. Author manuscript; available in PMC: 2012 Jun 1.

Published in final edited form as: Int J STD AIDS. 2011 Jun;22(6):310–314. doi: 10.1258/ijsa.2009.009363

Table 2.

HIV-1 viral load as measured by ultrasensitive heat-denatured HIV-1 p24 antigen assay (Up24) (log₁₀ fg/ml) compared to reverse transcriptase-polymerase chain reaction analysis (RT-PCR) (copies/ml).

HIV-1 viral load by RT- PCR (copies/ml)	< 400	400– 50,000	50,000– 100,000	100,000– 250,000	250,000– 500,000	>500,000
Number of samples tested	114	62	37	72	50	59
Number detected by Up24	38	28	23	49	40	53
Median Up24 (log₁₀ fg/ml) (Interquartile range)	1.9 (1.9–2.7)	1.9 (1.9–3.2)	3.4 (1.9–4.2)	3.6 (1.9–4.2)	3.9 (3.2–4.4)	4.1 (3.5–4.7)
Sensitivity of Up24^* (95% CI)	33% (25–42%)	45% (33–58%)	62% (47–78%)	68% (57–79%)	80% (69–91%)	90% (82–98%)

Number of samples detected by Up24/number of samples tested.

Χ², test for trend, p-value < 0.0001.