923 10.2217/FVL.12.83 © 2012 Future Medicine Ltd ISSN 1746-0794 Future Virology part of Future Virol. (2012) 7(9), 923–931 The HIV epidemic in Vietnam is mainly restricted to high-risk groups. By 2010 the num- ber of people living with HIV was 254,000, of whom nearly 50,000 accessed free antiretroviral therapy (ART) [101] . However, the virologic effectiveness of the ART programs in Vietnam has not been fully reported as access to HIV viral load (VL) by real-time PCR is limited and primarily used for assessing immunological or clinical treatment failure cases according to the Vietnam National Guidelines for HIV/AIDS Diagnosis and Treatment [102,103] . Meanwhile, the WHO has revised its guidelines, encour- aging low- and middle-income countries to increase access to VL testing where feasible, particularly for clinical decision making related to switching drug regimens [104,105] . The ExaVir™ Load assay, an ELISA-based method from Cavidi (Sweden), measures the activity of the HIV reverse transcriptase (RT) enzyme which is proportional to the VL in the plasma [1,106] . The RT assay costs approximately one-fifth as much as the PCR assays and can be used at district- or provincial-level laboratory facilities [2,3] . A good correlation between the ExaVir Load and the PCR has been shown in several studies [1,2,4–6] . However, there are no long-term longitudinal studies assessing ART monitoring using ExaVir Load in rural resource- constrained settings. Therefore, we conducted this study with the aim to investigate the fea- sibility of ExaVir Load in monitoring virologic outcomes during 24 months of ART among HIV treatment-naive adult patients in a rural setting in Vietnam. Methods Cohort study & patients This study is a part of the clustered random- ized controlled trial ‘DOTARV’, registration number NCT01433601, conducted in Quang Ninh province, northeast Vietnam. A total of 605 HIV-1 treatment-naive patients were enrolled from July 2007 through December 2009 (after having a written informed consent) from four district outpatient clinics (Ha Long CDC Lifegap, Ha Long Health Center, Uong Bi and Yen Hung). Monitoring the efficacy of antiretroviral therapy by a simple reverse transcriptase assay in HIV-infected adults in rural Vietnam Do Duy Cuong* 1,2 , Eva Agneskog 3 , Nguyen Thi Kim Chuc 4 , Michele Santacatterina 1 , Anders Sönnerborg 3,5 & Mattias Larsson* 1,6 1 Division of Global Health (IHCAR), Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden 2 Department of Infectious Diseases, Bach Mai Hospital, Hanoi, Vietnam 3 Division of Clinical Virology, Department of Laboratory Medicine Huddinge, Karolinska Institutet, Stockholm, Sweden 4 Hanoi Medical University, Vietnam 5 Unit of Infectious Diseases, Department of Medicine Huddinge, Karolinska Institutet, Stockholm, Sweden 6 Oxford University Clinical Research Unit (OUCRU), Hanoi, Vietnam *Authors for correspondence: Tel.: +46 707 663 068 n Fax: +46 831 1590 n mattias.larsson@ki.se n doduy.cuong@gmail.com Aim: To determine the feasibility of viral load (VL) monitoring using ExaVir™ Load in a cohort of 605 HIV treatment-naive adult patients initiating antiretroviral therapy in rural Vietnam. Materials & methods: VL monitoring every 6 months, survival and intention-to-treat analysis were used. Roche Cobas TaqMan ® VL was compared with ExaVir Load using Spearman’s rank correlation coefficient and Bland–Altman analysis. Results: After 20.7 months mean follow-up time, 78% remained on treatment. Virologic suppression rate (VL <200 copies/ml) after 24 months was 64% in the whole cohort and 94% among patients assessed with VL. The cumulative virologic failure rate (VL >1000 copies/ml) was 6.8%. Baseline VL ≥ 100,000 copies/ml was predictive for virologic failure [adjusted hazard ratio: 2.26 (1.16–4.39); p = 0.016]. ExaVir Load and the Roche Cobas TaqMan showed a strong correlation (r 2 = 0.97; p < 0.001), high agreement (difference in log = 0.34; 95% CI: -0.35–1.03), high sensitivity (98%) and high specificity (100%). Conclusion: Using ExaVir Load to monitor efficacy of antiretroviral therapy programs in resource-limited settings is feasible. Keywords n antiretroviral therapy n ExaVir Load n HIV n resource-limited settings n reverse transcriptase n Vietnam n virologic failure Research Article For reprint orders, please contact: reprints@futuremedicine.com