Worldwide variations in prevalence of symptoms of allergic rhinoconjunctivitis in children: the International Study of Asthma and Allergies in Childhood (ISAAC)

Rhinitis (allergic and nonallergic) in an atopic pediatric referral population in the grasslands of inland South Africa

BACKGROUND

Allergic rhinitis is a common condition, which causes considerable morbidity. South African data are scarce.

OBJECTIVE

We sought to describe allergic rhinitis in atopic children in inland South Africa.

METHODS

An observational, descriptive study of rhinitis occurring in 771 new patients seen consecutively by a single observer at a referral pediatric allergy clinic (Universitas Hospital, Bloemfontein) over an 8 1/2-year period (August 1984 to March 1993) was carried out. A detailed questionnaire was used to record clinical data. Chest and sinus x-rays, skin prick testing, and radioallergosorbent test were performed, and serum immunoglobulin E levels were determined. Response to drug treatment regimens was recorded at subsequent followup visits.

RESULTS

Significant rhinitis was reported in 78.1% of patients, and mild intermittent rhinitis was reported in 21.4%. Male to female ratio was 1.6:1. Median age at onset of rhinitis symptoms was 6 months (range 0 months to 12 years), with 30.1% experiencing symptoms from birth. Rhinitis was chronic in 61.3%, although 53.5% reported seasonal variation. More children with rhinitis were born in midsummer than during other seasons, although this did not reach statistical significance (P = 0.46). Breast-feeding had no protective effect, and parental smoking and household pets were not found to be risk factors. Family history was positive for allergic rhinitis in 88% of patients. Exposure to dust, weather changes, strong odors, pets, pollens, and tobacco smoke were the most common trigger factors. Sinus x-ray findings associated poorly with clinical findings. The most common allergens identified were grass pollen, tree pollen, and cat. Oral antihistamines provided good symptomatic relief in 62.9% of patients who used them. Intranasal corticosteroids provided good relief in 78.0% of those who used them, and ketotifen provided relief in 54.4% of those who used it.

CONCLUSIONS

Rhinitis is a common manifestation of allergy in the population studied. Onset occurs early in childhood. A family history of allergy is a risk factor for the development of the condition, and grass pollen is the most common allergen involved. Special investigations are of limited value. Appropriate treatment is very effective.

Epidemiological studies of the very high prevalence of asthma and related symptoms among school children in Costa Rica from 1989 to 1998

The aim of our study was to determine the prevalence of asthma and related respiratory symptoms in school children from Costa Rica during the last 10 years, from 1989 to 1998. Using nationally representative samples of school children from Costa Rica during the last 10 years we have performed three studies. Altogether 9,931 children were investigated. The age groups: study I, 5-17 years (n = 2,682), study II, 6-7 years (n = 2,944), 13-14 years (n = 3,200) and study III, 10 years (n = 1,105). The diagnostic criteria for asthma used in these studies was as follows: study I (1989), diagnosis by a doctor in combination with the presence of four kinds of respiratory symptoms; studies II (1995) and III (1998), history of wheeze in the past 12 months. The two latter were part of the International Study of Asthma and Allergies in Childhood (ISAAC). A very high prevalence of a history of wheezing was found in the three studies (46.8%, 42.9%, and 45.1%) as well as a diagnosis of asthma (23.4%, 27.7% and 27.1%). The physician's diagnosis of asthma reported in the first study (23%) increased from 23.1 in study II to 27.7% in study III (p = 0.004). This increment could be a real increase in asthma prevalence, or be due to a better awareness about asthma. In study II the group of 6-7-year-olds had respiratory symptoms significantly more often than 13-14-year-olds (p < 0.001). Boys more often had a history of wheezing (p = 0.001), wheeze during the previous 12 months (p = 0.01) and an asthma diagnosis at the age of 6-7 years (p = 0.002) than girls, but girls had more respiratory symptoms than boys at the age of 13-14 years (p < 0.005). Wheezing in the past 12 months was more common for those living in urban areas aged 6-7 years (p = 0.04), and there was an increase of wheeze after exercise (p = 0.01). For the 13-14-year-olds the risk of wheezing was higher during the previous 12 months if they lived in temperate areas (<20 degrees C) and at a high altitude (>1,000 m). Living in a rural area and in a warm region (>20 degrees C), increased the risk of dry cough during the previous 12 months in the group of 13-14-year-olds. In conclusion, Costa Rica is located in the tropics with a very high humidity, an enormous variety of flora and fauna and a very high prevalence of mite and cockroach allergens, which provide important risk factors that may explain the high prevalence of asthma and asthma-related symptoms. Further possible factors, such as the change towards a more Western life style, resulting in fewer infections and parasitic diseases in the first years of life and changes in bedding material, may also be unresolved. Increased environmental pollution may add to the very high prevalence of asthma and related respiratory symptoms. The very extensive exposure to mites and cockroaches in bed material and in homes with poor ventilation may be an important factor, but many asthmatic children behave as non atopic, with a viral respiratory infection as a major precipitating factor.

Montelukast for treating seasonal allergic rhinitis: a randomized, double-blind, placebo-controlled trial performed in the spring

BACKGROUND

Cysteinyl leukotrienes are important proinflammatory mediators believed to have a role in allergic rhinitis.

OBJECTIVE

This multicentre, randomized, double-blind, placebo- and active-controlled trial evaluated the effectiveness and tolerability of montelukast, a cysteinyl leukotriene receptor antagonist, for treating patients with seasonal allergic rhinitis.

METHODS

After a 3- to 5-day, single-blind placebo run-in period, 1302 male and female patients (aged 15-81 years) with active allergic rhinitis symptoms were randomly assigned to receive montelukast 10 mg (n = 348), loratadine 10 mg (n = 602), or placebo (n = 352) administered once daily at bedtime for 2 weeks during the spring allergy season.

RESULTS

Mean patient characteristics and symptom scores at baseline were similar for the three treatment groups. The primary end-point, daytime nasal symptoms score (mean of nasal congestion, rhinorrhea, nasal pruritus, and sneezing scores; 0-3 scale), improved from baseline during treatment by (least squares mean, 95% confidence interval) - 0.37 (- 0.43, - 0.31), - 0.47 (- 0.52, - 0.43), and - 0.24 (- 0.29, - 0.18) in the montelukast, loratadine, and placebo groups, respectively (P < or = 0.001 comparing each active treatment with placebo). Mean changes from baseline in all other diary-based scores, including night-time and eye symptom scores, were significantly greater for each active treatment than for placebo. The rhinoconjunctivitis quality of life overall score improved significantly with montelukast and with loratadine as compared with placebo. Montelukast and loratadine showed a safety profile comparable to that of placebo.

CONCLUSION

Montelukast is well tolerated and provides improvements in daytime and night-time symptoms, as well as quality of life parameters, for patients with seasonal allergic rhinitis.

The Chinese herbal formulation biminne in management of perennial allergic rhinitis: a randomized, double-blind, placebo-controlled, 12-week clinical trial

BACKGROUND

Herbal therapies have been widely used in allergic rhinitis (AR), but none have been shown to be effective in controlled scientific clinical trials.

OBJECTIVE

The aim of this study was to test the effects of the Chinese herbal formulation Biminne in patients with moderate to severe perennial AR.

METHODS

In a randomized, double-blind, placebo-controlled clinical trial, 58 patients were randomized to receive either Biminne capsules (n = 26) or placebo (n = 32) in doses of five capsules twice a day for 12 weeks. Main outcomes were measured by changes in symptom diaries, quality of life scores, patients' evaluations of improvement on visual analog scores, and physicians' overall evaluation. Total serum immunoglobulin E was measured in all patients without knowledge of which group they were in. After 1 year we performed a randomized, double-blind, dose-response study in 22 patients who had previously received placebo.

RESULTS

The trial outcomes evaluated by four instruments showed a statistically significant improvement in some of the symptoms of AR, whereas others exhibited a positive trend that did not reach statistical significance. Followup 1 year after completion of the trial suggested that benefit of the treatment persisted. A pilot dose-response study showed both half and full strengths were effective. Total serum immunoglobulin E was reduced after the herbal treatment.

CONCLUSIONS

Our results suggest the Biminne formulation is effective in treatment of perennial AR. Its mode of action is unknown.

Allergic conditions in 5-8-year-old Maltese schoolchildren: prevalence, severity, and associated risk factors [ISAAC]

Allergic conditions, especially asthma, seem to be increasingly common worldwide. The International Study of Asthma and Allergies in Childhood (ISAAC) was the first study carried out worldwide using standardized questionnaires in order to create a reliable global map of childhood allergy. The Maltese Islands were one of the centres that participated in this study and in this article the data obtained from 3,506 5-8-year-old children from 24 state schools (78.5% response rate), and also data obtained from some added 'local' questions addressed to the same children, were analyzed in order to evaluate the problem of allergic conditions in Maltese schoolchildren. Of the participants, 19.1% were wheezers 'ever,' while 8.8% were current wheezers. Of the latter, 15.9% experienced nocturnal wheezing at least once a week and 13.3% had a wheezing episode of sufficient severity to limit speech. Nasal problems were present in 23.4% of these children, and in 20.7% of all respondents these symptoms persisted up to the year of answering the questionnaire. Hay fever had been diagnosed in 14.7% of all the children. Seven per cent of respondents had a recurrent, itchy rash (suggestive of eczema) for at least 6 months of their lives and 5.5.% had it currently. The prevalence of wheezing and eczema were slightly lower than the global mean, unlike rhinitis which in Malta was commoner than the world average. Multiple variables, such as gender, breast-feeding, passive smoking, family history of atopy, pets, soft furnishings, and living next to busy roads, were factors that affected the prevalence and severity of the allergic conditions studied. In conclusion, allergic conditions are very common in Maltese schoolchildren and cause great hardship to these same youngsters. The results of this study should serve as a stimulus to try to decrease this suffering through better management of these conditions, measures to control identified detrimental factors (such as passive smoking), and further research on asthma, allergic rhinitis and eczema.

Prevention of atopic disorders

Prevention of sensitization, onset of disease and disease exacerbations is a very important aspect of holistic approach towards allergic disorders. The prevalence of allergic or atopic disorders has increased significantly in children over the last three decades. There are significant variations in prevalence between countries and also within many countries. Environmental factors obviously play a major role. Environmental allergens are responsible for sensitisation, disease and exacerbations of disease symptoms. Preventive strategies at each level are important: Primary prevention is to stop the process of sensitisation and secondary prevention to prevent re-exposures or prolonged exposure in those who have become sensitized while tertiary prevention is to reduce or minimise morbidity. Various allergen avoidance measures are discussed, with reference to India so that physicians can incorporate these in the management not only of atopic patients but also as preventive strategy in high risk families.

Food allergy

Allergic disease is a major contributor to illnesses and mortality worldwide. Food hypersensitivity is often the first phenomenon in the allergic march that includes gastroenteropathy, eczema, asthma and hay fever. Recent evidence indicates that prevention of food hypersensitivity in early life is associated with reduction in the incidence of eczema and asthma in later childhood. Strategies for prevention include exclusive breast feeding, restriction of mother's diet during lactation, hydrolyzed formula, delayed introduction of allergenic solid foods and reduced exposure to house dust mites and tobacco smoke. This is a highly cost-beneficial and cost-effective approach.

The functional genomics of CD14 and its role in IgE responses: an integrated view

Several studies in recent years have suggested that there is a strong genetic component in the pathogenesis of IgE-mediated diseases. Epidemiologic studies have identified a number of genes that carry single base changes (single nucleotide polymorphisms) associated with parameters of allergy. What remain to be established are the mechanisms whereby genetic variation results in dysregulation of IgE-mediated responses. This is the task of functional genomics. In this article, some of the most powerful approaches that have been devised to provide a mechanistic explanation for the effects of genetic variation on the regulation of gene expression and function are discussed. Recent data on the impact of genetic variation on the regulation of CD14 are explored in the context of the potential role played by this gene in the pathogenesis of allergy. Also discussed is the notion that taken individually, each instance of variation might result in small effects. It is the combination of variations in the same gene and/or in genes arrayed along one functional pathway that might eventually lead to dysregulation strong enough to cause disease. In this scenario, the environment is likely to play an essential role in determining the functional outcome of genetic variation.

Environmental factors as a cause for the increase in allergic disease

LEARNING OBJECTIVES

To be able to understand the interaction among genetic factors, environmental exposure to allergens, and nonspecific adjuvant factors contributing to the increase in atopic diseases in developed countries.

DATA SOURCES

Peer-reviewed literature identified by searching medical databases.

STUDY SELECTION

Careful review of epidemiologic cross-sectional, sequential, and longitudinal population studies and, when appropriate, intervention studies. The criteria used to accept a study reporting environmental factors influencing the prevalence of allergic diseases were adopted from the report published by the US Department of Health and Education in 1964 (Hill AB, Principles of Medical Statistics, 9th Ed. New York: Oxford University Press, 1971, p. 323)

RESULTS

There is ample evidence that specific environmental factors may cause sensitization and development of allergic symptoms and disease in susceptible individuals. It is unclear when and how long a sufficient exposure will result in clinical symptoms related to the immunoglobulin E-sensitizing agents.

CONCLUSIONS

Environmental factors play an important role for the development and manifestation of allergic conditions in genetically predisposed subjects. It is well documented that increased exposure to indoor allergens and selected outdoor allergens (eg, grass pollen and molds) and smoking are important risk factors for development of asthma and allergic sensitization. The importance of other environmental factors is less clear and which environmental factors that cause the increase in prevalence of allergic disease is still unknown.

Clinical prescribing of allergic rhinitis medication in the preschool and young school-age child: what are the options?

Allergic rhinitis (AR) is the most common chronic condition in children and is estimated to affect up to 40% of all children. It is usually diagnosed by the age of 6 years. The major impact in children is due to co-morbidity of sinusitis, otitis media with effusion, and bronchial asthma. AR also has profound effects on school absenteeism, performance and quality of life. Pharmacotherapy for AR should be based on the severity and duration of signs and symptoms. For mild, intermittent symptoms lasting a few hours to a few days, an oral second-generation antihistamine should be used on an as-needed basis. This is preferable to a less expensive first-generation antihistamine because of the effect of the latter on sedation and cognition. Four second-generation antihistamines are currently available for children under 12 years of age: cetirizine, loratadine, fexofenadine and azelastine nasal spray; each has been found to be well tolerated and effective. There are no clearcut advantages to distinguish these antihistamines, although for children under 5 years of age, only cetirizine and loratadine are approved. Other agents include pseudoephedrine, an oral vasoconstrictor, for nasal congestion, and the anticholinergic nasal spray ipratropium bromide for rhinorrhoea. Sodium cromoglycate, a mast cell stabiliser nasal spray, may also be useful in this population. For patients with more persistent, severe symptoms, intranasal corticosteroids are indicated, although one might consider azelastine nasal spray, which has anti- inflammatory activity in addition to its antihistamine effect. With the exception of fluticasone propionate for children aged 4 years and older, and mometasone furoate for those aged 3 years and older, the other intranasal corticosteroids including beclomethasone dipropionate, triamcinolone, flunisolide and budesonide are approved for children aged 6 years and older. All are effective, so a major consideration would be cost and safety. For short term therapy of 1 to 2 months, the first-generation intranasal corticosteroids (beclomethasone dipropionate, triamcinolone, budesonide and flunisolide) could be used, and mometasone furoate and fluticasone propionate could be considered for longer-term treatment. Although somewhat more costly, these second-generation drugs have lower bioavailability and thus would have a better safety profile. In patients not responding to the above programme or who require continuous medication, identification of specific triggers by an allergist can allow for specific avoidance measures and/or immunotherapy to decrease the allergic component and increase the effectiveness of the pharmacological regimen.

Immunization and symptoms of atopic disease in children: results from the International Study of Asthma and Allergies in Childhood

OBJECTIVES

This study tested the hypothesis that immunization is related to the prevalence of atopic disease in childhood.

METHODS

We used data from the International Study of Asthma and Allergies in Childhood to perform an ecologic analysis of national and local immunization rates for tuberculosis, diphtheria and tetanus toxoids and pertussis (DTP), and measles and prevalence of atopic disease symptoms (asthma, allergic rhinoconjunctivitis, and atopic eczema).

RESULTS

In 13- to 14-year-old children, there were significant negative associations with local birth-year immunization rates for DTP and measles but none with rates for tuberculosis. No associations were found in 6- to 7-year-old children. No associations with national immunization rates were found.

CONCLUSIONS

International variations in childhood atopic diseases are unlikely to be explained by variations in immunization.

Evidence-based treatment of allergic rhinitis

Allergic rhinitis is an extremely common disease worldwide, affecting 10% to 50% of the population. An increasing prevalence of allergic rhinitis over the past decades and its frequent association with asthma have raised concerns about treating the disease appropriately. New knowledge of the pathophysiologic mechanisms underlying allergic inflammation of the airways has resulted in the development of newer and better therapeutic strategies. This review focuses on evidence-based treatment of allergic rhinitis, highlighting the most recent international consensus and evidence-based guidelines on allergic rhinitis.

Outdoor air pollutants derived from industrial processes may be causally related to the development of asthma in children

BACKGROUND

There is no consistent evidence that outdoor air pollutants are involved in the development of asthma.

OBJECTIVE

The aim of this study was to determine whether outdoor air pollutants derived from industrial processes were related to the prevalence of asthma, bronchial hyperresponsiveness, and atopy in exposed children.

METHODS

A total of 7,511 children from 7 to 12 years of age were recruited in the study. Eight hundred eighty-eight of 1,009 (88%) of the subjects living around industrial factories and 5,998 of 6,502 (92%) living in a less polluted neighboring area responded to the ISAAC questionnaire. A total of 1,492 subjects 8 to 9 years old underwent skin prick tests for 11 common aeroallergens. A total of 732 of the subjects from 8 to 9 years of age underwent bronchial provocation tests with hypertonic saline (BPT-HS).

RESULTS

The prevalence of ever experiencing wheezing and wheeze during the last 12 months was 25.6%, and 18.8% among the children living in the more polluted area. This was significantly higher than for those living in the less polluted area (14.2% and 9.0%, respectively). The positive rate of BPT-HS (the provocative dose of hypertonic saline causing 20% fall of FEV, < or = 23 mL) was higher among those in the more polluted area than in children living in the less polluted area (12.2% vs 7.5%). However, the rate of atopy based on the skin tests was the same in the two groups (28.3% vs 30.6%).

CONCLUSIONS

The prevalence of asthma and bronchial hyperresponsiveness was higher among children living around the heavily industrial area compared with those living in the less polluted area, despite similar atopic sensitization.

The prevalence of atopic disorders in children with chronic otitis media with effusion

We studied 209 children, referred to a multi-disciplinary 'Glue ear/Allergy' clinic at our hospital with a history of chronic or recurrent otitis media with effusion (OME), in order to determine the prevalence of atopic disease in this population. Referrals were made either from within the hospital by Ear, Nose and Throat (ENT) Surgeons and Audiological Physicians (internal), or by General Practitioners (external). Assessment of atopic status was based on medical history, physical examination, nasal smears and skin-prick testing (SPT) in all children; and on blood eosinophil counts and total immunoglobulin E (IgE) levels in a randomly selected subset. The main outcome measures were number of children with rhinitis, asthma, eczema, positive SPT, raised IgE level (> 100 IU/l), and nasal and blood eosinophilia. We found allergic rhinitis in 89%, asthma in 36%, and eczema in 24%. SPTs were positive to one or more of eight common inhalant aeroallergens in 57% of children. Blood tests in the selected subset revealed eosinophilia in 40% and a raised serum IgE in 28%. The worldwide prevalence of allergic rhinitis in children has been estimated to be 20%. The 89% prevalence found in this study is very high and there are a number of reasons which suggest that there may be a causal relationship. Whole-population studies will be required to confirm these findings, which could have important therapeutic implications for OME.

International Study of Asthma and Allergies in Childhood: validation of the rhinitis symptom questionnaire and prevalence of rhinitis in schoolchildren in São Paulo, Brazil

Written questionnaires (WQ) have been widely used in epidemiologic studies. In order to yield comparable results, they must be validated after translation to another language. The International Study of Asthma and Allergies in Childhood (ISAAC) WQ has been previously validated by a comprehensive study, but its validation in Brazil has not been performed. Our objectives were to validate the rhinitis component of the ISAAC's self-applicable WQ following its translation to Portuguese, and to determine the prevalence of rhinitis and related symptoms among Brazilian children living in the city of São Paulo. A group of 10 pediatricians and 10 pediatric allergists graded the questions from 0 to 2 and established a maximum score for each question. The WQ was answered by parents or guardians of children 6-7 years of age with rhinitis (R) (n = 27) and of control children of the same age without rhinitis (C) (n = 27). The WQ was also completed by adolescents 13-14 years of age with rhinitis (R) (n = 32) and without rhinitis (C) (n = 32). Half of these individuals answered the same WQ after 2-4 weeks, to ensure reproducibility. Cut-off scores of 4 and 3 were identified for the 6-7- and 13-14-year-old groups, respectively, as scores predictive of rhinitis. The prevalence of rhinitis was 28.8% in the group of 3005 children 6-7 years of age and 31.7% in the group of 3008 children 13-14 years of age, respectively. Using the global cut-off score, these prevalences were even higher, in the order of 34.7% and 40.7%, respectively. In conclusion, the rhinitis component of the ISAAC WQ was proven to be reproducible, adequate and able to discriminate children and adolescents with and without rhinitis, and revealed that the prevalence of rhinitis among Brazilian children living in the city of São Paulo was as high as the prevalence of rhinitis in other areas of the world.

Diet and asthma, allergic rhinoconjunctivitis and atopic eczema symptom prevalence: an ecological analysis of the International Study of Asthma and Allergies in Childhood (ISAAC) data. ISAAC Phase One Study Group

Several studies have suggested that the increasing prevalence of symptoms of asthma, rhinitis and eczema, could be associated with dietary factors. In the present paper, a global analysis of prevalence rates of wheeze, allergic rhinoconjunctivitis and atopic eczema was performed in relation to diet, as defined by national food intake data. Analyses were based on the International Study of Asthma and Allergies in Childhood (ISAAC) data for 6-7 and 13-14 yr old children. Symptoms of wheeze, allergic rhinoconjunctivitis and atopic eczema symptom prevalence were regressed against per capita food intake, and adjusted for gross national product to account for economic development. Dietary data were based on 1995 Food and Agriculture Organisation of the United Nations data for 53 of the 56 countries that took part in ISAAC phase I (1994/1995). The 13-14 year age group showed a consistent pattern of decreases in symptoms of wheeze (current and severe), allergic rhinoconjunctivitis and atopic eczema, associated with increased per capita consumption of calories from cereal and rice, protein from cereals and nuts, starch, as well as vegetables and vegetable nutrients. The video questionnaire data for 13-14 yr olds and the ISAAC data for 6-7 yr olds showed similar patterns for these foods. A consistent inverse relationship was seen between prevalence rates of the three conditions and the intake of starch, cereals, and vegetables. If these findings could be generalised, and if the average daily consumption of these foods increased, it is speculated that an important decrease in symptom prevalence may be achieved.

The relationship of per capita gross national product to the prevalence of symptoms of asthma and other atopic diseases in children (ISAAC)

BACKGROUND

Increasing prevalence and worldwide variation in asthma and other atopic diseases suggest the influence of environmental factors, at least one possibly related to socioeconomic wellbeing. This paper examines the relationship of symptoms of asthma, rhinitis and eczema with gross national product per capita (GNP per capita).

METHODS

The prevalences of atopic symptoms in 6-7- and 13-14-year-old children were assessed in 91 centres (from 38 countries) and 155 centres (from 56 countries), respectively, in the International Study of Asthma and Allergy in Childhood (ISAAC). These symptoms were related to 1993 GNP per capita for each country as reported by the World Bank. The relationships between symptoms of atopic diseases and infant mortality, the human development index and 1982 GNP per capita were also considered.

RESULTS

The countries in the lowest quartile of GNP per capita have the lowest median positive responses to all the questions on symptoms of asthma, rhinitis and eczema. There was a statistically significant positive association between wheeze in the last 12 months and GNP per capita in the 13-14-year age group, but not in the 6-7-year age group. There was also a positive association between GNP per capita and eczema in both age groups.

CONCLUSIONS

The positive associations between GNP per capita and atopic symptoms being of only moderate strength suggests that the environmental factors are not just related to the wealth of the country.

Paediatric issues relating to the pharmacotherapy of allergic rhinitis

The prevalence of allergic rhinitis in children has risen significantly over the last two decades. Important comorbidities like asthma have grown in parallel due to a complex mix of environmental and genetic factors. These conditions have similar allergic inflammatory mechanisms, which raises the possibility of treating both conditions by targeting shared inflammatory mediators pharmacologically. The first line treatment for paediatric allergic rhinitis is a topical nasal corticosteroid or a non-sedating antihistamine. Available intranasal corticosteroids show superior symptom control to second-generation antihistamines. However, most topical steroids and non-sedating antihistamines have equivalent clinical efficacy within their respective classes, so the choice of agent depends on safety and tolerability. Ideally, topical nasal steroids should exhibit high local receptor binding affinity and low systemic bioavailability, allied with a lack of long-term growth suppression in children and adolescents. Regular use of topical steroids is advisable, but intermittent and prophylactic use is also effective. Second-generation antihistamines are effective and some have no adverse cardiac or sedative effects. Non-sedating antihistamine treatment can ameliorate rhinitis-induced decrements in learning. alpha-Adrenergic nasal decongestants provide short-term benefit, but topical agents can cause rebound symptoms. Prophylactic treatment with chromones is safe and effective, but multiple daily dosing is needed. Ipratroprium bromide nasal spray is useful as an intermittent therapy for mild disease or as add-on treatment, but its effect is limited to the control of rhinorrhoea. Children with allergic rhinitis should receive pharmacotherapy if allergen avoidance measures are ineffective, ideally with a topical intranasal steroid or a second-generation antihistamine.

Prevalence and predictors of rhinitis in Danish children and adolescents

BACKGROUND

The prevalence of self-reported symptoms of allergic rhinitis is increasing in many countries, but the reasons for this trend are not well understood. Data from a 6-year follow-up study of a population sample of children and adolescents (n=408), aged 7-17 years at enrolment in 1986, were analyzed to investigate the prevalence and predictors of self-reported rhinitis.

METHODS

Case history was used to assess the presence or absence of rhinitis (sneezing and running or blocked nose not associated with a cold), asthma, and eczema. Pulmonary function, skin prick test reactivity, and airway responsiveness to histamine were measured in all participants; a screening test for IgE antibodies to common allergens (Magic Lite SQ, Allergy Screen, ALK, Denmark) was performed in 237 (58%) of the participants.

RESULTS

The point prevalence of rhinitis increased from the first to the second survey, 14% and 22%, respectively; 54 (13%) of the subjects reported rhinitis only at the second survey (new rhinitis). Confining the analysis to participants without symptoms of rhinitis at the first survey showed that self-reported eczema (relative risk [RR] 2.3, 95% confidence interval [CI] 1.2-4.7), airway hyperresponsiveness (RR 2.5, CI 1.8-3.0), atopy to grass pollen (RR 2.6, CI 1.7-3.3), atopy to dog dander (RR 2.4, CI 1.6-3.3), and atopy to house-dust mite (RR 2.7, CI 1.4-5.2) at the first survey predicted an increased risk of the presence of rhinitis at the second survey. A positive Allergy Screen test at enrollment was associated with an increased risk of self-reported rhinitis at follow-up (RR 2.4, CI 1.4-3.4).

CONCLUSIONS

This longitudinal population study of children and adolescents showed an age-related increase in the point prevalence of self-reported rhinitis; furthermore, sensitization to common aeroallergens, airway hyperresponsiveness, and the presence of self-reported eczema were significantly associated with an increased risk of subsequent development of rhinitis.

Pets and cockroaches: two increasing causes of respiratory allergy in indoor environments. Characteristics of airways sensitization and prevention strategies

The increasing prevalence of allergic sensitization to indoor allergens such as dust mites, pets and cockroaches is the result of the changes in indoor environments induced by human activities. The Westernized lifestyle and the increasing time spent indoors determine a reduction in natural air ventilation and, consequently, higher levels of allergen concentrations and longer exposure to allergens. The major cat allergen Fel d 1 is carried by small-dimension particles (< 5 microm diameter) that readily become airborne and persist immodified for a long time. Fel d 1 must be considered a ubiquitous allergen because it has been found in indoor environments and even in public places where a cat has never been kept. Recent research has demonstrated that clothing of cat owners may contribute to the dispersal of Fel d 1 in cat-free environments. Therefore, washing Fel d 1-contaminated clothes should be considered a simple and effective method for removing this allergen from clothing and, consequently, reducing the risk of Fel d 1 dispersion. Cockroach allergens constitute another important cause of environment-related respiratory allergy and may trigger asthma exacerbations in sensitized individuals. In the prevention of cockroach allergy, the use of chemical agents associated with an intensive vacuum cleaning of indoor environments is an important tool in removing cockroach material containing allergenic proteins. Early recognition of allergy-predisposed babies, monitoring indoor allergens and adequate strategies of allergen avoidance are likely to be important means for reducing the prevalence of bronchial asthma.

Development of seasonal allergic rhinitis during the first 7 years of life

BACKGROUND

Against the background of the controversial discussion about an increase in allergic rhinitis in recent years, intraindividual longitudinal data is lacking for IgE-mediated seasonal allergic rhinitis (SAR). Little is known about the development of SAR in terms of prevalence and incidence rates from birth to school age.

OBJECTIVE

In a prospective birth cohort, we investigated the development of sensitization and symptoms of SAR. SAR should be defined with high specificity, and associated risk factors should be determined.

METHODS

Annual longitudinal data about seasonal allergic symptoms and sensitization was available for 587 children from birth to their seventh birthday. The definition of SAR was based on a combination of exposure-related symptoms and sensitization.

RESULTS

Up to 7 years of age, SAR developed in 15% of the children. Incidence and prevalence of symptoms and sensitization were low during early childhood (<2%) and increased steadily with age. Children in which SAR had already developed in the second year all were born in spring or early summer, resulting in at least two seasons of pollen exposure before manifestation of SAR. Risk factors assessed by multiple logistic regression analysis were male sex (odds ratio [OR] = 2.4), atopic mothers (OR = 2.6) and fathers (OR = 3.6) having allergic rhinitis themselves, first-born child (OR = 2.0), early sensitization to food (OR = 3.3), and atopic dermatitis (OR = 2.5), whereas early wheezing was not associated with SAR.

CONCLUSION

The development of SAR is characterized by a marked increase in prevalence and incidence after the second year of life. Our longitudinal data further indicate that in combination with the risk of allergic predisposition, at least 2 seasons of pollen allergen exposure are needed before allergic rhinitis becomes clinically manifest.

Ethnicity, childhood environment and atopic disorder

BACKGROUND

The International Study of Asthma and Allergies in Childhood (ISAAC) has demonstrated large differences in the prevalence of atopic disorders in children between different regions in the world. Populations with a higher standard of living and a more westernized lifestyle tend to have higher rates of atopy and asthma. Many hypotheses regarding environmental causes of atopic disorder focus on the early childhood environment.

OBJECTIVE

To study the influence of ethnicity and country of birth for the prevalence of atopic disorders.

METHODS

The prevalence of atopic disorders in Swedish residents born in Turkey and Chile, who settled in Sweden as adults in the 1980s, was compared with their own Swedish-born children and a sample of Swedish-born parents and their children in interview data from the Survey of Living Conditions in 1996. The study group included 1734 adults 27-60 years of age and their 2964 children aged 3-15.

RESULTS

The Chilean-born parents and their children had the highest risk for allergic asthma; adjusted odds ratios (ORs) 2.2 (1.2-4.0) and 2.7 (1.6-4.5), respectively, and allergic rhino-conjunctivitis; OR 1.6 (1.1-3) and 1.6 (1.1-2.5) in both groups, when compared with the Swedish-born parents and their children. The Turkish-born parents and their children had the lowest risk for allergic rhino-conjunctivitis; both groups had OR 0.6 (0. 4-0.9) and the children in this group also had the lowest risk for eczema; OR; 0.4 (0.3-0.7). The risk for all atopic disorders was lower in the Turkish group compared with the Chileans.

CONCLUSION

This study demonstrates that ethnicity is an important determinant of atopic disorder independent of the external childhood environment. The value of international comparisons of environment and risk for atopic disorders can be questioned until more is known about factors related to ethnicity, such as genetic susceptibility and diet, for the development of atopy.

Reduced risk of hay fever and asthma among children of farmers

BACKGROUND

The prevalence of atopic diseases is on the rise. Traditional lifestyles may be associated with a reduced risk of atopy.

OBJECTIVES

To test the hypothesis that children living on a farm have lower prevalences of atopic diseases. To identify differences in living conditions between farmers and other families which are associated with the development of atopic conditions.

DESIGN

Cross-sectional survey among children entering school (aged 5-7 years). A written questionnaire including the ISAAC core questions and asking for exposures on a farm and elsewhere was administered to the parents.

SETTING

School health entry examination in two Bavarian districts with extensive farming activity.

SUBJECTS

10 163 children.

MAIN OUTCOME MEASURES

The prevalence of doctor's diagnoses and symptoms of hay fever, asthma and eczema as assessed by parental report.

RESULTS

Farmers' children had lower prevalences of hay fever (adjusted odds ratio = 0. 52, 95% CI 0.28-0.99), asthma (0.65, 0.39-1.09), and wheeze (0.55, 0. 36-0.86) than their peers not living in an agricultural environment. The reduction in risk was stronger for children whose families were running the farm on a full-time basis as compared with families with part-time farming activity. Among farmers' children increasing exposure to livestock was related to a decreasing prevalence of atopic diseases (aOR = 0.41, 95% CI 0.23-0.74).

CONCLUSIONS

Factors related to environmental influences on a farm such as increased exposure to bacterial compounds in stables where livestock is kept prevent the development of allergic disorders in children.

The environmental predictors of allergic disease

The prevalence of allergic diseases has been on the rise for the last 200 years, when hay fever, an easy and obvious-to-recognize illness, was virtually unknown in Europe and North America. Genetic factors are unlikely to explain these rapid increases. Among the potential environmental factors, exposure to ambient air pollution has been intensely debated. Besides passive smoking, which has convincingly been shown to increase the risk for asthma and bronchial hyperresponsiveness among exposed children, the evidence to suggest that outdoor pollution to sulfur dioxide, particulate matter, diesel exhaust, and ozone is causally related with the inception of allergic diseases is poor. Rather, factors associated with the lifestyle of populations or families, such as socioeconomic status, allergen exposure, sibship size, early childhood infections, dietary habits, and growing up in anthroposophic families or a farming environment, may prove to be of greater relevance. The future challenge is to tackle the complex interplay between environmental factors and genetic determinants that will eventually contribute to a better understanding and to better prevention strategies for such multifactorial conditions as asthma and allergies.

Hay fever, eczema, and wheeze: a nationwide UK study (ISAAC, international study of asthma and allergies in childhood)

OBJECTIVES

To describe the prevalence of atopic symptoms in children throughout the UK.

METHOD

A questionnaire 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.

RESULTS

A total 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 three symptoms.

CONCLUSION

In general, 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.

Changing prevalence of allergic rhinitis and asthma

OBJECTIVE

This review will enable the reader to discuss prevalence, risk factors, and prognosis of allergic rhinitis and asthma.

DATA SOURCES

MEDLINE (PubMed) search using the terms allergic rhinitis, asthma, prevalence, risk factors.

STUDY SELECTION

Human studies published in the English language since 1978, especially studies of relatively large populations in the United States, Great Britain, Australia, and New Zealand, with cross referencing to earlier relevant studies.

RESULTS

Current prevalence of allergic rhinitis at 16 years of age in cohorts of British children born in 1958 and 1970 increased from 12% in the earlier cohort to 23% and in the later cohort. Local surveys of allergic rhinitis at approximately 18 years of age in the United States in 1962 to 1965 disclosed prevalence of 15% to 28%, while the national survey of 1976 to 1980 disclosed a prevalence of 26%. Thus, it is uncertain whether prevalence of allergic rhinitis has changed in the United States based on these limited data. Data from several sources indicate worldwide increases in prevalence of asthma. Annual Health Interview surveys indicate increases in prevalence of asthma in the United States from 3.1% in 1980 to 5.4% in 1994, but prevalence among impoverished inner city children has been much higher. Combined prevalence of diagnosed and undiagnosed asthma among inner city children has been 26% and 27% at 9 to 12 years of age in Detroit and San Diego. Positive family history and allergy are important risk factors for allergic rhinitis and asthma. Prognosis is guarded; allergic rhinitis resolves in only 10% to 20% of children within 10 years, and at least 25% of young adults who have had asthma during early childhood are symptomatic as adults.

CONCLUSION

Increases in prevalence remain unexplained, but avoidance of recognized allergens should reduce the prevalence of allergic rhinitis and asthma.

Worldwide variations in the prevalence of symptoms of atopic eczema in the International Study of Asthma and Allergies in Childhood

BACKGROUND

Little is known about the prevalence of atopic eczema outside Northern Europe.

OBJECTIVES

We sought to describe the magnitude and variation in the prevalence of atopic eczema symptoms throughout the world.

METHODS

A cross-sectional questionnaire survey was conducted on random samples of schoolchildren aged 6 to 7 years and 13 to 14 years from centers in 56 countries throughout the world. Those children with a positive response to being questioned about the presence of an itchy relapsing skin rash in the last 12 months that had affected their skin creases were considered to have atopic eczema. Children whose atopic eczema symptoms resulted in sleep disturbance for 1 or more nights per week were considered to have severe atopic eczema.

RESULTS

Complete data was available for 256,410 children aged 6 to 7 years in 90 centers and 458,623 children aged 13 to 14 years in 153 centers. The prevalence range for symptoms of atopic eczema was from less than 2% in Iran to over 16% in Japan and Sweden in the 6 to 7 year age range and less than 1% in Albania to over 17% in Nigeria for the 13 to 14 year age range. Higher prevalences of atopic eczema symptoms were reported in Australasia and Northern Europe, and lower prevalences were reported in Eastern and Central Europe and Asia. Similar patterns were seen for symptoms of severe atopic eczema.

CONCLUSIONS

Atopic eczema is a common health problem for children and adolescents throughout the world. Symptoms of atopic eczema exhibit wide variations in prevalence both within and between countries inhabited by similar ethnic groups, suggesting that environmental factors may be critical in determining disease expression. Studies that include objective skin examinations are required to confirm these findings.

Is allergy prevention realistic and beneficial?

Allergic diseases among children have shown a marked increase during the last two or three decades, despite increased awareness of possible preventive measures. Preventive efforts have focused on new-borns and infants with a biparental history of allergy as they are at particularly high risk of developing allergic disease (40-60%). No good intervention studies have been performed in the general population, only in high-risk families. Unfortunately, so far known risk factors can only explain a small part of the recent increase in allergic diseases. The most important recommendation for everyone is not to smoke during pregnancy and when living/working with young children. Breast milk is the best for every baby, even from an immunologic aspect. Humidity problems should be reduced in homes, day-care centres and schools. It is probably wise not to keep furred pets indoors in homes when babies have a family history of allergy. However, the effect of such advice should be assessed, including the acceptability, compliance, costs and effectiveness. There is no doubt that we should go on with preventive measures both in babies at high risk of allergy and also in the general population. At the same time, research should try to find even more efficient ways to reduce the current "allergy epidemic".