Effect of accompanying antiretroviral drugs on virological response to pegylated interferon and ribavirin in patients co-infected with HIV and hepatitis C virus

Objectives: The effects of antiretroviral drugs on the response to pegylated interferon plus ribavirin remain uncertain. We evaluated whether antiretroviral drugs affected the response to pegylated interferon plus ribavirin in patients co-infected with HIV and hepatitis C virus (HCV). Methods: We conducted a retrospective analysis of two cohorts of HIV/HCV-co-infected patients treated with pegylated interferon plus ribavirin between 2001 and 2007 in Spain. The outcome measure was sustained virological response (SVR). Logistic regression models were used to test possible associations between non-response and pre-treatment characteristics, including accompanying antiretroviral drugs. Results: The study sample comprised 1701 patients: 63% were infected with HCV genotype (G) 1 or 4 and 88% were taking highly active antiretroviral therapy (HAART). Factors independently associated with increased odds of SVR were G2 or 3, HVC RNA,500000 IU/mL and CDC clinical category A or B. When we adjusted for these prognostic factors and dose of ribavirin/kg, the adjusted odds ratio (AOR) of SVR for patients without HAART was 1.31 [95% confidence interval (CI) 0.91-1.88; P=0.144]. Taking the backbone of tenofovir and lamivudine/emtricitabine as a reference, we found that, with the exception of regimens including zidovudine, the effect of other nucleoside reverse transcriptase inhibitor backbones had little effect on SVR. The AOR of SVR for zidovudine and lamivudine was 0.65 (95% CI 0.46-0.93, P=0.017). We carried out several sensitivity analyses, the results of which were consistent with the findings of the primary analysis. Conclusions: Our results suggest that, with the exception of regimens including zidovudine, accompanying antiretroviral drugs have little effect on the virological response to pegylated interferon plus ribavirin in HIV/HCV-co-infected patients.