What explains falling asthma mortality?

To the Editor: The Australian Bureau of Statistics recently released details of asthma mortality for 2002. These figures indicate that asthma mortality has continued to decline in 2002 and that deaths in young people aged 5–34 years are at their lowest level since the early 1950s (Box). In this age group, the number of deaths fell from 43 in 2001 to 33 in 2002 (a 23.3% drop), and for all ages the number of deaths fell from 422 in 2001 to 397 in 2002 (a 5.9% drop). This suggests that the various asthma awareness activities, spearheaded by the National Asthma Council and other interest groups, have been successful in raising awareness of asthma and its management. Or does it?

Emerging evidence suggests other changes in the epidemiology of asthma in Australia. Robertson recently reported a 26% decrease in the prevalence of asthma in Melbourne school children between 1993 and 2002, but increased reporting of rhinitis and eczema over the same period.1 The significance of these findings is difficult to interpret without measures of airway function. A second study supported these results and also observed a small decline in the prevalence of parent-reported asthma, but found little change in atopy or airway hyperresponsiveness.2 Age-adjusted hospital separation rates for asthma decreased by 31.1% in young people and 31.4% in all ages between 1989–90 and 1999–00.3

There is little evidence of improved management of asthma in the general practice setting. Data published from the BEACH (Bettering the Evaluation and Care of Health) survey of general practice activity indicates a significant reduction in rates of presentation for asthma among children but not adults, with no changes in indicators of severity over time.4 Our recent research in south-western Sydney, examining uptake of the “asthma 3+ visit plan”5,6 by general practitioners and their patients, is disappointing. It suggests reluctance on the part of both GPs and patients to participate in the plan.

Clearly, there remains much that we do not understand about the natural history of asthma.7 We need to continue to monitor asthma through regular surveys and routine data collection in order to understand more about fluctuations in asthma prevalence, the relationship to changing child-rearing practices (such as use of childcare facilities) and the impact of management practices.

Asthma mortality in Australians aged 5–34 years, 1920–2002*

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* Points on the graph represent 3-year “moving” averages — for example, the 2001 value is the average of 2000, 2001 and 2002 data; the 2000 value is the average of 1999, 2000 and 2001 data, etc. This technique is used to smooth annual fluctuations that occur in data of this kind.