such as exposure to allergens, infectious diseases, or tobacco smoke early in life, and dietary habits may be important, whereas the relevance of air pollution remains to be established. Unfortunately, we still do not know how to prevent the manifestation of childhood asthma.
While rural living protects from asthma and allergies in many countries, results are conflicting in Latin America. We studied the prevalence of asthma and asthma symptoms in children from urban, semiurban, and rural sectors in south Chile. A cross-sectional questionnaire study was conducted in semiurban and rural sectors in the province of Valdivia (n = 559) using the ISAAC (International Study of Asthma and Allergies in Childhood) questionnaire. Results were compared to prevalence in urban Valdivia (n = 3105) by using data from ISAAC III study. Odds ratios (+95% confidence intervals) were calculated. No statistical significant differences were found for asthma ever and eczema symptoms stratified by residential sector, but a gradient could be shown for current asthma and rhinoconjunctivitis symptoms with urban living having highest and rural living having lowest prevalence. Rural living was inversely associated in a statistical significant way with current asthma (OR: 0.4; 95% CI: 0.2–0.9) and rhinoconjunctivitis symptoms (OR: 0.3; 95% CI: 0.2–0.7) in logistic regression analyses. Rural living seems to protect from asthma and respiratory allergies also in Chile, a South American country facing epidemiological transition. These data would be improved by clinical studies of allergic symptoms observed in studied sectors.
Allergic disease and its comorbidities significantly influence the quality of life. Although the comorbidities of allergic diseases are well described in adult populations, little is known about them in preschool children. In the present study, we aimed to assess the prevalence and comorbidity of allergic diseases in Korean preschool children.
We conducted a cross-sectional study comprising 615 Korean children (age, 3 to 6 years). Symptoms of allergic diseases were assessed using the Korean version of the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire that was modified for preschool children. Comorbidities of allergic diseases were assessed by 'In the last 12 months, has your child had symptoms?'.
The prevalence of symptoms of asthma, allergic rhinitis, and atopic dermatitis as recorded using the ISAAC questionnaire, within the last 12 months was 13.8%, 40.7%, and 20.8%, respectively. The symptom rates of allergic conjunctivitis, food allergy, and drug allergy were 14.8%, 10.4%, and 0.8%, respectively. The prevalence of allergic rhinitis in children with asthma was 64.3% and that of asthma in children with allergic rhinitis was 21.6%. The prevalence of rhinitis in children with conjunctivitis was 64.8% and that of conjunctivitis in children with rhinitis was 23.6%.
The prevalence of current rhinitis in our preschool children is shown to be higher than that previously reported. Allergic conjunctivitis is closely associated with asthma and allergic rhinitis. However, further studies are warranted to determine the prevalence and effects of these comorbidities on health outcomes in preschool children.
Asthma; Allergic rhinitis; Preschool child; Prevalence; Comorbidity
the prevalence of atopic symptoms in children throughout the UK.
survey of 12-14 year olds throughout England, Wales, Scotland, and the
Scottish Islands using the international study of asthma and allergies
in childhood (ISAAC) protocol.
of 27 507 (86%) children took part. Recent rhinoconjunctivitis was
reported by 18.2%, with 6.2% reporting symptoms between March and
September; 16.4% reported itchy flexural rash in the past 12 months.
The prevalence of atopic symptoms was higher in girls and subjects
born within the UK. The prevalence of severe wheeze was highest in
subjects reporting perennial rhinoconjunctivitis, as opposed to
summertime only symptoms. Winter rhinoconjunctivitis was associated
with severe wheeze and severe flexural rash. One or more current
symptoms were reported by 47.6% of all children and 4% reported all
geographical variations were small but the prevalence of symptoms was
significantly higher in Scotland and northern England. The study
demonstrates the importance of atopic diseases both in their own right
and in association with asthma.
To validate the prevalence rate of symptoms of asthma produced by the phase I ISAAC (International Study of Asthma and Allergies in Childhood) study, hypertonic saline challenge test was carried out during the phase II study at a year after the phase I study. For the phase II study, six middle schools from three cities in the phase I study were selected. Finally, 499 children who responded to both studies were analyzed. All subjects were asked to complete the written questionnaire (WQ) first, followed by a video questionnaire (AVQ 3.0) during the phase I study. Of the 499 children, only 19 (3.8%) were positive to the hypertonic saline bronchial challenge test. The degree of agreement between responses to the two corresponding questions "wheezing at rest" and "nocturnal wheeze" in the AVQ 3.0 and WQ were moderate and weak with a Kappa indices of 0.45 and 0.23, respectively. The question on "severe wheeze" in the AVQ 3.0 had the highest Youden's index among the five questions related to asthma symptoms in the previous 12 months, but its specificity was low whereas its sensitivity was 1.0. There was no consistency of priority between the two questionnaires in predicting bronchial hyperreactivity in a group of Korean schoolchildren. Therefore we need to develop more appropriate WQ or AVQ to compare the prevalences of asthma to other countries.
Using the international study of asthma and allergies in
childhood (ISAAC) questionnaire, 3000 children aged 6-7 years from various schools in the north east of England were studied. In this
population, the lifetime prevalence rates of various symptoms and
diagnoses were: wheezing, 29.6%; atopic eczema, 27.8%; rhinitis, 23.1%; and self reported asthma, 22.7%. Rhinitis was reported by 44%
and 40% of boys and girls with asthma, respectively. Atopic eczema was
reported by 46% of both boys and girls with asthma. The prevalence
rates of reported asthma, and of symptoms suggestive of asthma, were
higher than those reported from studies conducted on UK children in 1992.