Genotypic drug resistance and long-term mortality in patients with triple-class antiretroviral drug failure.

OBJECTIVE: To examine the prevalence of drug-resistance-associated mutations in HIV patients with triple-drug class virological failure (TCF) and their association with long-term mortality.
DESIGN: Population-based study from the Danish HIV Cohort Study (DHCS).
METHODS: We included all patients in the DHCS who experienced TCF between January 1995 and November 2004, and we performed genotypic resistance tests for International AIDS Society (IAS)-USA primary mutations on virus from plasma samples taken around the date of TCF. We computed time to all-cause death from date of TCF. The relative risk of death according to the number of mutations and individual mutations was estimated by Cox regression analysis and adjusted for potential confounders.
RESULTS: Resistance tests were done for 133 of the 179 patients who experienced TCF. The median number of resistance mutations was eight (interquartile range 2-10), and 81 (61%) patients had mutations conferring resistance towards all three major drug classes. In a regression model adjusted for CD4+ T-cell count, HIV RNA, year of TCF, age, gender and previous inferior antiretroviral therapy, harbouring > or =9 versus < or =8 mutations was associated with increased mortality (mortality rate ratio [MRR] 2.3 [95% confidence interval (CI) 1.1-4.8]), as were the individual mutations T215Y (MRR 3.4 [95% CI 1.6-7.0]), G190A/S (MRR 3.2 [95% CI 1.6-6.6]) and V82F/A/T/S (MRR 2.5 [95% CI 1.2-5.3]).
CONCLUSIONS: In HIV patients with TCF, the total number of genotypic resistance mutations and specific single mutations predicted mortality.