In subgroups of two phase 3 studies, patients with high-risk features for failure of antiretroviral therapy, such as a low CD4 count, high base-line level of human immunodeficiency virus (HIV) type 1 RNA, or unfavorable genotypic or phenotypic sensitivity score, raltegravir was superior to placebo in terms of a virologic response at 48 weeks. However, among these patients, in whom antiretroviral therapy had been used previously, 23% of raltegravir recipients had virologic failure by 48 weeks.
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