Prevalence of complete resistance to at least two classes of antiretroviral drugs in treated HIV-1-infected patients: a French nationwide study.

The objective of the study was to estimate the prevalence of HIV-1 resistance to all drugs belonging to two or more antiretroviral drug (ARV) classes in treated patients in France. All genotyping assays performed in June 2001 and in November 2002 by the ANRS resistance laboratory network were analyzed by the ANRS algorithm. The 17 and 21 centers of the ANRS network participating in the study in 2001 and 2002, respectively, genotyped the viruses in plasma of 456 and 529 patients, respectively. In 2002, the proportions of patients harboring viruses fully resistant to one, two, and three ARV classes were 5.1%, 8.1%, and 2.5%, respectively. These results were similar to those obtained in 2001. In 2002, among the 56 patients with viruses completely resistant to at least two ARV classes, 98%, 96%, and 29% of patients had viruses with complete class resistance to NRTIs, NNRTIs, and PIs, respectively. Complete resistance to PIs was less frequent than full resistance to the other two ARV classes, and ritonavir-boosted amprenavir and lopinavir/r remained potentially active in respectively 71.4% and 42.9% of these 56 patients. In 2001 and 2002, respectively 30% of the 65 patients and 24% of the 56 patients with viruses completely resistant to at least two ARV classes were at an advanced stage of HIV disease, with CD4(+) cell counts below 200/microl and viral loads above 30 000 copies/ml. In France, the prevalence of HIV-1 viruses completely resistant to two or more ARV classes remained stable between 2001 and 2002. Resistance to RT inhibitors was more frequent than resistance to PIs in patients with viruses completely resistant to two or three classes of ARV.