Doubt cast on association between hepatitis co-infection and arterial disease in HIV-positive women

Co-infection with hepatitis C virus does not increase the risk of hardening of the arteries for HIV-positive women, according to a US study published in the August 24^th edition of AIDS. Hardening of the arteries is a major contributor to cardiovascular disease, and this study appears to contradict earlier research suggesting that HIV-positive individuals co-infected with hepatitis C have an increased risk of such disease. However, the current study did find that co-infected women had a modest increase in the risk of plaques forming in their carotid arteries.

There is now a considerable body of research indicating that HIV-positive individuals have an increased risk of hardening of the arteries (atherosclerosis) and cardiovascular disease. However, few studies have examined the association between HIV and hepatitis C co-infection and an increased risk of cardiovascular disease, and there is even less information on the relationship between the presence of these two infections and arterial disease.

Investigators from the Women’s Interagency HIV Study therefore designed a cross sectional study monitoring carotid artery intima media thickness and carotid plaques in 1675 women with differing HIV and hepatitis C infection statuses. Both of the measurements used in the study have beem shown in earleir to research to be an acurate marker of early arteria disease. A total of 220 women were co-infected with HIV and hepatitis C; 53 were mono-infected with hepatitis C; 950 were HIV mono-infected; and 452 women were controls and infected with neither virus.

The women infected with hepatitis C had a higher prevalence of traditional risk factors for arterial disease. They were older, were more likely to report a longer duration of smoking, had higher blood pressure, and a higher prevalence of diabetes.

Women co-infected with HIV and hepatitis C had lower median CD4 cell counts than women who were HIV mono-infected (367 vs. 442 cells/mm³), were less likely to be taking HIV treatment (58% vs. 67%) and had a higher median HIV viral load (800 vs 200 copies/ml). All these characteristics are are now considered potential risk factors for serious non-HIV-related illnesses such as heart disease.

Median carotid artery intima media thickness was comparable in co-infected women and women only infected with hepatitis C. However, it was higher in both hepatitis C-infected groups than it was in women who were only infected with HIV or who had neither infection.

But when the investigators adjusted their results for baseline characteristics, they found that infection with hepatitis C was no long associated with carotid intima media thickness.

However, co-infected women had a modestly increased risk of carotid plaques (adjusted odds ratio, 1.64; 95% CI: 0.91 – 2.94).

“In summary, contrary to prior studies, we did not find an association of hepatitis C virus infection and greater carotid intima media thickness after adjustment for demographic and traditional cardiovascular risk factors”, conclude the investigators.

They continue, “HIV/hepatitis C coinfection may be associated with a greater risk of carotid plaques; further follow-up over time should clarify this question. Additionally, whether hepatitis C infection may differentially affect the development and progression of subclinical atherosclerosis in the different segments of the carotid artery should be evaluated.”