628   Assessment of Bone Mineral Density (BMD) in HIV-Infected Antiretroviral-Therapy-Naive Patients.

I. McGowan*¹, A. Cheng¹, S. Coleman¹, A. Johnson¹, and H. Genant².
¹Gilead Sci., Foster City, CA and²Univ. of California, San Francisco.

Background:Tebas et al. (AIDS14:F63, 2000) have suggested that the prevalence of osteopenia and/or osteoporosis may be increased in HIV-1-infected patients receiving antiretroviral therapy compared to the general population. It is uncertain whether reduced BMD is a consequence of HIV infection or the antiretroviral agents used to treat the disease.

Methods:Study GS-99-903 is an international phase III trial in which 600 antiretroviral-naïve patients will be randomized 1:1 to receive tenofovir DF or stavudine in addition to efavirenz and 3TC. In order to assess the potential effect of these regimens on BMD, the first 300 patients enrolled into the study will have dual x-ray absorptiometry (DXA) of the lumbar spine (L1—L4) and proximal femur. Two baseline measurements will be performed at both anatomical sites, and measurements will be repeated at 6-month intervals. All DXA scans will be analyzed in a standardized format by a single organization to ensure uniform image and instrument quality control.

Results:Baseline data are presented on the first 151 patients. The population was predominantly male (78%), with a mean age of 37 years, weight of 75 kg, HIV-1 RNA viral load of 4.92 log₁₀and CD4 cell count of 277

cells/mm³. Mean baseline BMD at L1—L4 was 1.0686 g/cm², with a mean T score of -0.0786 and a Z score of 0.0238. According to WHO definitions using T scores, 24% patients were classified as osteopenic and 2% osteoporotic at L1—L4. The mean baseline BMD of the femoral neck was 0.8877 g/cm², with a mean T score of -0.1142 and a Z score of 0.0723. Using T scores, 23% patients were classified as osteopenic and 1% osteoporotic at the femoral neck.

Conclusions:Evaluation of 151 antiretroviral naive patients suggest that chronic HIV-1 infection is associated with a significant prevalence of reduced bone mineral density.