Gilead Sciences is one of the primary pharmaceutical manufacturers of HIV pre-exposure prophylaxis (PrEP) medications. In order to assess new HIV prevention medications, pharmaceutical companies must first determine a comparison group so they can evaluate whether their medications actually lower risk of infection. One way to do this is by calculating the “background” HIV incidence rate in settings where they conduct their clinical trials–meaning the HIV incidence rate in that population without them using the new medication. A recent infection testing algorithm (RITA) is one method used to estimate the background HIV incidence rate in an area, using different HIV tests to classify study participants as having “recent” or “longstanding” infection. However, this can be a complex statistical task.
Facente Consulting supported Gilead with statistical analysis relating to HIV incidence rates, assisting with the study design, analysis plan, and interpretation of study data for the PURPOSE trials. Facente Consulting’s role in this project included running simulations to assess the performance of various HIV recency assays in different local contexts as well as putting methods in place to account for common errors, such as the false recency ratio (FRR) and mean duration of recent infection (MDRI) in each study location.