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Bone Loss Common, Screening Advised

Summer/Fall 2010

Several recent studies looked at low bone mineral density among people with HIV. At AIDS 2010 (abstract THPDB104), ICAAC 2010 (abstract H-226), and in the November 27, 2010, issue of AIDS, Anna Bonjoch from University Hospital German Trias in Barcelona and colleagues reported that about half of a Spanish cohort of 671 HIV positive people on ART had osteopenia (mild-to-moderate bone loss), while about one-quarter had the more severe osteoporosis.

Among 391 participants who had at least two DEXA scans, 28% experienced progressive bone loss during a median follow-up period of 2.5 years (13% from normal to osteopenia, 16% from osteopenia to osteoporosis). Significant predictors of bone loss included older age, male sex, low body mass index, and longer use of tenofovir or protease inhibitors.

In related research presented at AIDS 2010, Richard Haubrich and fellow ACTG Study 5142 investigators (abstract WEAB0304) compared changes in bone density among people taking various ART combinations. Participants taking all regimens experienced bone mineral loss, but some were worse than others.

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People who took tenofovir experienced significantly more bone loss than those taking zidovudine (AZT, Retrovir) or stavudine (d4T, Zerit), while those taking a lopinavir/ritonavir protease inhibitor-based regimen had a trend toward more bone loss than those using an efavirenz NNRTI-based regimen.

In the September 10 issue of AIDS, Marlous Grijsen from the University of Amsterdam and colleagues reported that men with primary, or very early, HIV infection already had low bone density in the spine and hip compared with an HIV negative reference population. In a study of 33 newly infected men (average age 38 years), 45% had osteopenia and 6% had osteoporosis; though the study was small, the risk appeared to increase with higher viral load.

Turning to the clinical significance of reduced bone density among people with HIV, two recent studies produced conflicting results. At the 1st International Workshop on HIV and Aging in Baltimore in October, researchers from GlaxoSmithKline (abstract O_07) presented an analysis of more than 200,000 participants enrolled in the Ingenix Impact National Benchmark Database; 59,584 HIV positive people, about half of them on ART, were each matched with three HIV negative individuals.

During follow-up, 4.2% of HIV positive participants sustained new non-traumatic fractures (bone breaks not caused by trauma such as accidents) compared with 3.7% of HIV negative participants, for an incidence rate ratio of 1.14, or 14% higher risk.

Factors significantly associated with fracture risk included prior fractures, low physical activity, low body weight, heavy alcohol consumption, and use of bisphosphonates (a class of drugs used to manage bone loss). Among middle-aged people (30-59 years), HIV infection was an additional risk factor. The likelihood of fractures increased significantly more with advancing age among HIV positive people with or without AIDS compared with HIV negative participants.

But another recent study, published in the November 13, 2010, issue of AIDS, did not see an increase in fractures among 1,728 mostly premenopausal HIV positive and 663 at-risk HIV negative participants in the Women's Interagency HIV Study (WIHS).

Over a median follow-up period of about five years, 8.6% of HIV positive women and 7.1% of HIV negative women sustained new fractures; incidence rates were 1.8 and 1.4 per 100 person-years, a difference that did not reach statistical significance.

Significant fracture risk factors included older age, white race, hepatitis C coinfection, cigarette smoking, and opiate use. However, there was no observed link between fractures and use of any antiretroviral drug class or particular drugs, including tenofovir.

In the October 15, 2010, issue of Clinical Infectious Diseases, Grace McComsey and an international team of experts recommended that all HIV positive women who have reached menopause and all HIV positive men age 50 or older -- as well as those with a history of past fragility fractures -- should undergo DEXA bone density screening every two to five years. Those with prior fragility fractures (but not traumatic fractures) should be screened regardless of age. In contrast, recent guidelines from the National Osteoporosis Foundation recommend bone screening for women over 65 and men over 70 with no risk factors.

Individuals with signs of bone loss should consider treatment such as alendroate (Fosamax) to improve bone density and prevent further loss, the authors advised. To reduce the risk of bone problems, the authors recommended that HIV positive people quit smoking, take calcium and vitamin D supplements, get adequate sun exposure, and exercise regularly. However, they concluded that there is "currently no evidence" to suggest that switching to different antiretroviral drugs can improve bone density or lower fracture risk.

Liz Highleyman (liz@black-rose.com) is a freelance medical writer based in San Francisco.




This article was provided by San Francisco AIDS Foundation. It is a part of the publication Bulletin of Experimental Treatments for AIDS. Visit San Francisco AIDS Foundation's Web site to find out more about their activities, publications and services.
 

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