Changing prevalence of asthma in school children: evidence for diagnostic changes in asthma in two surveys 13 yrs apart (original) (raw)
Related papers
1998
Some children develop asthma and other atopic diseases, others asthma without atopic diseases. To better understand secular trends, we estimated the relative increase in asthma in children with (atopy related asthma) and without (non-atopy related asthma) other atopic diseases (eczema or hay fever) in two samples of school children born, 1965-1975 (n = 1674) and 1978-1988 (n = 2188). By analysing the samples as historical cohorts, age-specific prevalence rates were estimated and incidence rates were calculated (number of new cases by 1000 personyears under risk). Cox regression was used to estimate the relative risk (RR) of asthma by year of birth. The point prevalence of asthma was 1.9% (95% CI: 1.4-2.4) in the 1965-1975 cohort and 4.6% (95% CI: 3.8-5.4) in the 1978-1988 cohort for three-year old children, and remained fairly constant throughout childhood. The age-specific prevalence of non-atopy related asthma increased relatively more from 1965-1975 to 1978-1988 compared to atopy related asthma. The age-specific incidence rates of asthma showed that the RRs comparing the two cohorts tended at all ages to be highest for nonatopy related asthma. The relative risks of non-atopy related asthma by gender and birth cohort, showed that the effect of cohort was higher for non-atopy related asthma, aRR: 4.0 (95% CI: 2.5-6.5), than for atopy-related asthma aRR: 2.0 (95% CI: 1.3-3.2). Children without other atopic diseases have a higher relative risk of being diagnosed with asthma than children with other atopic diseases across all ages comparing two samples of school children born 1965-1975 and 1978-1988.
Changes in the relationship between asthma and associated risk factors over fifty years
Pediatric Allergy and Immunology, 2016
Supplementary table 1. A summary and explanation of variables included in the models A, B and C of the analysis. Supplementary table 2. Odds ratios [95% confidence interval] for a child having wheeze in last 3 years, over given time periods, following adjustment for changing prevalences of asthma and covariates. Supplementary figure 1. A line chart showing the population attributable risk for life time asthma in the context of eczema, parental asthma and parental smoking.
Atopic and nonatopic asthma in epidemiology Allergy and Asthma Proceedings 55
2009
Innumerable articles have tried to solve the " continuing enigma of atopic and nonatopic asthma " but notwithstanding the strenuous efforts to substantiate the few well-known clinico-epidemiologic differences between these two forms of asthma most studies have hitherto generated inconclusive statements. In a recent study based on the review of epidemiologic studies conducted worldwide in unselected populations of children, we documented that the prevalence of atopic asthma (AA) was high in the populations with a high prevalence of atopy. We systematically reviewed 36 articles that studied 48 populations of unselected children and reported prevalence rates for asthma and atopy in the total sample and in the subpopulations. No significant difference was found in the prevalence of asthma cases in the quartiles of childhood populations subdivided for the prevalence of atopy. In addition, atopy did not increase significantly in the subgroups of populations subdivided by asthma quartiles. In both subgroups, however, AA increased with increasing atopy or with increasing asthma (p 0.001). Using a positive skin-prick test reaction to define cases of asthma as cases of AA is misleading because the prevalence of subjects so defined is heavily influenced by the environmentally generated changes in the prevalence of atopy or asthma. Asthma in a child should be labeled as a case of AA only if skin-prick tests yield a positive reaction and the clinical history documents asthma symptoms triggered by allergen exposure. O ver the past 60 years innumerable studies have tried to solve the " continuing enigma of extrin-sic, atopic asthma (AA) and intrinsic, non-AA (NAA). " 1 However, notwithstanding the strenuous efforts to substantiate the few well-known clinico-epide-miologic differences between these two forms of asthma (including later onset, female prevalence, more severe clinical course, and less evident family history of asthma in NAA) 2 with immunopathological features , most studies have hitherto generated substantially inconclusive statements. 3,4 The lack of evidence that atopy suffices to identify an asthma phenotype casted doubts on the rationale for classifying asthma cases as intrinsic or extrinsic and reinforced the hypothesis that the propensity to develop asthma and to develop inappropriate IgE responses could be independent traits that are commonly juxtaposed in individuals. 5 Our understanding of these relationships is made even more complex by the two parallel epidemics of asthma and atopy, both taking place all over the world, albeit at different speeds and starting from different levels in the various geographical settings. 6 – 8 In a recent review of several epidemiologic studies conducted worldwide in unselected populations of children, even though the prevalence of both atopy and asthma varied more than 10-fold, we found a strict correlation between the prevalence of atopy in the asthmatic subjects and the prevalence of atopy in the nonasthmatic part of the population. 9 We therefore concluded that when atopy increases in certain populations it increases in parallel in asthmatic and nonas-thmatic subjects. No study has shown whether asthma increases in a similar way in atopic and nonatopic subjects. To understand how the epidemiologic differences in the prevalence of asthma and of atopy influence the prevalence of AA, in this article, we reexamined the findings for 48 populations of unselected children (37 analyzed in our previous article and 11 reported in recently published articles). 11– 46
Asthma severity and atopy: how clear is the relationship?
Archives of Disease in Childhood, 2006
Background: The relationship between asthma severity and atopy is complex. Many studies have failed to show significant relationships between clinical severity or lung function and markers of atopic sensitisation. Aim: To determine whether increasing asthma severity is related to atopic sensitisation in a population of children with asthma. Methods: A total of 400 children (7-18 years) with asthma were recruited as part of a multicentre study of the genetics of asthma. Detailed phenotypic data were collected on all participants. Associations between measures of asthma severity and atopic sensitisation were sought using multilevel models allowing variation at the individual and family level. Results: Children recruited to the study had a range of asthma severities, with just over a third having mild persistent asthma. The logarithm of total serum IgE was associated with increased asthma severity score, decreased FEV 1 , increased airways obstruction, risk of hospital admission, and inhaled steroid use. Increasing skin prick test reactivity to a panel of seven aeroallergens was associated with increased risk of hospital admission, use of an inhaled steroid, and airways obstruction. The results remained highly significant after corrections for age, gender, and birth order. Conclusions: In children with asthma, increasing atopy is associated with increasing asthma severity. However, the relationships between asthma severity and skin prick tests, and asthma severity and total serum IgE values, appear subtly different.
Thorax, 2007
Background: Phase I of the International Study of Asthma and Allergies in Childhood (ISAAC) was designed to allow worldwide comparisons of the prevalence of asthma symptoms. In phase III the phase I survey was repeated in order to assess changes over time. Methods: The phase I survey was repeated after an interval of 5-10 years in 106 centres in 56 countries in children aged 13-14 years (n = 304 679) and in 66 centres in 37 countries in children aged 6-7 years (n = 193 404). Results: The mean symptom prevalence of current wheeze in the last 12 months changed slightly from 13.2% to 13.7% in the 13-14 year age group (mean increase of 0.06% per year) and from 11.1% to 11.6% in the 6-7 year age group (mean increase of 0.13% per year). There was also little change in the mean symptom prevalence of severe asthma or the symptom prevalence measured with the asthma video questionnaire. However, the time trends in asthma symptom prevalence showed different regional patterns. In Western Europe, current wheeze decreased by 0.07% per year in children aged 13-14 years but increased by 0.20% per year in children aged 6-7 years. The corresponding findings per year for the other regions in children aged 13-14 years and 6-7 years, respectively, were: Oceania (20.39% and 20.21%); Latin America (+0.32% and +0.07%); Northern and Eastern Europe (+0.26% and +0.05%); Africa (+0.16% and +0.10%); North America (+0.12% and +0.32%); Eastern Mediterranean (20.10% and +0.79%); Asia-Pacific (+0.07% and 20.06%); and the Indian subcontinent (+0.02% and +0.06%). There was a particularly marked reduction in current asthma symptom prevalence in English language countries (20.51% and 20.09%). Similar patterns were observed for symptoms of severe asthma. However, the percentage of children reported to have had asthma at some time in their lives increased by 0.28% per year in the 13-14 year age group and by 0.18% per year in the 6-7 year age group. Conclusions: These findings indicate that international differences in asthma symptom prevalence have reduced, particularly in the 13-14 year age group, with decreases in prevalence in English speaking countries and Western Europe and increases in prevalence in regions where prevalence was previously low. Although there was little change in the overall prevalence of current wheeze, the percentage of children reported to have had asthma increased significantly, possibly reflecting greater awareness of this condition and/or changes in diagnostic practice. The increases in asthma symptom prevalence in Africa, Latin America and parts of Asia indicate that the global burden of asthma is continuing to rise, but the global prevalence differences are lessening.