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Higher Fracture Rate With HIV + HCV Than With Either Virus Alone
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18th Conference on Retroviruses and Opportunistic Infections, February 27-March 2, 2011, Boston
Mark Mascolini
People coinfected with HIV and HCV were more prone to hip and spine fractures than people infected with either virus alone or infected with neither virus, according to results of a large five-state study of Medicaid recipients [1].
Research links both HIV and HCV to low bone mineral density, but the combined impact of these viruses on fracture risk had not been studied. An earlier large case-control study at Massachusetts General Hospital found higher fracture rates in men and women with HIV than in men and women without HIV [2].
The new retrospective study involved adult Medicaid recipients in California, Florida, New York, Ohio, and Pennsylvania, representing 35% of all US Medicaid patients from 1999 through 2005. Recording rates of proximal hip and vertebral spine fractures by analyzing ICD-9 diagnosis codes, the investigators split the cohort into four groups:
Group 1: 36,950 HIV/HCV-coinfected people on antiretroviral therapy
Group 2: 276,901 HCV-monoinfected people
Group 3: 95,827 HIV-monoinfected people on antiretroviral therapy
Group 4: 366,829 people uninfected with either virus
Median ages of the four groups were (1) 42, (2) 47, (3) 39, and (4) 48. Proportions of women were (1) 29%, (2) 46%, (3) 37%, and (4) 29%. Median follow-up was longer in the HIV/HCV-coinfected group (5.2 years), than in group 2 (2.3 years), 3 (3.7 years), or 4 (2.2 years). Incidence of hip and spine fractures was higher in the coinfected group than in any of the other three groups:
Group 1: Hip 5.8 per 1000 person-years, spine 7.2 per 1000 person-years
Group 2: Hip 5.1 per 1000 person-years, spine 6.2 per 1000 person-years
Group 3: Hip 4.5 per 1000 person-years, spine 3.6 per 1000 person-years
Group 4: Hip 1.9 per 1000 person-years, spine 3.2 per 1000 person-years
The researchers built a multivariate statistical model that weighed the impact of age, gender, race, the interaction between age and gender, the interaction between cohort and race, propensity score, and state. In this analysis, coinfected women and men had more than a doubled risk of hip fracture compared with uninfected women and men: adjusted hazard ratio (AHR) 2.50 (95% confidence interval [CI] 2.09 to 3.00 for women and 2.07 (95% CI 1.85 to 2.32) for men. Spine fracture risk was 64% higher in coinfected women than uninfected women (AHR 1.64, 95% CI 1.36 to 1.97) and 37% higher in coinfected men than uninfected men (AHR 1.37, 95% CI 1.21 to 1.55).
HIV/HCV coinfected women had a 77% higher hip fracture risk than HIV-monoinfected women (AHR 1.77, 95% CI 1.45 to 2.17), and coinfected men had a 39% higher hip fracture risk than HIV-monoinfected men (AHR 1.39, 95% CI 1.22 to 1.57). Spine fracture risk was also higher in coinfected women than HIV-monoinfected women (AHR 1.65, 95% CI 1.33 to 2.04) and in coinfected men than HIV-monoinfected men (AHR 1.24, 95% CI 1.08 to 1.43).
Coinfected women and men ran a 44% higher risk of hip fracture than HCV-monoinfected women and men (AHR 1.44, 95% CI 1.31 to 1.59 for both women and men). But the risk of spine fracture was about 20% lower in coinfected women and men than in HCV-monoinfected women and men (AHR 0.81, 95% CI 0.73 to 0.89 for both women and men).
The researchers suggested that higher hip and spine fracture rates in HIV/HCV-coinfected antiretroviral-treated people may reflect additive effects of the two viruses plus antiretroviral therapy. They noted that reasons for the association between HCV and fracture remain unclear. How closely these results can be applied to a non-Medicaid US population also remains unclear.
References
1. Volk , Localio R, Newcomb C, et al. HIV/HCV co-infection increases fracture risk compared to HCV mono-infected, HIV-mono-infected, and uninfected patients. 18th Conference on Retroviruses and Opportunistic Infections. February 27-March 2, 2011. Boston. Abstract 914.
2. Triant VA, Brown TT, Lee H, Grinspoon SK. Fracture prevalence among human immunodeficiency virus (HIV)-infected versus non-HIV-infected patients in a large U.S. healthcare system. J Clin Endocrinol Metab. 2008;93:3499-3504.
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