Assessment of the accuracy of dried blood spot (DBS) sample in HIV-1 viral load as compared to plasma sample using Abbot assay

Prisca Benedicto, Philan Dladla, Gloria Goba, Isaac Thom Shawa


Background: HIV has claimed millions of lives with the Sub-Saharan Africa being the most affected. There is a significant increase in access to antiretroviral drugs which also demands frequent monitoring to determine the drug effectiveness and efficacy. Thus there is a great need to evaluate simplified methods to monitor treatment with such antiretroviral drugs. Use of dried blood spots (DBS) can be ideal if evaluated in resource limited countries such as Malawi since they are easy to collect, store and convenient. The main objective of this study was to evaluate the accuracy of a dry blood spot sample in the quantification of viral particles in HIV reactive patients using the Abbott m2000rt assay.

Methods: 87 participants were recruited from the ART clinic at Queen Elizabeth Central Hospital using convenience sampling method. 29 were on antiretroviral therapy and 58 had not started the therapy. HIV-1 RNA extraction and quantification was performed from DBS and plasma using Abbott m2000sp and m2000rt systems respectively. The results were statistically analyzed by Bland-Altman method using medcalc software version 12.6.1.

Results: 66 paired samples with detectable viral loads were analysed. These gave a correlation of 0.98. The mean difference was 0.05 log10 copies/ml with a standard deviation of 0.17 at 95% confidence interval.The Bland-Altman plots showed limits of agreement which ranged from -0.38 to 0.28 log10 copies/ml at 95% confidence interval.

Conclusion: Results showed strong agreement between the plasma and DBS samples. A slight and clinically insignificant difference was observed between the two methods. A larger sample size can give support to the study findings. Since samples were less than a week old, it is not known if the results would be different if they were to be stored for a longer period.


Viral load, Dry Blood Spot (DBS), HIV, Accuracy, Plasma, Malawi

Full Text:



UNAIDS. 2008 Report on the Global AIDS Epidemic. Geneva, Switzerland: Joint United Nations Programme on HIV/AIDS (UNAIDS); 2008. HIV and AIDS Estimates and Data, 2007 and 2001.

WHO. Priority Interventions, HIV/AIDS preventions, treatment and care in the health section. Geneva: WHO; 2009. Edited by Department HA

Calmy A, Ford N, Hirschel B, et al. HIV viral load monitoring in resource-limited regions: optional or necessary? Clin Infect Dis 2007;44:128-134.

Bagchi S, Kempf MC, Westfall AO, Maherya A, Willig J, Saag MS. Can routine clinical markers be used longitudinally to monitor antiretroviral therapy success in resource-limited settings? Clin Infect Dis 2007;44:135-138.

Reynolds SJ, Nakigozi G, Newell K, et al. Failure of immunologic criteria to appropriately identify antiretroviral treatment failure in Uganda. AIDS 2009;23:697-700.

Joint united Nation Program on HIV/AIDS (UNAIDS), World Health Organization (WHO). AIDS Epidemic Update: December 2009. UNAIDS, Geneva, Switzerland (2009).

Ferradini L, Jeannin A, Pinoges L, Odhiambo D, Mankhambo L, Karungi G, et al. scaling up of highly active antiretroviral therapy in a rural district of Malawi; an effectiveness assessment. Lancet 2006; 367:1335-42

Chaiwarith R, Wachirakaphan C, Kotarathititum W, Prapartanaphan J, Sirisanthana T, Supparatpinyo K. sensitivity and specificity of using CD4+ measurement and clinical evaluation to determine antiretroviral treatment failure in Thailand. Int Infect Dis 2007;11:413-6

IATA. IATA Dangerous Goods Regulations, January 4, 2010.

Abbott Labotories. Abbott Real Time HIV-1 [Internet]. Des plaines; 2007. Available from:

Gennari W, Tagliazucchi S, Pecorari M, Borghi V, Marri D and Zazzi M .evaluation of the Abbott Real-Time HIV-1 quantitative assay with dried blood spot specimens. Clin Microbiol Infect 2009; 15:93-97.

Ujjwal. N, Soham. G, Rashmi. R, Pravat N. S, Shwetha D. R, Bharat B. R, Suresh. S, De Costa. A & Shet A. dried blood spot HIV-1 RNA quantification: A useful tool for viral load monitoring among HIV-infected individuals in India. Indian J Med Res 2012;136: 956-962.

Metcalf. C, Fajardo. E Pannus. P, TriviƱo. L, Panunzi. I, Ellman. T, Coulborn. R, Kamisa. A, Mwenda. R, Chaillet. P. use of finger-prick dried blood spots (DBS) for quantifying HIV viral load: a diagnostic accuracy study conducted in Thyolo, Malawi.Poster O-132.

Garrido. C,Z honero. N, Corral. A, Arredondo. M, Soriano. V, deMedoza. C. Correlation between human immunodeficiency virus type 1(HIV-1) RNA measurements obtained with plasma by use of nuclisenseasyQ HIV-1and Abbott real time HIV load tests. J Clin Microbiol 2009;47:1031.