Pretreatment HIV-1 drug resistance to first-line drugs: results from a baseline assessment of a large cohort initiating ART in Vietnam, 2009-10.

OBJECTIVES: The objective of this study was to determine the prevalence and correlates of pretreatment drug resistance (PDR) to first-line antiretroviral drugs among people initiating therapy for HIV in Vietnam. METHODS: Blood was collected during November 2009 to October 2010 from people consecutively initiating ART in four purposively selected public outpatient clinics in three Vietnamese cities. At each study site, recruitment lasted for 6-10 months until the target sample size (range 120-130 individuals) had been reached. The viral load was measured in 501 samples; 490 samples (viral load ≥1000 copies/mL) were genotyped using a nucleotide population-based sequencing assay. Self-reported demographic and clinical data were elicited through interviews. We classified drug-resistance-associated mutations (DRMs) according to the 2009 WHO surveillance list. RESULTS: DRMs were identified in 17/490 participants (3.5%; 95% CI 2.2%-5.5%). The prevalence of DRMs was 1.6% (8/490) against NRTIs, 1.6% (8/490) against NNRTIs and 0.8% (4/490) against PIs; three (0.6%) participants were resistant to both NRTIs and NNRTIs. The overall prevalence of PDR to first-line drugs was low [2.7% (13/490); 95% CI 1.6%-4.4%]. The prevalence of PDR to first-line drugs was greater among 198 HIV-infected participants who injected drugs than among 286 participants who reported risks for sexually acquired HIV (4.0% versus 1.4%, P = 0.079). Multivariable logistic regression analysis suggested that PDR to first-line drugs was significantly higher among people who injected drugs (OR = 3.94; 95% CI 1.13-13.68). CONCLUSIONS: With low PDR, first-line ART may be effective in Vietnam and pretreatment genotyping may be unnecessary. Continuing strategies for the prevention and surveillance of antiretroviral resistance are important for maintaining a low prevalence of antiretroviral resistance in Vietnam. The association between resistance and injection drug use warrants further research.

HIV-1 drug resistance and associated factors among adults failing first-line highly active antiretroviral therapy in Ho Chi Minh City, Vietnam.

BACKGROUND & OBJECTIVES: Little is known about HIV-1 drug resistance (HIVDR) in people failing first-line highly active antiretroviral therapy (HAART) in Vietnam. The aim of this study was to investigate the frequency of HIV-1 drug resistance mutations (DRMs) and determine correlates of acquiring genotypic HIVDR among Vietnamese adults (age ≥ 18) who met the immunological or clinical criteria of first-line HAART failure according to the guidelines of the World Health Organization (WHO). METHODS: A total of 138 individuals participated in a descriptive study in Ho Chi Minh City between 2006 and 2009. Blood samples were collected for performing HIV-1 viral load (VL) and genotyping for specimens with VL ≥ 1,000 copies/mL. Stanford algorithm was used to interpret DRMs and multivariate analyses were performed to investigate predictors of HIVDR acquisition. RESULTS: Of the study population, most participants failed either stavudine/lamivudine/nevirapine or stavudine/lamivudine/efavirenz (116 individuals). Up to 51 people obtained a VL <1,000 copies/mL. Among 87 participating individuals with VL ≥1,000 copies/mL, 11 people still harbored a wild-type strain, while 76 participants harbored a HIV-1 drug-resistant strain (2 of which were against protease inhibitors); common DRMs were M184I/V (74%), Y181I/C/V (39%), G190A/S (32%), T215Y/F (32%), and K103N (31%). The proportions of K65R, Q151M, and T69 insertion were 13%, 11%, and 5%, respectively. Being antiretroviral-exposed before initiating first-line HAART in a public and free-of-charge outpatient clinic, having nonadherence to first-line HAART, per 12-month increase of duration on first-line HAART, and having clinical failure criteria were significantly associated with a genotypic HIVDR acquisition. CONCLUSIONS: In the absence of VL for the population with WHO immunological/ clinical treatment failure criteria, a large proportion of people still achieved a VL <1,000 copies/mL, while a high prevalence of HIVDR was observed in those with VL ≥1,000 copies/mL. Thus, VL monitoring should be implemented now for the HAART-treated population in Vietnam.