Dried blood spot viral load may be more accurate and useful than plasma viral load for patients with HIV in settings with limited resources, according to study results presented at the virtual Conference on Retroviruses and Opportunistic Infections, held from March 8 to 11, 2020.
HIV viral load is a reliable tool in the monitoring of antiretroviral therapy; however, collecting plasma samples is often burdensome and costly, which limits its use in community-based settings. The objective of this study was to validate the use and transport of dried blood spot cards containing finger-prick blood to a central laboratory for viral load testing against the gold standard method of plasma viral load.
In this study, researchers evaluated the community-based delivery of antiretroviral therapy in South Africa involving 760 patients with HIV. Ethylenediaminetetraacetic acid plasma and dried blood spot specimens were provided by patients from October 2017 through November 2019 and transported to Global Labs in Durban. Researchers used intraclass correlation, scatterplots, mean-difference plots, and 2-by-2 tables in R to compare 996 pairs of results.
Results revealed a significant association between log-transformed dried blood spot and plasma viral load results (intraclass correlation, 0.94; 95% CI, 0.93-0.94]; 86% within 0.5 log10 copies/mL). Overall, dried blood spot viral loads were lower than plasma viral loads (mean difference: -0.13 log10 copies/mL; 95% between -1.35 and 1.09). Researchers found that for every 100 persons in this population undergoing viral load monitoring using dried blood spot cards, approximately 1 treatment failure would be missed. No clinically significant differences existed with respect to sex or CD4 cell count.
The study researchers concluded that dried blood spot viral load is highly accurate compared with plasma viral load and that self-collection of dried blood spot cards should be considered to simplify specimen collection and monitoring in antiretroviral therapy for HIV.
Schaafsma T, Thomas K, van Rooyen H, et al. Dried blood spots provide simplified accurate measurement of HIV viral load. Presented at: 2020 Conference on Retroviruses and Opportunistic Infections (CROI); March 8-11, 2020; Boston, MA. http://www.croiconference.org/sites/default/files/uploads/croi2020-boston-abstract-ebook.pdf. Accessed March 18, 2020.