Why START? Reflections that led to the conduct of this large long-term strategic HIV trial.

This monograph describes a cohort of 4685 HIV-positive persons, most of whom were recently infected, who volunteered to dedicate several years to being participants in a research study that addresses the question of when antiretroviral therapy (ART) should be initiated. Should it be started early after HIV infection occurs, or should it be deferred until the infection has started to impair immune function but before the risk of AIDS increases? There has been consensus based on robust data for many years that ART should be initiated following the development of AIDS. Also, within the past 6 to 7 years, data from randomized trials [1–3] and observational studies [4–7] emerged that supported the initiation of ART when the CD4 cell count declined to < 350 cells/μL among asymptomatic individuals. It has been hotly debated whether the clinical benefits of initiating ART at a CD4 cell count > 500 cells/ μL, compared with deferring ART until the CD4 cell count decreases to 350 cells/μL, as is being tested in the Strategic Timing of AntiRetroviral Treatment (START) study, outweigh the risks [8–10]. The debate is lively because the data available are not optimal. The fact that 4685 persons from 215 clinics in 35 countries volunteered to be randomized in START reflects the considerable uncertainty that many individuals with HIV infection and investigators around the world have about the answer to the question being addressed by START.