COMPARING OUTCOMES OF DRIED BLOOD SPOT AND PLASMA VIRAL LOAD MONITORING FOR HIV TREATMENT IN RESOURCE-LIMITED SETTINGS USING A MARKOV STATE-TRANSITION MODEL
Adams, Zachary Elijah
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Background and Objective: People living with HIV who are receiving antiretroviral therapy need to be monitored to evaluate treatment failure. Gold standard plasma viral load is logistically difficult in many resource-limited settings; dried blood spot viral load testing may be a more accessible alternative. A Markov state-transition model was created in order to better evaluate the clinical consequences of this alternative. Outcomes were compared to those of plasma viral load, CD4 immunologic criteria, and clinical criteria for treatment failure. Methods: A Markov state-transition model was created with two cohorts of 10,000 sub-Saharan African adults, one ART naïve cohort and one ART experienced cohort. Outcomes of each cohort were simulated over 5 years of follow-up. Outcomes of interest were the number of patients who died or were virologically failing after five years, events of interest were cumulative misclassifications over five years. Results: Dried blood spot viral load testing was 91% as effective as plasma viral load at averting deaths in the ART naïve cohort and 85% as effective in the ART experienced cohort, compared with clinical symptoms monitoring alone. There were more misclassifications with dried blood spot viral load than with plasma viral load. Both dried blood spot and plasma viral load testing lead to fewer deaths and misclassifications than either clinical criteria for treatment failure alone or immunologic criteria. Estimated programmatic costs for plasma viral load and dried blood spot viral load testing were comparable. Conclusions: Dried blood spot viral load is a good alternative to plasma viral load (when the latter is unavailable), with comparable clinical consequences and costs. Viral load should continue to be the treatment monitoring mode of choice, as clinical and immunologic criteria are inadequate for timely and correct determination of treatment failure. Readers: Catherine Sutcliffe, Ph.D. and David Dowdy, MD, Ph.D.