Influenza - The role of burden-of-illness research

Influenza is associated with a significant economic burden on both society and the individual, resulting in considerable healthcare costs and loss of productivity, as well as intangible costs such as suffering, grief and soci al disruption. The incidence and severity of influenza infection depend, at least in part, on the age and health status of the population. For example , the incidence of influenza is relatively high among children and young ad ults, but serious complications are much more likely to occur among the ver y young (<1 year of age) and the elderly (>65 years of age). School absente eism tends to peak in the first half of a typical 6- to 8-week influenza ep idemic, followed by workplace absenteeism in the latter half as school-aged children pass the infection to family members. Cost-of-illness studies are used by policy-makers to justify budgets and se t priorities for prevention programmes, research and other expenditures. On the basis of German Sickness Fund data, recent estimates indicate that the cost of an influenza epidemic in that country is approximately 2 billion D eutschmarks (approximate to$US 1.4 billion). The bulk of these costs reflec ts indirect costs associated with lost productivity, a finding also noted i n an earlier French cost-of-illness study of influenza. Thus, the main econ omic burden of influenza falls on infected individuals, their employers and their relatives. Methodology used in cost-of-illness studies can be quite variable. For example, two main approaches are used in measuring indirect c osts (human capital and willingness to pay), although there is controversy as to which is the preferred method. Thus, investigators involved in cost-o f-illness studies must be explicit regarding study methodology in order to allow for appropriate interpretation of study results by interested parties .