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1.  Prevalence and co-occurrence of parentally reported possible asthma and allergic manifestations in pre-school children 
BMC Public Health  2013;13:764.
The aim of this study was to make an in-depth analysis of the prevalence and co-occurrence in pre-school children of possible asthma and atopic manifestations.
In Sweden 74%-84% of preschool children, depending on age, attend municipality organised day-care centres. Parents of 5,886 children 1–6 years of age, sampled from day-care centres in 62 municipalities all over Sweden, responded to a postal questionnaire regarding symptoms indicating prevalent possible asthma, allergic rhinitis, eczema, and food, furred pet and pollen allergy and other data in their children. Possible asthma was defined as any of the four criteria wheezing four times or more during the last year, physician diagnosis and current wheezing, ever had asthma and current wheezing, and current use of inhalation steroids, all based on questionnaire responses.
The overall prevalence of possible asthma was 8.9%, of eczema 21.7%, of rhinitis 8.1%, and of food allergy 6.6%. There was a highly significant co-occurrence between possible asthma and all atopic manifestations, 35.7% having any of the manifestations. Presence of pet allergy was the manifestation showing the closest co-occurrence with presence of possible asthma, presence of pollen allergy with presence of rhinitis, and presence of food allergy with presence of eczema. Assessed from plots of age-specific prevalence of possible asthma, rhinitis, eczema and food allergy, the prevalence of all manifestations increased from one to three years of age and then decreased, except for rhinitis where the prevalence increased until six years of age, indicating no specific ordered sequence.
Parentally reported possible asthma, eczema and food allergy had a curvilinear prevalence course across age with a maximum at age 3, while rhinitis prevalence increased consistently with age. Co-occurrence between possible asthma and atopic manifestations was common, and some combinations were more common than others, but there was no evidence of a specific ordered onset sequence.
PMCID: PMC3765705  PMID: 23953349
2.  Risk factors for non-atopic asthma/wheeze in children and adolescents: a systematic review 
The study of non-atopic asthma/wheeze in children separately from atopic asthma is relatively recent. Studies have focused on single risk factors and had inconsistent findings.
To review evidence on factors associated with non-atopic asthma/wheeze in children and adolescents.
A review of studies of risk factors for non-atopic asthma/wheeze which had a non-asthmatic comparison group, and assessed atopy by skin-prick test or allergen-specific IgE.
Studies of non-atopic asthma/wheeze used a wide diversity of definitions of asthma/wheeze, comparison groups and methods to assess atopy. Among 30 risk factors evaluated in the 43 studies only 3 (family history of asthma/rhinitis/eczema, dampness/mold in the household, and lower respiratory tract infections in childhood) showed consistent associations with non-atopic asthma/wheeze. No or limited period of breastfeeding was less consistently associated with non-atopic asthma/wheeze. The few studies examining the effects of overweight/obesity and psychological/social factors showed consistent associations. We used a novel graphical presentation of different risk factors for non-atopic asthma/wheeze, allowing a more complete perception of the complex pattern of effects.
More research using standardized methodology is needed on the causes of non-atopic asthma.
PMCID: PMC4068161  PMID: 24963333
Non-atopic asthma; Non-atopic wheeze; Risk factors; Mould; Respiratory infections
3.  530 Atopic Phenotype in Children under 6 Years with Persistent Wheezing in El Salvador 
Asthma is the most common chronic disease of childhood and the leading cause of childhood morbidity1. Even if an early intervention could improve their symptoms, the diagnosis of asthma in the first years of age is difficult. This study is the first effort to describe the atopic profile and the risk of developing asthma in a group of children from El Salvador with recurrent wheezing.
A questionnaire was designed for parents to determine the atopic background, while skin tests were performed in children. We used the modified Asthma Predictive Index (APIm)2 to assess the risk of developing asthma.
65 children under 6 years were evaluated, with an average age of 3.5 years. The average age of onset of wheezing was at 11 months of age. Family history of asthma, chronic rhinitis and eczema were presented respectively at 25%, 19% and 8% of the population. 42% of our population presents allergic rhinitis and 37% eczema. Among the factors related to wheezing risk, we found that one third of the population was born via caesarean section with a breastfeeding average of 3.76 months; also we found the presence of pets in 26% of households, a passive smoking and exposure to wood smoke in 17% and 35% of the studied population respectively. 23 children were sensitized to respiratory allergens. Dust mites were found in 73% of children sensitized. The APIm was positive in 66% of the population.
This is the first cohort of children described under 6 years with recurrent wheezing in El Salvador. We found an early presentation of wheezing, caused not only by viral conditions. These children had strong personal and family atopic background with a high rate of sensitization to respiratory allergens, especially dust mites. Most of the children studied are at risk of presenting asthma in later ages.
PMCID: PMC3512625
4.  Asthma in preschool children: prevalence and risk factors 
Thorax  2001;56(8):589-595.
BACKGROUND—The prevalence of asthma in children has increased in many countries over recent years. To plan effective interventions to reverse this trend we need a better understanding of the risk factors for asthma in early life. This study was undertaken to measure the prevalence of, and risk factors for, asthma in preschool children.
METHODS—Parents of children aged 3-5 years living in two cities (Lismore, n=383; Wagga Wagga, n=591) in New South Wales, Australia were surveyed by questionnaire to ascertain the presence of asthma and various proposed risk factors for asthma in their children. Recent asthma was defined as ever having been diagnosed with asthma and having cough or wheeze in the last 12 months and having used an asthma medication in the last 12 months. Atopy was measured by skin prick tests to six common allergens.
RESULTS—The prevalence of recent asthma was 22% in Lismore and 18% in Wagga Wagga. Factors which increased the risk of recent asthma were: atopy (odds ratio (OR) 2.35, 95% CI 1.49 to 3.72), having a parent with a history of asthma (OR 2.05, 95% CI 1.34 to 3.16), having had a serious respiratory infection in the first 2 years of life (OR 1.93, 95% CI 1.25 to 2.99), and a high dietary intake of polyunsaturated fats (OR 2.03, 95% CI 1.15 to 3.60). Breast feeding (OR 0.41, 95% CI 0.22 to 0.74) and having three or more older siblings (OR 0.16, 95% CI 0.04 to 0.71) decreased the risk of recent asthma.
CONCLUSIONS—Of the factors tested, those that have the greatest potential to be modified to reduce the risk of asthma are breast feeding and consumption of polyunsaturated fats.

PMCID: PMC1746115  PMID: 11462059
5.  Asthma and other wheezing disorders in children 
Clinical Evidence  2006;2006:0302.
Asthma is more common in children with a personal or family history of atopy, increased severity and frequency of wheezing episodes, and presence of variable airway obstruction or bronchial hyperresponsiveness. Precipitating factors for symptoms and acute episodes include infection, house dust mites, allergens from pet animals, exposure to tobacco smoke, and anxiety.
Methods and outcomes
We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of treatments for acute asthma in children? What are the effects of single-agent prophylaxis in children taking as-needed inhaled beta agonists for asthma? What are the effects of additional prophylactic treatments in childhood asthma inadequately controlled by standard-dose inhaled corticosteroids? What are the effects of treatments and of prophylactic treatments for acute wheezing in infants? We searched: Medline, Embase, The Cochrane Library and other important databases up to October 2005 (BMJ 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).
We found 84 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.
In this systematic review we present information relating to the effectiveness and safety of the following interventions: beta2 agonists (high-dose nebulised, long-acting [inhaled salmeterol], short-acting [oral salbutamol or by nebuliser, or metered-dose inhaler/spacer versus nebuliser]), corticosteroids (oral prednisolone, systemic, inhaled higher or lower doses [beclometasone]), ipratropium bromide (single or multiple dose inhaled), leukotriene receptor antagonists (oral montelukast), nedocromil (inhaled), oxygen, sodium cromoglycate (inhaled), or theophylline (oral or intravenous).
Key Points
Childhood asthma can be difficult to distinguish from viral wheeze and can affect up to 20% of children.
The consensus is that oxygen, high dose nebulised beta2 agonists and systemic corticosteroids should be used to treat an acute asthma attack. High dose beta2 agonists may be equally effective when given intermittently or continuously via a nebuliser, or from a metered dose inhaler using a spacer, in children with an acute asthma attack.Admission to hospital may be averted by adding ipratropium bromide to beta2 agonists, or by using high dose nebulised or oral corticosteroids.
Prophylactic inhaled corticosteroids improve symptoms and lung function in children with asthma. Their effect on final adult height is unclear. Inhaled nedocromil, inhaled long acting beta2 agonists, oral theophylline and oral leukotriene receptor antagonists are less effective than corticosteroids.Inhaled sodium cromoglycate does not seem to improve symptoms.
CAUTION: Monotherapy with long acting beta2 agonists reduces the frequency of asthma episodes, but may increase the chance of severe asthma episodes and death when those episodes occur. Intravenous theophylline may improve lung function in children with severe asthma, but can cause cardiac arrhythmias and convulsions.
We don't know whether adding higher doses of corticosteroids, long acting beta2 agonists, oral leukotriene receptor antagonists or oral theophylline to standard treatment improves symptoms or lung function in children with uncontrolled asthma.
In infants with acute wheeze, short acting beta2 agonists via a nebuliser or a spacer may improve symptoms, but we don't know whether high dose inhaled or oral corticosteroids or inhaled ipratropium bromide are beneficial.
Oral short acting beta2 agonists and inhaled high dose corticosteroids may prevent or improve wheeze in infants but can cause adverse effects. We don't know whether lower dose inhaled or oral corticosteroids, inhaled ipratropium bromide or inhaled short acting beta2 agonists improve wheezing episodes in infants.
PMCID: PMC2907635
6.  Poverty, dirt, infections and non-atopic wheezing in children from a Brazilian urban center 
Respiratory Research  2010;11(1):167.
The causation of asthma is poorly understood. Risk factors for atopic and non-atopic asthma may be different. This study aimed to analyze the associations between markers of poverty, dirt and infections and wheezing in atopic and non-atopic children.
1445 children were recruited from a population-based cohort in Salvador, Brazil. Wheezing was assessed using the ISAAC questionnaire and atopy defined as allergen-specific IgE ≥0.70 kU/L. Relevant social factors, environmental exposures and serological markers for childhood infections were investigated as risk factors using multivariate multinomial logistic regression.
Common risk factors for wheezing in atopic and non-atopic children, respectively, were parental asthma and respiratory infection in early childhood. No other factor was associated with wheezing in atopic children. Factors associated with wheezing in non-atopics were low maternal educational level (OR 1.49, 95% CI 0.98-2.38), low frequency of room cleaning (OR 2.49, 95% CI 1.27-4.90), presence of rodents in the house (OR 1.48, 95% CI 1.06-2.09), and day care attendance (OR 1.52, 95% CI 1.01-2.29).
Non-atopic wheezing was associated with risk factors indicative of poverty, dirt and infections. Further research is required to more precisely define the mediating exposures and the mechanisms by which they may cause non-atopic wheeze.
PMCID: PMC3002921  PMID: 21122116
7.  Asthma and other recurrent wheezing disorders in children (chronic) 
Clinical Evidence  2012;2012:0302.
Childhood asthma is the most common chronic paediatric illness. There is no cure for asthma but good treatment to palliate symptoms is available. Asthma is more common in children with a personal or family history of atopy, increased severity and frequency of wheezing episodes, and presence of variable airway obstruction or bronchial hyperresponsiveness. Precipitating factors for symptoms and acute episodes include infection, house dust mites, allergens from pet animals, exposure to tobacco smoke, and exercise.
Methods and outcomes
We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of single-agent prophylaxis in children taking as-needed inhaled beta2 agonists for asthma? What are the effects of additional prophylactic treatments in childhood asthma inadequately controlled by standard-dose inhaled corticosteroids? 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).
We found 48 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.
In this systematic review we present information relating to the effectiveness and safety of the following interventions: beta2 agonists (long-acting), corticosteroids (inhaled standard or higher doses), leukotriene receptor antagonists (oral), omalizumab, and theophylline (oral).
Key Points
Childhood asthma can be difficult to distinguish from viral wheeze and can affect up to 20% of children.
Regular monotherapy with inhaled corticosteroids improves symptoms, reduces exacerbations, and improves physiological outcomes in children with asthma symptoms requiring regular short-acting beta2 agonist treatment. Their effect on final adult height is minimal and when prescribed within recommended doses have an excellent safety record. Regular monotherapy with other treatments is not superior to low-dose inhaled corticosteroids.
Leukotriene receptor antagonists may have a role as first-line prophylaxis in very young children.
There is consensus that long-acting beta2 agonists should not be used for first-line prophylaxis. CAUTION: Monotherapy with long-acting beta2 agonists does not reduce asthma exacerbations but may increase the chance of severe asthma episodes.
Theophylline was used as first-line prevention before the introduction of inhaled corticosteroids. Although there is weak evidence that theophylline is superior to placebo, theophylline should no longer be used as first-line prophylaxis in childhood asthma because of clear evidence of the efficacy and safety of inhaled corticosteroids. Theophylline has serious adverse effects (cardiac arrhythmia, convulsions) if therapeutic blood concentrations are exceeded.
When low-dose inhaled corticosteroids fail to control asthma, most older children will respond to one of the add-on options available, which include addition of long-acting beta2 agonists, addition of leukotriene receptor antagonists, addition of theophylline, or increased dose of inhaled corticosteroid. However, we don't know for certain how effective these additional treatments are because we found no/limited RCT evidence of benefit compared with adding placebo/no additional treatments. Addition of long-acting beta2 agonists may reduce symptoms and improve physiological measures compared with increased dose of corticosteroids in older children. Long-acting beta2 agonists are not currently licensed for use in children under 5 years of age.Consensus suggests that younger children are likely to benefit from addition of leukotriene receptor antagonists. Although there is weak evidence that addition of theophylline to inhaled corticosteroids does improve symptom control and reduce exacerbations, theophylline should only be added to inhaled corticosteroids in children aged over 5 years when the addition of long-acting beta2 agonists and leukotriene receptor antagonists have both been unsuccessful.
Omalizumab may be indicated in the secondary care setting for older children (aged over 5 years) with poorly controlled allergic asthma despite use of intermediate- and high-dose inhaled corticosteroids once the diagnosis is confirmed and compliance and psychological issues are addressed. However, we need more data to draw firm conclusions.
PMCID: PMC3285219  PMID: 22305975
8.  524 Reccurent Wheezing in Childhood—Is It Always Asthma? 
Clinical presentation of the bronchial obstruction in children is most often highly suggestive of bronchiolitis, recurrent wheezing or asthma.
We present the cases of 2 patients diagnosed with recurrent bronchiolitis and asthma, non-responsive to treatment.
The first patient, a 9-year-old boy presented wheezing, non-productive cough, dyspnea, aquous rhinorrhea, sneezing and nasal itching interpreted as allergic asthma associated to allergic rhinitis as he was sensitized to house-dust mites and dog. A treatment with inhaled corticosteroids and antihistamine was prescribed with little improvement of asthma symptoms. Six months later the patient presented for vomiting and productive cough. Thoracic ultrasound suggested achalasia, diagnosis confirmed through esophageal manometry and barium swallow. Surgical treatment led to resolution of asthma-like symptoms with persistence of a mild intermittent rhinitis. In the second case, a female patient presented 2 episodes of uncomplicated bronchiolitis during the 6th and the 7th month of life and a 3rd episode of bronchiolitis complicated with pneumonia during the 8th month of life. When admitted for the 3rd episode, she presented an oxygen saturation of 91% in ambient air. Thoracic ultrasounds oriented the diagnosis towards a diaphragmatic hernia, confirmed through barium swallow and barium enema. The surgical treatment of the hernia determined the resolution of respiratory symptoms. Unfavourable clinical course, despite correct treatment in both cases required additional investigations which finally led to the correct diagnosis and treatment.
For the differential diagnosis of non-responsive bronchial obstruction in children, one must think to digestive diseases. Ultrasound was the elective non-invasive method in diagnosing our cases.
PMCID: PMC3513002
9.  Diet and childhood asthma in a society in transition: a study in urban and rural Saudi Arabia 
Thorax  2000;55(9):775-779.
BACKGROUND—The causes 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.
RESULTS—In univariate 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.
CONCLUSIONS—This study 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.

PMCID: PMC1745853  PMID: 10950897
10.  Effects of active tobacco smoking on the prevalence of asthma-like symptoms in adolescents 
The prevalence of asthma in adolescents markedly varies between different localities as found by the International Study of Asthma and Allergies in Childhood (ISAAC) and this may be due to environmental factors. Although tobacco smoke exposure is related to an increase in the prevalence of asthma, there is lack of information on that respect in children from developing countries, where active tobacco smoking usually starts early in adolescence. This study was undertaken to assess the effect of tobacco smoking on the prevalence of asthma symptoms in a random sample of 4738 adolescents aged 13.4 ± 1.05 years who responded the ISAAC video questionnaires plus questions on tobacco smoking. The prevalence of tobacco smoking in the last 12 months was 16.2%, with significant female predominance. The persistent smokers had a significantly higher prevalence of asthma-like symptoms ever and in the last 12 months (wheezing, wheezing with exercise, nocturnal wheezing, severe wheezing, and dry nocturnal cough) than ex-smokers and nonsmokers. More than 27% of asthma symptoms in our adolescents are attributable to active tobacco consumption (population attributable risk). This study strongly suggests that potent and more effective campaigns against tobacco smoking should be implemented in developing countries, where active tobacco smoking is dramatically increasing in children.
PMCID: PMC2692110  PMID: 18044067
asthma; prevalence; ISAAC; tobacco; video questionnaires
11.  International patterns of tuberculosis and the prevalence of symptoms of asthma, rhinitis, and eczema 
Thorax  2000;55(6):449-453.
BACKGROUND—An 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.
METHODS—Tuberculosis 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.
RESULTS—Tuberculosis 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.
CONCLUSIONS—These findings are consistent with recent experimental evidence which suggests that exposure to Mycobacterium tuberculosis may reduce the risk of developing asthma.

PMCID: PMC1745787  PMID: 10817790
12.  Asthma and atopy in overweight children 
Thorax  2003;58(12):1031-1035.
Background: Obesity may be associated with an increase in asthma and atopy in children. If so, the effect could be due to an effect of obesity on lung volume and thus airway hyperresponsiveness.
Methods: Data from 5993 caucasian children aged 7–12 years from seven epidemiological studies performed in NSW were analysed. Subjects were included if data were available for height, weight, age, skin prick test results to a common panel of aeroallergens, and a measure of airway responsiveness. History of doctor diagnosed asthma, wheeze, cough, and medication use was obtained by questionnaire. Recent asthma was defined as a doctor diagnosis of asthma ever and wheeze in the last 12 months. Body mass index (BMI) percentiles, divided into quintiles per year age, were used as a measure of standardised weight. Dose response ratio (DRR) was used as a measure of airway responsiveness. Airway hyperresponsiveness was defined as a DRR of ⩾8.1. Adjusted odds ratios were obtained by logistic regression.
Results: After adjusting for atopy, sex, age, smoking and family history, BMI was a significant risk factor for wheeze ever (OR = 1.06, p = 0.007) and cough (OR = 1.08, p = 0.001), but not for recent asthma (OR = 1.02, p = 0.43) or airway hyperresponsiveness (OR = 0.97 p = 0.17). In girls a higher BMI was significantly associated with higher prevalence of atopy (χ2 trend 7.9, p = 0.005), wheeze ever (χ2 trend 10.4, p = 0.001), and cough (χ2 trend 12.3, p<0.001). These were not significant in boys.
Conclusions: Higher BMI is a risk factor for atopy, wheeze ever, and cough in girls only. Higher BMI is not a risk factor for asthma or airway hyperresponsiveness in either boys or girls.
PMCID: PMC1746556  PMID: 14645967
13.  Prevalence of asthma and risk factors for asthma-like symptoms in Aboriginal and non-Aboriginal children in the northern territories of Canada 
Few studies have investigated the prevalence and risk factors of asthma in Canadian Aboriginal children.
To determine the prevalence of asthma and asthma-like symptoms, as well as the risk factors for asthma-like symptoms, in Aboriginal and non-Aboriginal children living in the northern territories of Canada.
Data on 2404 children, aged between 0 and 11 years, who participated in the North component of the National Longitudinal Survey of Children and Youth were used in the present study. A child was considered to have an asthma-like symptom if there was a report of ever having had asthma, asthma attacks or wheeze in the past 12 months.
After excluding 59 children with missing information about race, 1399 children (59.7%) were of Aboriginal ancestry. The prevalence of asthma was significantly lower (P<0.05) in Aboriginal children (5.7%) than non-Aboriginal children (10.0%), while the prevalence of wheeze was similar between Aboriginal (15.0%) and non-Aboriginal (14.5%) children. In Aboriginal children, infants and toddlers had a significantly greater prevalence of asthma-like symptoms (30.0%) than preschool-aged children (21.5%) and school-aged children (11.5%). Childhood allergy and a mother’s daily smoking habit were significant risk factors for asthma-like symptoms in both Aboriginal and non-Aboriginal children. In addition, infants and toddlers were at increased risk of asthma-like symptoms in Aboriginal children. In analyses restricted to specific outcomes, a mother’s daily smoking habit was a significant risk factor for current wheeze in Aboriginal children and for ever having had asthma in non-Aboriginal children.
Asthma prevalence appears to be lower in Aboriginal children than in non-Aboriginal children. The association between daily maternal smoking and asthma-like symptoms, which has been mainly reported for children living in urban areas, was observed in Aboriginal and non-Aboriginal children living in northern and remote communities in Canada.
PMCID: PMC2677938  PMID: 18437256
Aboriginals; Asthma; Children; Remote area; Risk factors; Smoking
14.  Toxocara Seropositivity, Atopy and Wheezing in Children Living in Poor Neighbourhoods in Urban Latin American 
Toxocara canis and T. cati are parasites of dogs and cats, respectively, that infect humans and cause human toxocariasis. Infection may cause asthma-like symptoms but is often asymptomatic and is associated with a marked eosinophilia. Previous epidemiological studies indicate that T. canis infection may be associated with the development of atopy and asthma.
To investigate possible associations between Toxocara spp. seropositivity and atopy and childhood wheezing in a population of children living in non-affluent areas of a large Latin American city.
The study was conducted in the city of Salvador, Brazil. Data on wheezing symptoms were collected by questionnaire, and atopy was measured by the presence of aeroallergen-specific IgE (sIgE). Skin prick test (SPT), total IgE and peripheral eosinophilia were measured. Toxocara seropositivity was determined by the presence of anti-Toxocara IgG antibodies, and intestinal helminth infections were determined by stool microscopy.
Children aged 4 to 11 years were studied, of whom 47% were seropositive for anti-Toxocara IgG; eosinophilia >4% occurred in 74.2% and >10% in 25.4%; 59.6% had elevated levels of total IgE; 36.8% had sIgE≥0.70 kU/L and 30.4% had SPT for at least one aeroallergen; 22.4% had current wheezing symptoms. Anti-Toxocara IgG was positively associated with elevated eosinophils counts, total IgE and the presence of specific IgE to aeroallergens but was inversely associated with skin prick test reactivity.
The prevalence of Toxocara seropositivity was high in the studied population of children living in conditions of poverty in urban Brazil. Toxocara infection, although associated with total IgE, sIgE and eosinophilia, may prevent the development of skin hypersensitivity to aeroallergens, possibly through increased polyclonal IgE and the induction of a modified Th2 immune reaction.
Author Summary
Toxocara canis and T. cati are roundworms found in dogs and cats, respectively, that can also infect humans and cause several clinical features, including asthma-like symptoms. Human infections with T. canis have been associated with an increased prevalence of atopy and asthma. In the present study, we investigated the associations between Toxocara seropositivity with eosinophilia, total IgE, specific IgE and skin prick test reactivity to aeroallergens, as well as atopic and non-atopic wheezing. Toxocara seropositivity was associated with elevated eosinophil counts and total and aeroallergen-specific IgE but was also associated with a decreased prevalence of skin prick test. Toxocara seropositivity was not associated with atopic wheezing. In conclusion, our data show that human toxocariasis, although associated with eosinophilia and raised levels of total and allergen-specific IgE, may play a role in the modulation of allergic effector responses in the skin.
PMCID: PMC3486906  PMID: 23133689
15.  Prevalence and Severity of Asthma, Rhinitis, and Atopic Eczema in 13- to 14-Year-Old Schoolchildren from Southern Brazil 
The objective of this study was to investigate the prevalence and severity of asthma, rhinitis, and atopic eczema in schoolchildren from southern Brazil. A cross-sectional study was carried out with the International Study of Asthma and Allergies in Childhood phase III written questionnaire. The questionnaire was self-applied by 2,948 randomly selected schoolchildren aged 13 to 14 years. The lifetime prevalence rates of symptoms were as follows: wheezing, 40.8%; rhinitis, 40.7%; eczema, 13.6%; self-reported asthma, 14.6%; rhinitis, 31.4%; eczema, 13.4%. Rhinitis was reported by 55% of adolescents with current asthma (60% females vs 46.9% males). Girls 13 to 14 years of age had higher prevalence rates of asthma, rhinitis, and eczema than boys had. Atopic eczema was reported by 42.7% of girls and 31.4% of boys with asthma. The prevalence rates were statistically significant for symptoms of asthma, rhinitis, and atopic eczema in females. However, there were no statistically significant differences between the sexes in regard to reported asthma and bronchospasm induced by exercise.
PMCID: PMC3231648  PMID: 20529214
16.  Prevalence and severity of asthma, rhinitis, and atopic eczema: the north east study 
Archives of Disease in Childhood  1999;81(4):313-317.
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.

PMCID: PMC1718111  PMID: 10490435
17.  Swimming Pool Attendance, Asthma, Allergies, and Lung Function in the Avon Longitudinal Study of Parents and Children Cohort 
Rationale: Cross-sectional studies have reported inconsistent findings for the association between recreational swimming pool attendance and asthma and allergic diseases in childhood.
Objectives: To examine whether swimming in infancy and childhood was associated with asthma and allergic symptoms at age 7 and 10 years in a UK longitudinal population-based birth cohort, the Avon Longitudinal Study of Parents and Children.
Methods: Data on swimming were collected by questionnaire at 6, 18, 38, 42, 57, 65, and 81 months. Data on rhinitis, wheezing, asthma, eczema, hay fever, asthma medication, and potential confounders were collected through questionnaires at 7 and 10 years. Spirometry and skin prick testing were performed at 7 to 8 years. Data for analysis were available for 5,738 children.
Measurements and Main Results: At age 7 years, more than 50% of the children swam once per week or more. Swimming frequency did not increase the risk of any evaluated symptom, either overall or in atopic children. Children with a high versus low cumulative swimming pool attendance from birth to 7 years had an odds ratio of 0.88 (95% confidence interval, 0.56–1.38) and 0.50 (0.28–0.87), respectively, for ever and current asthma at 7 years, and a 0.20 (0.02–0.39) standard deviation increase in the forced midexpiratory flow. Children with asthma with a high versus low cumulative swimming had an odds ratio for current asthma at 10 years of 0.34 (0.14–0.80).
Conclusions: This first prospective longitudinal study suggests that swimming did not increase the risk of asthma or allergic symptoms in British children. Swimming was associated with increased lung function and lower risk of asthma symptoms, especially among children with preexisting respiratory conditions.
PMCID: PMC3081279  PMID: 20889905
Avon Longitudinal Study of Parents and Children; pediatric; epidemiology, prospective; irritants
18.  Wheeze, cough, atopy, and indoor environment in the Scottish Highlands 
Accepted 20 August 1996

A questionnaire which included items on wheeze, cough, eczema, hay fever, and indoor environment, including parental smoking habits, pet ownership, heating and cooking methods, home insulation, damp, mould, and years lived in their houses, was given to 1801children, aged 12 and 14 from the Highland Region in Scotland. Of the 1537 (85%) who replied, 267 (17%) reported current wheeze, 135 (9%) cough for three months in the year, 272 (18%) eczema, and 317 (21%) hay fever. There was no consistent relationship between respiratory symptoms and indoor environment although cough was associated with damp, double glazing, and maternal smoking. The prevalence of wheeze, cough, and atopy was higher in children who had lived in more than one house during their lifetime. These results suggest that increasing mobility of families in recent years may be more important in the aetiology of asthma than exposure to any one individual allergen or pollutant.

PMCID: PMC1717042  PMID: 9059155
19.  The introduction of solids in relation to asthma and eczema 
Archives of Disease in Childhood  2004;89(4):303-308.
Background: Despite scarce scientific evidence, current feeding guidelines recommend delayed introduction of solids for the prevention of asthma and allergy.
Aims: To explore whether late introduction of solids is protective against the development of asthma, eczema, and atopy.
Methods: A total of 642 children were recruited before birth and followed to the age of 5½ years. Main outcome measures were: doctor's diagnosis of eczema ever, atopy according to skin prick test results against inhalant allergens, preschool wheezing, transient wheezing, all defined at age 5–5½ years. Introduction of solids as main exposure measure was assessed retrospectively at age 1 year.
Results: There was no evidence for a protective effect of late introduction of solids for the development of preschool wheezing, transient wheezing, atopy, or eczema. On the contrary, there was a statistically significant increased risk of eczema in relation to late introduction of egg (aOR 1.6, 95% CI 1.1 to 2.4) and milk (aOR 1.7, 95% CI 1.1 to 2.5). Late introduction of egg was furthermore associated with a non-significant increased risk of preschool wheezing (aOR 1.5, 95% CI 0.92 to 2.4). There was no statistical evidence of feeding practices playing a different role in the development of asthma and eczema after stratification for parental asthma and atopy status.
Conclusions: Results do not support the recommendations given by present feeding guidelines stating that a delayed introduction of solids is protective against the development of asthma and allergy.
PMCID: PMC1719882  PMID: 15033835
20.  Prevalence of asthma in Portugal - The Portuguese National Asthma Survey 
Asthma is a frequent chronic respiratory disease in both children and adults. However, few data on asthma prevalence are available in Portugal. The Portuguese National Asthma Survey is the first nationwide study that uses standardized methods. We aimed to estimate the prevalence of current asthma in the Portuguese population and to assess the association between ‘Current asthma’ and comorbidities such as upper airways disease.
A cross-sectional, population-based, telephone interview survey including all municipalities of Portugal was undertaken. Participants were randomly selected to answer a questionnaire based on the Portuguese version of the GA2LEN survey. ‘Current asthma’ was defined as self-reported lifetime asthma and at least one of 3 symptoms in the last 12 months: wheezing, waking with breathlessness or having an asthma attack.
Data were obtained for 6 003 respondents, with mean age of 38.9 (95%CI 38.2-39.6) years and 57.3% females. In the Portuguese population, the prevalence of ‘Current asthma’ was 6.8% (95%CI 6.0-7.7) and of ‘Lifetime asthma’ was 10.5% (95%CI 9.5-11.6) Using GA2LEN definition for asthma, our prevalence estimate was 7.8% (95%CI 7.0-8.8). Rhinitis had a strong association with asthma (Adjusted OR 3.87, 95%CI 2.90-5.18) and the association between upper airway diseases and asthma was stronger in patients with both rhinitis and sinusitis (Adjusted OR 13.93, 95%CI 6.60-29.44).
Current asthma affects 695 000 Portuguese, with a prevalence of 6.8%. People who reported both rhinitis and sinusitis had the highest risk of having asthma.
PMCID: PMC3480869  PMID: 22931550
Asthma; Computer-assisted-telephone–interviewing (CATI); Epidemiology; Prevalence
21.  Home exposure to Arabian incense (bakhour) and asthma symptoms in children: a community survey in two regions in Oman 
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.
PMCID: PMC2693130  PMID: 19450289
22.  Ecological association between childhood asthma and availability of indoor chlorinated swimming pools in Europe 
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.
PMCID: PMC2092577  PMID: 16847033
childhood asthma; atopic diseases; hygiene hypothesis, chlorine, trichloramine, nitrogen trichloride, swimming pool
23.  Foetal Exposure to Maternal Passive Smoking Is Associated with Childhood Asthma, Allergic Rhinitis, and Eczema 
The Scientific World Journal  2012;2012:542983.
Objective. We examined the hypothesis that foetal exposure to maternal passive smoking is associated with childhood asthma, allergic rhinitis, and eczema. Methods. The study was a population-based cross-sectional survey of Hong Kong Chinese children aged ≤14 years carried out in 2005 to 2006. Results. Foetal exposure to maternal passive smoking was significantly associated with wheeze ever (OR 2.05; 95% CI 1.58–2.67), current wheeze (OR 2.06; 95% CI 1.48–2.86), allergic rhinitis ever (OR 1.22; 95% CI 1.09–1.37), and eczema ever (OR 1.61; 95% CI 1.38–1.87). Foetal exposure to maternal active smoking was significantly associated with asthma ever (OR 2.10; 95% CI 1.14–3.84), wheeze ever (OR 2.46; 95% CI 1.27–4.78), and current wheeze (OR 2.74; 95% CI 1.24–6.01) but not with allergic rhinitis ever (OR 1.01; 95% CI 0.70–1.46) or eczema ever (OR 1.38; 95% CI 0.87–2.18). The dose response relationship between wheeze ever and current wheeze with increasing exposure, from no exposure to maternal passive smoking and then to maternal active smoking, further supports causality. Conclusion. There is significant association between foetal exposure to maternal passive smoking and maternal active smoking with childhood asthma and related atopic illnesses. Further studies are warranted to explore the potential causal relationship.
PMCID: PMC3425811  PMID: 22927783
24.  Underdiagnosed and Undertreated Allergic Rhinitis in Urban School-Aged Children with Asthma 
Allergic rhinitis (AR) is a risk factor for the development of asthma, and if poorly controlled, it may exacerbate asthma. We sought to describe AR symptoms and treatment in a larger study about asthma, sleep, and school performance. We examined the proportion (1) who met criteria for AR in an urban sample of school children with persistent asthma symptoms, (2) whose caregivers stated that they were not told of their child's allergies, (3) who had AR but were not treated or were undertreated for the disease, as well as (4) caregivers and healthcare providers' perceptions of the child's allergy status compared with study assessment, and (5) associations between self-report of asthma and AR control over a 4-week monitoring period. One hundred sixty-six children with persistent asthma participated in a clinical evaluation of asthma and rhinitis, including allergy testing. Self-report of asthma control and rhinitis control using the Childhood Asthma Control Test (C-ACT) and Rhinitis Control Assessment Test (RCAT) were measured 1 month after the study clinic session. Persistent rhinitis symptoms were reported by 72% of participants; 54% of rhinitis symptoms were moderate in severity, though only 33% of the sample received adequate treatment. AR was newly diagnosed for 53% during the clinic evaluation. Only 15% reported using intranasal steroids. Participants with poorly controlled AR had poorer asthma control compared with those with well-controlled AR. This sample of urban school-aged children with persistent asthma had underdiagnosed and undertreated AR. Healthcare providers and caregivers in urban settings need additional education about the role of allergies in asthma, recognition of AR symptoms, and AR's essential function in the comanagement of asthma. Barriers to linkages with allergy specialists need to be identified.
PMCID: PMC4062104  PMID: 24963455
25.  561 Distribution of Asthma Mortality in Various Districts of Salvador, Brazil 
Brazil still does not have a national program to combat asthma. Isolated initiatives have been developed in a non-standardized fashion. The Program for Control of Asthma in Bahia (ProAR) was established in Salvador, Bahia, in 2003, aiming for the control of the most severe cases.
To analyze time trends in mortality from asthma and its distribution in the districts of Salvador (2000–2009) and to correlate mortality rates with social indicators.
Observational study of deaths from asthma registered by the National Database of Mortality according to ICD-10. Mortality rates were calculated per 100,000 inhabitants and analyzed by simple linear regression. The distribution of mortality for asthma in the period was mapped into the 12 health districts of Salvador. The correlation of the number of deaths in Salvador with GDP per capita, HDI and Index Gini was evaluated.
The average asthma mortality in Salvador between 2000 and 2009 was 1.542/100.000 inhabitants, with a declining trend (R2 = 0.539, b = –11.1, P = 0.016). Deaths occurred more frequently in women than men (66% vs 34%). Asthma mortality rates were higher in subjects > 35 years. There was a reduction at ages younger than 1 year, 5 to 14 years, 25 to 34 years, and 45 to 54 years with a sharp decline between 55 and 64 (–8.14/100,000). The mortality rate (19.68/100,000 inhabitants in 2009) was higher for individuals > 75 years. The highest mortality rates were noted in more populated and poorer areas with less infrastructure and access to health services. It was observed that 78% of the deaths occurred in hospitals or health facilities. Deaths rates for asthma correlated directly with the district Gini index (rho = 0.400, P = 0.505) and inversely with HDI (rho = –0.300, P = 0.624), though not statistically significant.
Asthma mortality in Salvador is concentrated in the poorest areas with less infrastructure and access to health services, most commonly affecting women and the elderly. There was a reduction in mortality during the study period, possibly related to interventions for asthma control in the municipality. Mortality from asthma behaves differently in each district of the city.
PMCID: PMC3513127

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