Asthma prevalence increases as the economy develops
Asthma has been of high interest in New Zealand (NZ) since the asthma mortality epidemics of 1960’s and 1970’s which resulted in a lot of research and focus on better management. Subsequently NZ asthma management guidelines were published in 2002, 2016 and 2020 (adults) and 2005, 2017 and 2020 (children). Although there is no national asthma strategy, the Asthma and Respiratory Foundation NZ provides education and resources on asthma for the public and health professionals. These may have contributed to the fall of asthma prevalence and severity as shown in the Table.
ISAAC Phase Three was completed in 2003, a mean of 7 years after ISAAC Phase One in 5 NZ centres (Auckland, Bay of Plenty, Christchurch, Nelson and Wellington). Reported asthma ever significantly increased from 24.6% to 30.2% in children and from 24.1% to 32.4% in adolescents. Current wheeze (written questionnaire) significantly decreased in children from 23.6% to 22.2% and in adolescents from 29.7% to 26.7%, and for the video asthma questionnaire from 18.1% to 11.1%. 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. In 2003 a higher proportion of children with asthma symptoms reported having ever had asthma.
Subsequently, in 2018, the GAN Phase I study was completed in one NZ centre (Auckland). The prevalence of current wheeze showed a decrease in both age groups, however the proportion reporting asthma ever showed a decrease in the 6-7 year old children but little difference for the adolescents.
Although the prevalence of asthma symptoms in Auckland is showing a decrease the explanation for this decrease is unknown. It could be due to a combination of factors, including changes in unknown environmental causes of current asthma symptoms, changes in asthma awareness (the development of NZ asthma guidelines) or improved asthma treatment.
If this trend of decreasing prevalence of asthma symptoms, is maintained, it has positive implications for lessened burden of disease among asthmatics and lowered cost of treatment.