An algorithm‐based genotypic resistance score is associated with clinical outcome in HIV‐1‐infected adults on antiretroviral therapy

Abstract

The aim of this study was to evaluate the association between genotypic drug resistance and the occurrence of HIV-related diseases and death in HIV-1-infected adults on antiretroviral therapy. We performed an observational study on patients from an out-patient clinic in a university hospital. Genotypic drug resistance analysis after virological treatment failure was performed in 141 patients receiving two or more antiretroviral drugs. All patients had follow up of at least 6 months after the resistance test. An algorithm was developed to estimate the level of genotypic drug resistance and to assign an actual resistance score (ARS) for the drugs prescribed to each patient. The patient population was divided into quartiles according to patients' ARS values. Our endpoint was the risk of developing an HIV-related disease [Centers for Disease Control and Prevention (CDC) category B or C] during the period starting 6 months prior to and ending 6 months after the genotypic resistance test, or death during the 6 months following the resistance test. There was a significant association between the level of resistance to the drugs prescribed (ARS) and our clinical endpoint: the odds ratio for an endpoint (with 95% confidence interval) was 3.20 (1.28-7.99), adjusted for CD4 cell count and HIV RNA, in patients in the highest ARS quartile compared with patients in the other three quartiles. Our study indicates that patients with high-level genotypic drug resistance are at increased risk of developing an HIV-related disease. This association could not be explained by differences in CD4 cell count or HIV RNA levels.