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Table 2 Test characteristics of the Biocentric platform at two VL threshold levels

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

 

At 2.62 log10 copies/mL

At 3.0 log10 copies/mL

LAB-1

(n = 198)

LAB-2

(n = 166)

Combined

(n = 364)

LAB-1

(n = 198)

LAB-2

(n = 166)

Combined

(n = 364)

Sensitivity

% (95% CI)

92.3 (64.0–99.8)

84.4 (73.1–92.2)

85.7 (75.9–92.6)

100 (71.5–100)

86.4 (75.0–94.0)

88.6 (78.7–94.9)

Specificity

% (95% CI)

96.2 (92.4–98.5)

99.0 (94.7–100)

97.2 (94.6–98.8)

97.9 (94.6–99.4)

99.1 (94.9–100.0)

98.3 (96.1–99.4)

ROC area

% (95% CI)

0.94 (0.87–1.00)

0.92 (0.87–0.96)

0.92 (0.87–0.96)

0.99 (0.98–1.00)

0.93 (0.88–0.97)

0.93 (0.90–0.97)

PPV (at 10%)a

% (95% CI)

73.1 (56.3–85.1)

90.5 (57.6–98.5)

77.4 (63.2–87.2)

83.9 (66.3–93.2)

91.1 (59.3–98.6)

85.3 (70.7–93.3)

NPV (at 10%)a

% (95% CI)

99.1 (94.5–99.9)

98.3 (97.0–99.0)

98.4 (97.3–99.1)

100 (93.3–100)

98.5 (97.2–99.2)

98.7 (97.6–99.3)

PPV (at 20%)a

% (95% CI)

85.9 (74.4–92.8)

95.6 (75.3–99.3)

88.5 (79.4–93.9)

92.1 (81.6–96.9)

95.9 (76.6–99.4)

92.9 (84.5–96.9)

NPV (at 20%)a

% (95% CI)

98.0 (88.4–99.7)

96.2 (93.5–97.8)

96.5 (94.0–97.9)

100 (86.1–99.9)

96.7 (93.9–98.2)

97.2 (94.7–98.5)

  1. ROC Receiver operating characteristic, PPV Positive predictive value, NPV Negative predictive value
  2. aFor the calculation of predictive values, 10 and 20% prevalence of detectable VLs were assumed in a hypothetical population undergoing routine VL testing