Table 1.

Concordance Between DBS, DPS, and Plasma Specimens in Identifying Virological Failure

	Plasma Specimens
Specimen Type and VL, copies/mL	VL ≥1000 Copies/mL	VL <1000 Copies/mL	Total	κ Value, Mean ± SE (95% Confidence Interval)	P	Performance of DBS and DPS Specimens, %a
DBS				0.78 ± 0.08 (0.62–0.94)	<.001	Sensitivity, 77.8; specificity, 98.1; PPV, 82.3; NPV, 97.4
≥1000	14	3	17
<1000	4	152	156
Total	18	155	173
DPS				0.83 ± 0.07 (0.69–0.98)	<.001	Sensitivity, 77.8; specificity, 99.4; PPV, 93.3; NPV, 97.5
≥1000	14	1	15
<1000	4	154	158
Total	18	155	173

Viral failure was defined as plasma viral RNA levels ≥1000 copies/mL.

Abbreviations: DBS, dried blood spot; DPS, dried plasma spot; NPV, negative predictive value, PPV, positive predictive value; SE, standard error; VL, viral load.

^aPPV and NPV were calculated using a 10.4% prevalence of virological failure