Has the prevalence and severity of symptoms of asthma changed among children in New Zealand? ISAAC Phase Three

Aim To investigate time trends in prevalence of symptoms of asthma by repeating, during 2001–3 (Phase Three), the International Study of Asthma and Allergies in Childhood (ISAAC) Phase One study that was conducted in New Zealand in 1992–3. Methods ISAAC Phase Three involved repeating the cross-sectional questionnaire survey of two age groups of school children (6–7 years and 13–14 years, children and adolescents respectively) using the same methodology as Phase One. In New Zealand it was conducted in Auckland, Bay of Plenty, Christchurch, Nelson, and Wellington. Results After 9 years, reported asthma ever increased from 24.6 % to 30.2 % in children and from 24.1 % to 32.4 % in adolescents (p<0.001). Current wheeze (written questionnaire) significantly decreased in children from 23.6 % to 22.2 % (p=0.002) and in adolescents from 29.7 % to 26.7 % (p=0.047), and for the video questionnaire from 18.1 % to 11.1 % (p<0.001). There was a significant reduction in wheezing limiting speech from 5.0 % to 3.7 % in children, and 7.9 % to 6.2 % in adolescents. Little regional variation was found. A higher proportion of children with asthma symptom