A Phase 4 Cross-Sectional Study of Bone Mineral Density in HIV-1 Infected Subjects

Inclusion Criteria: * Must have the ability to understand and sign a written informed consent form, which must be obtained prior to initiation of any study procedures. * HIV-1 infected subjects regardless of race or ethnicity * Use of one of the following taken as a stable, continuous, NRTI-containing antiretroviral (ARV) regimen for ≥ 3 years are allowed (within-class change of agents other than TDF within 3 years of study entry are permitted as specified): * TDF plus PI/r-containing regimen including subjects who switched from one TDF plus PI/r regimen to another TDF plus PI/r regimen * a TDF plus non-PI/r-containing regimen including subjects who switched from one TDF plus non-PI/r regimen to another TDF plus non-PI/r regimen * a Non-TDF NRTI plus a PI/r-containing regimen including subjects who switched from one non-TDF NRTI plus PI/r regimen to another non-TDF NRTI regimen plus PI/r regimen * a Non-TDF NRTI plus a non-PI/r-containing regimen including subjects who switched from one non-TDF NRTI plus non-PI/r regimen to another non-TDF NRTI regimen plus non-PI/r regimen * Of note, subjects in the non-TDF groups must have never taken a regimen that includes TDF (including previous exposure to TDF for pre-exposure prophylaxis (PrEP)) * Subjects included in the TDF groups must have always taken a regimen that includes TDF. Non-PI/r agents include non-nucleoside reverse transcriptase inhibitors (NNRTIs), integrase inhibitors, triple nucleoside inhibitors and non-boosted protease inhibitors * Male subjects must be ≥ 50 years of age * Female subjects must be postmenopausal. Menopause can be assumed to have occurred in a woman when there is either appropriate medical documentation of prior complete bilateral oophorectomy or permanent cessation of previously occurring menses \> 12 months as a result of ovarian failure or bilateral oophorectomy with documentation of hormonal deficiency by a certified healthcare provided * Adequate records available to evaluate medical history for the 3 years prior to study entry Exclusion Criteria: * Subject has a contraindication to dual-energy X-ray absorptiometry (DEXA) scans * Subject has a history of osteoporosis before initiating Highly Active Antiretroviral Treatment (HAART)