Canadian Medical Association Journal 1996; 154: 841-843
Studies of the economic burden of asthma began to emerge in the 1970s.[3,4] Although informative, these early studies focused on the impact on patients and their families rather than on society and did not adhere to many of the basic principles of cost-of-illness methodology. Recently, a review was published of several international assessments of the economic burden of asthma.[5] These studies viewed costs from a societal perspective while attempting to adhere closely to the principles of cost-of-illness analysis -- all with varying degrees of success.[6] The study by Krahn and associates is the most meticulous of the recent analyses. The authors take the precaution of including the more transparent and comprehensive contributors to direct costs (e.g., nursing services, ambulance use, drugs and devices, outpatient diagnostic tests and research) than previous asthma cost studies have done. Also, multiple and overlapping data sources were used to provide ranges rather than single-point estimates for many key medical costs.
The authors estimate that the average annual costs of asthma in Canada totalled between $504 and $648 million in 1990. Although this seems large in absolute terms, international comparison reveals that the average annual per capita costs in Canada -- $19.06 -- are notably lower than those in several other industrialized countries, including Australia ($32.33), Sweden ($47.26), the United Kingdom ($36.48) and the United States ($29.99).[6] (These figures are based on US dollars, using the US-Canadian exchange rate [US$1 = Cdn$1.167] used by Krahn and associates.) The relatively low average annual per capita costs in Canada appear to be consistent both for direct and indirect costs.
Although the reasons for this finding are unclear, at least two explanations may be postulated. The relatively low costs of asthma in Canada could represent an undervaluing of medical and social services by the Canadian health and welfare systems. Alternatively, they could imply a more efficient use of economic resources. Although definitive testing of either postulate is unfeasible, the indirect evidence amassed in the epidemiologic literature would suggest that the latter hypothesis is true.
International comparisons of asthma-related disability and death demonstrate that per capita expenditures for asthma in Canada as well as key adverse-outcome measures such as death rates are similar to those in the United States and lower than those in several other industrialized countries.[7,8] Also, Canadian rates of asthma-related hospital admissions, at least for older children and young adults, are similar to those in the United States.[9,10] These comparisons suggest that resources for the treatment of asthma are being used more efficiently in Canada than in other countries.
Although this conclusion may be appealing, there may be other explanations. For example, lower rates of hospital admission and of death would also be expected if the intrinsic expression of the disease were less severe in the Canadian population. Thus, while it seems clear that the per capita costs of asthma in Canada are low compared to those in several other industrialized countries, the implications of this phenomenon are and will likely remain uncertain.
The study by Krahn and associates does, however, provide some plausible explanations for the comparatively lower per capita costs of asthma in Canada. In their direct comparison of categories of costs in Canada and the United States, they appropriately highlight the fact that "utilization patterns were strikingly similar and that differences in overall costs and costs by category were largely accounted for by differences in unit costs." This finding suggests that relative economic inefficiencies exist in the United States, one well-characterized example being the high cost of administration in the US health care system.[11]
Krahn and associates' analysis is an excellent example of a prevalence-based cost-of-illness study of asthma. In many ways it provides a benchmark for illustrating the extent and relative distribution of medical and nonmedical resources devoted to the management of asthma. By the very nature of its cost-of-illness methodology, however, it is limited to the quantification of economic burden and, hence, fails to address the important societal questions related to the relative benefits and costs of investments in asthma care. Specifically, cost-of-illness methodology does not provide direct information for clinical and administrative decision-makers regarding the relative cost-effectiveness of different asthma treatments.
A US task force recently reviewed the existing health-economics literature relating to cost-effectiveness of asthma management.[12] This review revealed many shortcomings in the available studies, including a lack of standard approaches for evaluating the economic costs and benefits of interventions, varying lengths of follow-up and the use of nonstandard outcome measures. These inconsistencies hinder decision-makers in their ability to compare the clinical and economic benefits of alternative treatments of asthma.
With the addition of Krahn and associates' study the international literature on the costs of asthma provides a comprehensive body of information establishing the economic burden of this disease from a societal perspective. The next task for those interested in enhancing the efficiency of asthma care is to improve the methods, standardization, breadth and scope of comparative economic studies of asthma management strategies. Perhaps topping the list of priorities is the need to study the cost-effectiveness of various proposed national and international guidelines for the management of asthma.
References