The prevalence of asthma and allergy is increasing. It is estimated that over 20% of the world’s population suffer from IgE-mediated allergic diseases such as asthma, rhinoconjunctivitis, eczema and anaphylaxis. Asthma, which in more than 50% of adults and 70–80% of children is allergic, occurs in around 5–15% in the paediatric population. Asthma is estimated by the World Health Organization (WHO) to affect 150 million people worldwide, placing an enormous strain on health resources in many countries, and is a major cause of hospitalisations for chronic diseases in children in the Western World. Prevention of Allergy and Allergic Asthma was a collaborative project between the World Allergy Organization (WAO) and the WHO. This collaboration was commissioned to advance the strategic objectives of the WHO as outlined in its Strategy for the Prevention and Control of Chronic Respiratory Diseases.
WAO and WHO created a working group consisting of seven ‘Chapter Chairpersons’, each with co-authors, and a meeting of the group took place on December 5–6, 1999, at the WHO headquarters in Geneva. The Chairpersons of the working group invited a number of international experts to contribute to the chapters, enabling WAO and WHO to benefit from the widest possible expert opinion in the development of this document. A report of the second meeting of the working group was published in September 2003 . The strategic guidelines and recommendations in this document have been developed for use by governments, health care professionals, research grant providers, lay organizations, and patients, and will be disseminated, amongst other routes, through the WAO educational program, Global Resources in Allergy.
In creating this document, authors were asked to code the referenced documents in accordance with the following WHO Categories of Evidence; on the basis of the categorisation of evidence, a strength of recommendation may be awarded to the ensuing guidelines. The Categories of Evidence are more easily applied to therapeutic interventions than to epidemiological and basic research studies, where randomisation or blinding may not be possible. A well-designed physiological study, for example, may not be able to be coded by these criteria. Thus, a recommendation awarded a ‘b’ cannot always be interpreted as a lesser recommendation than one coded ‘a’ – it is an indication only of the type of studies which have created the evidence base: a recommendation awarded ‘d’ may indicate that at the present time there is an absence of evidence. Accordingly, it was decided only to restrict strength of recommendation categories to the guidelines in chapters 5 and 6, where a clear interpretation of the evidence base is possible.