Pulmonary Substudy: 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') slows the rate of decrease in lung function over time compared to waiting to start ART until the CD4+ drops below 350 cells/mL ('deferred ART group'). Lung function normally declines with age, and both human immunodeficiency virus (HIV) infection and ART have been shown to case a decline in lung function as well. Decline in lung function can be an early indicator of chronic obstructive pulmonary disease (COPD), a significant cause of sickness and death in people with HIV. In this study, lung function will be measured at baseline and every year thereafter by using a spirometer.