HIV-positive people treated with antiretroviral therapy (ART) who are also co-infected with hepatitis C virus (HCV) are less likely to have abnormally high levels of cholesterol or triglycerides according to data presented at last week’s Forty-Sixth Interscience Conference on Antimicrobial Agents and Chemotherapy in San Francisco.
Hyperlipidaemia is a recognised complication of ART but exactly how HIV, HCV, hepatitis B virus and lipids interact is not fully understood.
Canadian researchers studied 729 people who were infected with HIV and compared their lipid levels with 305 HIV-infected people who also had HCV infection. All were taking ART and had their lipids checked at the beginning of the study and again at six and twelve months. The differences between the two groups were marked and statistically significant.
For those only infected with HIV the total blood cholesterol levels rose by an average of 0.99mmol/l at six months and by 1.43mmol/l at twelve months. But in those with HIV/HCV co-infection cholesterol rose by only 0.16 (p
When the total cholesterol findings were broken down to look at the most unhealthy types of fat carried in the blood - low density lipoprotein (LDL) and triglycerides - similar results were seen.
Disorders of the metabolism, such as high cholesterol levels, led to 7% of people with HIV stopping or changing their ART, compared to less than one per cent of those who were co-infected.
Twenty-two per cent of HIV-infected people went on to take a lipid-lowering drug such as a statin compared to just four per cent of those with co-infection.
The researchers also looked at what happened when people with co-infection were treated for the HCV infection using the drug interferon. Intriguingly they found that successful treatment of HCV means that the protection against raised lipids with ART is lost.
Total cholesterol rose by 0.85mmol/l in co-infected patients whose HCV levels dropped long-term after treatment with interferon. But the level was unchanged in patients who did not respond to interferon.
The researchers also looked at whether hepatitis B infection had any effect on lipids but found nothing to suggest it did.
They conclude that it remains to be seen whether this effect has any impact on lipodystrophy or the risk of heart disease in co-infected patients.
The protective effect of HCV infection on lipid levels has been suggested in previous studies.
Earlier this year at the Thirteenth Conference on Retroviruses and Opportunistic Infections in Denver delegates heard data which suggest that one particular type of hepatitis C virus - genotype 3 - has a much greater protective effect that others.
The other HCV genotypes (1, 2 and 4) were associated with an 18-fold lower risk of high total cholesterol compared to a 45-fold lower risk of high total cholesterol with genotype 3.
Cooper CL et al. HIV antiretroviral-related hyperlipidaemia is mitigated by HCV co-infection. 46th Annual Interscience Conference on Antimicrobial Agents and Chemotherapy, abstract H-1902, 2006.