Background:  It has been suggested that HIV/hepatitis C virus (HCV) -co-infected patients have a more rapid progression of HIV disease, and that the response to ART may be impaired, in comparison to HIV-mono-infected patients. In addition, hepatotoxicicty may be higher after starting ART leading to discontinuation and frequent switching in this subgroup of patients, making more difficult a successful, durable treatment.

Methods:  This was a cohort study of 912 ART-naive HIV-infected patients initiating ART from January 1997 to June 2005 in a single institution. Outcomes (clinical progression of HIV disease, and immunological recovery at the end of follow-up) were analyzed according to the CD4⁺ cell count at initiation of therapy stratified in 4 categories (<200, 200 to 349, 350 to 500, >500). Clinical progression was defined as the development of HIV-related event in patients who were previously asymptomatic or the development of AIDS. Patients with AIDS prior to initiation of ART were excluded from analysis. A multiple logistic regression approach with LOCF was used.

Results:  Among 912 patients, 280 (31%) with prior AIDS were excluded; 476 patients were co-infected with HCV (of whom 92% were injection drug users). Patients were followed for a median 56.23 months (IQR 27.03 to 78.20). Median CD4⁺ cells at initiation of therapy was 194 cells/mm³ (IQR 70 to 338) and median HIV RNA was 5 log₁₀ copies/mL (IQR 4.4 to 5.4). Clinical progression was observed in 204 of 632 (32%). At the end of follow-up, CD4⁺ had increased to a median 442 cells/mm³ (IQR 267 to 649) and 61% patients had HIV RNA <50 copies/mL. The risk of clinical progression (29%, 33%, 33%, and 36%, respectively) and the possibility to reach an undetectable HIV RNA (66%, 64%, 48%, and 47%, respectively) was not significantly different in the four CD4⁺ cell count categories.

Conclusions:  In HIV/HCV-co-infected patients with no AIDS at initiation of combination ART, the risk of clinical progression and the response to ART was similar across all the CD4⁺ cell count strata. Initiation of ART in co-infected patients should follow the same guidelines as in HIV-mono-infected patients.