Whole blood versus plasma spots for measurement of HIV-1 viral load in HIV-infected African patients.

The increasing availability of antiretroviral drugs to HIV-infected populations in developing countries highlights the need to develop field-friendly practical methods for HIV-1 viral load measurements to monitor the effects of treatment. We compared use of whole-blood spots versus plasma dried on filter paper to quantify HIV-1 viral load in 51 African patients with HIV-1. The mean log10 HIV-1 viral loads were 4.22 for dried plasma spots (DPS) and 4.20 for dried whole-blood spots (DBS). The difference between the pairs of log10 viral load for DPS and DBS were significantly correlated with their mean (Spearman's r=0.31, p=0.03). This correlation between the difference and mean of viral load was no longer evident for values of log10 DPS that were less than 5 (r=0.01, p=0.93). For the 38 paired values with log10DPS of less than 5, the mean difference (log10DPS-log10DBS) was -0.04 (SD 0.29). Dried whole blood stored on filter paper at room temperature shows potential as a field-friendly alternative to plasma for measurement of HIV-1 viral load.