Bone and Body Comp: A Sub Study of the SECOND-LINE Study

The use of anti HIV drugs (ART), and in particular a class of drugs known as nucleoside reverse transcriptase inhibitors (N(t)RTI), has been associated with changes in body fat and in particular loss of peripheral fat in the limbs. Low bone mineral density and osteoporosis are also common in HIV-infected patients. There appears to be some association between ART and bone loss, but this is poorly understood and requires further research. The SECOND-LINE study provides an opportunity to examine if a new anti-HIV drug (raltegravir) can result in greater increase in limb fat than a drug regimen containing N(t)RTI, which is currently standard of care. This study also provides an opportunity to examine if additional bone loss occurs with the second regimen of anti-HIV drugs and whether non-N(t)RTI regimens of ART used in second line therapy result in more or less bone loss than use of other classes of anti-HIV drugs such as protease inhibitors or N(t)RTI combinations. It is hypothesized that subjects randomised into Raltegravir arm will demonstrate greater increases in limb fat and smaller reductions in bone density at the proximal femur over 48 weeks than those randomised into the control arm (LPV/r + 2-3N(t)RTIs).