631   Lactic Acidemia Is Associated with Spinal Osteopenia in HIV-Infected Men.

A. Carr*¹, J. A. Eisman², J. Miller³, and D. A. Cooper¹.
¹St. Vincent's Hosp.;²Garvan Inst. for Med. Res.; and³Natl. Ctr. in HIV Epidemiology and Clin. Res., Sydney, Australia.

Background:Osteoporosis is increasingly recognised in HIV-infected patients and has been associated with both nucleoside analogues (NRTIs) and protease inhibitors (PIs). Trabecular bone mineral density (BMD), which predominates in the spine, changes more rapidly in response to external stressors than does cortical BMD.

Methods:We assessed bone parameters (total body BMD, t- score and z- score, and spinal and BMD) by DEXA in a lipodystrophy (LD) prevalence cohort (221 otherwise well, HIV⁺men, mean 43 yrs) between 11/98 and 2/99 with the following: demographics, smoking and exercise history, type(s)/duration of all ARV therapies, physician-assessed LD (overall and by region), CD4 counts, HIV RNA, fasting metabolic parameters (lipid, glycemic, lactate, liver enzymes, testosterone), and regional body fat and lean mass (DEXA, L4 abdo CT).

Results:32 patients were drug-naïve, 42 were receiving NRTIs and 147 were receiving NRTI-PIs. Osteoporosis (t-score <-2.5 SD) was found in 7 (3%) patients, and osteopenia (t-score -1.0 to -2.5 SD) was found in 44 (22%). No patient had a fracture since being HIV⁺. The only factors independently associated with osteopenia or osteoporosis were higher lactate (OR 2.39 [95% CI 1.39 to 4.11] per 1 mmol/l increase; p = 0.002) and lower weight pre-ARV therapy (OR 1.06 [95% CI 1.02 to 1.11] per 1 kg decrease; p = 0.006). Parameters independently associated with lower total BMD on linear regression were lower lean body mass, greater age and greater duration of d4T therapy. In contrast, independent parameters for lower spinal BMD were higher lactate, greater total NRTI duration, the product of lactate × total NRTI duration and greater age.

Conclusion:Osteopenia in HIV⁺men is more likely with lower weight pre-ARV therapy and in the presence of NRTI-related lactic acidemia. Lactic acidemia was mostly associated with reduced spinal, but not total, BMD, suggesting that the reduced spinal BMD has developed relatively recently in these patients and that patients with lactic acidemia may be at greatest risk of vertebral fractures rather than fractures of long bones.