When to Initiate Combined Antiretroviral Therapy to Reduce Mortality and AIDS-Defining Illness in HIV-Infected Persons in Developed Countries

Background: Most clinical guidelines recommend that AIDS-free, HIV-infected persons with CD4 cell counts below 0.350 109 cells/L initiate combined antiretroviral therapy (cART), but the op-timal CD4 cell count at which cART should be initiated remains a matter of debate. Objective: To identify the optimal CD4 cell count at which cART should be initiated. Design: Prospective observational data from the HIV-CAUSAL Col-laboration and dynamic marginal structural models were used to compare cART initiation strategies for CD4 thresholds between 0.200 and 0.500 109 cells/L. Setting: HIV clinics in Europe and the Veterans Health Administra-tion system in the United States