The economic burden of allergic rhinitis: a critical evaluation of the literature.

Although a large number of economic analyses of allergic rhinitis have been published, there are relatively few empirically based studies, particularly outside the US. The majority of these analyses can be classified as burden-of-illness studies. Most estimates of the annual cost of allergic rhinitis range from dollars US 2-5 billion (2003 values). The wide range of estimates can be attributed to differences in identifying patients with allergic rhinitis, differences in cost assignment, limitations associated with available data and difficulties in assigning indirect costs (associated with reduced productivity) of allergic rhinitis. Approximately one-third of burden-of-illness studies include direct and indirect costs of allergic rhinitis, about one-third focus on direct costs only, and the remaining one-third focus exclusively on indirect costs due to reduced productivity. Indirect costs attributable to allergic rhinitis were higher in studies only estimating indirect costs (dollars US 5.5-9.7 billion) than in those estimating both direct and indirect costs (dollars US 1.7-4.3 billion). Although there are many economic evaluations of allergic rhinitis treatments in the published medical literature, very few represent formal cost-effectiveness evaluations that compare the incremental costs and benefits of alternative treatment strategies. Those that are incremental cost-effectiveness analyses have several limitations, including small samples, short study periods and the lack of a standardized measure of effectiveness. To date, the medical literature is lacking a comprehensive economic evaluation of general treatment strategies for allergic rhinitis. In undertaking such an analysis, serious consideration must be given to the study population of interest, the choice of appropriate comparators, the perspective from which the analysis is conducted, the target audience, the changing healthcare marketplace and the selection of a measure of effectiveness that incorporates both positive and negative aspects of treatments for allergic rhinitis. Future work would benefit from the development of a consensus on a summary measure of effectiveness that could be used in cost-effectiveness analyses of therapies for allergic rhinitis as well as additional empirical work to measure the association between severity of disease and its impact on worker productivity.