To establish the influence of genotypic resistance-guided treatment decisions and patient-reported adherence on the virological and immunological responses in patients failing a potent antiretroviral regimen in a randomized, controlled trial in a tertiary care infectious diseases department. A total of 174 patients with virological failure were randomly assigned to receive standard of care (SOC) or additional genotypic resistance information (G). Adherence was measured by a self-administered questionnaire. Primary endpoints were the proportion with HIV-RNA < 500 copies/ml at 3 and 6 months by intention-to-treat analysis. Secondary endpoints were changes from baseline HIV-RNA levels and CD4 cell counts. At entry, 25% had failed three or more highly active antiretroviral therapy (HAART) regimens and 41% three drug classes; there were more resistance mutations in G. In 127 evaluable questionnaires, 43% reported last missed dose during the previous week. At 3 months, 11 of 89 patients (12%) in SOC and 23 of 85 (27%) in G had HIV-RNA < 500 copies/ml (OR 2.63, 95% CI 1.12-6.26); the relative proportions were 17 and 21% at 6 months. CD4 cell changes did not differ between arms. Six month CD4 cell changes were +62 in adherent and -13 cells/microl in non-adherent patients (P < 0.01). Being assigned to G, good adherence, previous history of virological success, fewer experienced HAART regimens and lower baseline viral load were independently predictive of 3 month virological success. The virological benefit of genotype-guided treatment decisions in heavily pre-exposed patients was short term. Patients adherence and residual treatment options influenced outcomes.
