Acute-to-Chronic Ratio as a Metric for HIV Surveillance

Abstract

Early diagnosis is important for HIV control on both the individual and the population level. Patients who are diagnosed shortly after infection have more treatment options which can result in delayed progression to AIDS. Early diagnosis can also help to reduce the spread of HIV: with viral loads at the highest level, the newly infected have the highest risk of transmitting HIV to partners. Accordingly it is important to evaluate at a population level whether individuals are diagnosed shortly after infection. For this purpose, we introduce the acute-tochronic ratio, which is the odds of the infected individuals being diagnosed in the acute infection stage versus the chronic infection stage among those who seek HIV testing. We demonstrate this new metric through HIV testing results from sexually transmitted disease clinics of four cities, and compare the four populations with respect to how quickly the infected get HIV testing.