The U.S. Department of Health and Human Services (HHS) guidelines recommend that HIV-infected people who have never received anti-HIV therapy be treated with a triple drug regimen. The most commonly prescribed and successful regimen contains the medication efavirenz (EFV). However, this regimen has been shown to cause undesirable side effects for some patients and is therefore not an option for them. Alternative regimens are needed for these patients.

The main study will look at how well different combinations of anti-HIV drugs work to decrease the amount of HIV in the blood (viral load) of and allow immune system recovery in people who have never received anti-HIV therapy. It will also examine drug tolerability and safety for the various drug combinations.

This substudy of A5257 will further examine the effects of these new regimens on metabolic, skeletal, and cardiovascular factors. The need for this substudy stems from data showing an increasing number of HIV -infected patients with metabolic, skeletal, and cardiovascular diseases, which may be directly related to the effects of antiretroviral therapy. Conventional understanding of disease development, risk factors, and consequences pertain to persons receiving older antiretroviral drugs. Consequently, it is necessary to examine the impact of newer antiretroviral drugs on metabolic, skeletal, and cardiovascular factors. The purpose of this substudy is to understand the contributions of HIV disease-related factors and antiretroviral therapy to the development of metabolic, skeletal, and cardiovascular disease among HIV -infected patients.