Background:  Prior studies examining the effect of hepatitis C virus (HCV) co-infection on lipid levels among HIV-infected patients have provided contradictory results. Furthermore, the impact of HCV on HAART-associated dyslipidemia is not known. We conducted this study to examine the effect of HCV on lipid levels among patients in the University of Washington HIV cohort.

Methods:  This was an observational cohort study of all patients initiating their first HAART regimen. Patients were included if their lipid levels had been assayed within a year prior to HAART and while on their first HAART regimen. Generalized estimating equations were used to account for repeated measures, and to examine the relationship between lipid levels and demographic and clinical characteristics, individual antiretroviral medications, and HCV. Effect modification was assessed with interaction terms.

Results:  Of 306 HIV-infected patients included in the study, 54 (18%) had HCV. HCV was associated with lower mean total cholesterol (–27 mg/dL, p <0.001) and triglyceride (–82 mg/dL, p = 0.002) values compared with patients without HCV in adjusted analyses. Including body mass index did not alter the association between HCV and total cholesterol or triglyceride levels. Compared with patients receiving tenofovir (TDF)/lamivudine (3TC), patients whose regimen contained (4dT) stavudine/3TC (141 vs 114 mg/dL, p <0.001) or didanosine (ddI)/3TC (146 vs 114 mg/dL, p = 0.03) developed higher total cholesterol levels, while patients receiving 4dT/3TC (397 vs 252 mg/dL, p = 0.001) and TDF/ddI (390 vs 252 mg/dL, p = 0.03) developed higher triglyceride levels. Compared with atazanavir (AZT), patients who received amprenavir (APV) developed higher total cholesterol levels (153 vs 114 mg/dL, p = 0.04). HCV resulted in less of an increase in total cholesterol among patients receiving nevirapine (NVP) and lopinavir (LPV)/ritonavir (RTV). HCV resulted in less of an increase in triglyceride levels among patients receiving 4dT/3TC. We did not find an effect of HCV on LDL and HDL cholesterol levels.

Conclusions:  HCV has a dramatic effect on total cholesterol and triglyceride levels among HIV-infected patients, which does not appear to be mediated through lower body mass index. Effect modification is present among HCV, ART medications, and total cholesterol and triglyceride levels resulting in a smaller increase in lipid values among patients receiving those medications who have HCV. The influence of ART medications on cardiovascular disease risk factors, such as dyslipidemia, will increasingly influence treatment decisions.