Challenges and statistical issues in estimating HIV incidence

Knowing the trends and current pattern of HIV infections is important for planning and evaluating prevention efforts and for resource allocation. However, it is difficult to estimate HIV incidence because HIV infections may not be detected or diagnosed until many years after the infection. Historically, HIV incidence was estimated based on the numbers of AIDS diagnoses and the back-calculation method. This method was no longer valid when the highly active antiretroviral therapy was introduced in 1996. This is because the therapy changes the incubation distribution by extending the period from HIV infection to AIDS diagnosis. Since then, the estimate of 40000 was used until the new estimate for 2006 was published. This presentation will tell the stories about the development of the new HIV incidence estimation methods and the statistical issues in estimating HIV incidence in the United States.