Background:  The efficacy and safety of pegylated interferon + ribavirin (pegIFN-RBV) may be compromised in patients receiving HAART due to potential interactions between RBV and NNRTI. Our objective was to compare the effectiveness and safety of pegIFN-RBV in HIV/hepatitis C virus (HCV)⁺ patients with a HAART including tenofovir (TDF) vs those not including TDF.

Methods:  We carried out a retrospective study (35 sites) of all HIV/HCV⁺ patients who initiated pegIFN-RBV between January 2003 and November 2005 and who were receiving concomitantly a HAART regimen consisting of 2 NRTI plus either 1 NNRTI, 1 protease inhibitor (PI), or abacavir (ABC). We excluded patients receiving didanosine (ddI) or TDF+ zidovudine (AZT)/stavudine (d4T)/ABC. Patients were categorized in 2 groups:  TDF (n = 238) that included patients whose NRTI components were TDF + lamivudine (3TC) or emtricitabine (FTC); and non-TDF (n = 481) that included patients whose NRTI components were AZT + 3TC (n =265), d4T + 3TC (n = 164), or ABC + 3TC (n =52). The primary efficacy endpoint was a sustained virologic response.

Results:  Patients on TDF and non-TDF groups were well matched in baseline characteristics except for a lower CD4⁺ cell count mean (535 vs 601; p = 0.003), exposure to more HAART regimens (7.2 vs 5.7; p <0.001), and a higher mean glutamic oxaloacetate/glutamate pyruvate transaminases (GOT/GPT) quotient (0.84 vs 0.77; p = 0.04). Safety analysis revealed no differences between the groups in relation to death, hepatic decompensation and interruption of pegIFN-RBV due to adverse events. A dose-ribavirin reduction was more frequent in non-TDF treated patients (12.8 vs 19.5%; p = 0.03) , particularly in patients treated with AZT (23.2%; p = 0.003). No significant differences were found in the sustained virologic response among patients in the TDF and non-TDF groups by ITT analysis (45% vs 39%; p =  0.119). Factors associated with sustained virologic response in univariate analysis were HCV genotype 2/3, HCV viral load <500,000 IU/mL, baseline HIV viral load <50 copies/mL, GOT/GPT quotient, and alcohol intake >50 g/d. When we adjusted by these variables, the OR of achieving a sustained virologic response in the different dual NRTI groups by logistic regression is shown in the table.

*including patients with AZT+3TC+ABC

Conclusions:  Our results suggest that in HIV/HCV⁺ patients the use of TDF + 3TC or FTC is associated with an improved response to pegIFN-RBV. On the contrary, the concomitant use of AZT and pegIFN-RBV is associated with a worse tolerability and effectiveness.