Background Anti-HCV treatment may add significant complexity to antiretroviral treatment (ART). The complexity of the medicines regimen could be a risk factor for non-adherence or increasing incidence of blips.

Purpose To determine if the addition of anti-HCV treatment to antiretroviral treatment increases the complexity of the treatment, therefore modifying medicines adherence and incidence of blips.

Materials and methods We conducted a retrospective observational study. HIV/HCV co-infected patients treated with interferon alfa-2a plus ribavirin for at least 12 weeks between 01/2008–06/2012 were included. We excluded patients with HIV viral load >50 copies RNA/mL in the six months prior to the introduction of anti-HCV treatment. The following variables were collected: sex, age, weeks on anti-HCV treatment and incidence of blips. Additionally, adherence (≥95%) and complexity index were collected before and after the addition of anti-HCV treatment. Blips were defined as a detectable HIV-RNA level (>50 copies/mL but no more than 1000 copies/mL) occurring between 2 negative assays. Complexity index was calculated based on a score (Martin et al , 2007) which considers number of pills taken per day, dosing schedule, dosage form and any specific instructions related to drug use. Quantitative and dichotomous variables were compared using the t-test for related samples and McNemar’s test respectively (confidence interval (CI) 95%). Data analysis was carried out using SPSS 20.0.

Results 36 patients were included (75% male, mean age 47 ± 5). The mean duration on anti-HCV treatment was 41 ± 18 weeks. The mean value of the complexity index before and after the addition of anti-HCV treatment to ART was 5.3 ± 1.9 and 11.4 ± 1.6 respectively (p < 0.001, CI:-6,68;-5,56). 4 out of 36 (11.1%) patients experienced viral blips (p > 0.005). After the introduction of the anti-HCV treatment, the number of non-adherent patients showed a non-significant increase from 11% to 22%.

Conclusions The addition of anti-HCV treatment to ART correlates with a significant increase in the complexity index, leading to higher non-adherence and blips rates.

No conflict of interest.