Evaluation of effect of specimen-handling parameters for plasma preparation tubes on viral load measurements obtained by using the Abbott RealTime HIV-1 load assay.

HIV-1 viral load testing is essential to the management of HIV-1-infected patients, and proper specimen handling ensures accurate viral load (VL) results. This study was performed to (i) evaluate the effect of freezing plasma in situ in BD Vacutainer plasma preparation tubes (PPT) on the accuracy of HIV-1 viral load results using the Abbott RealTime HIV-1 assay and (ii) evaluate the effect of whole-blood storage in the PPT for 6 h at room temperature prior to centrifugation (PPT6H) rather than 2 h as specified in the PPT product insert. Of the 64 HIV-positive subjects evaluated, 29 had average viral load counts of >40 copies/ml in at least one of the tubes tested and 35 subjects had a result of either "undetected target" or "below the limit of quantification" (LOQ) for all or some of the tubes regardless of handling condition. For the 29 subjects with VLs that were >LOQ, the mean biases between plasma from Vacutainer K(2)EDTA tubes and plasma frozen in situ in PPT and between K(2)EDTA tube plasma and plasma from PPT6H (log(10) copies/ml) were 0.005 and -0.001, respectively, and r(2) was >0.92 for all correlations. We conclude that VLs determined from plasma frozen in situ in PPT are equivalent to VLs in K(2)EDTA tube plasma and can be used for accurate quantification of HIV-1 RNA in the Abbott RealTime HIV-1 assay. Furthermore specimens collected in PPT can be stored for 6 h at room temperature with no effect on viral load results as measured by the Abbott RealTime HIV-1 assay.