After following 93 patients for at least 72 weeks, researchers at Washington University School of Medicine, St Louis, have concluded that duration of HIV infection, together with traditional risk factors for osteopenia, play a more significant role in the bone mineral loss experienced by some people with HIV.
Findings from the longitudinal study were published in the online edition of Clinical Infectious Diseases on January 28th.
Fifty seven of 128 patients screened at baseline had osteoporosis or osteopenia. 68% were taking a PI-containing HAART regimen, 70% had undetectable viral load and the mean nadir CD4 cell count was 236 cells/mm3 . A substantial proportion had a history of significant weight loss (27%) or severe wasting (14%), and 70% had a calcium intake below the US recommended daily minimum. The average age of the cohort was 42, and 86% were male.
Thirty two patients declined follow-up and three were excluded from the analysis.
Patients with osteoporosis were somewhat more likely to smoke (p=0.06) and to have a history of steroid use lasting more than one month (p=0.08), and significantly more likely to have low current weight, low body mass index, low truncal fat mass and low peripheral fat mass (p<0.01 for all). Osteopenia was not correlated to the ratio of central to peripheral fat.
A strong association with duration of HIV infection was found (p=0.05), but no association between exposure to any antiretroviral class and osteopenia was found, although the authors caution that many patients changed therapy during the study, making it difficult to draw conclusions.
During the 72 week follow-up, a small but significant increase in lumbar and hip bone mineral density was noted (2.6% +/- 0.6%, p=0.01), regardless of duration of HIV infection or HAART. The increase in lumbar BMD (but not hip) was significantly correlated with the degree of CD4 cell increase over the 72 week follow-up, and patients who had undetectable viral load at baseline saw greater gains in lumbar BMD than patients who were viremic. Weight gain did not affect bone mineral density.
Despite the improvements in bone mineral density, patients continued to experience a state of high bone turnover, reinforcing the view that antiretroviral therapy exerts some effect on bone metabolism. Indinavir has been shown to inhibit bone formation, but ritonavir may be protective against osteoporosis, according to studies presented at the Fourth International Workshop on Adverse Drug Reactions and Lipodystrophy in HIV last year.
Related story on bone mineral loss
Bone loss linked to low CD4 count on treatment - is bone a reservoir for HIV?
Further information on this website
Reference
Mondy K et al. Longitudinal evolution of bone mineral density and bone markers in human immunodeficiency virus-infected individuals. Clinical Infectious Diseases 36 (online edition), 2003.