Impact of human immunodeficiency virus type 1 subtype on first-line antiretroviral therapy effectiveness.

OBJECTIVE: The effectiveness of antiretroviral treatment (ART) was compared in 416 naive patients from a French clinical cohort infected with B and non-B HIV-1 subtypes.
METHODS: Time to HIV viral load (VL) undetectability was calculated for each subtype group. Three other parameters were estimated 3, 6 and 12 months after enrolment: clinical progression (that is, AIDS-defining events or death), changes in CD4 cell counts from baseline and proportion of patients achieving an undetectable VL (<400 HIV-RNA copies/ml).
RESULTS: In this cohort, 317 patients (76%) were infected with a B subtype and 99 (24%) with a non-B subtype. Median time to VL undetectability was similar in the B subtype group [147 days, 95% confidence interval (CI) 119-165] and non-B subtype group (168 days, 95% CI: 105-234; P=0.16). After adjusting for AIDS-defining events at enrolment, baseline CD4 cell counts and VL, and for the treatment on which patients were initiated, no association was found between HIV subtypes and time to VL undetectability (B subtype vs non-B subtype: hazard ratio=0.80, 95% CI: 0.62-1.02, P=0.07). In the 3, 6 and 12 months after enrolment, subtype had no impact on clinical progression, CD4 cell count or VL responses to ART. This suggests that B and non-B subtypes do not affect first-line therapy efficacy, which is encouraging in view of the worldwide spread of non-B HIV-1 subtypes and the increasing availability of ART in developing countries. However, in this study we did not take into account individual non-B subtype species, therefore further studies should be designed to evaluate the efficacy of these regimens in patients with particular non-B subtypes.