Abstract
SummaryBackgroundAsthma is the most common chronic disease in children globally. The Global Asthma Network (GAN) Phase I study aimed to determine if the worldwide burden of asthma symptoms is changing.MethodsThis updated cross-sectional study used the same methods as the International study of Asthma and Allergies in Childhood (ISAAC) Phase III. Asthma symptoms were assessed from centres that completed GAN Phase I and ISAAC Phase I (1993–95), ISAAC Phase III (2001–03), or both. We included individuals from two age groups (children aged 6–7 years and adolescents aged 13–14 years) who self-completed written questionnaires at school. We estimated the 10-year rate of change in prevalence of current wheeze, severe asthma symptoms, ever having asthma, exercise wheeze, and night cough (defined by core questions in the questionnaire) for each centre, and we estimated trends across world regions and income levels using mixed-effects linear regression models with region and country income level as confounders.FindingsOverall, 119 795 participants from 27 centres in 14 countries were included: 74 361 adolescents (response rate 90%) and 45 434 children (response rate 79%). About one in ten individuals of both age groups had wheeze in the preceding year, of whom almost half had severe symptoms. Most centres showed a change in prevalence of 2 SE or more between ISAAC Phase III to GAN Phase I. Over the 27-year period (1993–2020), adolescents showed a significant decrease in percentage point prevalence per decade in severe asthma symptoms (–0·37, 95% CI –0·69 to –0·04) and an increase in ever having asthma (1·25, 0·67 to 1·83) and night cough (4·25, 3·06 to 5·44), which was also found in children (3·21, 1·80 to 4·62). The prevalence of current wheeze decreased in low-income countries (–1·37, –2·47 to –0·27], in children and –1·67, –2·70 to –0·64, in adolescents) and increased in lower-middle-income countries (1·99, 0·33 to 3·66, in children and 1·69, 0·13 to 3·25, in adolescents), but it was stable in upper-middle-income and high-income countries.InterpretationTrends in prevalence and severity of asthma symptoms over the past three decades varied by age group, country income, region, and centre. The high worldwide burden of severe asthma symptoms would be mitigated by enabling access to effective therapies for asthma.FundingInternational Union Against Tuberculosis and Lung Disease, Boehringer Ingelheim New Zealand, AstraZeneca Educational Grant, National Institute for Health Research, UK Medical Research Council, European Research Council, and Instituto de Salud Carlos III.
Highlights
Asthma is the most common non-communicable disease in children and one of the most common chronic diseases in adulthood.[1,2] It is a major global health problem, with estimated 495 100 deaths from asthma in 2017,3 and 22·8 million disability-adjusted life-years in 2017.4 More than 1000 asthma deaths each day are similar to the number of deaths from malaria.[5]
Each Global Asthma Network (GAN) Phase I investigator completed a registration document and followed the GAN manual.[14]. They gained approval from their local ethics committee and replicated the methods that had been used in their centres for ISAAC; this was documented in the centre report,[14] which enabled checks to ensure the use of the same geographical sampling frame, sample size, age groups, method of selecting pupils, time of year for comparable estimates of prevalence and severity of asthma symptoms in school-aged children over nearly three decades (1993–2020), from 27 centres in 14 countries in the Africa and Eastern Mediterranean, America, Europe, and South-East Asia and Western Pacific regions
Data were available for 27 centres, in 14 countries in all four regions (Africa and Eastern Mediterranean, America, Europe, and South-East Asia and Western Pacific) that had completed ISAAC Phase I, Phase III, or both and for which GAN Phase I methods and data checks were completed by Jan 29, 2021
Summary
Asthma is the most common non-communicable disease in children and one of the most common chronic diseases in adulthood.[1,2] It is a major global health problem, with estimated 495 100 deaths from asthma in 2017,3 and 22·8 million disability-adjusted life-years in 2017.4 More than 1000 asthma deaths each day are similar to the number of deaths from malaria.[5] Crosssectional comparisons of the prevalence of asthma in populations require standardised methods that can be implemented in a wide range of settings, and the International Study of Asthma and Allergies in Childhood (ISAAC) is the only worldwide study to achieve this.[6] ISAAC Phase I (1993–95), repeated in Phase III (2001–03), identified that the prevalence of asthma symptoms (current wheeze) in school-aged children (aged 6–7 years and 13–14 years) was rising in some low-income and middle-income countries.[7,8]. The Global Asthma Network (GAN) was established in 2012, building on the success of ISAAC and incorporating a new collaboration with the International Union Against Tuberculosis and Lung Disease. One of GAN’s core activities, GAN Phase I (building on ISAAC and using an identical approach and methods)[9] includes
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