Childhood Allergies Have Increased Globally Since 1991

Childhood allergies have become more widespread around the globe since 1991, according to a large study. The most common allergies are hayfever, asthma and eczema. In the UK, a study of 1,700 children found asthma prevalence went up from 18.4% in 1991 to 20.9% in 2003 - for the same period hayfever prevalence went up from 9.8% to 10.1% and eczema rose from 13% to 16%.

Between 2002 and 2003, Professor Innes Asher, Department of Paediatrics, Faculty of Medical and Health Sciences, University of Auckland, New Zealand, and team, repeated a 1991 study called The International Study of Asthma and Allergies in Childhood (ISAAC) to asses global prevalence of asthma, hayfever and eczema.

193,400 children, aged 6-7, from 37 different countries were monitored for symptoms of asthma and other allergies, such as wheezing. The researchers used feedback from the children's parents for this study. Another 304,680 children, aged 13-14, from 56 different countries, were surveyed directly with the same questions. The study included children from developing countries, such as Brazil, South Africa and Iran, as well as developed countries, such as the UK, Swede, Canada and New Zealand.

The researchers found that:

-- Rises in prevalence were more common than falls - especially among younger children

-- Eczema has become more widespread worldwide among younger children

-- Hayfever has become more prevalent globally among all age-groups

--Asthma prevalence among older kids, which had previously been high, more commonly decreased

--Only in India and the Asia-Pacific region has the prevalence of all three disorders - asthma, hayfever and eczema - increased in all age-groups.

Prof. Innes Asher concludes that the data have direct relevance for health-service delivery in the countries included in the study, as well as providing a basis for understanding these disorders. Almost everywhere there has been a change in prevalence of one or more disorders over time. Seemingly small increases of 0.5% may seem insignificant. However, they have substantial public-health implications, especially as they often appear to take place in densely populated areas.

Worldwide time trends in the prevalence of symptoms of asthma, allergic rhinoconjunctivitis, and eczema in childhood: ISAAC Phases One and Three repeat multicountry cross-sectional surveys
Prof M Innes Asher MBChB, Stephen Montefort MD, Bengt Bjцrkstйn MD, Christopher KW Lai DM, David P Strachan MD, Stephan K Weiland MD and Hywel Williams PhD, the ISAAC Phase Three Study Group
The Lancet 2006; 368:733-743
DOI:10.1016/S0140-6736(06)69283-0
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Written by: Christian Nordqvist
Editor: Medical News Today