Field suitability and diagnostic accuracy of the Biocentric® open real-time PCR platform for plasma-based HIV viral load quantification in Swaziland

Table 3 Original and reclassified viral load test results between the Biocentric platform and the reference assay

Lab	Reason for VL testing	Time to freezing (hours)^a	VL results during first round of VL quantification				VL results after re-quantification
			Reference method (log₁₀ copies/mL-l)	Biocentric platform (log₁₀ copies/mL-l)	Misclassification		Biocentric platform (log₁₀ copies/mL-l)	Misclassification
			Reference method (log₁₀ copies/mL-l)	Biocentric platform (log₁₀ copies/mL-l)	2.62 log₁₀ copies/mL	3.0 log₁₀ copies/mL	Biocentric platform (log₁₀ copies/mL-l)	2.62 log₁₀ copies/mL	3.0 log₁₀ copies/mL
Lab-1	ART	2.7	0	3.14	upward	upward	*	*	*
Lab-1	ART	3.8	0	2.65	upward	CON	0	CON	CON
Lab-1	ART	1.1	0	3.03	upward	upward	0	CON	CON
Lab-1	ART	0.9	0	4.00	upward	upward	0	CON	CON
Lab-1	ART	0.5	0	2.70	upward	CON	*	*	*
Lab-1	ART	0.3	2.25	2.92	upward	CON	*	*	*
Lab-1	ART	1.5	2.37	2.68	upward	CON	0	CON	CON
Lab-2	Pre-ART	2.2	2.48	3.34	upward	upward	2.78	upward	CON
Lab-2	ART	4.4	2.72	0	downward	CON	0	downward	CON
Lab-1	ART	1.6	2.73	0	downward	CON	*	*	*
Lab-1	ART	2.4	2.78	3.03	CON	upward	*	*	*
Lab-2	Pre-ART	2.6	2.84	0	downward	CON	2.84	CON	CON
Lab-2	Pre-ART	1.2	2.90	0	downward	CON	0	downward	CON
Lab-2	Pre-ART	1.4	2.91	0	downward	CON	3.00 (999^b)	CON	upward^b
Lab-2	Pre-ART	1	3.13	0	downward	downward	0	downward	downward
Lab-2	ART	2.6	3.21	0	downward	downward	3.51	CON	CON
Lab-2	Pre-ART	3	3.31	0	downward	downward	0	downward	downward
Lab-2	Pre-ART	3.2	3.40	2.96	CON	downward	3.84	CON	CON
Lab-2	Pre-ART	4.7	3.63	2.89	CON	downward	3.60	CON	CON
Lab-2	Pre-ART	4.1	3.77	0	downward	downward	3.06	CON	CON
Lab-2	ART	0.3	3.82	0	downward	downward	3.95	CON	CON
Lab-2	Pre-ART	2.5	4.17	0	downward	downward	4.29	CON	CON

*Re-quantification on the Biocentric platform was not possible as no leftover plasma samples were available due to contamination. Reclassification of test results was not performed
Zero values indicate that the VL results were below the detection limit of the VL assays
CON Concordant
^aTime from sample collection to freezing at − 20 °C before testing
^bDue to rounding, the 3.00 log₁₀ copies/mL values represent a false-positive test result at the 3.0 log₁₀ copies/mL threshold but a concordant result according to the non-log₁₀ values

ISSN: 1471-2334