Measurement of viral load by the automated Abbott real-time HIV-1 assay using dried blood spots collected and processed in Malawi and Mozambique

BACKGROUND: The use of dried blood spots (DBS) for HIV-1 viral load quantification can greatly improve access to viral monitoring for HIV-infected patients receiving treatment in resource-limited settings. OBJECTIVES: To evaluate and validate HIV viral load measurement from DBS in sub-Saharan Africa, with a reliable, all-automated, standard commercial assay such as the Abbott m2000. METHODS: A total of 277 DBS were collected in different health centres in Malawi and Mozambique and analysed for viral load determination using the Abbott m2000 assay with the corresponding plasma samples as gold standard. Samples were extracted using the m2000SP automatic extractor and then processed as the plasma samples using the specific 1.0 mL HIV-RNA DBS protocol. RESULTS: Among samples with detectable HIV-RNA the correlation between viral load obtained from the paired 131 plasma and DBS samples was high (r=0.946). Overall, viral load values between DBS and plasma differed by less than 0.5 log unit in 90.1% of cases and by less than 1 log unit in 100% of cases. Using a threshold of 1 000 copies/mL (defining virological failure in resource-limited settings), sensitivity was 94.2% and specificity 98.6%, and both positive and negative predictive values were high (98.5% and 94.5%, respectively). CONCLUSION: DBS extracted and processed using the Abbott automated system can be reliably used in resource-limited setting to diagnose virological failure.