SUMMARY: People with both HIV and hepatitis C are more likely to sustain hip or spine fractures than people with one or none of these viruses, according to a study of nearly 39,000 Medicaid recipients presented at CROI 2011.

By Liz Highleyman

Approximately one-third of HIV positive people are also infected with hepatitis C virus (HCV). HIV/HCV coinfected individuals experience more rapid liver disease progression, on average, and studies indicate that they are more likely to have reduced bone mineral density (osteopenia or the more severe osteoporosis). Likelihood of bone fractures, however, has not been well studied.

As described at the recent 18th Conference on Retroviruses and Opportunistic Infection (CROI 2011), researchers from Massachusetts General Hospital and the University of Pennsylvania compared fracture rates among HIV/HCV coinfected people on antiretroviral therapy (ART) and those with just one of these viruses.

This retrospective analysis looked at U.S. Medicaid participants age 18 and older from California, Florida, New York, Ohio, and Pennsylvania, between the years 1999 and 2005. A total of 36,950 patients were HIV/HCV coinfected, 95,827 had only HIV, 276,901 had only HCV, and 366,829 had neither virus. About 30% to 50% in the various cohorts were women, and the average age range was about 40 to 50 years.

The researchers used ICD-9 diagnosis codes in patient medical records to determine the number of hip and vertebral spine fractures, and ART use was determined based on pharmacy claims.

Results

	HIV/HCV coinfected people had an increased risk of hip fractures compared with HCV monoinfected, HIV monoinfected, or uninfected participants:
	HIV/HCV coinfected: 5.8 per 1000 person-years; HCV monoinfected: 5.1 per 1000 person-years; HIV monoinfected: 4.5 per 1000 person-years; Uninfected: 1.9 per 1000 person-years.
	Coinfected patients and people with HCV alone had a higher risk of spine fractures than HIV monoinfected or uninfected participants:
	HIV/HCV coinfected: 7.2 per 1000 person-years; HCV monoinfected: 6.2 per 1000 person-years; HIV monoinfected: 3.6 per 1000 person-years; Uninfected: 3.2 per 1000 person-years.
	The increased risk of fractures associated with coinfection was more pronounced for women than for men:
	Women -- hip:   HIV/HCV vs HCV only: adjusted hazard ratio (aHR) 1.44, or 44% higher risk; HIV/HCV vs HIV only: aHR 1.77; HIV/HCV vs uninfected: aHR 2.50, or 2.5 times higher risk.
	Women -- spine:   HIV/HCV vs HCV only: aHR 0.81, about a 20% lower risk; HIV/HCV vs HIV only: aHR 1.65; HIV/HCV vs uninfected: aHR 1.64.
	Men -- hip:   HIV/HCV vs HCV only: aHR 1.44; HIV/HCV vs HIV only: aHR 1.39; HIV/HCV vs uninfected: aHR 2.07, or about twice the risk.
	Men -- spine:   HIV/HCV vs HCV only: aHR 0.81; HIV/HCV vs HIV only: aHR 1.24; HIV/HCV vs uninfected: aHR 1.37.

Based on these findings, the researchers concluded, "Antiretroviral-treated HIV/HCV coinfected patients experienced increased rates of hip fractures compared to HCV monoinfected, antiretroviral-treated HIV monoinfected, and uninfected persons."

"Mechanisms for the association between HCV and fractures are unclear," they added, but "[h]igher rates of fractures among HIV/HCV patients might be due to additive effects of HIV infection, HCV infection, and ART."

Investigator affiliations: Massachusetts General Hospital, Boston, MA; University of Pennsylvania, Philadelphia, PA.

4/5/11

Reference
J Volk, R Localio, C Newcomb, 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 (CROI 2011). Boston. February 27-March 2, 2011. Abstract 914.