Siblings, asthma, rhinoconjunctivitis and eczema: a worldwide perspective from the International Study of Asthma and Allergies in Childhood

Abstract

BackgroundAssociations of larger families with lower prevalences of hay fever, eczema and objective markers of allergic sensitization have been found fairly consistently in affluent countries, but little is known about these relationships in less affluent countries.MethodsQuestionnaire data for 210 200 children aged 6–7 years from 31 countries, and 337 226 children aged 13–14 years from 52 countries, were collected by Phase Three of the International Study of Asthma and Allergies in Childhood (ISAAC). Associations of disease symptoms and labels of asthma, rhinoconjunctivitis and eczema were analysed by numbers of total, older and younger siblings, using mixed (multi-level) logistic regression models to adjust for individual covariates and at the centre level for region, language and national affluence.ResultsIn both age groups, inverse trends (P < 0.0001) were observed for reported ‘hay fever ever’ and ‘eczema ever’ with increasing numbers of total siblings, and more specifically older siblings. These inverse associations were significantly (P < 0.005) stronger in more affluent countries. In contrast, symptoms of severe asthma and severe eczema were positively associated (P < 0.0001) with total sibship size in both age groups. These associations with disease severity were largely independent of position within the sibship and national GNI per capita.ConclusionsThese global findings on sibship size and childhood asthma, rhinoconjunctivitis and eczema suggest at least two distinct trends. Inverse associations with older siblings (observations which prompted the ‘hygiene hypothesis’ for allergic disease) are mainly a phenomenon of more affluent countries, whereas greater severity of symptoms in larger families is globally more widespread.

Patterns of Sensitization to Inhalant Allergens in Japanese Lower-Grade Schoolchildren and Related Factors

“…A recent large cohort study reported an inverse trend for the presence of allergic disease (such as hay fever/eczema) with an increasing number of total siblings, specifically older siblings [12] . These findings lend support to the hygiene hypothesis as an explanation for the increased incidence of allergic diseases [13] .…”

“…The hygiene hypothesis posits that the rising prevalence of allergic disease is due to a reduction in exposure to infectious agents in modern industrialized society [12,13] . In our study, not being firstborn, exposure to passive smoking, keeping pets and living near busy roads were factors related to decreased AORs of allergic sensitization.…”

Perbedaan Prevalensi Alergi pada Anak Obes Dibandingkan dengan Indeks Massa Tubuh Normal

“…Penelitian oleh Ball 16 pada anak menunjukkan bahwa kehadiran >1 orang saudara kandung di rumah melindungi terjadinya asma. Hasil penelitian phase three of the international study of asthma and allergic in childhood (ISAAC) 17 pada anak usia 6-7 tahun dan usia 13-14 tahun menunjukkan bahwa memiliki >3 orang saudara menurunkan risiko rhinitis alergi (usia 6-7 tahun) dan asma (usia 13-14 tahun) dibandingkan anak tunggal. European community respiratory health study II (ECRHS II) melaporkan insidensi rhinitis alergi menurun dengan bertambahnya jumlah saudara kandung.…”

Multilevel regression modelling to investigate variation in disease prevalence across locations

“…The number of siblings has been shown to be an important factor influencing the occurrence of allergic disease 17 and we chose therefore to investigate its relation with an objective marker of allergy i.e. skin prick test positivity.…”