As illustrated in Figure Six, three medical costs - pharmaceuticals, hospitalisations and medical consultations - represent close to 85% of the asthma medical cost burden. The majority of these costs, however, are incurred by a minority of adult asthmatics who suffer severe and very severe disease.

A similar distribution of medical costs between adult asthmatics who are well controlled and those receiving sub-optimal treatment is also evident. Respiratory specialists estimate that some 45% of Australia's adult asthmatic population, especially the more severe sufferers, are poorly controlled. Research into the under treatment of asthma in children also suggests that poor control is a problem for all age groups (Barnett and Oberklaid, 1991; Bauman et al, 1992). Thus, the additional demands on health services and the resultant cost to society of this widespread poor control is likely to be substantial.

Apart from the cost savings available from improving the proportion of asthmatics who are well controlled, there are quality of life benefits to consider. A reduction in activity restrictions and better self-confidence may result from improved symptom control. While these benefits are almost impossible to measure financially, they should not be discounted.

The indirect costs, or the economic costs of foregone output, as estimated in this study are predominantly the costs of absenteeism. Direct and caregiver asthma related absenteeism together account for over 60% of the total indirect cost estimates. The cost of lost productivity due to reduced work effectiveness and time spent attending consultations is much lower.

Even though available data is not complete and some assumptions are required to calculate the indirect costs of asthma, the magnitude of the costs requires that they be included. The more conservative estimate of asthma related lost productivity of around $220 million, derived from the alternative financial evaluation method, gives validity to the magnitude of the economic estimates. To exclude completely the cost of foregone output due to asthma related illness from the analysis would result in greater inaccuracy and a gross underestimate of the true cost of the disease.

Although the total cost estimate was developed from the best available data sources, it is not entirely comprehensive. Some medical and indirect costs have been omitted from the analysis because of a lack of reliable data. This analysis has valued an asthmatic's time with respect to what an individual can produce. Obviously, improved health status allows for additional benefits to an individual other than an individual's greater capacity for production. No attempt, however, has been made to place a financial value on the large impact asthma has on an individual's quality of life. While such intangible costs are difficult to quantify, they should not be ignored. Nor can an assessment be made on whether or not the current resource allocation for asthma is efficient. This falls beyond the scope of this cost of illness study.

As the pressure on healthcare resources continues to rise, there will be an increasing interest in understanding the economics of disease. A natural consequence of this trend will be improved data collection and the opportunity to refine existing disease cost estimates. For example, there is currently considerable debate over the method for valuing indirect costs in cost of illness studies. New methods of estimating the cost of lost productivity are now being investigated (Koopmanschap and van Ineveld, 1992). The estimates of the total cost of asthma developed in this study must be interpreted with these provisos in mind. This examination therefore represents a springboard for discussing the substantial impact of this common chronic disease on both the individual and the community. Raising awareness of the cost of asthma is only a step towards both improving the control of the disease and enabling better use of resources in the future.

Content Updated 1992