Arterial Elasticity: A Substudy of Strategic Timing of AntiRetroviral Treatment (START)

The purpose of this study is to find out if starting anti-retroviral therapy (ART) above 500 cluster-of-differentiation-4 (CD4)+ cells/milliliter (mL) ('early ART group') is better at reducing the stiffness of arteries than waiting to start ART until the CD4+ drops below 350 cells/mL ('deferred ART group'). Artery stiffness has been associated with an increased risk of cardiovascular (heart) disease, and could be useful as an earlier indicator of heart disease. In this study, the stiffness of arteries will be measured at study entry, months 4, 8, 12, and annually thereafter, using a tonometer on the participant's forearm.