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Personnel

• Professor H Ross Anderson
• Dr Michael Burr
• Dr Balvinder Kaur
• Dr Jan Poloniecki

Why this centre was chosen

In ISAAC Phase 1, Wales was included as part of the United Kingdom centre, whereas in Phase 3 it functioned as a distinct centre. The age group (13-14 years), the sampling frame, the method of selecting schools (one comprehensive school from each education authority area in Wales) and the survey procedure were the same on both occasions, so the findings are comparable, and reflect the situation across the whole of Wales rather than in one area.

Wales was selected as a centre partly because it is a distinct part of the UK, with its own cultural traditions, and partly because several other epidemiological studies of asthma have been conducted here, including repeat surveys of asthma in schoolchildren and the European Community Respiratory Health Survey in young adults.

Our experience of ISAAC

There is a widespread belief in Wales that asthma is particularly common and severe here. This belief was advantageous to us, in that most of the schools were interested and co-operative in the survey, as addressing a topic that the staff saw as important.

We also used the opportunity to conduct a subsidiary survey on children with symptoms of eczema. The ISAAC questionnaire that we used contained a supplementary questionnaire for children who had experienced an itchy rash or eczema in the last 12 months. This presented a list of 19 factors for which there is some evidence of favourable or unfavourable effects on eczema, and the children were asked to indicate whether each factor made the rash better, if it made it worse, if had no effect, or if they did not know its effects. They were also asked to report any other factors that they thought might influence the rash. So far as we know, this is the first population-based survey of children’s perceptions of exacerbating and relieving factors in eczema, as distinct from studies in special groups such as hospital patients. It therefore provides information about the whole range of the disease.

Findings for this centre

Contrary to the local belief, the prevalence of wheeze in Wales is not markedly different from that reported from other parts of the UK, although it is in relation to many other parts of the world. There are also no gross disparities in the indices of severity between Wales and South-east England or Scotland.

Comparison with Phase 1 data showed that the 12-month prevalence of wheeze fell from 33.6% in 1995 to 27.5% in 2002, although lifetime prevalence of reported asthma rose from 21.8% to 27.1%. Another repeat survey of schoolchildren in the Cardiff area showed that wheeze in the past 12 months rose from 15.2% in 1988 to 19.7% in 2003, and “wheeze ever” from 22.3% to 28.0%. Thus, while both studies show a rise in lifetime prevalence, there is some apparent conflict as to whether the 12-month prevalence of asthma has recently been increasing or decreasing. Possible explanations might involve the following considerations:

• The prevalence of asthma symptoms may have peaked in the mid-1990s.
• Year-on-year fluctuations in the prevalence of wheeze, due to differences in the incidence of virus infections or bad weather, could falsely suggest a temporal trend when surveys in two different years are compared.
• Children in the Cardiff survey were younger (aged 11-12 years) than those in the ISAAC survey; perhaps teenagers are tending to grow out of asthma symptoms earlier.

The supplementary questionnaire about factors that children believe aggravate or alleviate eczema was answered by 90% (225 out of 250) of those who reported eczema symptoms. Sweating from exercise, fabrics (especially wool) and hot weather were the exacerbating factors most often identified (by about 40% of responders in each case), while steroid creams, moisturizers/makeup and medicines/tablets were the three principal relievers. Only 5% of responders believed that symptoms were aggravated by certain foods or drinks, which is somewhat surprising, given the widespread belief that food allergy is an important component of atopic eczema.

Although these findings do not demonstrate the extent to which various factors actually influence eczema, they suggest their relative importance, particularly as perceived by affected children.