• Carotid artery intima-media thickness (CIMT) [ Time Frame: At study entry and Weeks 48, 96, and 144 ] [ Designated as safety issue: No ]
  
• Absolute changes in brachial artery FMD from prior to treatment initiation [ Time Frame: At Weeks 4, 24, and 48 ] [ Designated as safety issue: No ]
  
• Absolute changes in trunk fat from entry as measured by dual-energy x-ray absorptiometry (DXA) [ Time Frame: At study entry and Week 96 ] [ Designated as safety issue: No ]
  
• Absolute changes in visceral fat as measured by single slice abdominal computed tomography (CT) scan [ Time Frame: At study entry and Weeks 48 and 96 ] [ Designated as safety issue: No ]
  
• Fasting serum total cholesterol, high-density lipoprotein (HDL) cholesterol, direct low-density lipoprotein (LDL) cholesterol, triglycerides, glucose, and apolipoprotein B-100 [ Time Frame: Throughout study ] [ Designated as safety issue: No ]
  
• Fasting glucose and insulin [ Time Frame: Throughout study ] [ Designated as safety issue: No ]
  
• Pro-inflammatory HDL and high sensitivity C-reactive protein (hsCRP) [ Time Frame: Throughout study ] [ Designated as safety issue: No ]
  
• CD4/CD8 and CD38 levels [ Time Frame: Throughout study ] [ Designated as safety issue: No ]
  
• Percent changes in bone mineral density of the lumbar spine and left hip [ Time Frame: At study entry and Week 96 ] [ Designated as safety issue: No ]
  
• Carboxy-terminal collagen CTX and osteocalcin [ Time Frame: Throughout study ] [ Designated as safety issue: No ]
  
• Calculated tubular maximum for phosphate corrected for glomerular filtration rate (TmP/GFR) using urine phosphate [ Time Frame: At study entry and Weeks 4, 24, 48, 96, and 144. ] [ Designated as safety issue: No ]
  
• Changes in self-reported fat distribution from entry as measured by the body image questionnaire [ Time Frame: At study entry and Week 144 ] [ Designated as safety issue: No ]
  

Of the five anti-HIV drug classes, three are recommended as first-line regimens for patients who have never received anti-HIV treatment before (treatment naive): nucleoside reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs), and protease inhibitors (PIs). The U.S. Department of Health and Human Services (HHS) guidelines recommend that treatment-naive HIV- infected people be treated with a triple drug regimen that includes two NRTIs + one NNRTI or two NRTIs + one PI as their initial treatment regimen.

According to data, an efavirenz (EFV)-containing regimen (two NRTIs + one NNRTI, with EFV as the NNRTI) requires fewer pills for the patient, has mild and few side effects, and is more effective in reducing viral load than other regimens, making it the preferred choice for most patients. However, for some patients, an EFV-containing regimen is not possible due to dangerous side effects, acquired NNRTI-resistant HIV virus, or other undesirable effects. For these patients, it is necessary to find alternative regimens with comparable safety and efficacy. The main study will examine how well different combinations of anti-HIV drugs work, including safety and drug tolerability for various combinations.

Some participants of A5257 will be asked to participate in this optional metabolic substudy of A5257. It will only take place at some study sites and may last up to 144 weeks, including time on A5257. The primary focus of this substudy is to examine carotid artery intima-media thickness (CIMT) as it relates to both ritonavir (RTV)- and raltegravir (RAL)-containing regimens. Randomization, stratification, treatment assignments, and study visits will be as per A5257. Female participants who become pregnant while in the study must inform the study staff immediately, and will subsequently be discontinued from the study without any further evaluations.

In the first 10 participant at each imaging site, the flow-mediated vasodilation (FMD) test, which measures cardiovascular risk, will be completed twice. This test will be performed on Week 24.

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.